Build up on intake valve
 

I have about 1000 miles on a new rebuild. I took the carbs off due to some running issues and looking down the intake I noticed a bit of oil behind the valves and a fair bit of buildup on the backs. What could be causing this?

Todd

Incorrect valve stem seal replacement? Improper installation or incorrect seals.

I suppose that could be a possibility, but I would hope not as the engine was rebuilt by a very reputable shop.

The car has sat for weeks, not sure if that matters. When it sits I get a bit of smoke for probably less than a minute, but no smoke under normal driving.

Todd

There was a fairly recent thread by Mike (VFR750) where he was concerned about oil puddling on the valves. The heads were done by a reputable shop, the same as did mine so I watched his thread closely. He also had a long thread about ring break-in as well.

What kind of break-in procedures have you used?

Just be sure you are not keeping the oil level too high..or checking the oil level when the engine is not completely warmed-up and running.

Any excess engine oil will end up in the intake manifold and on the valves.

My 911s like the oil level right in the middle of the dip-stick range..engine hot, at idle and on level ground. The engines like to "blow-off" that first 1/2 to 1 quart if you keep the oil level at the MAX mark.

Are you sure its oil? perhaps it is gas.

It's a carb'd engine if that makes a difference.

No, I'm not at all certain it's oil. I took the carbs off as I'm having issue with the car running. In fact, I couldn't get it to start a couple weeks ago and yanked the carbs this past weekend. I thought about gas myself because of the starting issues, but it's pretty dark.

I have tall manifolds (left those on when removing carbs), so a little difficult to check.

Motor was dyno'd after build, so rings should have seated then.

Todd