Archive for the ‘Tech’ Category

Auto Math 101

Posted: January 14, 2015 in Tech



4.030 x 4.030 x 3.750 x .7854 x 8 = 382.6 ( 383 Chevy )



EXAMPLE:   4.030 X 4.030 X 12.87 X .009 = 1.88cc



EXAMPLE: 4.030 X 4.030 X 12.87 X .030 = 6.27cc











64cc + 1.88 + 6.27 =84.15cc




EXAMPLE: DIVIDE 355 BY 8 = 44.375

MULTIPLY 44.375 BY 16.39 = 727.306





EXAMPLE: 4.030 ÷ 3.48 = 1.158



EXAMPLE: 5.700 ÷ 3.489 = 1.637




EXAMPLE: 3.48 X 6000 ÷ 6 = 3480 FPM














EXAMPLE: .477 ÷ 1.5 = .318 [ LOBE LIFT ]

.318 X 1.6 = .5088 [ GROSS VALVE LIFT ]




Quick Reference – “Bore Spacing”

Bore spacing is the distance from the center line of one cylinder bore to that of the adjacent cylinder. Assuming the bores are perfectly round, this distance can be determined by measuring the distance from one cylinder wall edge to the far cylinder wall of the adjacent cylinder. To save all of our Greaseralley readers the trouble, here’s the bore spacing (in inches) on common American V8’s:


  • AMC: 4.75
  • BUICK 350: 4.24
  • BUICK 400-430,455: 4.75
  • CADILLAC 472, 500: 5.00
  • FORD FE: 4.63
  • OLDSMOBILE: 4.625
  • PONTIAC: 4.62



Ford used the 9 inch rear from around the 1957 model year right up until the early 1980’s in cars and trucks. It was not the only axle used, but was by far one of the best. Variations by Ford exist in the size of the outer axle bearings in the housings and carriers both, as well as with the spline count on the axle shafts. Generally most cars received the small axle bearings and 28 spline axle shafts. Exceptions to this were the ultra Hi performance Boss 302’s, Boss 429’s, 427’s, 428 CJ/SCJ and the 429 cars which received the 31 spline carriers and axle shafts. Some of the heavier cars like the Galaxies also received the larger wheel bearing housings.The trucks varied more, early half ton trucks got the 28 spline axles and carriers, while sometime in the early 70’s the switch was made to mostly 31 spline axles and carriers for most trucks. Most of the later trucks also received the larger axle bearings housings.One exception to this was the Bronco’s from 1966 to 1977, they stayed with the 28 spline units. A small bearing housing can be differentiated from a large bearing housing by the size of the nuts and thread used to retain the brake backing plates to the housing, the small bearing housings use 9/16 socket size nuts with 3/8” fine thread, while the larger bearing use 11/16” socket size and 7/16” fine thread. Gross Vehicle Weight ( GVW ) would determine which axle housing many cars and trucks received.
Because many one half ton trucks continued to utilize the 9 inch (both 2 wheel & 4 wheel drives) right up until about 1982 these housings are by far the most abundant(*Note:my recent findings are that the 9 inch axle was either utilized again in limited quantities in some 1985/6 truck/van applications or continued to be used up until that time by Ford in limited quantities*), and with many 1973 to 1979 pickups to still be found on the road and in junk yards,these are the most plentiful. And since the “Limited slip” or Locking rear end (often referred to as a “POSI”) came to be a popular option and more plentiful starting in the early 1970’s, many of the units found today at car swap meets and shows are the units pulled from trucks with the 31 spline carriers with the “Traction Loc” style posi unit. The actual car posi units which were primarily 28 spline carriers can be much more difficult to locate since the supply is limited to the few cars and early Broncos (and some early trucks) which received them-the 28 spline posi’s.When it comes down to actual shafts as well, since the truck lug pattern in most cases differed from the car, and due to the bearing size differences, 28 spline car axle shafts are much more abundant than car 31 spline axle shafts, and often aftermarket shafts have to be purchased if one wants to use a truck 31 spline carrier in a car 😦
The carrier housing I see most is the C7AW-E, it is the one most commonly found in the trucks right up until around 1982. I am not sure if this “E” version of the case came into use in 1967 or in subsequent years, but it is by far the most abundant case being used in both full size Ford cars and trucks throughout the 1970’s. I have heard that it has a higher nodular iron content and better casting than the earlier single ribbed cases it replaced and that is why it remained in use so long, and the double ribbed N case was no longer needed for passenger car/truck applications (this also coincided with the demise of most performance engine options in the 70’s)- I have never seen this substantiated however. Most carriers I have seen for sale at swap meets/ car shows are this C7AW-E case which leads me to believe most were pulled from trucks and cars from the 1970’s.
Axle housings as noted in the examples below also evolved over the years, the earlier housings used in cars from 1957 to mid 1960’s tended to be the weakest and had abrupt ending but welded carrier centers to tubes and a smooth backside. Later housings appeared in either 1966 or 1967 with the familiar “Hump” in the backside middle and stronger tubes.The later truck housings received even beefier center carrier housings and tubes and this style of center carrier housing is best suited for drag cars or narrowed rear ends in my opinion due to the added strength in the middle. Most of the early housings are ok for the average street performance cars. The popular early swap being the 57 to 59 Ford for the 65/66 Mustang.I haven’t completed an axle housing width chart yet, but here is what I can tell you about some that I have seen, they often group Mustangs and Fairlane axle housings together as often it is true they are the same width, but I can tell you for a fact, the distance between spring perches is different between Mustangs and Fairlanes.Spring perches must be cut and re-welded inorder for the swap to be performed. The “rough “ widths I keep in mind for Mustangs are the following: 52” for 1965 to 1966 (the same width as 64-65 Falcons and 62 to 65 Fairlanes-as in the Mustang line, most however never received a factory 9 inch), 54” for 1967 to 1970 (same as 66 to 69 Fairlane,Torino,Comet & Cyclone non station wagons-cars with 351 and up engines received 9 inch units-as did some 302 4V cars with optional gear ratios) and 56” for the 1971 to 1973 Mustangs-cars with 351 engines and up receiving the 9” housings.Keep in mind as mentioned, the Fairlane spring perch distances were not the same as the Mustang. All the Galaxies I have seen from throughout the 1960’s used the 9 inch rear, regardless of engine size.

