kmetros

iTrader: (2)

I used Comp's push rod length tool to determine that my base push rod length was 7.300. I checked two intake and two exhaust on both sides and came up with little variance and an average of 7.299. I have installed an EPS 226/230 cam ground by Comp. Their lash spec is 0.030 +/-0.010. I am using LS7 lifters and their spec operating range is something like 0.040 to 0.080. I'm looking to run as little lash as I need to to minimize valve train noise while staying above 0.040 to avoid converting my hydraulic LS7 lifter into a solid lifter. So, with a base length of 7.300 I can either go to a 7.3250 (only 0.025 lash - too little for the LS7 lifter) or 7.350 for a lash of 0.050, which is what I opted to pick up. So, now when I install the 7.350 push rods and torque them to spec their is no play on the tip of the rocker arm where it meets the tip of the valve stem. I made the assumption that when I was done torquing the bolt to 22 ft/lbs that I could place a 0.050ish thickness feeler gauge between the rocker and tip of the valve stem. Both lobes are on base circle. I have confirmed this by feel and visually (only one head on block and looking through from other side). Am I missing something? Isn't lash something I should be able to measure if I've done this right??

bww3588

iTrader: (49)

your doing it right...these are net lash engines meaning there is no valve lash at the tip of the valve and the rocker arm. all valve train clearance is in lifter preload. you went with a .050 longer pushrod than what you measured meaning you set your lifter preload at .050. (plunger should be .050 from the top of the retainer clip)

kmetros

iTrader: (2)

Can you clarify what you mean here? I'm not sure if you are referring to the lash at 0.050 or the cup depth difference of 0.050?

I know the cup is shallower on the LS7 lifters vs the stock LS1 lifters (0.050 shorter) and I'm confident that as well as the 0.040 gasket (0.014ish shorter) and light mill job (0.006ish shorter) are what is accounting for the difference between the 7.425 rod EPS thought I would need and the 7.350 rod I in fact need.

NVR_SPDS

iTrader: (39)

Someone correct me if im wrong, but you want zero lash. Even on the base circle, you wont be able to get a feeler gauge between the rocker tip, and valve tip.

Austinma62

Your right, if your able to stick a feeler gauge in there. That would mean you have no preload since there is an air gap. Im doing a h/c install myself with LS7 lifters and were going with .084 preload, with 7.350 pushrods. I have had many ranges but the typical is between .050-.100. This whole are seems wierd how you ask different people but thats just what I have seen. Good luck man.

bww3588

iTrader: (49)

there is no difference in the LS7 and LS1 style lifters. this has been beaten to death on here. LS7 lifters are direct replacements for the LS1's.

I mean when you have .050 preload, the plunger is pushed .050 down in the body from the retainer clip by the pushrod, when the rocker bolt is torqued to 22ftlbs.

kmetros

iTrader: (2)

OK, that's what I thought you meant.

With regards to the LS7 and LS1 cups being the same mine look different and I have no other way to explain the large variance in length between what EPS said I would need and shipped me for a push rod (7.425) and what I ultimately did need (7.350). Does anyone have any other explanation for the variance? Just curious.

Darkman

iTrader: (2)

EPS shipped a 7.425 pushrod in order to maintain the same pre-load you had with the stock cam and the 7.400 pushrod. The diference in pushrod length is based solely on the difference in the stock cam's base circle and the EPS cam's base circle.

kmetros

iTrader: (2)

Oye. Now I'm getting more confused. If the difference is due to the difference in base circle, why wasn't I sent a shorter pushrod? You're not saying I need to run the 7.425's they sent me, are you?

Darkman

iTrader: (2)

The base circle on the EPS cam is smaller to accomodate a higher lift, so a longer pushrod is required to maintain the same preload you started with, assuming, of course, no other changes (e.g. millled heads, a change in lifters.)

In your caase whether the 7.425 pushrod will accomplish its intended purpose depends on the effect of the lifter change. As has been pointed out, the effect of LS7 lifters on pushrods has been beat to death, but never actually resolved. So all you can do is follow your measurements.

https://ls1tech.com/forums/14981732-post23.html

kmetros

iTrader: (2)

Ok, read the post and I get it. I'm still baffled by it all. The lifters are the most likely culprit. The cleanup work to the heads and thinner head gasket couldn't account for that large of a difference (0.075) in push rod length. I wish I would have put one of my original LS1 lifters in another cylinder/head and checked what I came up with length wise for the LS1 lifter vs the LS7 lifter. Of course, the heads are on now. :-) I have a friend that's going to be putting an LS1 in an RX7. I may send one of my old lifters to him as he is planning on running LS7 lifters also and ask him to do this to see. So, I guess the mystery continues!!

Darkman

iTrader: (2)

At this point you really do not need to know how much difference the lifter change is making, how much difference the thinner gasket is making, or any other change - you need only base your new pushrod length what you can measure now with the adjustable pushrod.

https://ls1tech.com/forums/7957678-post2.html

kmetros

iTrader: (2)

Yes! This is the procedure I used. I even setup a spreadsheet to do the math and average the 4 cylinders I checked. I'm good.

Thank you VERY MUCH for your posts today. They have put me at ease today, but even more so when it comes time to turn the key!