Checker may have installed whatever they had ready to go and not the original stuff!

Kevin Bigwin

 

This is true. They could have. But honest opinion I think the heads are the original ones. I suppose they could have machined the heads and milled the block for a combined problem. But if they did couldnt theoreticly put in a thicker head gasket to compensate?

 

The key is what the lift is at the cam lobes on both banks. Measure the lift on one of the "bad" side pushrods and one on the "good" side (both intakes or both exhausts). Milling/decking wouldn't change the amount of cam lift, just the angle of the rockers (which would affect valve lift somewhat).

Were the lifters re-faced or replaced? I take it from Dueller's comments that these had mushroom lifters? Any chance someone dropped in lifters from a 302 on one side???

 

Not sure if they were replaced or refaced. I dont have dial indicators so is there another way I can check for the lobe lift? Or am I going to have to go buy some?

 

I think you're looking for a difference of 1/4" or more, a steel rule should work at this point.

 

Ok guys thanks for all the ideas. Ive got to sighn off for the night. If you have any other thoughts on this feel free to post them. I will check in tomorrow. thanks again.

 

If the cam is wipped out there sould be some metal floating around in the oil or at the very least at the bottom of the oil pan. Have you drained the oil or cut open the oil filter? I have not heard of many people having issues with a stock cam as the pressure on the lobes is not as high as it would be compared to a performance cam. I have never worked on a y block before so I cannot offer advise on the valve train as I am not familiar with it. I assume it is solid lifter and adjustable?

 

What's the update on this? It really helps everyone if we know what worked or didn't!

 

Right now its looking like they installed the wrong lifters. But I cant break into the engine without voiding their warranty. So it looks like were going to send it back to the builder.

 

If one bank doesn't have lift it ain't additives, lifters or other nonsense...

 

I have been scratching my head and other body parts on this one. It seems to me that there are only two possibilities. The cam is bad (either machined wrong or wore out) or the wrong rockers are installed.

Here is my logic. The lifter and push rods are a set length. Any difference in the lengths is taken care of when you adjust the valves. This would also take care of any milling difference. In other words if you had a head planed, and you re-installed it, when you adjusted the valves it would compensate for the metal you removed with the plane. If after you properly adjusted the valves and you had the same clearance all the way around, any differences between the two sides has now be compensated for, the push rods with now rise exactly the amount the cam lube forces them to.

So if the push rods are rising the same on both sides but the valves on one side are opening farther on one side than the other, the only thing that can do this is the wrong rockers. If the push rods are not rising the same on both sides, the cam is bad and needs replaced. BTW Mummert has replacement cams, that is were we got ours.

Bad CAM Causes: 1)improperly machines cam, 2)installing a thinner head gasket or planning a head and NOT re-adjusting the valves- this would wear the cam quickly and it would run poorly at best. 3) poor oil flow to one side of the CAM - this seems somewhat of a stretch, I am finding it difficult to understand how one side had good lube and the other didn't.

Good luck and let us know what they find.

 

If the adjuster on the rocker isnt in the center of the rocker (meaning threadded up or down too far) then the geometry is in fact incorrect. This causes all kinds of problems.

I understand that you can "adjust" the clearance issues out, but when that has to be done there will be issues with how the rocker contacts the top of the valve stem. There was a big article on this in y block magazine a few months ago with pictures. Its hard to visuallize but the magazine there were pics showing the differences of rocker to valve stem contact.

Decking the block, milling heads, using wrong push rods, all change rocker geometry.

Kevin Bigwin

Kevin Bigwin

 

I'm not an engine builder by any means...and this might sound silly...but have you checked to be sure the rocker arm shaft is fully seated on the head? Could having the shaft(s) installed wrong cause incorrect movement?
I would (if you havnt already) reset to T.D.C. and relash the valves cold and make sure they are all correctly adjusted....
Just trying to help, Ed

 

Sorry about my previous post. Too many frosties last night. Didn't mean to poo-poo on anyone else's attempts to help.

I would try to get a dial indicator (or even a steel rule) at the pushrod and determine what the cam is giving you directly off the lobe. If the lobe is round, you may not have a cause, but you'll have the problem identified.

 

Rocker rods are fully seated on the head so that doesnt appear to be the problem. I did however just complete a compression test on this engine. The results of which dont look good for the engine builder. Heres what Ive got. Cylinder #1 120psi #2 0psi #3 120psi #4 120. Thats the left bank. As for the right bank #5 135psi #6 125psi #7 117psi #8 150psi. For just the reading on cylinder #2 this thing is going back to the builder on a warranty claim. They better get it right this time. I will keep you guys posted. Thanks again for the help. I appreciate it.