How to Identify some typical Ford 9 inch Centers

I have heard various stories as to the reliability of the WAR marked cases, some say avoid them like the plague, others say this is false.Here is what I understand, while having the extra ribbing like the N case, they do not have the nodular iron content and are prone to cracking at the bearing support.They seem to have been used on the 57 to 60 Fords from casting dates I have seen.Another early case, the WAB was similar to the WAR case with the double rib and lower nodular content. I do not have a photo example at present.I believe this case utilized the larger 3.063 side bearings.

The N Case vs WAR Case

Standard or WAR cases, were cast in gray cast iron which has a grain structure that does not have the best shear strength characteristics. The N stands for nodular iron, which is made by adding magnesium to molten iron. What this does is change the grain structure from flakes to nodules – much stronger and less likely to fail under shear load.The case of course most desirable is the N case, first used on the 427 Galaxies around 64-65 I believe.They are most often found behind the later 428CJ and 429CJ cars.From what I have seen don’t expect to find them in 390 or 289 Hipo cars.The N cases went with 31 spline centers and are for rugged duty.And believe it or not, they were also used in some FE equipped Ford 1/2 ton 4X4 pickups!

Here is the early N case, the C4AW-B casting, which can either have the N or not.

Have also viewed a N case marked with an “N” with a C2AW-4025-A casting number,it was used in conjunction with a C5AW-4668-C Daytona pinion support.Case was double ribbed, this casting number is not listed in my books or references, will have to do further research regarding this one.

The C7AW-E case seems to have been in use for quite sometime, have found them with date codes up to 1981.Other standard cases encountered: C1AW-4025-C,C4AW-4025-ASome standard cases are also machined to take the larger 3.063” side bearings, most cases however (including N cases) will take the 2.892” side bearings. Aftermarket spools and cases are available that accommodate even larger bearings-3.250″ and 3.812″, but Ford used just the two sizes from what I have seen.The carrier I have seen with the 3.063″ larger side bearings is the C7AW-G marked single ribbed case, it came from a late 60’s Galaxie.

Other standard pinion supports encountered: WAT B2(on a WAR case),C0AW-A,C6AW-4668-A,C7AW-C(guarded support as well) and a D2SW-4668-C(marked with the 4668).The D2SW-C seems to be the most common encountered through 1979 on the C7AW-E cases I have viewed.

Earlier Daytona pinion supports: C5AW-4668-C

8″ information:

The casting number should be C2OW-4025-F, NOT C2DW listed for the case.Another later 8 pinion support with guard built in that I have seen had casting number C6OW (the 6 however may have been a 5-this support came out of a 65-66 mustang center).

Later improved carrier for the 8″ found in 67 and up

Note the presence of fill plug, and that the casting number is moved to the outside of case, while other previous 8 and 9 inch carriers it has always been on the inside.The number here is the familiar C7OW-4025-A.

Visually Spotting the 9″ and 8″ Axle Housings

Shown above is the typical 1967 and up 9″ (lower) and pre-1967 8″ housing (upper).Note no fill plug on back of the 67 and up housing, this is true for the 67 and up 8 inch housings too.Earlier housings, like the 65-66 Mustang 8″ pictured have the fill plug in the back, this is true for the earlier 9″ as well.

One of the ways many people spot a 9″ rear end in the car is by looking for the hump in the center of housing, this is not always the best way, as 9″ housings made prior to sometime in 1966 do not have the this large center protrusion.The one shown above is out of a 63 Galaxie, note its roundish appearance, two dimples and fill plug in housing back.

Here is the housing style familiar to most, note the large center protrusion or simply the “hump” in the middle.Housing also has the two dimples, but note lack of fill plug.This housing is out of an early Bronco.

The little brother to the 9″ housing is the 8″ housing, note its more oval appearance when compared to the above two 9″ housings.This one is out of a 65-66 Mustang, note the two dimples and fill plug.

Another area of concern when swapping axle housings into earlier Mustangs (65-66 models especially)is the diameter of the outer axle tube.Note the taper on this 8″ 65-66 Mustang housing, a smaller U bolt and lower shock plate were used originally with these cars.The HIPO 289 cars were the only 65-66 Mustangs to recieve factory 9″ axles, the tubes are tapered as well at the end to utilize the same lower shock plate as the regular 65-66 Mustangs.

Notice this axle tube has no taper at end,as is typical for most housings.A typical early Mustang swap is a later Granada housing, were the non-tapered tube can become an installation problem at times.

