Cam duration

[Stan Weiss]

Stan where do you set the VE % at?
My 421 came out pretty close but the VE really throws the curveball.

I will have to add a list of different type engines and what a reasonable VE range would be.

Stan

[Steve.k]

Narrow spread from peak TQ to peak HP rpm.

Randy

Randy I've heard this before but is not more critical with two speed trans setups?

[randy331]

Narrow spread from peak TQ to peak HP rpm.

Randy

Randy I've heard this before but is not more critical with two speed trans setups?

Well, in a drag race car you don't run them at peak TQ, so the spread only impacts ideal stall speed.

What I was saying is, the spread is narrower than what I've seen on good engines, so something may be signing off a little early. And you mentioned 7100 rpm for a peak HP rpm which would put the spread at what I've seen. It wasn't pulled our far enough to tell, but if it hung on well past 7000 rpm, it could be a sign the heads (or somethings) are wanting to run on up in the rpm range and something isn't.

I'd lean towards a lttle more duration too, but that's without knowing much about your combo.

Randy

[Steve.k]

Ok thanks Randy. The build is 13.6 comp, 4.05 x 4.25 stroke. Chi 4v heads with above work. Ur19 Cleveland ram with dual 6464 carbs. 2" header and 3.5 collector.

[cjperformance]

Id have to look and see if i wrote that down craig. Figure it out as if Im good on clearance if you like. Even more duration could make it close to ii guess.

Cool, giving a lift figure at min pv clearance is really just working toward the same as Camking is asking on valve drop figure. Knowing at what lift you have min clearance just helps to know where in the curve you can add lift. You never have pv contact at full lift so you will be able to have more net lift and more area under full lift than you do now.
With your intake and head type i'd want 268*@.050" & .775"net lift on the intake. For the exhaust if anything just 3 to 5 degrees more @.200". But id happily leave it as is if you dont need it to have to hang on a lot after peak.

[hoffman900]

If you have the time luxury, giving valve drop to your cam designer is always worth it. Why not use up all the real-estate if you can?

[cjperformance]

If you have the time luxury, giving valve drop to your cam designer is always worth it. Why not use up all the real-estate if you can?

Exactly !!

[Steve.k]

Thanks guys. I'll get you some numbers next few days.

[Steve.k]

IMG_2275.JPG

. Guys this was run before our highest. We switched from c12 to torco 112 oxy fuel on these. Notice one side uses less fuel. We tried adjusting float levels to get back to the same. Wouldn't change. We mic'd jets all equal. Any ideas what caused discrepancies?

[treyrags]

IMG_2275.JPG. Guys this was run before our highest. We switched from c12 to torco 112 oxy fuel on these. Notice one side uses less fuel. We tried adjusting float levels to get back to the same. Wouldn't change. We mic'd jets all equal. Any ideas what caused discrepancies?

Had the same thing happen on my engine that was dynoed a few weeks ago. It happens to be a 438W as well but that has nothing to do with it unless you are running the same manifold. Finally had to richen one bank to get them equal. I suspect it is in the manifold. Was thinking about trying a "spivy" on the boosters but ran out of time.

[Steve.k]

Yes Pierre did mention about trying different jets in that side. The weird part was we had jetted up to 86 to compensate for oxy fuel. On the c12 we were 84's all around and it was dead on.

[tuffxf]

Gday,
Silly question here but how are you figuring a difference side to side?
All i see is fuel flow numbers which would mean a difference front to back?
Very easy to have a difference there.
Nice results by the way!☺
Cheers
Paul

[Steve.k]

Thanks Paul the ur19 manifold the dual dommies sit cross ways. We had the bowls of each carb tied together per side. The low numbers would be 5678 cylinder on 400. The goofy part egt is close and a/f is also. Although unhooked in that sheet i posted. He has his a/f sensor in header extensions which we replaced with my own car extensions with evacs that I wanted to try.

[tuffxf]

Gday Steve,
Well there you go!☺
Didnt realize it had two carbs.
I'll take foot out of mouth now☺
Are you sure everything btween the front and rear of the carbs are identical,
Floats
Float height
Emulsion stack, bleeds
Etc, etc.
May be a slight difference there somewhere?
Cheers

[Steve.k]

Everything is the same other than front carb sits 1inch higher. However before jet change fuel consumption equal.