86Tri-z

So I’m changing pushrods after putting smaller head gaskets and milled heads. I ran the 7.4s with these heads before I swapped gaskets but I suspected them to be too long back then. Ran ok though just sounded like it didn’t have compression when I shut it off before. Didn’t turn off immediately almost like dieseling. Anyway I used the adjustable pushrod had the rocker torqued was at zero lash got 7.24400 on the adjustable pr plus the .090 preload for ls7 lifters it comes close to the 7.35 pushrod. I measured the adjustable pr to 7.35 and tighten the rocker down with a nut runner screwdriver then tighten it with a ratchet it fully seated at about 1 1/4 turn to 1 1/2 turn but it looks like it’s pushing the spring down still. Should this be happening? When I loosened it and did it again it tightened all the way at like a 1/4 turn so it must have pushed the oil out of the lifter. Every cylinder I measure comes close to the 7.35 pr I’m just rounding to it. I can post the exact measurements I’ll go do it again on another cylinder

86Tri-z

I guess I should have put stock bottom end 98.

86Tri-z

I get 7.246 on the other side. So 7.246+.090=7.336. Should I be trying the 7.35 pushrod?

86Tri-z

Just measured the adjustable pr to 7.325 and the rocker seats at 1 full turn but still looks like it’s pushing the spring down. Should this be happening?

jetech

If it is, the lifter could be pumped up and holding oil pressure which could be opening the valve slightly. If it is only depressing a couple of thousandth of a inch it's probably an ok length push rod

86Tri-z

1 full turn to seat the rocker is too short of a pushrod right? Isn’t it 1 1/4 or 1 1/2 turns for correct length

02EBC5Z06

iTrader: (1)

Do not count the turns of the bolt. Take a set of calipers, follow EOIC (Exhaust Opening Intake Closing). So when you measure an intake rod, you will turn the motor over until the Exhaust rod is opening the valve (coming up from the lifter).

Get the pushrod tool close (tape the threads so it can't turn too easily) and install it. Tighten the rocker bolt down just snug. The rocker just needs to be sat in the pedestal. Not torqued.

Check for lash, and adjust the pushrod tool out until there is no lash left. Measure the pushrod tool end to end, and then add your preload amount to that.

Follow this video from Brian at Summit. This is the proper way to do this.

86Tri-z

I was doing it the eoic method but was torquing the rocker. But I can’t for the life of me adjust the pr up without spinning the whole thing. I have to keep pulling the rocker off and adjusting it up. I get it where the rocker moves side to side easily doesn’t seem to move up and down so should be zero lash.

01CamaroSSTx

iTrader: (3)

Unfortunately that's about the only way to do it. Basically trial and error until you have the right length and once you've found it then check some other lobes to be certain that you have the correct length at zero.

86Tri-z

I keep getting different numbers on each one but still seems to be close to 7.35 when I add .090 preload. Some go above 7.35 then I add .085 it’s still right about 7.35. What is the ls7 lifter preload range again .060-.100 right

jetech

LS7 lifter plunger travel is right at .200". Good lifter preload article

01CamaroSSTx

iTrader: (3)

Yeah I'd shoot for someting around .080-.090 on preload so it sounds to me like you're there. Techinically, this should be done with some homemade solid LS7 lifters because it would be difficult to get an exact measurement everytime when working with hydraulic lifters so it wouldn't surpirse me if you were getting differences but not enough to matter when you have such a large range of preload. Keep measuring until you're confident that you've determined the length that puts you where you want to be.

grinder11

iTrader: (1)

It's likely you ARE getting slightly different readings on each one. Some might be .005"-.010" different than the next, and so on....

86Tri-z

I try to do it as gentle as possible to not put any preload on the lifters. It’s a pain when I can’t get the adjustable pr to turn when it’s in there. But soon as it’s out seems like it turns by itself. Still not fully confident on what to order. I found btr has 7.37 pr’s

01CamaroSSTx

iTrader: (3)

Do the electrical tape on the PR tool, it will keep it from turning so easily.

86Tri-z

was a good article