The Stovebolt Site Forums The Shop Area Engine Shop Initial Valve Lash?

All my manuals give me the "warm" valve lash specs, but they do not specify an initial "cold" lash setting. I am guessing that I should set the valves initially to the warm valve setting for now. What do you guys think?

I would leave them slightly on the loose side of the warm setting. Leaving them a little loose won't hurt them at all. Leaving them too tight can burn out the valves or seats in short order.

Define a little loose...Say 0.002-0.004" from spec for example? Thanks.

That should be fine.

Patrick and my Howard cam card say different. They say to set .005" tighter for a new cam, cuz she'll slack up as the valvetrain breaks in. I tried setting the valves to the "hot" settings, even then it ended up sounding like a hailstorm on a tin roof. Had to go back and take up mad slack after the break-in.

chip

Chiphead, I had heard/read that somewhere as well, that the clearances actually get wider as the engine heats up. At first I thought this sounded back words to me, since as metal heats up it expands, so if the cam, lifters, and rockers expand you would think they would get tighter. But if think about all the metal in the block and head from the cam up to the top of the head, which is also expanding as it is heating up, that this expansion is going to widen the clearance more than the other components are going to tightening them.

Any chance you could send me a copy of your Howard Cam Spec Card? I never received one with my Howard M4F cam I just installed. What are the valve lash specs from the Howard's card?

Sorry, I didn't realize this was with all new parts. It is bound to loosen up then. I was assuming you just replaced the head gasket or something.

Some engines do get looser as they warm, and some get tighter. I was erring on the side of conservatism.

The Howard M4F card says hot setting .014 & .016 so .005 tighter would be .009 & .011. My experience with these settings in a rebuilt 235 was too tight and ran hot. After much fussing it ran better and cooler at .011 & .014. The .011 exhaust setting does not leave enough time for the exhaust valve to transmit heat to the head.

52pu

Thanks for the info, I will try 52pu settings to start with, but I won't be able to start the engine for 3-4 months, since I have much to do on the rest of the truck before I can put the engine back in the truck.

That'll work, set them cold with the lifter on the base circle of the cam. I usually set each cylinder when piston is at TDC of compression stroke. And dont be worried if starts to clatter during the 20 minute break-in. Just let it cool off some and reset to what 52pu said.