Intake Manifold for Vintage

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hardingfv32-1
Posts: 1014
Joined: December 1st, 2006, 8:01 pm

Intake Manifold for Vintage

Post by hardingfv32-1 »

I wish to make intake manifolds for vintage Vees. There have been 2-3 set of rules that have applied to Vee intake manifolds over the years. How does a vintage Vee owner know what rule they are operating under for a given car?

Brian
ajax
Posts: 131
Joined: July 4th, 2006, 9:22 pm

Re: Intake Manifold for Vintage

Post by ajax »

Brian, With the many different groups promoting vintage vee racing today, not an easy task! likely the best place to start is from FV engine rules used for http://www.monoposto.com/ They cover a fair % of the vintage vee racing in US and other groups usually use at least some of their rules.
Good luck.
FV80
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Posts: 1195
Joined: June 27th, 2006, 9:07 am

Re: Intake Manifold for Vintage

Post by FV80 »

Brian,
I think maybe you have a misconception about the old rules. In the rules, it specifically says "any allowable modifications,
changes, or additions are as stated herein. There are no exceptions. IF IN DOUBT, DON’T
." - that means that enlarging the manifold using steel balls (or any other method) is illegal - sanding on the manifold is illegal - REPAIRING the manifold is illegal - most EVERYTHING you can imagine is illegal.
In recent years, it has become apparent that manifolds are getting harder to come by (not many found in junk yards these days) so specific allowances are now being made for repairing them. However, I still have not been able to find a place in the rules where it says you can use 'steel balls' to enlarge a manifold - it's just not there. I don't know where you found "2 or 3 sets of rules" (with implications that they are different), but the only changes that I've seen are the recent ones that CLARIFY existing rules - no "changes". Although some are under consideration now as I understand - simply specifying some dimensions that were previously unspecified. - and BTW, "porting the flanges" is not allowed. "MATCHING" the flanges IS allowed 8) . I must say, though, that I don't have a 1970 GCR. The earliest I ever saw was about 1977.

Just my opinion...
Steve
The Racer's Wedge and now a Vortech, FV80
hardingfv32-1
Posts: 1014
Joined: December 1st, 2006, 8:01 pm

Re: Intake Manifold for Vintage

Post by hardingfv32-1 »

I'll change my wording: There were 2-3 sets of rule clarifications.......

IF IN DOUBT, DON'T is all well and good, but when you can't prove a DON'T has taken place what is the point. I assume changes to the intake manifold rules were because all stock manifolds are not dimensionally the same.

May I assume there was no minimum weight before about 1973?

Brian
FV55inSpokane
Posts: 196
Joined: June 25th, 2006, 5:31 pm

Re: Intake Manifold for Vintage

Post by FV55inSpokane »

Brian,
I believe that the GCR (current) states that the manifolds will be checked for O.D. in three different places ( just taking into consideration the cross tube and not the down tube) per side and around the circumfrence at several spots at those places. It lists the maximum O.D. allowed at those places on the manifold so the way I see it, and lots of other folks as well, is that if the manifold starts out smaller than that you can bring it up to that dimension by using balls to do so. As far as removing material from the O.D. to make the manifold meet those dimensions and ball-size the I.D. larger than normal: I believe that is not legal. There is the minumum weight also. If someone were to over ball-size their manifold and then require a 'repair' somewhere they could get passed the intent of the rule by having an over-sized manifold I.D. (and sand it down) but still be over the minimum weight.
As far as using the ball-sized manifolds for vintage: It's probably not legal since the old GCR's most likely did not allow any other modification than removing the heat riser and matching the ports. I assume that in those days people went through a bunch of manifolds to find the ones that were the best.
GCR also states that their shall be no othe coating on the O.D. of the manifold than a thin coating of clear. This would allow techies to see if the O.D. surface has been messed with.

Don't know if I helped or not...
Lawrence
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