crochunter

Hi i have a 351 clevo,4v heads,tfc manifold,630 lift crow solid cam, and going to put a 750 hp holley on it. Standard jetting is 73 front and rear. It still has power valves front and rear. So i am going to take power valves out. That means usually u go up 10 sizes. But i reckon go more cause car is used for street AND STRIP. I run 2 ranges colder plug. What jetting would be best. Hey brendan what do u have on your car. any help please.

ch7472

Why use a 750? The clave in my XC is a 387 stroker and i run a 650 holley and have never had any problems with it. And it has around 450 h.p

STROKEXD

Removing the power valve, especially the front one is not recommended these days. Few people bother.

Though you will be able to get the AFR right at WOT you will have lean spots at cruising rpm that will cause you some obvious problems, and potential engine damage.

So the mod is a strip car only proposition.

For the secondaries - about 8 sizes difference is how Holley set it up themselves so it is a good starting point.

I have a 378 stroker with a slightly smaller cam than yours and my primaries range between 72-75 depending on conditions and fuel type, secondaries 60-84, with a 750DP.

Richer jetting won't make your car go any better, only the right jetting (AFR) will.

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crochunter

I think 81 front 85 rear seems to be working ok. Will find out when go to the drags. What times you run at the drags.

TruBlu351

Those jets you have are a fair bit bigger than standard. A 750HP Pro comes with 70/80 jets.

Have you had it on the dyno?

Best option for you............ + quickest and most reliable..........

Get it on a dyno with a wideband AFR meter..............and a heap of jet sizes. Get a base reading of where its at now and work from there. Won't cost too much either.

You never know, it may be right on the money now. Looking for about 13:1 @ WOT.

Too much fuel and you may lose power. What are you revving this beast to?

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XE Falcon
393 Tremec TKO 9"

crochunter

It done 11.2@120mph at drags. Makes about 480 hp worked out with slide rule with weight of car. Revving it to 7000.

xdclevo

I only run a front powerevalve, and have an 8 jet split. I have a Barry Grant 750dp and it runs 75 and 83 and is SLIGHTLY rich after my last dyno run. I think 73 and 81 would be near perfect for my combo. Sounds close for yours too if you loose the rear powervalve.

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10.70 @ 125.00 on the black fun top
408 Cube Cleveland.

crochunter

Yeah will try that jetting but have never had it on a dyno. When i rang up hume performance on jetting on a 750 hp holley they said 72 front and rear. Cause a 750 hp holley runs power valve front and rear.

xdclevo

Are you going to block the rear p.v.?

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10.70 @ 125.00 on the black fun top
408 Cube Cleveland.

crochunter

Yes it is blocked. I dont run pvc. I run hoses from front of tappet covers into breather tanks.