cam thoughts???

[572 BBC]

question...my rpm range is say 3500-7000 or a tick over 7000.10.2"1 compression 572 cnc355 heads super vic 1150 three circuit.

at what point should nitrous be figured in when it comes to best cam for opperating rpms? total rolling weight 3000lbs,33 tire,tube chassis,4.11 gear

i currently have comp cam 7/4 swap 286/296 @ .050 321/336 total on a 112 lob sep.748 lift on both...

a fellow nitrous buddie said the cam true is big(perhaps im thinkin 10 degrees at .050)but the nitrous loves over cammed over headed motors....

dunno...ive heard some say up to 250 or so hp nitrous, use cam best for n/a.on larger nitrous doses then cam grind will be different...

the only thing im seeing is that a motor on nitrous will reach peak hp about 500 rpms sooner,if true then a slightly larger cam might be best,but just best guessing

any real world track testing to shed light here john or anyone?

[572 BBC]

john do u have input here?if so id appreciate as always

by the way i just thought if you would rather have this post in engine category,u can move it for me or i will....let me know.thanks again russ

[John_Heard]

First off, I'm no cam guru that's for sure. I call and get recommendations from gurus and try them to see what seems to work. The biggest thing I see is your low compression (why 10.2??) which might require less duration than normal to get some cylinder pressure in it. Low cranking compression is a good indicator of having too much duration from what I've seen - course that may just be a by product, but I know on one old motor of mine (the 505) I had way to much duration in it with one cam and I got a new one that Patrick Budd made for me, that cam picked the car up 1/2 second - along with some head work at the same time, really woke it up. There are a few people I would try, one Mike Stark at CFM Performance - http://www.cfmperformance.com see if he is willing to spec a cam out for you, also Harold Brookshire not sure what he's doing now but his phone is 662-301-1245. Patrick Budd is real good at this too.. budd.patrick@yahoo.com. Of course regular cam grinders as well, but I wouldn't want to talk to the same dude selling RV cams.

Ideally if you have head flow data, that will tell the cam grinder what to do lift wise. When Harold Spec'd out my last cam he wanted to know where the ports stalled at, etc. Also what is available lift wise on your spring setup.

[572 BBC]

my thoughts when building were pump gas on nines spray into eights...well now my springs are getting tired(265 lbs on seat and comp told me i need 285-310) so wondering if i can ditch the current cam for a smaller cam maybe keep the springs for a tad longer...but i was hoping someone might of had back to back comparison testing to get a general opinion on cam theories when using nitrous


oh by the way harold brookshire would be my choice for ive read tons of guys experiences and read his background since the 70's

[supernova]

I also think the compression is a big factor with your motor combo. My 525 c.i. motor is 12.2 - 1 static and 9.4 -1 dynamic compression. I built it to run pump gas with a cam that I've been told is too small. .716-.714 lift, 276-283 dur., 111 cl. Now what allows me to run pump gas is the valve timing. This motor was built to run in a pump gas class. You can have more compression and still run pump gas depending on your cams valve timing. Your combo could have a dynamic compression as low as 8.2 - 1. When you look at different cams and talk to the guru's, I like John am not one, ask questions about dynamic compression and how valve timing can effect it. You might learn that a totally different cam grind what you need.

Now I have to tell the true.
My motor is all apart now. I sent the haeds to Mike at CFM performance for the works. With Mikes help we're changing things to make more power. Even the cam, springs, and intake is changing. I had to make a choice of street or all out strip and all out strip won. The size of the motor isn't changing but lots of other things is. The cam is growing to over .800 lift.

You can do some things that don't cost a lot of money to raise the compression of your motor like take the heads off and have them milled, use thinner head gaskets. You could bring the level up 2 point and with the right cam still run pump gas.