Valve Sequence - 1990 L98
 

Let me say, in advance, that this may likely qualify for the dumb question of the month to the well-schooled L98 folks. But I've learned way too many times to NOT assume anything.

I have a '90 Corvette L98 in an infrequently-driven street rod. The valves have not been adjusted since the engine was installed quite a few years ago....and it's time. I have read the adjustment procedure in the Chevrolet SM and on this forum. However, I cannot find the valve sequence (i.e., E,I,I,E, etc.) front to back, Driver/Passenger side in the SM, and I have not had the valve covers off in quite some time. I guess I could assume that each exhaust valve is directly over the exhaust port on this engine, but I don't really want to do this. Since my experience with Chevrolet engines is not as extensive as that of many folks on this forum, would someone here please provide this to me or show me where I might find it? Many thanks for you help!! By the way, the L98 is an awesome powerplant for my toy!

Yes, the valves line up with the ports. Once you pull the valve covers, it will be obvious.

i think this what the OP is looking for -

(from the 90 FSM) - with the engine in the #1 firing position, adjust the following:

exhaust - 1, 3, 4, 8
intake - 1, 2, 5, 7

rotate the crank 1 turn, and adjust the following:

exhaust - 2, 5, 6, 7
intake - 3, 4, 6, 8

you can use the "rotate the push rod" thing to find zero lash, or my method - use a .0015 feeler gauge, adjust the rocker arm nut until the feeler gauge grabs, then turn the nut another 1/2 turn.

Thanks mcm & Joe C.

I do have the valve adjustment procedure, as stated in the SM and read on this forum. What I needed was the valve sequence, front to back, for both the Driver's and Passenger's side. MCM....I will pull the covers and undoubtedly see what you mentioned re the valves lining up with the port. That answers my question. And Joe, I will use your method with the feeler gauge....I like that. Thanks again, both, for the quick response!!

never had luck doing them all in sequence like that.
Just go one at a time, exhaust valve starts to open adjust intake.
Intake valve starts to close do the exhaust. :cheers:

Whatever suits you

What I found was that the lifter would leak down while adjusting the valves and I could never get them right.

Now I only adjust them hot and running. I have a pair of old steel valve covers with 8 holes punched in them to keep the oil where it belongs.

See....I said this was the dumb question of the month!! Thanks to all that replied....good thoughts. As it turns out, it is obvious to me that my question was also very unclear.

I am aware of the valve adjustment process, doing the first I/E group with #1 at TDC and the second I/E group after one crankshaft revolution with #6 at TDC. I just wanted to be sure, when looking down at the valve train with the v/covers off, which valves were intakes...and which were exhaust...on each cylinder head. That is what I was calling "sequence" from front to back. Poor word choice on my part...sigh. I now know that the exhaust valves will be obvious, with each above their respective exhaust port. Not being overly knowledgeable on the L98, I wanted to be sure....and confusion followed my original post. Sorry 'bout that. And thanks all for your thoughts!!