The Stovebolt Site Forums The Shop Area Engine Shop 235 valve adjustment issue

I’ve got what i think is a '59 Chevy 235 truck engine. I didn't know the history of this motor and have only had it on the road a couple of times for very short test runs. It seemed sluggish so I thought it was a good idea to remove the head to check out the valves and see what cylinders looked like. I was pleased to find that the cylinders had crosshatching and no lip. The valves looked new and pistons were clean. Pistons revealed that it had been bored 60 over.

In putting everything back together and I got to the valve adjustment phase I found that 2 of the valves had to have the adjustment screw turned way out to get the proper clearance. Those being # 4 and #6. When I turn the engine over #4 has nearly a 3/4 in gap between the pushrod and the rocker cup.

I’ve rechecked it several times, double checking to make sure it’s on the correct sequence(tdc, etc) and both valves still require the screws to be turned way too far out.
I’m pretty sure I’m following the instructions correctly and I’ve done this before on Chevy 6 engines with no problems. I’m much older now and realize I definitely could be missing something very obvious. Anyone experienced this before? Any suggestions? Thanks much in advance. David

Have you removed the lifter side cover and inspected in there. I sounds like you may have either a bent push rod or someone has installed the incorrect length push rod. Having 3/4 of inch of clearance at the rocker is a sign something is seriously wrong.

Site down the top of the valve stems, all 12 should be pretty close to the same hight. Yes or No ?

Next, verify the rocker arms are the same as the others in the position you are working on. Are the exhaust and intake the same? could they be swapped? Yes or No ?

Set #4 cylinder on compression stroke, both lifters on base circle of cam, both valves closed, no need for TDC, just be on the base circle of the camshaft.

Set both valve adjustments at zero lash, if hydraulic lifters, do not compress the inner portion, if solids, adjust to zero, and if possible finger tighten only.

Once at zero lash, adjust to proper spec's, but start at zero for a solid starting point.

Rotate engine two revolutions and recheck, then move to #6 and follow same procedure.

Report back if it didn't work.


Makes no since, the cam doesn't have 3/4" lift so how are you getting that much clearance?

First, measure the pushrods. The symptom you're describing can happen if a couple of 216 pushrods get used in a 235 engine, or a pushrod for a "milk can" type lifter gets used with a later model flat top lifter. One engine I worked on actually has the rocker arm lock nuts UNDER the rockers to compensate for a set of too-short pushrods.
Jerry

I put all the pushrods back into the same holes they came from but I will take it apart and carefully measure them. There is one milk can lifter among the others and it has a thicker and shorter pushrod. Thank you for the advice!

Yes I have the side cover off. I will pull everything apart again and measure the rod and the lifters. Thank you for your advice!

Also, it might be a good idea to check for badly worn cam lobes on the cylinders with a wide gap between the pushrods and the rocker arm adjusters. A couple of nearly flat cam lobes could account for the lack of power. All the lifters should rise about the same amount as the engine is turned over. Milk can and flat top lifters shouldn't be used on the same engine- - - -somebody might have cobbled together a bunch of mismatched parts.
Jerry