Solid roller valve adjustment hot Vs cold

[ghittner]

I just broke in my new solid roller blower motor. Time to adjust valves. Getting to the valve when the engines hot is difficult in that I have to loosen my exhaust manifolds to get the valve covers off. So, by the time I get to the valves, they will be luke warm. Is that warm enough for the adjustment or do I have to modify the clearance as the engine will not be hot? Thanks

[WannabeRacing]

First things first, we need to know a little about the engine. If it is an aluminum block or cast iron, the deck height and are the heads aluminum or iron. Stuff like that. Because aluminum grows way more than cast iron. An aluminum block can grow almost three times as much as a iron block. Similar with the heads. Also the more meat (deck height) the more material to grow. So when you have a solid iron block and heads- something like standard deck Merlin stuff, you can see as little as two thou difference hot to cold. An all aluminum real tall deck deal can grow as much as 15 thou. I have heard of more in certain very high heat applications, but lets stay with the real world for now. Cast iron chevy big block with aluminum heads with good fresh water flow in a boat, you will see less growth than a car or a dry drag race engine. You will probably see somewhere around 4-5 thou.
When you warm the engine up, it will not grow right away. Don't expect all the growth after two minutes of warming it up. Allowing the heat to sink in takes some time. So the time to get your valve covers off may be just right to get at the valves at optimum temperature and growth. If you want to get the thing warm, but not skin bubbling hot, just do so and set them a half to a thou tight for iron heads or a thou or two thou for aluminum. Make tripple sure they are perfect, then tighten the girdles down and run the thing.

[ghittner]

Gen 4 iron low deck block, Canfield aluminum heads. Solid roller.

[WannabeRacing]

I would go about four thou tighter than the cam spec cold, or just fire it up and by the time you get the valve covers off, set it and be done.

[River Rat 005]

I always set mine cold. That way theres no burnt fingers and the block and heads stay the same temp during the time it takes to adjust them. I don't think a thousandth or so difference in the settings is going to make any difference in how the motor is going to run. Unless this is a pro stock motor.

[ghittner]

Thanks for the info. I set them warm. It took about 45 minutes from the time I shut it down to finishing the adjustments.

[beernut]

just a thought but you could set them warm, and leave the cover off overnite and check the lash again cold, and you would then know what to set them at cold :idea:

[ghittner]

just a thought but you could set them warm, and leave the cover off overnite and check the lash again cold, and you would then know what to set them at cold :idea:
Brilliant..... But I have already put them back together... Next time.:mad:

[WETTE VETTE]

just a thought but you could set them warm, and leave the cover off overnite and check the lash again cold, and you would then know what to set them at cold :idea:
I did that in reverse order. Set the lash cold, warmed the motor up and checked the lash. On my aluminum head 598" the lash opened .005 when hot consistently across the board. Now I always set cold at .020" for a .025" hot lash.

[H20MOFO]

Just Curious. Would Anyone Go Iron Heads, Instead Ofalum.(with Solid Roller) Just Because Of Expansion- Valve Adj. Issues? Nothin Sounds Worse Than A Valve Rattlin

[ghittner]

Yes, absolutely!!!!!!!!!!!! By all means run them. That's what I wanted to run B4 I got all crazy. Lemme know how they run, should be good!

[WETTE VETTE]

Just Curious. Would Anyone Go Iron Heads, Instead Ofalum.(with Solid Roller) Just Because Of Expansion- Valve Adj. Issues? Nothin Sounds Worse Than A Valve Rattlin
Have done iron heads on several motors with solid rollers. With iron the lsah closes .002" - .003" from cold to hot. If the lash is set correctly the vlave clatter is minimal in either case. Also today's cams have very soft lash ramps so the noise really isn't much more than hydraulics. Some cam mfg's offer tight lash cams the require hot lash settings as small as .010". I prefer a little more lash for insurance against burning a valve particularly on the exhaust.