What Would You Do?

[Joe C.]

A friend of mine recently finished a resto of his 1964 with 327/365 engine. He did a beautiful job, but there is one thing that bothers him about the car. It uses oil at the rate of 1 quart every 600 miles. I have driven the car, and it runs excellent. The plugs do not foul, in fact, they are dry and tan, as they should be. There is no visible smoke from the exhaust. There is no oil residue anywhere, including the air cleaner, and exhaust pipes. The rebuilt motor has less than 2000 miles on it, and is so well gasketed, that there is absolutely no leakage or sweating from anywhere!
In a memo, he asked for my advice, and I didn't know what to tell him, other than some talking points. What say you? Pithy comments appreciated.

[Terry F.]

Re: What Would You Do?

Something doesn't seem right. After 2000 miles it should have settled down a bit. I am sure the more experienced will chime in but I would do a compression test and a leak down test and see if something is not consistant. I would want to be confident that the work to the engine was done correctly on an engine like that. I would just start collecting the facts. Seems like a lot of oil for a new engine. Terry

[Duke W.]

Re: What Would You Do?

What was done to the valve guides? What is the range of valve stem clearances? What type of valve stem seal system was used?

It's all in the details.

Duke

[Dave F.]

Re: What Would You Do?

I agree with Duke, to look toward the valves as the problem. My recently rebuilt engine was going through quite a bit of oil and it was thought the rings weren't seating, but two weeks ago the engine rebuilder changed out the valve stem seals with a different type (don't know what type it was) and the oil consumption has dropped dramatically.

-Dave

[Duke W.]

Re: What Would You Do?

Valve guides and seals must be viewed as a SYSTEM. The OE system of integral cast iron guides (running within the shop manual spec clearance range), spring "shields" to keep oil splash off the valve stems from below, and the O-ring seals between the retainer and valve stem to keep oil from draining down the valve stem from above works pretty well. Oiling was adequate, but not excessive, and guide longevity is decent for a street engine.

There are several field guide rebuilding systems using different materials and processes and each has it's own oiling and seal requirement. Some require less oil, and some require more oil, and the guide manfucturer should recommend a seal that provides adequate guide oiling - not too much, but not too little. Also, follow the clearance recommendation for the guide manufacturer, which may be different than OE.

When selecting a guide rebuilding system, always follow the guide system MANUFACTURER'S (not installers) valve seal recommendation. If the OE shield and O-ring are deemed adequate, use it (but upgrade the O-rings from nitrile to viton - O-ring life will at lease double). If the recommendation is for a "positive" type seal - one that snaps over the guide and seals the stem like a shaft seal, use the seal they recommend.

If you combine a specific guide type with an incorrect seal architecture, the result could be short guide life due to lack of lubrication or excess oil consumption.

Like I said, it's all in the details!

Duke