TR4/4A I Can't Stop Burning Oil; Engine Missing at Take Off

[KVH]

Unless my eyes deceive me, I'm seeing black smoke, not blue, but I can see my oil going down on the dip stick. My HS6 Carbs have new floats, needles and seats, and the carb pistons rise and fall smoothly. The Needles are the standard ones, .095 at the upper limit of the taper. Carb mixture seems correct, but on take off it misses, then goes fine.

I don't like thinking this way, but when I rebuilt the engine in the fall of last year did I fail to seat the rings? I ran it they way recommended, as I recall. ZDDP in the oil, 2500 rpms for 25 minutes, something like that. Then I dumped the oil and reloaded. But as I posted last week, my oil was shockingly low after three weeks of not checking it.

Could the missing be something else? I think the timing is fine. My distributor is a Flame Thrower Pertronix.

I'm beginning to think the smoke is oil, not rich carb mixture. Can the missing be related to either my coil or Pertronix Distributor?

Any other ideas or encouragement out there? Things I can check?

 

[TR3driver]

What do the plugs look like? Preferably after doing a "plug cut", run the engine so it smokes and then drop the clutch, turn the key off, shift to neutral and coast to the side of the road. Carbon from too-rich mixture will look dry and fluffy; while oil burning leaves a coating of oil (so the deposits look oily).

The miss could be ignition; but I'd work on the smoke and oil loss first. Chances are very good that the miss is related to the smoke (meaning not ignition). Also try changing the plugs (again) after you solve the smoke problem. Poor combustion can sometimes leave a conductive glaze on the insulator that won't burn off.

I'm really hesitant to recommend the Bon Ami trick; it's a terrible thing to do to an engine. But if you're sure it's oil going past the rings, and the only other option is to tear the engine down, it might be worth a try. Be sure to get the right Bon Ami, you want the one that says it's safe for glass. Kind of hard to find the last time I looked for it; found it at OSH.

 

[karls59tr]

What is the "Bon Ami trick"? In regard to seating the rings....what would be the wrong way to seat them. The reason I ask is there is a fellow here that rebuilt his Tr3 motor about 3 months ago and I see when he starts his car up it puffs blue smoke?

 

[Geo Hahn]

...on take off it misses, then goes fine...

That sounds mostly like carbs that are still too rich and load up a bit at idle. Is it notably worse if you sit at idle for awhile (like a long stop light)?

What is the "Bon Ami trick?

When I got my TR4 the PO had recently replaced the rings (among other work). He was a poor record keeper so I did not know what rings he used or what break-in he used - but I finally convinced myself that the rings had not seated. I went the Bon Ami route.

I read up on it a bit but generally I recall having the stuff in a teaspoon and blowing it into the throat of each carb with the engine at higher revs. It is not an abrasive that does the work, but rather the absorbency of the stuff which robs the cylinder walls of lubrication for a stroke or two.

The Bon Ami I used is calcium carbonate which may be the later formulation - I'm thinking the one Randall describes (safe for glass) may have been diatomaceous earth.

In any case, it is really a last resort but I believe it worked for me.

...there is a fellow here that rebuilt his Tr3 motor about 3 months ago and I see when he starts his car up it puffs blue smoke?

That sounds more like the valves/valve guides are allowing some oil to seep into the cylinder while the engine sits.

 

[TR3driver]

Both versions of Bon Ami use very soft minerals (basically industrial waste from other refining processes), too soft to scratch steel. However, the new formula (the one that warns not to use it on glass) supposedly has occasional small particles of a much harder abrasive (silica IIRC, aka quartz aka sand) which can scratch glass (and steel). The older formula supposedly does not.

Evidently, Bon Ami has redesigned their label to make the difference clearer. Here's the current 'glass safe' version
https://www.amazon.com/Bon-Ami-04030-Cleaning-12-Ounce/dp/B000BQYBC6

And the more common 'not safe' version
https://www.amazon.com/Bon-Ami-Polishing-Cleanser-Powder/dp/B000RPXJ8S

 

[Andrew Mace]

I don't like thinking this way, but when I rebuilt the engine in the fall of last year did I fail to seat the rings? I ran it they way recommended, as I recall. ZDDP in the oil, 2500 rpms for 25 minutes, something like that. Then I dumped the oil and reloaded.

I'm not sure, but I thought that was the recommended procedure for bedding in a camshaft and tappets. What I've been told (and have done) to help seat the rings is a succession of 8-10 sessions of somewhat brisk acceleration from, say, 30 mph or so in top gear to maybe 50 mph, let off and repeat. Worked a treat on the Subaru EA-81 engine my son and I rebuilt several years ago!