351 GMC V-6 in a grain truck

[J. Schwiebert]

Have an early 1970's GMC truck in the shop. It had bent push rods on one side. It was a repeat problem. We put the new push rods in and started the truck, runs good now BUT the side with the bent push rods does not have near as much oil going to the rocker arms as the other side. Question how do the rocker arms on each side oil and if it is metered where is it metered? We have an older Truck manual but no schematic of the oiling system. Thanks in advance for any help/ Any one have a GMC shop manual that could maybe copy some pages? J.
 

[duane o.]

Not familiar with that engine specificslly but maybe its like a 302 oliver with hollow rocker arm bolts? Its possible that there is a chunk of casting in the oil gallery to that side of the head causing this problem
 

[oliver fan]

FYI I don't know if it helps, but the oil pressure is what controls the governor on those engines, There is a oli line that attaches to the lower right side of the caburetor. To much oil pressure will slow/cut back on action of the carb. so the engine will not over rev.
 

[OLarry from MD]

From a chilton truck manuel it appears to show the oil to the right rockers comeing from the rear camshaft bearing and the left side comeing from the front camshaft bearing.Like duane says below through a hollow bolt.
 

[BANDITFARMER]

You may need to replace the rocker arms. If the rocker arms are wore enough you wont get oil through the push rods to oil the rockers or valves and the valves will stick and bend the push rods. Hope this helps. Bandit
 

[Carlton Grambo]

J.,I know a little about the old V6 engines by GMC. They can pull a good size fuel oil truck all day to different customers. But in the end they did become antiques. GM in about 1975 or so went with Chevy engines for the money to build one and not the other. My father in law drove a V6 for years until the last truck he had a 366 V8. that is still running around the country with and old 1800 gallon tank on it. The others are history. What I am trying to say if you are just using it for hobby farm or there about, good old truck. Any bigger and it will eat your wallet. By the way my father in law will probaly smack me from the grave for writing this. He love those old V6s that much.
 

[J.Wondergem]

[OLarry from maryland]

Thats the same one i have.
 

[ken77]

So it is possible the rear cam bearing spun causing the no oil problem.