Valve train side loading

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06-20-2019

Wickidflash

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Location: Snohomish Washington

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Valve train side loading

Exhaust valve tip contact wear through paint marker

Intake valve tip contact wear through black sharpie

Exhaust valve tip contact wear through black sharpie

Intake valve tip contact wear through paint marker
A little history- 2.3 turbo head from an 87 turbo coupe- new guides and hardened exhaust valve seats installed and valve job done at highly recommended local machine shop. Boport 1.5 cam. Roller followers, shimmed lash adjusters all within spec.

20k later, exhaust valve leakage, slight loss of compression. Upon disassembly and inspection, all exhaust valve seats have worn crooked, the face width difference is .025, consistently from the front engine side to the back engine side of the seat face, the non worn edge still being within spec. Guide wear is also identical across all exhaust valves.

Intake valves are normal and show no obvious signs of accelerated wear.

I had checked the contact surface of the valve stem tips, and the contact wear area of the exhaust valve tip was much larger than the contact area of the intake valve tip. So I painted the tips, and turned the cam a few full rotations by hand, to take a look at the contact location at the valve tip.

Verified that the wear is caused by side loading of the valve tips, I had checked the camshaft lobes for squareness with an e bar from Esslinger engineering. The bar does NOT make full contact on both, the intake lobe and the exhaust lobe at the same time.

I can only assume that the lobe faces are supposed to be ground parallel with the camshaft’s centerline. I can not find any verification of this online though. Still waiting on a response from bo at boport. Has anybody else had experience with this kind of problem? Anybody have experience with setting up their cam advance with an e bar, and can verify whether the bar should sit squarely on BOTH lobes?

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