I have a 71 429 that I put a RV cam into. The specs on the cam are .305 intake, .534 exhaust. The motor still has the stock valve springs, and I was wondering if I am in danger of breaking one. Thanks

 

Best person to answer that would be the cam manufacturer. They will be able to tell you the needed seat pressures to the type of cam you are running.

 

Thanks for the reply! I'm not sure what brand the cam is. All I got from the machine shop is the cam card and it doesn't even say the brand on it. I know its stupid, but its true and it sucks. I was just thinking that .534 is alot of lift for the stock springs, just wondering if anyone knows how much the stock spring can hold up to. I found some edelbrock springs for around $50 or $60. Not bad. How hard are they to change, and do I have to remove the heads to change them so the valves don't drop in the cylinder. I've never messed with this before. Thanks again

 

I would suggest still contacting the people who gave you the cam. They will have some record of what brand cam it is. If not look for any #'s on the ends that will narrow down the cam maker. As for swapping springs if you have to, make sure you double check the spring pressure open/closed with a spring scale. The machine shop you used can do this for you for a small fee if you don't want to spring for the guage, pun intended. There is a spark plug hole air adapter that allows for you to pressurize the cylinder to keep the valves in place as you are removing the keepers. Just make sure you put the cylinder at top dead center before removing them. If the air pressure happens to cut out all you have to worry about is pulling them back up with a magnet. The piston will keep the valve from completely falling in the cylinder. Also you will need a spring compressor for removing the keepers with the heads on. My machine shop allowed me to borrow their spring compressor and air chuck.

 

FYI most stock springs wont handle more than .500 lift without problems.

 

Thanks for the reply. I think I'm gonna get some new springs now and have the shop put them in. I'm thinking of changing the cam too, to a basic performance cam with less lift, probably something like a comp cams 268H. I'm running stock 71' Dove-A castings(the motor was a 2bbl originally). I might keep the cam RV cam in it for now due to money. If you have any suggestions let me know. Thanks again.