1971viking

I noticed a ping noise at about 95 mph on the highway (4100 RPM). I let off the gas and white smoke came out of the exhuast. After 10 seconds no more smoke and car ran fine. I went home and checked the timing and it was at 17 (not total timing). I backed it off to 14 and will test again tonight. HEI system. ( I think the distributor has 20 degrees timing)

1968 455 with C heads mild cam, single plane intake, and Holley 750 DP.

I assume that smoke was related to too much timing advance?

Funny thing is the car had no ping until I was at 95 MPH 4100 RPM. I assume this is when the distributor had no engine vacuum holding it back?

MaxDog

Dude, you are awesome . . .

1971viking

OK Timing is at 14 now and no more ping at high speed.

I still get some blue smoke when I reach high speed and high rpm. I assume this is the PCV valve working at WOT. The crank case pressure builds and the oil gases get sucked into the manifold and burnt off.

MDchanic

More likely it's the higher combustion chamber pressures pushing oil past the rings.

- Eric

1971viking

I will test that tonight.

I will disconect the PCV from the vacuum source. If smoke still happens I have a ring problem.

Although it is really not a problem below 100mph which will only occur at the end of the 1/4 mile run.

A compression test will also reveal an ring issue.

RetroRanger

I dont think it will, maybe they wont get as high a comp but if all cyl are close and you havent already established a baseline reading then all you have a is a pass fail reading

a leakdown this would show this

1971viking

Good idea. I doubt it is the rings as it does not smoke when I accelerate.

I did notice smoke on cold startup only. Which is a clear indication of valve stem seals being bad.

Wills72455

Faulty oil control rings won't necessarily show anything on a compression test.

oldcutlass

Smoke on cold startup is actually normal vapor in the difference between cold air and warm exhaust.

The white smoke at 95 mph is probably an over rich conditon, do to timing and carb settings. Was it a gentle climb or full WOT? If it was a gentle climb, perhaps your vacuum canister is in need of a limiter.

You will not have any vacuum to the dist @ WOT. Set your distributor for total timing @ around 34* - 36* @ 3500 RPM with vacuum disconnected, and see where your initial winds up.

1971viking

It was full WOT. Initial timing is currently 14 @ 700RPM with no vacuum to distributor.

I will check and see where the total timing is @ 3500. I will do this with distributor vacumm on. Correct?

Other than that what I mentioned early (smoke @ 100+ when let off gas)the car runs great. Super responsive and no lack of power.

MDchanic

Incorrect.
Vacuum advance should be disconnected.

Wait. I must have missed that.
The smoke happened when you let OFF the gas?

Sounds more like loose valve guides to me.

- Eric