I have a Firebird with the Pontiac 400 engine. I am just putting the engine back together after a crank regrind. Haynes tells me just to tighten the rocker arm pivots nuts to 20 lb-ft which is what I did last time I had this engine apart and I am wondering if this is what caused the 2 bent push rods. I have read elsewhere that I should tighten the rocker arm nuts so that there is no play in the push rods and then tighten them another half turn. I have tried this but they are nowhere near 20 lb-ft. (except for the 2 where the nut has "bottomed out" at about a quarter of a turn). I am worried that they are going to rattle loose. What is the correct way to set them. Thanks for any information.
Pontiac 400
Aug 31, 2005
3 Replies
The 20 ft lbs is correct. The 400 has a non-adjustable valve train. The other procedure is for adjustable valve train engines like the Chevy. If you bent push rods something else was wrong. Did you over rev it?
If ANY of the original factory valve train has been replaced you need to switch to an adjustable valve studs.
You need to intall Big block Chebbie rocker studs with crimp nuts. Then you turn the engine in 90 degree increments and adjust the respective rocker arms.
I worked on a friend's 350 Pontiac and tried to adjust the valves like it was a Chevy small block. The rocker nuts all backed off and he made it back to my place on three cylinders.
The Summit tech line told me there were special locking nuts available or I could probably just torque them all down. So I tightened them all the way and it worked fine.
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