What is the cams max lift that you can put on a set of 305ho heads. I had 1.94 intake valves put into them, but when we put the motor togather we ran into a problem, the cam is a 515/515 solid. And when it opens up the valve the coil is almost compltly compresed.



I really dont have any more money at this point to put into it. So what im asking is if anyone has had this problem before, and what they did to fix it.
It is a 350 bored .60 over, 305 ho heads, SpeedPro pistons, Isky cam, Gear Drive,Excel by wiend intake,650 holly,accel super coil, msd box,7 quart oil pan, Elite valve covers,accel 8.8 race wires.

 

305 HO heads are no different from any other 305 heads of the same vintage. I'm going to assume you're referring to "416" castings; that's what came on my 83 305 HO, as well as my wife's former 84 Caprice, my brother's LG4, etc.

Your problem isn't the heads, it's the valve springs, you'd have the same problem no matter which cast-iron they're stuck on. IMHO .515" is too much lift for any stock-diameter (1.25") springs, but some of the spring suppliers claim otherwise. If it was my motor I'd get the heads cut for 1.45" springs.

The Comp conical springs might work OK for that without machine work, you'd need both the springs and the retainers to go with them.

 

Also some more advice.....that cam is very big for a 350. You are gonna need I'd say at a MINIMUM 10.5:1 compression, a VERY good set of heads and some RPM to take advantage of it.

Just pointing this out because OVERCAMMING is very common these days & all it will do (BELIEVE IT TRUST ME!) is make the motor a dog down low in the RPM range, run poorly & eat gas for NOTHING.

The best flat-tappet cam i have seen run on a mild 350 with a good dual-plane intake, 650 carb, a set of headers & good free flowing exhaust is the Comp280H (12-212-2)

Honestly, this cam wakes up any small block. Its hydraulic with .480/.480 lift & i cant remember the duration.

Anyhow i hope this helps,

-Carm