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.
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.
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.
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.
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?
How does it give .100 more clearance with checking springs..? Do you mean the valve goes down .100 less making you think you have .100 more clearance..? The lifter, cam, pushrod, rocker and valve stem tip are all in contact and essentialy a connected unit in both scenarios regardless of spring pressure so the rocker should push the valve into the clay either way if youre doing the clay method..... unless youre talking about using a hydraulic lifter to check p/v..? Then the running spring would squish the lifter spring down and give the more clearance youre talking about. checking spring isnt hard enough to so iis more accurate there, but you said the checker Spring gives more clearance... you wont get deflection with the checker spring like you would the running spring if the rest of your valvetrain isnt up to snuff so that cant be what you mean.. And even if you use the dial gauge on the retainer with a checker spring, that wont cause .100 less clearance and cant be done with the running spring.. im having a hard time picturing a scenario where a checker spring gives a .100 clearance error, care to explain..?
Yea, i read what you said.. but if you read what i said, i was asking for clarification... i might have worded it poorly, stuff makes more sense in my head than when it comes out.. if you have .100 MORE clearance with the checker springs, that must mean the rocker hasto be pushing the valve down .100 LESS At that same degree wheel spot, less valve motion equals more p/v clearance doesnt it? I mean, the fact that the checker spring allegedly gives more clearance than the running spring (meaning you think you have more clearance than you actually do) that extra hasto come from somewhere... and im struggling to see where it comes from.. like i said, the valve train is all connected together, touching, i just dont see HOW it ends up with more and where that more comes from.. like, why does it end up with more, simply because its a lighter spring..? Im just struggling to see where its coming from..... the checker doesnt seem strong enough to deflect anything and prevent the rocker not pushing the valve down as far...
@@benjaminrutledge7675 I understand what you are trying to say, but what I am saying unless you really do it you will never understand how much the P2V changes. If I have an engine with say .020 on the intake with test springs I will put on the running springs on and then test it again. I use a tool made by Manley that goes on the rocker arm and then I test it again. On a very max effort you want the P2V very close on the intake like he was saying in the video. This is the 55th year I have been building racing engines, so I have learned a lot over the years.
Interesting. I could definately see a small amount of tolerance stack up there contributing to it.. Im not at that stage yet due to all the shipping delays on parts right now but ill have a look when the time comes, might be a couple months.. i might do a video on it.. i guess it must be one of those “it is what it is” things. Good talk.
