Dokken10

iTrader: (18)

I have a 91 L98 with 30K on rebuild. Its now has been cleaned, paint and all new gaskets and seals. Its on an engine stand and I'm lashing the valves. I installed a stock 94 Vette LT1 cam. I'm using the stock hydraulic roller tip lifters.

I've followed the GM 91 Firebird service manual for setting the valves but I'm worried its not right. I haven't done this for about 20 years now so I'm a little rusty.

GM manual way:

1. set at #1 TDC with HB lined up at 0 on the timing tab.

2. adjust 1, 3, 4, 8 EX.

3. adjust 1, 2, 5, 7 IN.

4. to set lash: rotate push rod until it won't spin while tightening rocker arm nut.

5. then tighten rocker arm nut 1 full turn.

6. rotate crankshaft 1 revolution and align HB with 0 on timing tab(#6 TDC).

7. adjust 2, 5, 6, 7 EX.

8. adjust 3, 4, 6, 8 IN.

9. see #4 and #5.

I did this method 4 times before giving the RA nuts the 1 full turn.


For some reason I'm thinking this is too tight

What about the lifters losing their prime or collapsing?

I seem to have more threads showing on the rocker arm studs now than I did with the cam I replaced with the LT1 cam.

Apeiron

The idea is to locate the lifter plunger somewhere in the middle of its travel, which is something like 2 full turns. Anywhere from half a turn to one and a half turns should be fine. As things wear the amount of preload on the lifter will decrease. On a brand new flat tappet cam you'd want it somewhere further down in the travel, on an already broken-in setup you could have it further up.