Hi all, I have flat head standing in the garage to go in my Model A. I believe it's 1946, it has 59 on the back of the engine, 59 A-B on the heads. I was stripping some bits off to clean and paint it. When I took the clutch off. I rotated the clutch to get better access to the mounting bolts, effectively using the clutch cover plate to turn the engine by hand without too much trouble. To me that seems like it turned rather easily, is that normal for one of these, are they very low compression or could it be sticking valves or just plain knackered? Thanks for any advice. D.
Usually the problem is that the engine will not turn. The fact that it turns too easily may be stuck valves or some other problem. Probably not anything too serious. A complete teardown is in order, or at least pull the heads, pan, and intake.
All the valves stuck open? At the same time? I would always pull the intake, pan, and heads on any flathead I was going to use. You should at the very least want to know how clean it is.
After an engine sets for a while the oil will leave the rings,leaving them with a poor seal. The Flathead, if stock, will have a low compression ratio, compared to modern engines. Compression test would be in order, then squirt some oil in each cylinder, see it that raises the compression. This could also indicate worn rings. A small camera to look at the ring groove at the top of the cylinder would help too, if you can get it there on the Flathead. Bones
If your valves were sticking I doubt that you would be turning it over, except for what alchemy sez. Strip it & do it right
i had one you could spin with one finger on the fan! all valves stuck open. some oil, some time and all were free, and it ran ok. rebuilt now, may dollars later
My 8BA used to get rust inside the valve guides on at least one cylinder after setting a couple of weeks and that valve would stick open. It wasn't always the same valve. Initially I would remove the guide ,spring and valve knock the valve out and stick the proper size drill bit in( I think it was 11/32 and spin it with my fingers then reassemble it....after about four times doing that I had bronze sleeves installed in the guides and they never stuck again!
Thanks for all of your input so far. The plugs are out now, but it was turning easily with them in, they are nice and clean. So far I've put some oil into the bores, I tried turning it with a socket onto the nut on the pulley but can't turn it over fast enough to get a reading on the compression tester. I refitted the starter after oiling the bendix, but it only spins and doesn't engage with the flywheel, I tried a few whacks with a rubber mallet but no joy. I will eventually take the sump/ pan off and give it a new oil pump or overhaul it, heads too, but was then hoping to run it as is for a while and concentrate on the metal work, it may not be the case though. A friend has one of those little cameras, I may tried that into the plug holes, good idea, thanks. D.
(Most of the time) you can look in the plug holes and see with your eyes if the valves are opening properly. No camera needed.
A friend of mine had another shop in Campbell, CA., right down the railroad spur from my shop, 1/4 mile. A customer of his sold him a flathead that had sat in his Dad's garage for some years, it turned freely by hand, didn't have a flywheel or starter. I told him I had some of those items, I'd drop one of each by. Couple of days later, I went to his shop and he had the flathead mounted in his 'run-in' stand. He had welded a rope-pull pulley off a large 9 H.P. lawn mower engine, and asked me if I thought he was getting enough crankshaft speed to record compression accurately. (he had a good Blue-Point gauge with the screw-in hoses, and Schrader valve release) He gave it a healthy pull, registered something shy of 20 PSI...I laughed, and we installed the starter and flywheel. Most of the cylinders had 20 to 35 PSI, the one Dave had checked was still 20 with the starter! Dave did have an arm... LOL Rings had 1/4" end gap...cylinders shone like a shoe-shine boy. Dave tore it down, took it to Clark to have it bored. Clark said he'd bore it, didn't need the pistons...Dave grabbed it back and took it to Furtado. LOL
I run everything in as found condition and never have engines built. I never put kingpins in front axles and always run used tranny mounts etc.. You get the idea. That being said. Pull the heads off that engine and pull the oil pan. Roll it over and check it out then at least re seal it that much. Its not expensive but tells you a lot about what you have and helps you to not make expensive mistakes which I've also done. Seriously. I'm not a guy that'll talk you into rebuilding everything with your last dime but I promise you this is time and money well spent. I'm about to do the same in the engine in my car that runs but is a junkyard special 8ba And having had done headgaskets on flatheads I can tell you it takes about as long as a valve cover gasket on most modern ohv cars. Its super easy and not at all worth dicking with looking down the plug hole with mirrors and other McGyver stuff.
Here's an update. Today I put a hose clip round the shaft of the bendix to keep it engaged with the flywheel, then connected a big battery and it all spun over OK, so having shot a little more oil down the bores I tried it with a compression tester, here are the results. 1- 110 psi 5 - 75 psi 2 - 110 psi 6-100psi 3 - 75psi 7-100 psi 4- 110 psi 8-110 psi Maybe a few valve issues on 3 & 5, who knows at this stage. When the time comes I'll take the sump / oil pan and heads off, replace or rebuild the old pump, and look at the valves. Hopefully for now I can avoid a total rebuild. I'll give it a new starter of course. Any fatherly advice always well received. D.
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