Axle Shafts

Shown above is a 31 spline shaft end in a 69 Cyclone CJ

Ford used either 28 spline or 31 spline axle shafts with the nine inch, the eight inch came only in 28 spline, as did the majority of nine inch car applications.For the most part eight inch and nine inch car axle shafts will interchange between housings of the same width,spline count and bearing size (ie. 8″ 67 Mustang 28 spline axle shafts will work in 9″ 67 Mustang housing, etc.).A method to identify 28 spline axle shafts can be by looking at the center brake hub area, a rectangular slot in the center will indicate 28 spline axles.The 31 spline axle shafts will have a different appearance, with one small center chamfer and two outer holes in the center hub, however, 28 spline shafts can also appear like this to, so it does not always indicate 31 spline shafts (see photo below). Early axle shafts of the 28 spline variety cannot be shortened, due to either a reduced diameter between spline end and bearing end (early Mustangs,Fairlanes, Falcons etc.), or because of a tapered shaft which doesn’t allow for re-splining (early full size).It appears starting around 1967 the 28 spline shafts became more solid and the shaft diameter increased along the entire length, so shortening is possible and they can be be resplined to their original 28 count.Most 31 spline shafts can be shortened and resplined with no problems.

Rear Axle Tags

Rear axle tags if present on your housing can aid in identifying what is behind your center for gears,splines etc.Ford has changed the tag over the years, but generally the application number-which begins with the W on line one, the gear ratio and date code are always given.Tags are generally found attached to the passenger side of carrier assembly secured by one of the nuts on the housing studs.Here are some examples I have:

Here is the early style tag used by Ford, this one is off a 62 Galaxy with a 3.00 open 9 inch.Tag reads C2AA4001 DV 100, second line: 3.00 1MA

Here is a common Mustang tag WCZ-V identifies it as a 67-70 Mustang and 67-68 Cougar 8″ rear with 2.79 ratio, open.Note no L between 2 and 7 on second line.

A “posi”, equa-lock or traction lock rear is identified by an “L” in between the 1st and 2nd digits of the ratio given on the second line of tag.Here is a 2L80 ratio with tag number WDJ-B,which corresponds to a 8 inch used in 65-66 Mustangs.

This tag is off an open 3.25 ratio 66-70 Fairlane or 67 to 69 Comet with an open 9 inch differential.Note date code of 7BD ( 7= model year:1967,B= Month:February and the D= week: 4th week of Feb.1967)

Ford changed the layout of the tags sometime in the early 70’s or late 60’s, here is a WFE-BK2 tag, followed by a date code of 4E24 (April 24,1974), the second line now gives besides the ratio-here a 3L50, the ring gear actually used inside-this one is a true 9″ gear.This tag is off a 74 Ford truc


Here is an example tag of a 9 inch that isn’t quite up to the full measure,it is a 3.50 ratio, but followed by that are the numbers 8.7 which denote that this carrier is sporting a ring gear of an actual 8 3/4 inch diameter.This one is off a 1970 Bronco, built 3rd week of April 1970.This would have been a 28 spline unit when checked in manual.

How to identify a Posi

The two basic types of “posi” units (posi is the G.M. name for its positive traction system which has been become a part of the nomenclature) are the early Equa lock and the subsequent Traction lock units ( I will refer to them here as “spools” to simplify things). I am not exactly sure when the Equa-locs first appeared, early units are scarce – I haven’t seen many prior to 1964/65 and these are quite rare.From what I have seen the Equa locs were used up until 1969, which is when I believe the Traction Loc units first appeared. There are visual and internal differences between the two spools and most parts do not interchange.

Shown above is an example of an equa loc in its carrier, you will note the recessed bolt holes and 5/8” headed bolts, as well the rough cast appearance of the cover assembly, it is not machined as it is in the Traction Loc units.

Internally the number of clutch disc and plates differs between the equa loc and trac loc spools, the equa loc having only 3 fiber plates and 4 steel with one large belveder spring applying force.The trac loc unit utilizes 4 fiber plates and 5 steel plates, with 4 smaller springs applying force.Both equa lock and trac loc units were available in 2 pin and 4 pin varieties, in either 28 spline or 31 spline versions.The four pin 31 spline unit would be more commonly found as a trac loc piece. The four pin being the heavier duty unit utilizing 4 spider gears vs just two in the two pin variety (as noted in figure above a four pin variety will have actually just 3 pins and a two pin will in reality just have 1 pin- the number of spider gears is actually what is being referred to).Shown below are the internals of a four pin equa loc, note the five “fingers” on the steel clutch plates-the tiny circular tabs on outer edge- (trac loc units will have only 4).

The Traction Loc

Shown above is an open 28 spline spool (on left) and a traction loc “Posi” 28 spline 2 pin spool ( to the right).

Here is a close up of the trac loc spool, note recessed bolt holes through cover for holding ring gear on.

Notice the flat surface around holes on the open spool.

The heads of the bolts which pass through cover and fasten ring gear to the spool are also smaller on the trac loc piece 5/8” socket size, and they use a thin metal washer.

The bolt retaining ring gear on the open spool is 3/ 4” socket size, no washer used.

Above are a 28 spline 2 pin traction loc unit and a 31 spline 4 pin trac loc unit, notice anything wrong?

The arrows are pointing to the cracks in the 31 spline unit removed from an N case carrier.

