LS Tech: Measuring Piston to Valve Clearance

How to measure piston to valve clearance. If you're going big on a cam, don't skip this step. It can end badly.
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[@daren9721]

Always great video's. Gives me the confidence to do it myself. Started wirh exhaust and headers, man those headers are hard to get off lol . Thanks for your video's and happy new year from Canada 👍🏼

[@ScrufsGarage]

Yea getting headers on/off can really test your patience haha. Good luck!

[@daren9721]

@@ScrufsGarage thanks

[@isidrosevier1125]

So you just put in the 4 head bolts around that piston? What did you tighten then too?

[@WhiteBuffalo187]

Yo scruf, been using your videos for a long time I really appreciate all the help. I currently cannot find my old compressed head gaskets and I’m finishing up a 5.7 build for my Camaro. I need to check for proper push rod length before checking my PTV clearance can I do this whole process without head gaskets and just add the thickness of my compressed gasket accordingly to each measurement I need. Or should I go ahead and install the head gasket torque down the heads then check for proper push rod length remove the heads check the PTV clearance and reuse the unused new compressed head gaskets afterwards ?

[@jeremyeubanks2387]

So with the solid lifter you don't tighten the rocker arm to 22ft lbs you just set it to zero lash ???

[@WATCHMEWRENCH]

Hey Scruf, I enjoyed the video and some of your others as well. I also hace PRC heads on my LS3, in fact I have a similar channel and also work on my corvette and share my build just like you. You may enjoy my channel as well. Good luck with this build, very well executed and looking forward to the final outcome.

[@ScrufsGarage]

Thanks. I've watched some of your videos as well. You've got a beast of a Corvette! Great videos.

[@WATCHMEWRENCH]

Thanks Scruf

[@curlynigero6417]

What's the specs of you motor?

[@CarportGarageDragRacing]

Wouldn't a hydraulic lifter that has not been pumped up just compress a little under the spring pressure?

[@ScrufsGarage]

Yes that's correct. Here's a trick on how to make a solid lifter for use when measuring PTV clearance and push rod length. kzbin.info/www/bejne/Zl7Hp594nrJ5i5Ysi=YX3Rgi-f2BAX82r0

[@isidrosevier1125]

Hey are these the SRP pistons that JE sells?

[@ScrufsGarage]

No, these are the FSR series pistons from JE Pistons. www.jepistons.com/Catalogs/Automotive/Chevy_SB/15_ls1.aspx

[@dangerousfreedom4965]

Good vid, I’m in the process of rebuilding an LS2 with an aftermarket cam. In the process of tearing the motor down and cleaning the piston tops I noticed two very small marks on two pistons that look like a valve had mad contact in the top of the piston any suggestions? Seams strange that only two would have marks.

[@ScrufsGarage]

407ForRent hmm not entirely sure. Perhaps an over-rev at some point and it floated a valve?

[@baby-sharkgto4902]

What lift cam?

[@ScrufsGarage]

I was using a Cam Motion Titan 4. 227/232. .612"/.595". 113 +4 LSA. cammotion.com/camshafts/titan-4-ls1-camshaft-227-232-113-4/

[@jeremyeubanks2387]

How tight are the head bolts

[@ScrufsGarage]

If you're using old head gaskets, they will already be crushed, so you don't have to go through the full torque sequence on the head bolts. But they do need to be snug. There can't be any movement in the head or it will throw off the measurements.

[@jeremyeubanks2387]

@@ScrufsGarage but u can just put the head bolts around the cylinder I'm checking like you did in the video

[@JuanyJuanes]

Do you use the old gasket while testing this? It could change the clearance distance, but it looks like you did a temp install just to check the clearance

[@swackhammer2139]

I'm not 100% sure this is correct. Seems like measuring PTV with solid lifters and pushrods measured for preload would give tighter PTV measurements. With solid lifters wouldn't you need a 0 lash length pushrod? Otherwise the solid lifter would use the pushrod with the added preload length to push the valve closer to the piston making it seem like clearances are tighter than they really are. Is that right?

[@michaelcouey1383]

correct. But if you know your lifter preload, you can add that to the clearance. If his PTV clearance in this video is .160, and his preload on a non-solid lifter is .080, if I am thinking correctly you'd multiply that preload by the rocker ratio and add that to the clearance. so for a 1.7 rocker you'd get .136, which gives a total PTV of .296

[@1Kile1]

This method is so wrong. If you are doing this. Your are getting false reading and sense of clearance.

[@rubberbandman2540]

hey mate which method do you reccomend ?????? I use the check springs with a dial indicator and eliminate guess work what do think cheers