1991 K1500 5.7L K engine problem

Asked by Jun 09, 2017 at 08:44 AM about the 1991 Chevrolet C/K 1500 Silverado Standard Cab LB 4WD

Question type: Maintenance & Repair

I have tuned up my 350 TBI (K) long block two bolts 210 HP California engine and I believe that all timing and emission issues are squared away and in great shape. Also have a new CalCat catalytic converter and Oxygen en sensor.  idles like a charm and drives normally good when not pushing it. My engine has 286 K miles. But under load it is acting as if (feels like if a cylinder pressure was off) as if one cylinder was delayed from the others. did a compression test and to my surprise I get about 180 psi on the front cylinders and about 170 psi on the rear cylinders.  So to me it means that #1 I do not have piston ring issues and #2 I do not loose pressure from the valves.  To me, I am left with two other possibilities namely The Cam is worn out or some hydraulic lifter are faulty or not fed with oil.  I have to say that I have been running on low oil pressure for about 5 years now (28 psi underload when hot and about 20 PSI at idle when hot-like just after underload) .  I have to say that my compression test was accomplished on an engine that had time to cool down quite a bit (about an hour after running hot).

Could my high compression ratio be tricked by a worn cam or lifters that fails to open the valves properly?

Before removing the intake to examine the lifters rise I am thinking of removing the valve covers and measure the displacement (lift) of each push rods. (with a china marker against a flat bar- measure distance between the two marks on each push rods)...

I have no shop and working over the hoods kills me...Loll

I will gladly consider inputs from the community of gear heads!

I am about to pull my 4000lbs small fifth wheel for a good ride. I was thinking of adjusting the valves with the engine running as shown on u-tube but I am somewhat fearful of making things worst.

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