Corey Hunt

Has anyone used these in an LT1 ? I'm trying to check pushrod length and having issues .

With OEM pushrods everything goes together good, I tighten the poly lock until I get drag while spinning the pushrod. Then I turn it a half turn and then tighten down the lock . I rotate the engine two full rotations and remove the ticket arm .I'm showing a bit off centre, closer to the exhaust side.

I repeat the above steps with an adjustable pushrod set to 7.10, when tightening the poly lock I get to the point I can't turn it by hand and have to use a wrench and the pushrod is still not right. I have to put quite a bit of force on the wench.

Am I doing something wrong? Should I have to use alot of force to tighten the poly locks? I have tried using a longer pushrod then stock the mark is even more to the exhaust side. I used a solid lifter and a regular hydraulic lifter with the same results.

atlantadan

Make sure you are on the base-circle of the cam. You don't spin the pushrod - you move it up and down. When there is no more vertical movement, that's zero-lash. The spinning method has too many variables to be accurate. If you want the easiest way to check PR length, get and have at it.

Corey Hunt

I got the same results moving the pushrod up and down as I did with the spinning method .

It looks like the rocker arm is bottoming out on the stud when the pushrod length is below stock . I went back and checked out the part number of the studs the machine shop installed. Sure enough they are the not the right studs. According to arp's website they are for a small block ford .(134-7104). I'm thinking this might be my issue.

atlantadan

Ya think?

Good luck - hope the correct studs get you straight. Don't rely on the spin method.

Corey Hunt

I wont be using the spin method going forward. I also ordered one of the tools the poster above mentioned.

I did some more looking around and both Summit and Jegs list the studs I have as working for the LT1 and SBF engines. Im going to try to find a set of 134-7101 and compare to the studs I have and see if the length difference is what is causing me issues here.

atlantadan

You are correct - those studs appear to be correct for the LT1 so your issue is elsewhere. I have to ask - have you ever set lash before? If not, maybe enlist the assistance of a pal or a shop because getting this wrong is a quick way to lighten your wallet by a lot of money.

There is nothing special about those rockers, but they're 1.5's which is not something I'd bother with. Have you backed out the center lock on the nut enough? You said: The answer is "probably". You should be able to spin the NUT down until the stud runs out of thread with zero problems. I am guessing that you are running into the actual lock (the center hex) on the valve-lock. If you've got the hex backed out enough, something else is going on. Have you turned the center trunion of the rocker to the correct orientation before install? On most rockers, there's a convex side and a flat side. The flat side faces the polylock. I believe if the trunion is upside down (flat side down) the rocker will sit too low on the stud.

Corey Hunt

I was able to source a set of arp134-7101 studs to try, same issues.
i did have the locks removed from the poly locks somew installing so the stud wouldn't bottom out.
I've not had much experience setting lash, so I did have someone with more experience come take a look this morning, he had the same issues as I.
I tried removing the guide plates and using OEM studs and everything seemed to line up ok, but this won't work with NSA rockers.
it seems the guide plate might be moving the rocker arm stud up too high. Does this seem possible? I did a search and found one thread with someone who had similar issues. I'm wondering if going to SA rockers and ditching the guide plates might me the best bet .
​​​​

BALLSS

are your RR studs for guide plates?

ARP makes 2 kinds....I for use with guide plates (guide plate shoulder shank) and one without

also if going to RR it's a good idea to buy 7/16" size and 7/16" RR studs vs the stock 3/8" size. The thread size is the same for both so it's a direct fit into the heads

Corey Hunt

They are for guide plates. I'm going to take the valve train apart today and start over. I'll install everything again and try to check push rod length again. It really looks like the guide plates are moving the stud up too high on relation to the valve spring.

My springs are installed high (1.81) compared to the original springs that were 1.73, could my install height me messing up the rest of the valve train geometry

I'm at a loss here as to what's going wrong.