Unfortunately this is the end result, a destroyed posi unit, this is even the improved cover – D0O part number, earlier units were even more prone to cracking here, thus the necessity for the Detroit Locker units used behind many of the higher performance applications.

Gears, Yokes etc.

Here are two nine inch ring gears side by side, one from a 3.00 ratio (thinner gear), the other from a 3.50 ratio (thicker).An easy way to spot a nice ratio after a while is by visual id.-the thicker the gear the better the performance ratio, thinner the gear= less performance, more fuel economy and better highway performance.

these two gears are the same ratio- 3.00, but one is only 8 3/ 4” diameter, the other a true 9” when gear is installed in the case, a true 9″ ring gear will have very little clearance between housing and large gear (most noticeable at bottom), while an 8 3/4″ setup will have almost enough room to put your finger tips into between gear and case (but don’t due it- it can hurt).Don’t feel slighted if you find you only have an 8 3/4″ setup, they are plenty strong, Ford used them behind the HiPo 289 applications in many Mustangs and others.


Can you spot the difference in the above two pinion gears? Both are 10 tooth gears taken from 3.50 gear ratios, but one has been used behind a Daytona pinion support with the larger inner bearing (see above sections for discussion on Daytona pinion support identification).Note the larger bearing on support to the left.

These two yokes are quite similar and take the same U joint, except the shorter one is used with the larger bearing Daytona Pinion used in an N case. I believe the shorter yoke was necessary due to the added size of inner bearing.When installed on there respective carriers, supports equal out to approximately same height.I am told that the standard yoke can be machined down to work with the Daytona pinion.

Crush sleeves are used when setting up most 9 inch carriers to set bearing load, but on the N case with Daytona pinion a non-crush solid spacer is used, shown above are the two side by side (solid spacer on right).
No guarantee as to the accuracy of this data.

Year & Model

Axle Length


1965-1966 Mustang 57.25 inches  
1967-1970 Mustang 59.25 inches  
1971-1973 Mustang 61.25 inches  
1977-1981 Versailles  58.50 inches  
1967-1973 Mustang, Torino, Ranchero, Fairlane 59.25 inches to
61.25 inches 
1957-1959 Ranchero and station wagon 57.25 inches  
1966-1977 Bronco 58 inches  
1977-1981 Granada/Versailles 58 inches  
1967-1971 Comet, Cougar, Mustang, Fairlane 59.25 inches  
1971-1973 Mustang 61.25 inches  
1964 Falcon 58 inches  
1967 Cougar 60 inches  
1967 Fairlane 63.50 inches  coil springs 
1972 Ford Van 3/4 ton 68 inches  
1973-1986 Ford Van 3/4 ton 65.25 inches  
1957-1959 Ranchero and station wagon  57.25 inches  narrowest 9″ housing
1966-1977 Bronco 58 inches 5-on-5 1/2 inch diameter bolt circle 
1967-1973 Torinos, Rancheros, Fairlanes 59.25 inches or
61.25 inches
1967-1971 Comets, Cougars, Fairlanes  59.25 inches   
1975 Mustang II 8″ 57.00 inches  
1974 Maverick 8″ 56.50 inches  

Where To Find The Nine Inch Rear Axle

1967-1973 medium and big block Mustangs and Cougars 1966-1971 Fairlanes, Torinos, Montegos, Comets, and other Ford intermediates with big blocks.
1957-1959 V8 Fords and Mercurys
1977-1981 Lincoln Versailles & Trucks

Types Of Nine Inch Axle Housings

1967-1973 Mustang/Cougar – light duty, thinnest housing material, small axle bearings, 28 and 31 splines.
1957-1968 passenger car and 1/2 ton truck – medium duty, stronger than Mustang type, 28 and 31 splines.
Ranchero/Torino – heavy duty thick wall housing, 3.25 inch diameter axle tubes with flat tops.
1969-1977 Galaxies (coils), Lincolns (coils), and late pickups (leaf)- 3.25 inch diameter all the way to the backing plate, coil housings have upper control arm mount

How To Recognize Nine Inch Housing Centers

1957 – no dimples, flat center band up the center of the rear cover, bottom drain plug.
1958-1959 – two dimples on back of housing, flat center band, some had drain holes.
1960-1967 – two dimples, flat center band, oil level hole in back cover.
1963-1977 Lincoln, LTD, Thunderbirds had 9.375 inch centers, housings were cut away at the gasket surface for ring gear clearance, one curved rib at the front top portion of differential, strong but no gears.

Tip On Shortening Nine Inch Axles

1972 and earlier 31 spline axles have the ability to be shortened.

28 spline axles are tapered and cannot be shortened and re-splined.
1973 and later cars have a 5-on-5 bolt circle and the axles cannot be shortened.
1967-1973 Mustang axles can be identified by wheel flange:
Oval hole = 28 splines.
Two large holes and counter-sunk center = 31 splines.

Info From:

Dakota Digital Series III instrument systems offer the latest technologies and features for your custom vehicle. High brightness vacuum fluorescent displays provide a lifetime of trouble free use while offering increased accuracy and features!

Full 6 Gauge Instrument System fits into OEM bezel for 1954 Mercury.

