I have a 383 stroker engine here is my setup

-10:1 compression
-all forged internals and bored .40 over
-Brodix IK200 200cc,64cc.
-1.52 ratio ultra pro magnum Roller rockers
-edelbrock performer intake
-Quick fuel 650 double pumper
-m20 wide ratio trans and 3:08 rear end

I want to be in the 450hp range and I’m having trouble deciding what hydraulic roller cam I want. I’m between comp cams 12-423-8 and 12-432-8. The thing is I want to be able to have my headlights pop up and my power brakes to still work. That’s why I’m nervous the 12-432-8 is going to be to big of a cam which would not give me enough vaccum. But I’m nervous the 12-423-8 won’t get me in the power range I want. Somone help me out here Any suggestions????

 

Add a small rotary vane vacuum pump with some one way valves. It will do everything you want

 

Your cam is not the problem here.
Its the 3.08 rear that will kill any low end torque from a new cam.

You want more get-up & go ditch those gears. They are just a couple notches above Salt Flat gears.

 

Use the 12-432-8.....it will have plenty of vacuum to pull the headlights.....
But your carb is too small.....you need at least a 750 here.

Jebby

 

I believe the performer intake and the carb both present a restriction with either cam at the higher rpm ranges.

with the 3.08 rear and wide ratio trans you’re gonna be happier with the smaller cam. The intake and the carb are not going to allow sufficient airflow at higher rpm’s in any case, so real reason to go there. It would be a mismatch of components leading to suboptimal performance.

if the rear diff is change to 3.55 or better and the intake is an rpm version or the current one is ported for greater flow and the carb is changed to a 750 CFM then the larger cam would do well. Better yet is a close ratio trans as well, but just changing the rear would do wonders.
Just uncorking the intake side without changing the rear gear would help a lot. It’d be a bit weak down low but recover above peak torque rpm and give a higher peak rpm for making HP.

the spec’d rpm ranges for those cams is for a 350. With a 383 you could expect too come in sooner and rpm out sooner.

And since this is a hydraulic roller cam get the lifts up. Put in some 1.6 rr’s.

In fact putting in the 1.6 with the smaller cam and the current drive train may be a pretty good combo without shelling out $$$ for different gearing. Got to remove the intake side restrictions though.

 

-hey thanks for the feedback, the intake I have is the edelbrock rpm performer intake. What do you mean by remove the intake side restrictions??? I have already bought the 1.52 rockers because that’s the size stud in my heads is it really that big of a deal even if I go with the smaller cam?

 

- I know😭 but I really don’t have the money at the moment to switch them out, Mabye in the future.

 

-if I went with the small cam(12-423-8) I looked around and saw posts about how the 650 double pumper would run better and have more torque. I also did like a equation based on the displacement and rpm and it said I need a 670cfm. So I figured a 650 was fine. I don’t know Mabye I’m totally wrong.

 

The "edelbrock performer intake" as stated in the first post would be an intake restriction for any reasonable 383. The RPM edelbrock performer intake will likely not.

Using a 650 CFM carb on an engine that demands more than 650 CFM will limit the top end performance. That is an intake restriction. You'd be better off with a 750 carb. Better yet the original Q-jet. it's rated @ 750 and properly tuned will outperform any after market 650 you're likely to put on it. Is that carb still around?


It would be a bigger deal with the smaller cam vs the larger cam. It just depends on what you are willing to give up with each component choice. Your choices add up for the end product and it's performance.
Lifting the valve higher effectively makes for a longer duration cam. It allows a greater area for the intake charge to get into the combustion chamber. Each degree of rotation of the crankshaft lifts the valve higher. That means for each degree of rotation on the intake stroke more area is available for flow into the chamber and that the valve will have greater area open for intake charge over the opening and closing cycle of the valve. More charge into the chamber produces more torque and thereby more HP at every RPM. Not just Max HP or max torque that everyone wants to focus on.

 

Agree with Jebby....those cams already have a quick ramp, wouldnt add 1.6 rockers

If you have to you always have the option of a vacuum reservoir. Can put them anywhere and they are cheap
I use one wtih factory power brakes a cam that makes 7 or 8 inches at idle on a good day and the pedal is perfect.

Id get it running, perfect the tune and drive it for awhile before buying any more parts.

 

-so you wouldn’t suggest putting 1.6 rocker on instead of the 1.52? How come?

 

-I do still have the 650 but I really liek it and don’t want to buy a new 750 the 650 quick fuel was really expensive. You think I can just jet it higher that way I still have the better low end torque that the 650 gives but with diffrent jetting not restrictive at the top end

 

A 650 carb will work, but you will want more carb to get the most out of it. With that kind of HP 750 CFM +