hey guys need some help. i'm doing a cam and intake swap and the camshaft i bought has a minimum spring rate of 370 lbs/in will stock 350 heads with 64cc chamber be able to handle the larger springs or will i have to do screw in guide studs??

 

What lift at valve with new cam and what ratio rockers?

 

stock rockers and 490 lift

 

I would not recommend that much lift with stock rockers. Rocker bind will be an issue. Ive also seen the stamped rockers blow out at the fulcrum. Even a cheap set of rollers would be better. Screw in studs definitely. You can get away with that lift and 1.25 springs. Youll want about 125lbs closed, 175-180 open. Is this a roller cam? Roller cams tend to have faster ramps, thus quicker valve events. This requires higher spring rates and higher silicone content spring alloys. Spring manufacturer will specify roller or non.

 

no its hydraulic flat tappet. a set of roller rockers will help with the coil bind? like a set of stock rockers would be okay.

 

No. The roller rockers will prevent rocker bind, not coil bind. The stock fulcrum, the slotted area where the rocker rides on the ball, which attaches to the stud, is a weak link and at high lift rates this area can bind and cause valve float. As I said, Ive had this area blow out, using your same cam specs. Roller rockers eliminate this. Coil bind you will prevent by using springs that allow for a minimum of .020 more lift than your cam produces. You also need to verify installed height according to spring manufacturer's specs. Finally, before finishing installation verify atleast .020 free coil compression by measuring total compression of an installed rocker assembly and comparing it to coil bind. Remember to account for lifter pump up too.

Your cam sounds alot like an old Z28 325-375hp cam. 125lbs seat pressure, 175-180lbs open. That should work fine for you.

 

okay that makes a lot of sense.. i did an engine and trans swap about @ months ago and im not impressed with the cam so i ordered a comp cams kit with cam, lifters, and valve springs. plus a new intake to match just wasnt to sure if it would hold up or not..

 

Just be sure not to go over 1.25 diameter if you want to avoid machine work. Also, check for maximum valve lift before the retainer contacts the guide boss.