Fits directly into existing bezel. (not included)









Dakota Digital

Hidden Tunes Via An Ipod

A few weeks ago, I mentioned that I was itching to get some tunes into my daily driven ’39 Ford Sedan. Installing a simple stereo in an old car is easy as pie, but this car presented a challenge of sorts. See, the ’39 still has the original interior and wood grained dash and come hell or high water, there was just no way I could talk myself into cutting anything on the car at all. Whatever I was gonna do, had to be completely hidden from sight and require zero hole drilling or cutting of any kind.

I decided right away that the smartest install would be an iPod/iPhone controlled system backed by a small amp and a single speaker located just behind the stock ’39 dash louvers. Easy enough, right? Here’s all of the equipment needed:

1. iPod Classic ($125 on eBay). I actually already had one sitting around, but they are easy enough to find on eBay for silly cheap money. Any iPod with a dock connector will do, including your iPhone.

2. Pioneer GM3400 2-Channel Amp ($95). A good buddy of mine donated this unit to the project and it is probably overkill for this application. However, they are affordable and work well.

The Pioneer GM3400. It’s small, affordable and gets the job done.

3. Rockford Fosgate Amp Install Kit ($25). You don’t really have to buy one of these kits, but they are handy as they come with all of the power wires, fuses, speaker cables, and RCA cables needed for installing an amp.

I got the Rockford Fosgate 10g install kit. It was just nice to know that I had everything I was going to need before I started.

4. PAC IS75 ($24.99). This is a simple cable with RCA connections on one side and a iPod doc connector along with power and ground wires on the other side. This allows your iPod to charge while it’s playing music and gets you the added benefit of a cleaner signal than your headphone jack.

My PAC IS75. It looks like spaghetti here, but it’s actually quite simple to wire.

5. PAC LC-1 ($12.50). The one downside of using the PAC IS75 above is that when you connect your iPod via the dock connector, you lose the capability of controlling volume through the iPod. Typically, the PAC LC-1 is used to control sub levels on high-end systems. I found that it is also a great volume knob.

The PAC LC-1. I removed it from the plastic casing and ditched the press fit knob. You don’t need any of that…

6. Custom Autosound DVC 5″x7″ Speaker ($49). I don’t know my ass from a hole in the ground when it comes to speakers, but I decided to give one of these a shot. They were designed to replace stock dash speakers in big 1950′s era cars and give you an almost stereo sound. In fact, it’s one speaker with a left and right channel… I guess that’s what “Dual Voice Coil” means.

I had a memory card issue and lost the pictures of my 5×7″ DVC featuring a handy and custom made bracket. But it looked similar to this… Promise.

The first task at hand is always the hardest for me – figuring the speaker location and mounting it securely. The 5×7″ speaker fit the stock ’39 radio opening pretty well. All I had to do was fabricate a simple bracket that utilized the stock ’39 radio holes for mounting. Once done, the speaker was out of site and I was ready to move on to the volume knob (PAC LC-1).

I kind of broke one of my rules here and drilled a hole. However, the hole was only drilled in an extra “radio delete” plate that I had laying around. Through that hole went my gutted LC-1 (as mentioned above, I removed the LC-1 from its casing and ditching the press fit knob) and on the LC-1′s shaft went a stock ’39 Ford window crank knob that I drilled to fit. The result is a volume knob that is easy to reach and doesn’t look out of place.

I think this all looks pretty rad. Sure, the knob protruding from the radio delete plate isn’t stock, but it does fit the part.

With the speaker and knob mounted, only the amp is left to locate. I decided to put the Pioneer under the seat on the passenger side. Rather than drill a bunch of holes in my floor plan, I just put some “no skid” pads on the bottom of the amp and set it under the seat. It’s not going anywhere…

With the “hard” shit done, it was time to get out the wire and go to town. Wiring an iPod system like this couldn’t be more straight forward. If a hack like me can do it, you can to… So, don’t let your knees start to knocking. Take a deep breath and follow the diagram:

Easy, right? Even if you take your time and do proper soldered connections, this install shouldn’t take you more than an hour an half or so. I already had the speaker and volume knob mounted when I went out in the garage last night around 11pm. By midnight, I was sipping on Gin and Juice.

Surprisingly, the sound quality isn’t half bad. It’s immeasurably better sounding than a stock ’39 radio that I can’t afford, quite a bit better sounding than any stock 1960′s car stereo I’ve ever rocked, and almost as good as the last rental car stereo I blew up. For a single speaker, it really is quite impressive. And the best part? This is the only hint that the car has a stereo at all:

Original Post From:  The Jalopy Journa Tech

Gauge (ga) Standard Steel Thickness (inches) Galvanized Steel Thickness (inches) Aluminum Thickness (inches)
3 0.2391   0.2294
4 0.2242   0.2043
5 0.2092   0.1819
6 0.1943   0.1620
7 0.1793   0.1443
8 0.1644   0.1285
9 0.1495 0.1532 0.1144
10 0.1345 0.1382 0.1019
11 0.1196 0.1233 0.0907
12 0.1046 0.1084 0.0808
13 0.0897 0.0934 0.0720
14 0.0747 0.0785 0.0641
15 0.0673 0.0710 0.0571
16 0.0598 0.0635 0.0508
17 0.0538 0.0575 0.0453
18 0.0478 0.0516 0.0403
19 0.0418 0.0456 0.0359
20 0.0359 0.0396 0.0320
21 0.0329 0.0366 0.0285
22 0.0299 0.0336 0.0253
23 0.0269 0.0306 0.0226
24 0.0239 0.0276 0.0201
25 0.0209 0.0247 0.0179
26 0.0179 0.0217 0.0159
27 0.0164 0.0202 0.0142
28 0.0149 0.0187 0.0126
29 0.0135 0.0172 0.0113
30 0.0120 0.0157 0.0100
31 0.0105 0.0142 0.0089
32 0.0097 0.0134 0.0080
33 0.0090   0.0071
34 0.0082   0.0063
35 0.0075   0.0056
36 0.0067    
37 0.0064    
38 0.0060  

