Figured this would be the best site to ask.I want to use a cam with 500lift,302 advertised duration;in.opens 21deg./closes 45 deg.;Exhaust valve opens 53deg.,/closes 13deg.Using the 416 heads with mild intake porting and pocket ported.Was wondering if these heads would choke this cam .This is not a street vehicle,is a brackett racer.
I have read quite a bit from the site and know that some here have quite alot of experience with these heads and I would appreciate any and all response.Thanks.

 

What size valves? What engine? What RPM peak?

I'm hoping that the upper valve guides were cut down to allow those lifts, too.

 

Vader,valves are original 1.84 in.1.50 ex. Engine is a .030 over 283.Guides/bosses are cut down to allow .050 safty clearance.Trying to build for 3500-6500 RPM but was wondering if these heads will limit peak power to below 6000.

 

NHRA Stockers are limited to that head and spin their little 305's to 7700+rpms...from what i'm to understand, the runners are untouched...though they are not running that much lift.

 

The more ya port the 416's the more power you'll make and the more the motor will like the upper rpm band. "Mild porting" and stock sized valves will get you a modest increase over a stock head. Nothing is stopping you from porting further if you'd really like to have a rev-er. I recommend full porting and 1.94" intake valves for best results

A 283 with that large a cam will want tons of rear gear and a very high stall 8" racing torque converter (4000 to 5000stall) or a 5 speed. Consider 4.56's a starting point.
(largest gear available for a 7.5 rear) You really want 5.xx gearing.
The engine is going to want to rev. Get good valve springs and shim them to optimize seat and open pressure. Use a Performer Rpm Intake. it will pull hard well past 6500 on top of a 283. Install the cam advanced in the motor to maximize overall torque. 99 to 102 intake C/L.
You want to measure and adjust the engines' compression ratio. You want 10:1 for pump gas. If you are going to use racing gas, the more compression ratio you build into it the better the big cam will work for ya. I have flat milled 416 heads right to the spark plug boss and intake valve seat and gotten 52cc chambers.
You can also get compression using thin head gaskets and decking the block.
Remember, 10:1 for pump gas, max compression for racing gas. Pick one and go with it.
Don;t let all this scare ya off, just realize that big cams in little motors like compressionratio and gearing and lots of R's.