Engine vacuum

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Rumblin_440

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Ok I'm not 100% sure this is the correct area to post this in but I'm going for it.
I have a 440 that I'm building for a pulling truck and I need to be able to make as much power as possible while creating 15" of vacuum at 1000RPMs. Is there any sort of mathematical way of figuring this before building or at least a way to get me close. Any tips or hints will be greatly appreciated.
 
Rumblin_440 said:
Ok I'm not 100% sure this is the correct area to post this in but I'm going for it.
I have a 440 that I'm building for a pulling truck and I need to be able to make as much power as possible while creating 15" of vacuum at 1000RPMs. Is there any sort of mathematical way of figuring this before building or at least a way to get me close. Any tips or hints will be greatly appreciated.
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call comp cams
 
Summit is a distributer. Comp cams makes cams. If you know the cam you want you could order from summit but don't expect to rely on their tech's to help you get that pick right.

Now why do you need 15" of vacuum at idle on a pulling truck? Why does it need to idle at 1,000 RPM?

Can you tell us the engine specs?

What style cam do you want? Obviously max power output will come from a roller but you are also talking$$$
 
The reason for 15" at 1000RPMs is the class in which I'll be pulling that is one of the limitations of the engine, it's a "factory stock" class that's running trucks with over 500 horse I'm just trying to be a little more competitive. As for the engine it's out of a 76 champion motor home, it's a 440 looks really good and runs great(I've already pulled numerous times with it) just looking to get some more out of it in the off season. I put a comp cam in it part# 21-215-4, cloyes double roller timing chain, quick performance 700cfm carb, about 20* advanced timing, hei kit, hooker headers, edelbrock performer 440 intake, headers and intake may be coming off tho for stock intake and exhaust manifolds depending on rule changes. I'm mainly trying to figure out how to squeeze more power out with stock appearance and maintaining that vacuum without assistance.
 
20161206_085620.jpg
 
I see the rationale now.

You have a low compression 440 with anemic heads. I'd be looking into working the heads first rather than a trick cam.

How much does that current combo make for vacuum?

First thing I'd be looking into is a solid lifter cam.
 
Here are a couple cams that might work for you though.

Crane 683801

Howards 721941-12

Crower 32242
 
I'll run the vacuum test this weekend and see where it is for sure now, I was wanting to do headwork but not sure what I'd be able to do and keep that vacuum. Is that something the machinist would be capable of figuring out?
 
if the rules allow use a roller more hp with less overlap. also re-curve the dist. you want to limit the amount of mech advance so that the initial timing is very high and still total in 32 35 or so (what your total that you are using). if they will let you run the vacuum advance straight to the manifold this will raise the vacuum higher. there maybe hesitation when you step on the pedal but you can tune around it and since it a sport were you will be doing a lot of wide open you wont need as much driving flexibility. all these things will make it so you can get away with a pretty aggressive cam. sound like fun
 
You could just run the timing locked out or very little advance like the wall suggested and just use a start retard.
 
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