More displacement and greater leverage means more torque. This concept is obvious when you compare the torque ratings between factory small block motors and factory big block motors. However, nowadays it is not necessary to suffer the time and switching costs of leaping to a larger block if you are only after more displacement. Displacement is just a factor of bore and stroke, by increasing the stroke of your current motor Formula A. Displacement. Simply a factor of bore and stroke. Increase the stroke of your current motor and reap the benefits of more torque.

you can enjoy the satisfaction of more torque disguised in the same package.

Widespread awareness of the facts above and an abundance of aftermarket stroker kits have made the stroker option extremely popular. If you are out for performance, a stroker is a wise alternative to building a motor that only meets the factory displacement. Whether you have already built a stroker motor or are simply researching them, take a little time to learn the basics and understand the benefits and possible compromises of the now popular engine building practice.

Stroker Motor (def.)

A motor that has greater than stock displacement due to an increase in the factory crank throw. An increase in crank throw increases stroke (the difference between the piston’s top dead center and bottom dead center position).

The illustrations below show the difference between a stock and a stroked rotating assembly. Study the differences and you can see what makes up a typical stroker motor. Though a bit exaggerated for effect, the stroked cross section in Figure 2 incorporates:

Increased Crank Throw (distance between C and D)
Increased Rod Length (distance between B and C)
Decreased Piston Compression Height (distance between A and B)

Keep in mind that rod length does not affect the displacement of the engine, it is common to have a stroker motor that uses an increased crank throw, decreased piston compression height, and stock rod length to achieve additional stroke. We’ll discuss why longer rods are often used in stroker motors later in the article.


Figure on the right is a Stock Cylinder
Figure on the left is a Stroked Cylinder

The animation below helps visualize the effect of increased stroke and rod length on piston travel and speed.

Figure 1. Stock Cylinder

Figure 2. Stroked Cylinder

Stroker Evolution

Stroker engines are nothing new, and in fact they are not even an aftermarket invention. If you look closely at factory engine offerings, you’ll see that changes in displacement are often nothing more than a change in stroke. This was a cost effective way for the factory to increase power for larger vehicles, or future models, while reusing the same block and accessory components.


Performance enthusiasts then caught on and they found that creative machining and parts matching could yield more cubes while hidden in the stock block to fool fellow racers.

One of the methods used to increase stroke with a stock crank, is called offset grinding. By offset grinding the rod journal you move the centerline of the rod journal away from or toward the centerline of the main journal. This will result in increased or decreased stroke. Figure 3 above illustrates the case we are interested in, the rod journal is ground in a manner to increase stroke. Keep in mind that when the rod journal is offset ground it now has a smaller diameter. The motor will require special connecting rods with correctly sized bearing bores. Additionally, if the rod journal is ground too much it becomes weak. Unless you add material and regrind, you can only stroke a motor so far with a stock crank.

Due to a demand for more stroke than offset grinding a stock crank could achieve, many aftermarket companies developed specialized cast and forged cranks with relocated rod journals. The specialized stroker crank has dramatically increased the amount of stroke you can add to your stock bottom end. Stroker cranks require a shorter piston to keep the factory sized piston from extending beyond the deck surface, it is also shortened to accommodate a longer rod. In the past the only way to complete a stroker motor was to find the right combination of rod lengths and piston heights. This often meant researching other factory motors for the right dimensions. It was not uncommon to have a Small Block Ford stroker motor consisting of Pinto rods and Chevy pistons.

Longer rods are often required to increase leverage and minimize the high degree of rod angularity created by the increase in stroke. The longer rod also prevents the piston from being pulled out the bottom of the cylinder bore. Rod Ratio and rod angularity are especially important issues to consider before simply choosing the stroker kit that yields the largest displacement for your application. We will discuss these topics in the following section.

Rod Ratio (Rod to Stroke Ratio)

Rod Ratio or Rod to Stroke Ratio is the figure achieved when dividing a motor’s rod length by its’ stroke. This is an important calculation to understand since it informs us about a motor’s rod angularity. A low Rod Ratio yields a high rod angle. For example, a motor with a 5.400″ rod length and a 3.000″ stroke yields a rod ratio of 1.8:1. If we maintain the same stroke and shorten the rod length to 5.000″ we get a 1.7:1 rod ratio. The rod angle has increased.

A high rod angle or low Rod Ratio creates a greater potential for accelerated wear to cylinder walls, pistons, and piston rings. The illustrations below show why this is so. Figure 5 is exaggerated for effect but clearly shows how an extremely low Rod Ratio can drive the piston into the side of the cylinder wall.


Figure on the right is a Low Rod Angle. (High Rod Ratio)
Figure on the left is a High Rod Angle. (Low Rod Ratio)

By lengthening the rod, as stroke is increased, we can offset the increased rod angle. However, this requires further shortening of the piston. The further the piston is shortened the more likely the piston pin will intersect the oil ring groove, creating a potential for increased oil consumption.

