BStone

Alright guys....

Sometime back I posted re shooting the compression on my car. All checked out ok.

I had tweaked her a bit low so though I woudl check the dwell and set idle/timing etc.

The dwell is sitting at 35 deg. which is about 5 deg too high based on the manual. I set timing at 10 advanced (am at a relatively high altitude) and tweeked idle to 850.

It sounds pretty solid (a bit high for my ear) but man does it smoke more now.

Have replaced plugs, wires are like new. I'll get around to gapping new points and throwing a new coil, rotor, and condenser on but in the mean time...

Could the excessive smoking (pretty sure it is rich and not oil burn) be a result of the dwell being off by 5 degrees?

MDchanic

Well, first dumb question: Why don't you just set the dwell right?

To answer your question, I know of no way that a slightly misadjusted dwell angle could cause rich running if the timing is basically set right. If my understanding is correct, too long a dwell can cause overheating of the coil, starting at higher RPMs, and too short a dwell will cause a weak spark.
Electrical engineers may wish to correct me.

So, how much smoke we talking about? Is it there all the time or just under accel., decel., starting, high load, or at some other time? Is it black, blue, white? Is it a smell, or can you actually see it? What does it smell like?

- Eric

BStone

Was thinking I will replace te points etc but need to get them first.

The smoking appears to be rich grey smoke which stinks like strong exhaust. Less noticeable when I retard the timing and the rpm drop back. Pretty much always there but obviously pumps out more when I rev it up.

I'd assume a poor spark would pump alot of gas out the ***?

MDchanic

You should never drive the car out of the garage without a spare set of points and condenser.

It sounds like it's running rich to me.
Do you know for sure that your timing is correct? That is, do you know that your timing mark actually corresponds to #1 TDC?


A poor spark would burn the fuel inadequately, but you'd notice drivability problems long before you noticed smoke, except in cases where one or two cylinders aren't firing but the rest are.

How's your float level?

- Eric

Sugar Bear

If this is an automatic transmission car it may simply be a leaking/bad transmission modulator. Follow the steel line from the transmission modulator on the right side of the transmission to the intake manifold. Disconnect it and see if there is any trans fluid in it. There should not be any at all, if there is any fluid in the steel line the modulator needs to be replaced. This could be linked to timing changes as timing adjustments change vacuum levels.

MDchanic

"The smoking appears to be rich grey smoke which stinks like strong exhaust." -
I took this to be a description of a rich smell, but I suppose he could mean the smell of ATF - it's completely different, but it's a bit hard to describe smells, even if they're very distinctive.

I'm sure we'll hear more...

- Eric

oldcutlass

Why don't we get our tune corrected and set your carb correctly!! Make sure the choke is working correctly! I would do all those things prior to asking us to troubleshoot an engine you know is not set right!

BStone

Well adjusted dwell today to 30 degree. To get the timing back to 10deg I had to back off the distributor quite a bit. This resulted in pretty low idle. Bumped this back up to 850rpm.

Car does not like this set-up and ran real hot with dieseling on shut off. I advanced the timing "off the mark" and it seems to like that a bit better.

Listen, I ain't necessarily a good mechanic so that's why I was looking for some ideas. If I could tune it correctly, I suspect it wouldn't be smoking! One thing I was always taught though is the last thing you mess with is the carb.

MDchanic

So you messed with the dwell and timing, and got them to a place that looks good, and there's no change in the smoke, right? Good. That's progress.

Now would be the time that I would recommend confirming what sort of smoke it is, if you do not feel absolutely certain of it. Go to a local trustworthy mechanic, or to a neighborhood "old guy" who is known to have been good with cars in his day, and have them take a whiff and tell you what it smells like to them.

Also, you should confirm that all of your cylinders are firing by pulling and then replacing each plug wire, with the engine at idle, preferably with a tune-up tach hooked up so you can be absolutely sure of whether there are any changes. If you have one or more cylinders that don't make the engine go slower when you pull their wires, you could be putting out raw gas from them, which partially burns off in the manifolds, thus causing your problem.

Right now, I'm betting on the carb.

- Eric

BStone

No the smoke difinetly decreased with the timing being retarded. I am starting to wonder if the timing is off. ie the distributor was serviced at some point and put it in 180 out etc. The PO did tell me that he had the timing gear replaced so am wondering if they did not index it correct.

I did try and line up the timing mark with the #1 cylinder but never seemed to line up with the scale.

The car runs happily enough right now but that timing mark is off the scale and there is a bit more exhaust then I am used to seeing. Overall I think it is less than before.

I'll take it into a local shop and get their thoughts

Thanks Eric.

MDchanic

Check for TDC on #1.

Ideally, you should use a spark plug base with a bolt threaded through it (you can buy these), but you can get within about 10° or so by using a pencil or similar in the spark plug hole - just take out all the plugs, put a bit breaker bar on the crankshaft bolt (I think it's 1 1/8"), and keep turning the engine back and forth, holding the pencil, and watching it go up and down - put it right between the places where it seems to stop moving (it moves very little at the very top), and look to see if the timing mark is anywhere near 0. If it's within a few degrees, it's probably good, but if it's in a place that doesn't make sense, you know you've got a problem.

It's not accurate, but it's a fast dirty way to rule out a severely mislocated timing mark with no tools.

- Eric

oldcutlass

Most olds's like about 12-14 deg's BTDC on timing with the dwell at 30. Is your vacuum advance line connected to ported or manifold vacuum? Did you set your timing with the vacuum disconnected?

We can tackle the smoke after we get the tune correct!

BStone

Well I just set it by ear as it wouldn't run well at all with a 10deg advance.

Its off the mark but the smoking (I am fairly certain it is richness) definetly drops off with the timing adjusted

MDchanic

If your timing mark has wandered, you could be running very retarded, which can cause incomplete combustion and rich exhaust.

I'd double check it.

- Eric

BStone

OK...so big fail tonight. Backing car out of yard and hear a wicked noise start coming from motor. Shut car off and look under hood...nothing appears amiss at first glance. Start her back up and watch the motor.

The bloody harmonic balance has separated from the rubber and is free spinning/bouncing off the crank. It snags a bolt and kills the motor.

Tries to bungee it in place so I can get the car back in position for a tow but no luck there as the bungee snapped as soon as I started it.

The balance is a bit dinged up on the side.

I think this explains the difficulty getting the timing mark on the scale as I surmise there must have been some slippage at the rubber belt before it completely dissolved.

Any pointers/advice on changing out the balancer?

Thanks God this didn't fly off on the highway!

MDchanic

Sorry.

Remember, the harmonic balancer does exactly what it says: It balances out harmonic vibrations inherent in the design of the rotating assembly, and by doing that keeps the engine from vibrating itself apart.

You should avoid running it until this is fixed, and definitely not drive it.

As far as changing it:
Just remove the pulley (4 small bolts, and possibly a whack from a hammer, as Rob learned), remove the big balancer bolt, which is on with about 1,000,000 ft/lbs (and air wrench works best, but you'll need to remove the radiator for clearance, which you may need to do anyway. You can also use a big breaker bar wedged against the frame and nudge the starter), then use a harmonic balancer puller and the holes from the little bolts to puller the balancer.

There has been talk of some of the new, made-in-China, auto parts store replacements being crap. I'd personally prefer an old one in good condition from a similar motor.

- Eric

BStone

Any idea where I can get a new damper? I am in Canada

Thanks