I recently purchased my first T A 1924 roadster pickup. It has a very original appearance and I plan on only using it as transportation around the antique tractor and engine shows that I attend. The old gal runs and drives but smokes more than I like . Should I just install new rings after checking the piston condition or go deeper with a more detailed overhaul .
Well, it's likely you'll find some more things to fix when you open up a smoking engine. You'll probably find original valves that were made from a shaft with a cast on head, commonly called two piece valves - and who by now, when 90+ years old has a disturbing tendency to break apart in use. Thus you'll better get new valves and a valve job too. If the babbitt isn't cracking you'll probably just need to tighten the rod bearings some and can drive at engine shows for many years with a simple hone and ring job.
But there is another safety item you may need to fix on an original car - the thrust washers in the rear axle has a tendency to suddenly disintegrate with age and may then allow the pinion and ring gear to slip - and that's bad when the main brake is in the transmission.
Usual procedure with a unknown T is to make a rear axle overhaul to be sure what's in there. Bronze thrust washers replaces the brittle originals.
If you just want the easiest/cheapest first step you might stop your oil burning and may prolong an O/H for awhile. Of course it could be from other sources like valve guides. Check the clearance on the rod caps while you have them apart.
You can use the next size larger set of rings if your bore is worn too much. I've had good luck with that when the end gap of the new rings was extra large.
A very simple compression test before you tear it down could tell you much just removing the spark plugs! Bud.
Bud is of course right - if the first result in the compression test goes up by dripping some oil in the cylinders, then you have rings that seals bad, but if it doesn't change much - but is low, then it's valves that doesn't seal as they should.
The compression in a model T is very low by today's standards - the readings would be around 45-55 psi on a good engine, but it will run down to 30 psi.
First thing is to make sure you haven't over-filled the crankcase with oil.
Also, if the car has not been run much over the years or has been sitting for a number of years, simply running and driving the car may loosen up the rings around the pistons and lessen the blue smoke.
What color is the smoke? Blue smoke is from oil burning. Black sooty smoke is too rich fuel mixture, and white smoke is coolant leak which will usually occur when you first start it and diminishes as the engine warms up. If a rich mixture, it is easy to adjust. If you do replace the rings, you need to hone the cylinders to rough up the surface. And check the end gap of the rings, especially if you use oversize rings. Check at both the top and the bottom of the cylinders because the cylinders could be tapered. The top ring should be .008-.012. The second ring should be .006-.008 and the bottom ring should be .004-.006. If the cylinders are excessively tapered, you might find that the engine burns more oil after replacing the rings than before, but will decrease as it wears in.
If your not driving it all the time and just puttering at the shows keep oil in it an let her puff. If you open it up you will end up doing way more work than rings. Just my thinking Tim
Tim I was thinking the same thing. Most of the old tractors at those shows are putting out enough smoke so no one will notice a little more.