Photobucket “Shortened Piston. The further the piston is shortened the more likely the piston pin will intersect the oil ring groove.”

Many piston companies however have engineered pistons to avoid this problem with tighter ring packs and bridge rings. Either way, there comes a point when you cannot shorten the piston any further before dependability is compromised. As in the discussion about offset grinding, we have reached a limit to how far you can stroke a motor before some component or function is sacrificed.

The consensus amongst engine manufacturers is that a ratio of 1.50″ is the lowest acceptable rod ratio for a street motor. Realistically, rod ratios between 1.65″ – 1.80″ are ideal. See the tables in the following section about stroker kits. Notice how the Rod Ratio decreases as stroker displacement increases.

Piston Dwell Time and Piston Speed

An often overlooked factor that contributes to the advantage of a stroker motor has to do with piston dwell time, the amount of time the piston remains at the top and bottom of the stroke. The increased stroke and rod length of a stroker motor yields a longer piston dwell time. Longer dwell time allows for better flow of combustion and exhaust gases since the piston accelerates slower in the transition between “up” and “down” strokes. Intake gases have a longer time to enter the cylinder while exhaust gases are given more time to escape. This translates into more natural torque over a longer range of rpm. Power and torque can also be enhanced with valve event timing and cam profile.

Even though the piston accelerates slower in transition, the piston ultimately reaches higher speeds to cover the additional stroke. This increase in piston speed means greater component strain. Another factor to consider before simply going with the kit or components that give you largest stroke increase.

Stroker Building Considerations
As you may have guessed, there are certain issues which must be addressed when actually assembling any stroker engine. First and foremost is the issue of clearances. Due to the increased stroke and rod length changes, it is common for the rod and crank to interfere with cylinder bore end, pan rails, piston skirts, windage trays and other areas inside the block. Therefore it is mandatory that you preassemble the engine components, mark the areas needing grinding for clearance, disassemble and make the necessary clearances, and then reassemble and check again. As a rule of thumb you should have at least 0.030″ clearance between any interfering points. Another set of considerations unique to stroker engines is rotating assembly balancing. Whether the stroker kit is custom made, or off-the-shelf, the use of new or offset ground cranks, longer rods, and stroker specific pistons ensures that the assembly is not going to spin evenly. Any stroker kit, even off-the-shelf ones, must be balanced by a competent machine shop. Not doing so is a recipe for failure. Always perform the balancing with the harmonic balancer and flywheel you intend to use.

Stroker Kits
Many of the issues that arise when planning a stroker motor are solved by using a kit that provides a crank, connecting rods, and pistons. Rather than purchasing the components separately, you can purchase predetermined safe combinations for your block. You will get a thousand differing opinions regarding the best stroker for your application. We urge you to gather opinions from fellow enthusiasts and engine builders. Also use the information about rod angularity in this article to make your decision. Stroker displacements remain fairly consistent from kit provider to kit provider. We have highlighted the most popular stroker displacements for Ford blocks in the tables below.

289-302 based strokers (4.030″ bore – 0.030″ over stock)
Displacement 289 302 315 331 347 355
Rod Length 5.155″ 5.090″ 5.205″ 5.400″ 5.400″ 5.205″
Stroke 2.870″ 3.000″ 3.076″ 3.250″ 3.400″ 3.500″
Rod Ratio 1.796:1 1.696:1 1.692:1 1.662:1 1.588:1 1.487:1

351W based strokers (4.030″ bore – 0.030″ over stock)
Displacement Stock
351W 383 393 408 418 426
Rod Length 5.956″ 6.250″ 5.956″ 6.125″ 6.200″ 6.125″
Stroke 3.500″ 3.750″ 3.850″ 4.000″ 4.100″ 4.170″
Rod Ratio 1.702:1 1.667:1 1.547:1 1.531:1 1.512:1 1.469:1

351C based strokers (4.030″ bore – 0.030″ over stock)
Displacement Stock
351C 383 396 408 426 –
Rod Length 5.778″ 5.850″ 6.000″ 6.000″ 6.000″ –
Stroke 3.500″ 3.750″ 3.850″ 4.000″ 4.170″ –
Rod Ratio 1.651:1 1.560:1 1.558:1 1.500:1 1.44:1 –

429 and 460 based strokers (4.440″ bore – 0.080″ over stock)
Displacement Stock
429 Stock
460 501 532 557 –
Rod Length 6.605″ 6.605″ 6.800″ 6.800″ 6.800″ –
Stroke 3.550″ 3.850″ 4.150″ 4.300″ 4.440″ –
Rod Ratio 1.861:1 1.715:1 1.638:1 1.581:1 1.531:1 –

In reality there are many more displacements possible for the blocks above if you decide a kit does not meet your needs.

 This does however require a greater understanding of custom engine building and that is where you friends at Bessel Motorsports and can help you out. Call them today and speak with one of super tech reps for all of your stroker questions 636-946-4747 or email them direct at

Tell them your buddy over at Greaser Alley sent you & maybe they will give you a discount.

Love the look of classic pin-ups from the 1930s, ’40s and ’50s? Ever wondered what makeup tricks they use to get that perfectly flawless finish, those sultry bedroom eyes and those ruby red lips? Learn to do it yourself in this quick video tutorial, and you can look like a retro pin-up model, too!

