S/S crankshafts

[smokey]

OK, what is goin on with S/S crankshafts. Sounds like there are several engine builders and a few racers out there that have been running cranks with rifle drilled rod journals and even main journals. Supposedly there was a letter floating around out there from NHRA that said rifle drilling was legal and then some NHRA folks saying no. Which is it???
The rule book is, as usual, as clear as mud on this one.

[junior barns]

..

[Jack McCarthy]

there is a letter and a FAQ sheet being circled around now dated this week from jim skelly and it is very explicit that there have been NO RULE CHANGES to the SS cranks period and it is supposed to be enforced as such...

seen it myself recenlty

jack mccarthy

[SS Engine Guy]

Better show it to certain manufacturers/racers because they too have letters. What a mess. What is the final word? Rule book or signed letter?

[smokey]

Jack...I heard about that letter but also understand it is a follow up letter to one that came out of Glendora back in February that said it WAS legal.
That is crux of the real problem. They put out a letter in February that said it was ok so some racers and engine builders heard about it and went out and ordered cranks and then a month or two later they send the same letter with different answers! That is bull****!!
Hey Skelly......what is the right answer and will it change again next week????

[Jim Skelly]

We'll finalize this next week, when everyone comes back. The "letter" was circulated internally, waiting for feedback. It's unfortunate that negative feedback came in after some racers got wind of it. But it happens.

It's a bit confusing, but I highly doubt that any engines were built based on that first "letter". It was only out there for a couple of weeks at most. Anyone who has a crank with items that are under "discussion" at this point, had it before any letters went out.

Unless, of course, engine builders haven't been telling the whole truth about how long it takes to put a Super Stock engine together.

[smokey]

Well I hope ya'll stick to the letter of the rule. Never seen a rifle drilled crankshaft main neccesary for balancing a crankshaft. That does for sure fall under the rule "lightening other than normal balancing job prohibited". Throw em out!
We don't need comp eliminator short blocks.
Also, please get Gracia to start doing more tear downs to keep this class honest!!!!!!

[Jack McCarthy]

and while your on the topic of teardowns... here it is 25% into season and not a single dropped pan in stock eliminator ... damn all those new piston & rod weight specs just sitting around being lonely...

hell i cant afford stock anymore... much less a $4000 crank

captain jack

[joe176]

Crankshaft ruling announcement on NHRA

NHRA clarifies crankshaft rules in Super Stock

--------------------------------------------------------------------------------
4/18/2007


The Tech Department has issued a list of frequently asked questions and answers on the subject of crankshaft modifications in Super Stock and Super Stock GT. As with any category, engine builders in Super Stock are constantly looking at smaller and smaller details in their quest for horsepower, necessitating periodic clarifications or interpretations of the text contained in the NHRA Rulebook. Input from NHRA Technical Inspectors, engine builders, competitors and manufacturers was used to determine the correct and current answers to these frequently asked questions, and to better clarify NHRA's position on what is and what is not acceptable. The following information pertains to Super Stock (Section 6A) and Super Stock GT (Section 6B) ONLY. For questions and answers on other classes or categories, consult the 2007 NHRA Rulebook or contact NHRA Technical Services headquarters.



1. Can the mains be gun drilled? YES



2. Can the rod journals be gun drilled? YES



3. Can the counterweight be turned down in radius for balancing purposes? YES



4. Can the counterweight be narrowed? NO



5. Can the counterweights be pendulum cut to remove weight? NO



6. Can the leading edge or trailing edge of the counterweight be radiused or bull nosed? YES, because there are OEM cranks that are made in this configuration. BUT, knife edging the leading or trailing edge of a counterweight is prohibited.



7. Can the rod journals and main journals be any size? YES



8. Can a billet crank be used? NO



9. Can a forged crank be polished? NO. The rules state that crankshafts must retain OEM configuration. If a polished crank and a billet crank were set side by side you could not tell the difference by just visual inspection.



10. Can additional oil holes to the main and/or rod journals be added? YES



11. Can additional weight, such as heavy mallory, be installed in the counterweights? YES, BUT only in amounts relative to a ?normal balance job?. A normal balance job on a Super Stock engine such as a SBC 350 may involve turning down the counterweights to balance up with the ?lighter than stock? piston/pin/rod assembly. A normal balance job on a Super Stock engine such as a SBC 400 that is internally balanced may involve installation of mallory to offset the piston/pin/rod assembly. If mallory metal is used, it may mean too much was taken off the crank. So a small amount of mallory is ok for ?normal balancing purposes?. Otherwise, mallory metal means the counterweights were turned too much, beyond that necessary for a ?normal balance job?, and would be grounds for disqualification.



12. Is there a method to find out if a particular mfg crank is an accepted part? Contact Technical Services in Glendora. If you have a crankshaft that you would like to have accepted, send a link, catalog, or other information to Jim Skelly in Glendora.



NHRA #7494 SS/H
1970 AMC AMX 390
"Best Appearing" @ NHRA '06 Pacific Sports Nationals
Arizona's BEST Realtor since '93 and I support racers!
Property in AZ or moving here? I can help! Call me @ 602-418-9797 or e-mail JeffLeeAzRealty@Qwest.net