Qhestion on Cam lift & Stock Heads

[ROYAL_6]

Ive read on here on different threds, than when going with an aftermarket cam, regardless in roller, solid, flat-tappet, ech.. there is a certain "MAX" lift that the stock guides can clear before having to machine them.. my question is, what is that "MAX" cam lift? I read that once you start hitting .500 and up , is when you HAVE to get the guides (heads) machine. i understand that you also have to change the springs, but my concern is the guides. the current cam that i purchace has a cam lift of .448 (208/208) now would i need to machine the guides? what would you guys consider to be the max lift point you can go before having to machine the guides? sorry for the long question, thanks for all your help..

 

[Jerryl]

........the current cam that i purchace has a cam lift of .448 (208/208) now would i need to machine the guides? what would you guys consider to be the max lift point you can go before having to machine the guides? sorry for the long question, thanks for all your help..

You'll be fine.
After 0.500 lift you typically run into problems.
ALWAYS verify the clearances on anything over 0.450 as the heads are raw castings. You want about 0.050 clearance.

 

[ROYAL_6]

You'll be fine.
After 0.500 lift you typically run into problems.
ALWAYS verify the clearances on anything over 0.450 as the heads are raw castings. You want about 0.050 clearance.

thank you for the reply.. truly appreciated... :biggrin:

 

[charlief1]

We had a thread on here a few months ago so I decided to check the 293 castings I have sitting here. With the stock valves and keepers on it you can get away safely with a .448 lift but going bigger you will need to check to see if it will clear as Jerry said. In the long run it's easier to have them cut the guides down when the heads are getting a valve job and change to the TTA exhaust valves so you don't develope an oil sucking issue. Just make sure that you use the Chevy valve seals which are a little smaller o.d. so they clear the springs better. Hope this helps.

 

[BlackBandit]

Is that .448 on the lobe or on the valve side of the rocker?

 

[thadeal4real]

retainer to guide clearance

what about coil bind

 

[charlief1]

.448 lift is at the valve, the lobe would be .289. As far as coil bind that's why you need to check everything but if you go with comp springs you should be ok.

 

[ROYAL_6]

Is that .448 on the lobe or on the valve side of the rocker?

thats on the lobe... :biggrin:

 

[mygn276]

thats on the lobe... :biggrin:

silly