I'm the first to admit that the engine in my '24 Touring is pretty tired. I don't really have the money to do a full rebuild and I can only really afford to keep it running and do the most urgent repairs on it. I intend to do a proper rebuild after I graduate and (hopefully) have some money after I get my first real job. Despite this, it runs surprisingly well and starts very easily!
The babbitt is okay and the clearances are acceptable, but there are no shims left. The valve guides and valve seats are shot, but the springs and valves are new. It still has iron pistons, and I recently replaced the rings. The wrist pins are a little loose but still within tolerances. The cylinders are worn, but not too bad, and I bead-honed them when I replaced the rings. It has excessive camshaft endplay, resulting in an inconsistent ticking noise.
Today, I decided to do some basic tests to see how my engine was performing. Overall, I'm quite pleased with how they came out! My results from a compression test were surprisingly good. I haven't performed a leak-down test. Here are the results:
Cyl 1: 45
Cyl 2: 44
Cyl 3: 45
Cyl 4: 47
The condition of the spark plugs also amazed me. They show almost no signs of oil fouling and indicate that the mixture was just about right, even coming from a crude Holley NH! There was minimal carbon buildup to boot.
I'm not surprised at all. I was getting very good performance with my original 1926 engine for seven years. I clocked up a lot of miles on it too. All the conrod shims were long gone, and was into the cap filing stage. The 3rd main had to be severely filed, and shims taken from 1&2. The cast iron pistons ran great with new rings. Cylinder wear was about .006". Valves guides worn. Yet, oil consumption was very low.
What killed it in the end was a broken crankshaft. It had been cracked for years.
Cameron what is the average speed that you drive your T.
If the original engine is still going it must have been driven reasonably over the years.
Good to hear that the engine is still going without a major rebuild.
Only thing I see that needs attention is the endplay of the camshaft and that is very easy and inexpensive to remedy without replacing the cam or bearings. If it ain't broke, don't fix it.
Old tired engines get a bad rap. I was surprised how well the old engine in my last project runs. It starts easily and runs smoothly. Not as much power and a little smoke. Cast iron pistons and new rings.
If you can get some fun miles out of it, why not?
There's a reason why ol Henry used the same basic engine from 09 to 27. The Model T engine will run on the ragged edge of disintegration for years, as long as you don't try to make it do something it doesn't want to do.
You wouldn't push your 80+ year old grandmother to go run a marathon.
I'm in the same boat as Cameron. I've never had my engine apart. I lapped the valves and had the coils rebuilt. Previous owner put a rebuilt carb on it. Never had a problem, except the mag wasn't wired. Bought a new wiring harness as part of my "restoration", so we'll see if the mag is any good. I'm just hoping she remembers how to run. Let them sit for a year and they tend to need some reminding...
John, I drive my T at 32 mph on the dot according to every chase vehicle I've ever had. I guess I must really be in tune with my car because I'm so consistent!
Cameron, 30 to 35 mph is the speed these cars were designed to run at. Granted a Model T will do 45 mph but that 3 main bearing crankshaft wasn't designed to spin fast and you don't want to join the '2 piece crankshaft club'.
These engines 'talk' the fact that you find yourself doing a consistent 32 miles per hour means that your engine is telling you that's where it's wants to be.
Those are not terrible comp readings. Especially if it was done cold where you'd expect them to be a bit lower. In fact the only thing I'd keep in the back of my mind is the cam end play/noise you mentioned. Take it easy on her and you'll probably go past graduation easily.
I did take those compression readings when the engine was cold.
I like to do T's cold because of their relatively low compression compared to a "modern". I consider hot readings somewhat false because a drop in an engine with maybe 40 to 50 lbs comp. can be the difference between cold starting and not starting and a noticeable power difference. You'd never notice say a 5 or 10 pound difference in an engine with 150 Lbs. comp. Just my opinion.