Aftermarket Cranks

[Mike Crutchfield]

Terry / Tom
Concerning STOCK
There is not an approved list yet for cranks. At first NHRA did not think it would be necessay for a list because the only thing they were changing from the orginal rule was, it could be a aftermarket instead of a factory crank. It still has to have the Stock Configuration and stock pin size minus .070 no matter what can be read into it. The rod rule could be a little misleading but the bottom line is, you must use the stock size and lenght rod for the application.
I have spoken with Bruce recently and ask if he could clarify more clearly the Rod and Crankshaft rule. He indicated that there could be a approved list and a claification if the misunderstanding of the rules presisted.
Basicly the rule change was not a re-write of the rule just an addition. The intent was to allow after market Cranks and rods in the same as STOCK configuration that could be stronger and safer.
Hope this help clear up any misunderstandings.

Thanks
Mike C

[RJ Sledge]

JimR

The Wizard was trying to tell you in his post, if you go back and re-read it he makes a comment about the difference in C/H of the piston. This is how its done and he also states that the only way to check C/H is with a piston and rod removal request (sic). Don't feel bad about being honest you are in the majority.

Larry

FYI 390/427 are not 3.980, they are 3.780 so the weight loss is only very slight and I don't have a clue about "change in polar moment of inertia" maybe polar movement of inertia is what you meant, anyway its way over my head. But from my 12th grade basic math class that I took for the 3d time I would guess that the weight difference would be about the same as a "popcorn fart" or maybe the same weight as a "gnats ***".

I believe that you are confused about the stroke of these motors and the rod pin size. Yes there would be a difference, but I doubt it could be measured. I may be wrong, and it wouldn't be the first time.

And to answer your question of "why is the 390/427 allowed these rods", is because NHRA approved them 9 years ago and its a little late to be closing the barn door after the cows are already out.

Luv ya Bro!!

RJ

[KRatcliff]

RJ,

This should help you brush up on that math thingy. www.khanacademy.org

Plus, it has the instructions for the BigStuff3.

[RJ Sledge]

BS Kyle, I'm a little bit long in the tooth to be trying to figure that out! Besides, I have you to figure it out for me. YOU need to brush up on the BS3 by the way!! Old folks need help.

Happy Thanksgiving!!

RJ

[KRatcliff]

You are going to shame me into helping you, aren't ya. Consider it a sympathy tune.

Happy Thanksgiving to you and yours.

[Rusty2211]

Popcorn fart.... RJ, you crack me up!

I have a pretty good understanding of moment of inertia and I can tell you that 1.5lbs on a 70 lb crank is not going to cause a noticeable increase in acceleration. Heck, if that is true I'm going to have my torque converter polished.

[Larry Hill]

Rusty it will not hurt.

[Larry Hill]

If a 400 "B" block is used in place of a "RB" 383, 413, 426, and 440 blocks the rod will be to short center to center and the compression height of the piston would be short. The rod and piston would be wrong.

Rods have a service life. I think NHRA should resend the use of "custom length" rod in Stock at the end of the 2014 season, for the FE Ford engine. If a racer has a new set of rods of "custom length" they will get two years service life from their investment.

NHRA has a chance to right a wrong that affects all of us that race stock. If you don't believe it affects all just think of this real life scenario.

Indy 2013 Stock. 180 entrants 128 qualifiers, what 52 cars can you out qualify? Lets say you are #129 and everyone is legal. Above you on the qualifying sheet are four FE Fords, all have the approved rod. All four are in bottom half of the field, just a few hundreds of a second in front of you. Part of the reason they are ahead of you is that every time the crank is turned from 2.437" to 2.200" the surface area of the original is approximately 10% bigger than the new finished size of 2.200. So if my math is correct the FE Fords have a 10% reduction in surface area and a big reduction in friction.

People who had a hand in getting the "Custom Length " rod approved by NHRA knew they were cheating the system. The worst thing they did was to cheat me and the other racers!