289 FIA vintage race engine with Webers

[1795]

Brent,

Not taking any offense at your comments. It will probably be at least a couple of weeks before I can get the engine installed, and then there will be some suspension modifications. Probably will not get it running for about a month. Timing sucks, I am in the middle of building a new house and just do not have enough time to do all that I have to do.

Time to run out, drop off some scaffolding and then pick up 2x4's and build a few more walls.

Jim

[1795]

Rick,

I greatly appreciate all of the support both through parts and sweat equity that you, Ross, Roy and Dennis have supplied and continue to offer. That is what makes a race team, and I am proud to be associated with this one.

I see us as being the privateers of old competing with the big money teams and showing that you do not have to be rich to race. Bringing the sport back to it's roots of everyday people getting on the track. Carrol was not rich when he started racing.

Jim

[Gaz64]

Jim,

I see your cam as a wider LSA of one of these:

ULTRA-ACTION / Performance Level 5 Fast 3/8 to 1/2 mile super oval track profile. RPM Power Range: 4000 to 7500 / Redline: 8000+CUSTOM GROUND SOLID

This cam is 292/302, 256/266 @ .050, 106 LSA, .606/.600.

Yours would be an 112 LSA of this grind.

Gary

[1795]

Gary,

Maybe the cam developer did a little research and found that cam and decided to use it as a basis for this cam. I think that the only suggestion given to the cam developer was to go with about a 112 LSA as Jim is concerned that under hard acceleration with a tight lobe center that there would be too much reversion and that fuel would end up going back up the velocity stacks as there is no common plenum in an independent runner system and therefore no place for the reversion to go. I know through discussions with Jim that fuel use at higher rpms is one of the factors that he uses in determining the jetting. It is quite possible that with a street engine and milder driving that I could have gotten away with the 106 LSA with only a little bit of fuel misting under heavier acceleration that I may not have really noticed; hard to say and I am by no means an expert.

Hope that all is well with you.

Jim

[1795]

Brent,

I was just doing a little research because you mentioned that a single plane intake manifold with a 4 barrel would produce more peak HP at higher rpms. I agree with you on that, from what I have read. The problem is, that because single plane intake manifolds were not in use in the 1960's on race cobras, I cannot use one in vintage racing. I can only use the style of manifold that would have been in use then. Seems like an inconsistent rule, given that I can run roller rockers and those weren't is use then either, but I don't make the rules.

Again, thanks for your thoughts and input, they are always greatly appreciated.

Jim

[blykins]

Originally Posted by Gaz64

Jim,

I see your cam as a wider LSA of one of these:

ULTRA-ACTION / Performance Level 5 Fast 3/8 to 1/2 mile super oval track profile. RPM Power Range: 4000 to 7500 / Redline: 8000+CUSTOM GROUND SOLID

This cam is 292/302, 256/266 @ .050, 106 LSA, .606/.600.

Yours would be an 112 LSA of this grind.

Gary

That camshaft, even with changing the LSA to 112, still has 73° of overlap.

Just randomly changing a cam to a wider LSA doesn't make it "friendly".

[Gaz64]

Originally Posted by blykins

That camshaft, even with changing the LSA to 112, still has 73° of overlap.

Just randomly changing a cam to a wider LSA doesn't make it "friendly".

Yes, that's correct.

Reducing the overlap by widening the LSA delays the inlet closing point, all else being equal.

So the late closing inlet will still have reversion out the stacks on an IR intake.

One camshaft grind that sticks in my head is for the Cosworth DFV 3.0 V8. 68/86 for the inlet, 86/68 for the exhaust. 136 degrees of overlap. LSA 99. IR intake, Lucas mechanical injection.

Extreme example, I know.

Gary

[moar_carbz]

Originally Posted by Gaz64

Yes, that's correct.

Reducing the overlap by widening the LSA delays the inlet closing point, all else being equal.

So the late closing inlet will still have reversion out the stacks on an IR intake.

One camshaft grind that sticks in my head is for the Cosworth DFV 3.0 V8. 68/86 for the inlet, 86/68 for the exhaust. 136 degrees of overlap. LSA 99. IR intake, Lucas mechanical injection.

Extreme example, I know.

Gary

Wow. The intake closed at 86? What was the reversion like?