Aluminum  characteristics:

The 3003-H14 has superior strength characteristics over pure aluminum and is easily welded with either TIG (tungsten-inert-gas) or oxygen-acetylene gas welders, yet remains malleable for shaping and bending. By comparison, a 6061-T6 aluminum alloy would yield even more strength than the 3003-H14, but the 6061-T6 is also more brittle and if welded, may develop stress cracks at the weld.

Following is a list of aluminum alloys defined by a four-digit numeric code to identify the alloy content. The first digit represents the main element of the alloy. The alphanumeric code that follows the four digits (i.e “H14” or “T6”) is the hardness and temper specification of an alloy. For example, a letter “F” in the temper code refers to fabricated, which is an aluminum that has not been treated for hardness. A letter “O” indicates annealed, or softened by a process of heating and cooling. A letter “H” indicates a strain-hardened alloy (hardened by cold-working), and a letter “T” means heat-treated. Generally speaking, the higher the number in the temper code, the harder and stronger the alloy.

1XXX (1000-series) is the designation for unalloyed (99 percent pure) aluminum. The 1000-series offers high corrosion resistance, excellent workability and welds easily; however, its low strength limits its use in certain applications. This is still a common alloy for use in automotive fabrication where strength is not an issue. Non-heat-treatable.

2XXX (2000-series) is an aluminum containing copper as its main alloy. 2000-series aluminum alloy provides a better strength-to-weight ratio than 1000-series and is also easy to work with. The trade-off, though, is that this alloy is not as ductile, meaning that bend radii must be fairly large and gradual, and joining pieces of 2000-series alloy must be accomplished by riveting or chemical bonding rather than welding. Heat-treatable.

3XXX (3000-series) indicates an aluminum with a main alloy of manganese. The addition of manganese yields a 20-percent increase in strength over 1000-series, yet it retains the working qualities of pure aluminum, and can be TIG or gas welded. For these reasons, 3000-series aluminum alloy is the most popular choice among automotive fabricators. Non-heat-treatable.

4XXX (4000-series) is an aluminum alloyed with silicon. Moderate strength.

5XXX (5000-series) is an aluminum alloyed with magnesium. Moderate-to-high strength. Non-heat-treatable.

6XXX (6000-series) such as 6061-T4 or 6061-T6 is commonly used in production due to its relatively low cost and excellent mechanical properties. Annealed 6000-series aluminum alloy (or 6000-series with an “O” temper code) also lends itself to forming. Heat-treatable.

7XXX (7000-series) is an aluminum alloyed with zinc. 7000-series offers the greatest strength, but is the least ductile. Heat-treatable.

Steel characteristics:

 The same basic code system that defines aluminum alloys similarly defines steel.

 1XXX (1000-series): Basic open-hearth and acid Bessemer carbon steel that is non-sulfurized. 1020-series cold-rolled steel sheet metal is a common material for automotive fabrication.

2XXX (2000-series): Steel alloyed with the addition of nickel.

3XXX (3000-series): Steel alloyed with nickel and about 1.25 to 3.50 percent chromium.

4XXX (4000-series): Steel alloyed with molybdenum or nickel-chromium-molybdenum. You’ve probably heard the term “4130 chrome-moly” a few times. 4130 is a steel alloyed with chromium and molybdenum. Stress-relieved 4130 chrome-moly is used where structure strength is most critical. Annealed chrome-moly is used for fabricating structures that require forming and bending.

Here’s a straightforward way to build your own “Runtz” type voltage reducers so that you can use your 6 volt gauges on your 12 volt system.

The regulator is based on the LM7806 integrated circuit, which is able to reduce voltage while maintaining a constant current. Use one regulator for each gauge; this allows you to keep each circuit separate which is useful for sorting any troubles you might have. While it is possible to use one regulator for all gauges using a power transistor, it has a bigger footprint and produces more heat, requiring it to be carefully mounted away from any heat sensitive parts.

Here are the components:

1x LM7806 voltage regulator
2x 1μ 25-35 volt tantalum capacitors
1x Heat sink (around one inch long)
3x wires cut to 3 or 4 inches in length

You will also need a soldering iron, solder, some pieces of shrink tubing, and a bit of heat sink paste.

First, bend the leads on the capacitors into an “L” shape. Usually the longer lead is the positive side and since we want to attach the positive ends to the outer leads on the LM7806, make sure the capacitors are bent in opposite directions.

With the LM7806 sitting with the tab side down, solder one capacitor to one of the outer leads of the LM7806, then solder the other capacitor to the other outer lead. Again, be sure these are the positive ends of the capacitors. Carefully bend the remaining lose capacitor leads to make contact with the center lead of the LM7806. Solder them in place.

Next, trim the three posts on the LM7806 so they are just long enough to solder the wires into place. First solder the center wire (ground), then the left (12V) and the right (6V).

Cut some short lengths of shrink tubing and slide them along the wires all the way to the regulator side and heat them. Then take a larger piece and wrap the three leads together. This will both insulate the leads from each other and protect the connections.

Finally, put a dab of heat sink paste to the back side of the LM7806 and attach it to the heat sink with a screw.

When connecting them, select the appropriate connectors for your application. In the photo below, the red lead is connected to a switched 12V source (usually your ignition), the white lead is connected to the positive post on a gauge, and the black lead is connected to a ground.

Finally, attach your harness and reinstall your gauges!