Cam Recomendation

[arrowhead1]

I just finished my engine on my 68 Firebird. The engine is 400 .030 over with forged flat tops. Heads are the cast # 16 heads CNC ported by SD perf. The intake is also ported by SD perf. The cam I was recomended was the Summit 2802 degreed to 107 with 1.65 roller rockers. I have a Temporary 800 CFM Rochester on it until I can send out the original to get worked. On the exhaust I'm running the long branch H.O maniflolds with 2.5" X-pipe to the rear. The car is a factory 4 spd M20 with 3.36 Posi.  I ran the engine and gave it the proper cam break in. I'm still babying the engine but I've given it a few revs and I feel the power band is higher than what I wanted. Also the cam is more radical than what I wanted. I'm trying to keep the stock look but with a less radical cam and more bottom end torque. Oh almost forgot comp ratio is around 10.5 to 1. I want a cam that will start pulling at a lower RPM. Any recomendations?

[73 Z28]

Try the summit #2801 cam. It has less duration and less lift which will take the powerband to a lower RPM range. The current combo you describe is designed to make power at a much higher RPM range and with the 1.65 ratio rockers your bleeding off most of your cylinder pressure at low speeds. With the 3.36:1 axle ratio, unless your using a manual trans that you can wind the motor up with between gear changes, you aren't really getting into the power band of the motor.
Paul

[arrowhead1]

You know I really never gave much thought to the summit 2801. Three cams that were recomended for my combo are the 068, the Nunzi 2401 and the crower 60916. The 068 and the Nunzi sound like old technology cams but some people swear by them especially the 068. If my budget wasnt tight I would go with the roller, but at the moment I cant. Thanks for the tip Paul.

Rob

[Cliff Ruggles]

Another option would be to swap in a set of 1.5 rocker arms for the 1.65's.  This is the same as a cam change, and will improve vacuum at idle, off idle power, and move the power curve down some in the rpm range.

An even better move would be to retain the 1.65's and add a set of Rhoad's lifters.  The 2802 is the right cam for what you are doing.  A smaller cam in a 400 with 10.5 to 1 compression may lead to detonation problems with currently available pump fuel.

A good friend of mine has a Firebird with a 10 to 1 compression 400 engine and that cam.  It runs mid-12's in full street trim, with an auto transmission and cheap "shelf" converter from Summit.  He's never once complained of the engine not having plenty of low end power, and judging by the numbers it runs, it's got plenty of top end charge as well......Cliff

[arrowhead1]

Thanks Cliff I will get a set of roads lifters and slap them on A.S.A.P.

Regards
Rob