Understanding Piston to Valve Clearance – Part 1

There's a lot that goes into understanding proper piston-to-valve clearance and how to set it up. Steve Morris of Steve Morris Engines walks you through the key things to know in this episode of Steve Tech.

[SteveV]

Steve Morris is a modern day Engine genius. I've learned so much from him.

[EllweinEngines]

Thanks for the clear and detailed info. Please keep us fed with the Steve Tech

[ezsautomotive]

Great info Steve..& perfect timing for a 15:1 alky BBC 540 motor we're building now...

[AB-X]

Finnegan on his Allan Johnson obsession. "I just want to tackle Allan Johnson, so that maybe some of his smarts will come over to me via osmosis.". Well. time to tackle Steve too lol.
Cool stuff. Thinking about ordering a new set of slugs for my 583 just to see if I can get the efficiency up even more.

[hoonaticbloggs]

Checking my ls1 with 25 thou shaved heads, no gasket and 7.375 pushrods I got contact with the piston. With a 50 thou gasket and 7.4 pushrods I got 60 thou.

[frozenstang]

Its stretching farther than that if you factor in HG thickness.

[marlonbarrentine]

Steve....I'm going to need a shortblock soon...

[genemounce]

1st time I've ever been told about 'valve bounce'... I totally understand why PTV clearances are so important now. So much for that .700 lift cam in my LQ4. LOL , jk.

[racerd]

A common mistake I see inexperienced engine assemblers do, is they check the P to V with checking springs. The proper thing to do is check it with the running springs. Test springs can give you as much as .100 more clearance than the running spring. So if you want to run the intake valve as tight as .035 you better check it with running springs. Also I feel running the intake valve that tight to the piston will help the piston start the column of air in the intake track start falling into the cylinder sooner. Maybe this is why pro stock engines have it that tight?