Proper way to measure PTV and verify pushrod length…what order?

[TexasRoadRunner68]

I finally got the call that my T&D rockers are ready to ship. I have the cam installed and degreed and all that. Cam button installed and cam endplay verified. I do not have an old head gasket…and I’d rather not waste a set of head gaskets just to take measurements. Will the compressed height of the gasket drastically affect the needed pushrod length? I would assume I need the proper pushrod length to measure PTV clearance? What order should these be done in, and which should be first?

 

[pnora]

You can just add the compressed thickness of the head gasket to the desired length of the push rod. Lots of videos out there on piston to valve measuring.

 

[pnora]

You can just install a gasket and just snug the bolts. That way you will not ruin a gasket. Lots of guys will reuse them. Myself I do not. You can measure the thickness of the new gasket and subtract the compressed thickness and use that number to subtract from the P to V.

 

[rickseeman]

I'm sure you already know this but it's worth saying. You have to know if the T&D's take ball/ball pushrods or ball/cup. Most wedges came with ball/ball. Then people put in solid cams and go ball/cup and have to measure for pushrods. Then high end stuff like T&D might be ball/ball. The pushrods measurements will be different. And of course you have to order a different measuring pushrod for ball/ball. You probably already knew all this but I've been caught in that trap before. Once you get the rockers installed, take the valve springs off of your #1 cylinder and put checking springs on. As stated above, just put your head gasket on there and snug the bolts. That's close enough. Now measure for pushrod length. While you're there, if you want to measure PTV using the dial indicator method, the measuring pushrod will be strong enough for this. I think you will find the exhaust valve is closest at 8-14 BTDC and the intake is closest at 8-14 ATDC at overlap. You can verify that, I haven't had to do that in decades because Hemi strokers don't have domes anymore. Sorry for the long post.

 

[diesel_lv]

I went from Comp hydraulic roller cam n lifter to Hughes hydraulic roller cam n lifters. All are different. Pushrods for Hughes combo are "about" 3/8" shorter than the Pushrods for the Comp combo. Lifter plunger/body on Hughes is longer.

When I did all my ptv, roller to valve tip geometry and pushrod length measurements, I installed heads w gaskets to spec. Engine never fired, and gaskets totally reusable. Never had an issue on any engine doing that.