I am biulding a 350 for my 56 chev . Edelbrock 650 carb, air gap intake and Alum RPM heads with a 9.5 to 1 comp ratio. It is a 4 speed stick and 3:73 rear axle. The car has power disk brakes so I need vacum. What should I look for in specs. for a good cam
To be completely honest, you will be better served to call Comp Cams and give them all the info.. They can calculate what is opimum for that setup.
Not dodging the question, I just think they would be more accurate.
Their number is 1-800-999-0853
A vacuum canister will store enough vacuum for the brakes to work properly.. Check out the 268H comp. cam. I thing it has a 487/490 hydraulic lift, builds good power, has a somewhat lopey idle, but is very streetable. I had one in a 10-1 compression 355 with worked over 462 casting double hump heads and a single plane intake and a 750 holley. The 68 Camaro it was in was driven almost daily and built plenty of power and had a real good sound for a mild build.
Get a cam with 218-220 duration on the intake (@0.050") and 220-230 on the exhaust. This is enough duration to easily get you 300+ hp. Aim for .460-.480" valve lift for a street car to avoid needing super beefy valve springs.
Try to get one with 110 lobe separation angle. This will give you a nice lope and you will have plenty of vac to rum power brakes without an ugly canister. And it will still be super streetable with a good dual-plane intake.
This cam should be good from just off idle to 5500+ RPM.
For my street small blocks I will always go for a Hydraulic cam about this size.
If you had a bigger motor (say...383) I would go more aggressive with the duration.
If you had the scratch for a Hydraulic-roller cam I would go for that, and then you could get even crazier on the cam specs and still be super streetable.
I have one in my car ( a 517 Big Block), and I gained 100 horsepower and the car is still very docile on the street. 246 and 256 duration @ 0.050" and .645" lift on both sides with a 112 separation. Car drives to the track, 45 miles away runs 7.50's in the eigth-11.80's equivalent (Can you believe in my area of So Cal we're down to one 8th mile track! Whats the world coming to?)
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