camshaft- head- bbc ??????

[royo]

big block people how much cam lift can you use before you have to cut the guides on bbc heads thanks

[royo]

what nobody knows? all these drag motors and no body has wondered how much bigger than stock you can put in the motor.

[Outlaw72]

Well, I'm not a head guy so I really don't know but I think piston to valve is a bit more important than the guids. I'm no head expert though. What I do know is that springs are designed to not exceed certain pressures when the valve is open. I don't think the guids are so much of an issue as PV and spring tolerances.

[ProStreet68SB]

Originally Posted by Outlaw72

Well, I'm not a head guy so I really don't know but I think piston to valve is a bit more important than the guids. I'm no head expert though. What I do know is that springs are designed to not exceed certain pressures when the valve is open. I don't think the guids are so much of an issue as PV and spring tolerances.

piston to valve in important, but if you dont cut your guides your could end up dropping a valve. So i wouldnt say it's more important.

But to answer your question....I'm sorry but i dont know the answer either. Sorry.

[nxtruck]

There's no hard and fast answer to this. First, you have to determine how much lift you will have. Then, once this figure is known, you check the distance between the retainer and the top of the guide with the valve closed ( your installed height ) and subtract your gross lift figure from your installed height. Hopefully, you'll end up with at least .060 or so extra clearance. If not, then you know the guides will have to be machined.
Sorry for not being more specific, but there's no way of knowing for sure without taking these measurements.

[royo]

thanks guys

[70rs/ss]

BBC are not like the Vortec SBC that only take 430 in stock form. BBC heads are a lot more forgiving, but the shop doing your heads can check the clearance.