Basic question of rings and p's and c's

[t951]

I hope this question isn't too basic. When I perform a search I get a ton of non specific answers..

So, I have a 3.0L that is really enjoyable expect for the fact that it burns oil.

I had the top half redone a couple of years ago. (Converted to PMO's, Carrera oil tensioners, MSD, etc). I didn't do anything on the bottom.

My car has a small drip and I know that adds to the oily smell and a bit of the smoke, but....

When I start my car I get LOTS of gray smoke. If I am at an intersection and I pull away there is good sized puff of the smoke.

My question is...can I just replace the rings or do i need to go with a new P&C set with the rings. Is it foolish not to do them both. I ask b/c there is NO way I can afford new P's&C's. I am hoping a re-ring would be vastly cheaper.

Any advice or info would be greatly appreciated. Oh, and here are pics of my little ol' engine!

thanks,

t.

[tom1394racing]

You should do a leak down test first and find out where the problem is.

You can get the leakage for each cylinder and then listen to where the leak is coming from to determine if the problem is valves or rings. If you had the heads done with you top end, it's likely to be worn rings.

If you determine that it is the rings, usually these can replaced and the cylinders de-glazed. The pistons and cylinders are usually within factory wear limits and the rings take the wear.

[lindy 911]

Something else to look into is the cause of the smoke. It could be something other than oil. Does the motor use oil to the point where you have to add oil regularly? If not it may be smoke caused by a rich condition with your carbs. My Webers had a float set too high and the overflow caused a rich condition in #3 so it would puff smoke after a stop light. I though it was oil but it was actually running fat as a pig. Food for thought.

Lindy

[James Brown]

Most smoking on start up is not oil but unburned fuel. Mine does that when it first fires up. (first nanoseconds). Engine is too cold for it to be oil. More on carb engines. You can smell the half burned fuel wafting by, mmmmmmm love that, then it changes to a more Olly smell and a little bluish for a few seconds. So yeah, make sure your looking at the right thing before you fix something that ant broken. Food for thought.

BTW, sometimes I run 100LL avgas, man, that stuff smells great!! (not many brain cells left).

[lvporschepilot]

You surely can just replace the rings if everything else measures in spec. With the pistons, specifically check the skirts and ring lands and obviously clean the lands and everything really well. Deglaze with a flexhone and reassemble.

[Rusty 356]

On reassembly you can't be too clean. After a flex hone I clean the cylinders in warm water and tide until no dark color can be wiped from the cylinder. Re ring can be just fine. I don't oil the rings or have oil in ring lands. my .02 cents worth

[lvporschepilot]

Some good advice Rusty. My *final* cleaner of choice just before the pistons go in and after scrubbing is lacquer thinner. A few good wipes with lint-free cloth really makes the surface good to go.

[lindy 911]

James Brown,

I hear ya on the AVGAS. I had a 30' Scarab for a time with twin blown big block Chevys that loved AVGAS. It had the best smell in the world when fired up at the local pub docks. It had big lumpy cams that made it spit and grunt when it idled, man almost better than you know what.

Lindy

[304065]

Avgas has WAY too much lead per gallon for automotive use, stick to unleaded racing fuel if you plan to use it for any period of time. Bruce Anderson's book has a mixing chart that can mitigate the TEL.

[James Brown]

I have no cat and it's free!

[304065]

FREE avgas? Will an IO-720 fit back there?

[911pcars]

Could be very worn valve guides. Try a vacuum test:



It's not definitive, but an indication. Big difference doing head work versus rings/pistons/cylinders.

more gauge pics: Blowby Discussion

Hope this helps.
Sherwood