jobe_ls1

iTrader: (9)

Please help, I was doing some maintenance yesterday sealing the intake rocker bolts as they were seeping oil in the FAST intake. Upon reassembly of the rocker arms I removed the rockers while on the base circle but compressed the valves when I re-torqued them to 22ft-lbs. This had me concerned so now I am going to recheck my pushrod length tonight.

I built the entire engine myself and it seems to be running good with no strange noises but I was chasing down a possible intake leak a found the intake rocker bolt needed sealant.

I have a LS3 416 with TFS 235cc heads 70cc chambers, yella terra rockers shimmed 0.072" (perfect wipe) ,0.051"cometic head gaskets, Manton 7.635" pushrods and comp cams 237/254 0.62x,0.63x LSr.

During the build, I had checked the pushrod preload using an adjustable and 1.5 turns to give 0.075" preload. I ended up with a 7.635" pushrod and now thinking about it seems long but I wanted to check here to see if anyone has used one this long on a similar app. As I said I am going to recheck tonight but wtf why couldn't I have gotten this right on the stand?

kirbyman03

iTrader: (7)

When Josh at the WS6 STORE assembled my new build this year with Patriot Predator heads which have the 3/4 in deck and a custom speced EPS cam. he checked push rod length the same way as you with checker and to get to 1 1/2 turn to 22ft lb it came out to 7.625, it worried me too. but others I have talked to on here with the Predator heads or other brands with the thicker deck were any where from 7.557 to 7.644. So I guess it's in the norm. I have had no issues when dyno tuned engine showed no signs of valves hanging open to long and the tuner was pleased with the results 436RWHP 391RWTQ Thru a 12 bolt. Also spoke Patrick G who speced the cam and Geoff Skinner who had the cam built had no problem with my pushrod length. hope this helps, glad to know I'm not the only one who questioned this.

jobe_ls1

iTrader: (9)

Thanks, I just read some guy over on CF had ran a 7.7" pushrod

I was able to check the intake tonight and it is 1.75 turn from 0 lash which would be .086" preload? Checking 0 lash with the adjustable I got 7.530" so running a 7.635" Manton gives me 0.105" preload for the intake.

I have not checked the exhaust with the adjustable yet but when assembling I recall 1.5 turns from 0 lash which gives 0.074"? Will check with the adjustable and verify.

Based on the LS7 lifter GM recommended preload of 2.09mm or 0.082" am I ok on the high side?

Check out my cool wipe pattern. The valves are doing some interesting dance moves.

vettenuts

iTrader: (4)

1.75 turns per my calculations is 0.110" which is more in line with your measured value. Your exhaust may come in higher as well, my calculations indicate 0.091" with 1.5 turns.

Your wipe pattern is fairly narrow for a stock rocker, what rockers are you running?

jobe_ls1

iTrader: (9)

I was not sure if the threads are 1.25 or 1.5. It matches up with my intake adjustable measurement and your calc if I use 1.5 thread pitch times # of turns.

Are these accecptalbe preloads or do I need shorter pushrods? Like 7.600"?

Thanks, I am using yella terra ultralights 1.7 ratio shimmed 0.072".

Sales2@Texas-speed

iTrader: (5)

What are you multiplying by per turn?

soundengineer

iTrader: (16)

also, why are you looking at .110 preload? that is WAY TOO MUCH

you should be around .060 at the most.



this ^^^ is for a stock cam and heads....not for an aftermarket cam and heads setup

jobe_ls1

iTrader: (9)

Ok I will go with a 7.590" or 0.045" shorter pushrod.

vettenuts

iTrader: (4)

No, its 1.25 not 1.5. However, you need to correct for bolt rotation that doesn't add to preload (1/3 turn on my car) and then correct for rocker ratio. So the 1.75 is done like this:

(1.75-0.333) X (1.25/25.4) X (2.7/1.7) = 0.110"