Im currently at the stage of measuring pushrod length for my heads and cam swap on my 01 TA. Im using 243 heads milled .015, TSP 228R cam, GM MLS gaskets, Morel 5315 lifters, Strub bushing trunnions in stock rockers. To measure I have the comp cams adj. pushrod tool. At zero lash the pushrod is at 10 3/4 turns. 11 turns feels the same, maybe a little tighter. At 10 1/2 turns it has play. At 11 turns and .050 preload, that puts me at 7.4 inches, or stock length. Does this sound right? I thought they would be shorter than stock. At 10 3/4 turns and .050 preload the length is 7.3875.

My question is what length pushrod should I order? Should I run less preload and order 7.375 or run stock length at 7.4? The spec that came with the lifters is .045-.050. Im plan on ordering Manton 11/32 pushrods if than matters.

This is my first time doing this so I want to make sure I get it right.

Thanks

 

I very highly recommend getting a 8" caliper and measuring the length you got. Add 050" to your measurement. Manton will make whatever length you want. Just tell them you want them at whatever length you get as measured with a caliper. They'll be +/- .005 on length.

If you really want to optimize, measure all 16, and when you get the pushrods, put the shorter ones and longer ones where you need them. Optimization is time, but it frees up ponies.

 

Ok, I will buy a caliper. How big is the margin of error with it comes to pushrod length? I ask because then I had the tool at 10 3/4 turns and at 11 turns I could move the rocker side to side without any play up/down. That length difference would be .0125. I've never done this before so I don't know what the prefect "feel" is.
I installed 2 stock pushrods in one cylinder and the rockers felt pretty good to me. I also turned the motor over to make sure it didn't bind up.

 

I got a 8" caliper and now Im even more confused. I measured the comp pushrod tool closed and got 6.815. I Measured a stock pushrod and got 7.390. Then measured the comp tool at 10 3/4 turns and got 7.355. So add .050 and I get 7.405. So should I run stock length push rods? Why is the comp tool off by .015? I also measured the comp tool at 11 turns and got 7.365.

 

It's not actually off, it's measuring gauge length not overall length.

 

Then how will using a caliper help if it gives different measurements?

 

Just tell your pushrod manufacturer your measurements are overall length if using the caliper or gauge length if using turns on the checking pr

 

I like to be +/- 005, but sometimes you have to be practical about it. If you're +/- 010 you'll be fine. That'll put you between 040-060 preload.

 

Ok, I just measured 2 cylinders, one on each side, using the caliper. I got between 7.345 to 7.355. Biased on that, I should tell Manton to make them 7.4 overall length after adding .050 for preload?
Oh and sorry if these are dumb questions!

 

Based on using a caliper and 0.050" preload, you want 7.400 inch overall length. I believe Manton still uses OAL so that would be OK. Tolerance on the length is usually +/- 0.005" anyhow.

 

Yep! And if you take the time to measure them all, you can optimize. Put the shorter ones and longer ones where they are needed.

 

I went ahead and ordered the Manton 11/32 pushrods at 7.4 overall length. Hopefully I don't have any problems with that length. I didnt check every cylinder because I did want the numbers to get more complicated in my head haha. Thanks for the advice though.

 

I just put unmilled 243 heads, an eps 222/226 cam, and ls7 lifters on my ls1. Got 7.4 pushrods with 1 1/4 turns (60-80 preload I think). Hope that helps