It's been a great summer cruising around in my 1925 Ford model-T. This photo was taken on 5/12/24. Someone that works with my son was traveling behind me and they took the photo and sent it to my son. I have put on 1,029 miles on the car this summer. Everything works fine and the " hotrod " flathead engine that I have in it works just fine for regular everyday driving. However, the engine develops a spark knock under load, such as pulling a trailer up a hill or under heavy acceleration. I have tried everything I can think of to get rid of the spark knock even going as far as setting the initial timing at retarded 6 degrees and limiting the spark advance to 20 degrees total. The spark knock is still there but not as much as it was with the initial timing set a 5 degrees advance and 25 degrees total timing as recommended for the flathead. As expected, the retarded initial timing really drops the performance. When I got this engine back in the late 1970's, I was told that it had been run in a dragster in the late 50's and early 60's. I went thru it in 2023 with all new rings and bearings to freshen it up simply because it had been sitting in storage since the late 70's. Before this, the last time the engine had been apart was in 1963. I know this because the rod bearings are date stamped: 9-63. ( that's two months before president Kennedy was shot ). A stock 49-53 Ford flathead V-8 is 239 CID with 100 HP. Bore is 3.187 diameter with 3.750 stroke and the cam lift is .338. This engine has been bored and stroked so it is 276 CID with estimated 217 HP. Bore is 3.307 diameter and the stroke is 4.016 with .390 valve lift. I couldn't find the paper with the readings for when we did the compression test on it but I know it was a little over 200 PSI and it reached that PSI with the first cycle on a three cycle engine rollover. I believe the stock compression is 110-115 PSI. This engine just has too much compression to run properly on the grade of fuel that is available at the pumps these days. So .... I have picked up another engine that is stock except for being bored .060 oversize. Here I'm getting ready to start lapping the valves in. Here are most of the internal part for this block. I've also started dismantling the old dragster engine that is in the car now in preparation of pulling it out. Except for the heads, everything is removed from the top side of the block. It's a awkward working on the engine with the front fenders on so I'll pull the heads after I get the engine out of the car. These fenders are mounted with a lot more bolts than the stock fenders are and it is easier to work across them than it would be to remove them. The crank pulley and timing gear cover are removed. I have already removed the oil pan and the high volume oil pump and I have built a wood base that is bolted to the underside of the block for it to sit on once it is removed from the car. .. Note .. being an old race engine, this has a metal timing gear on the camshaft instead of the stock fiber gear. I still have to unfasten the exhaust and the transmission bolts before I can pull it out. The transmission is going to stay in the car for this engine swap.
I don't know nothing about anything so this is just something to read. did you clay the pistons, or cc the heads...maybe your at 13.1 comp, and they ran it on methanal?????dis regard if you don't like the post... with all due respect... also in 1963 gas could be had @ 105
Yes we CC'ed the heads. We had to in order to figure the cubic inch displacement of the engine. The heads are marked 9.7 to 1 compression. As I understand it, that is figured on a stock engine. this engine is bored 1/8 inch over and 1/4 inch stroke so that puts a lot more compression in the cylinders.
Looks like you have a well ordered set-up. Thanks for showing your work. I love T's ( and A's for that matter ) Yours Stands as a solid machine.
I assume you pulled the heads to measure bore and stroke. Ie Combustion Chambers don’t affect compression ratio.
Obviously. You can't measure the bore diameter and put in new rings or CC the heads without pulling them off.
My son thinks the the compression was around 140 - 150 PSI. His memory is much better than mine so that is more likely what it was.
Bearing dates are interesting, but don't really tell us when the last time an engine was apart was. I've put NOS bearings into engines, and also reused the original bearings if they were in good condition. All the date really tells you is that the bearings were installed "some time" after the date they were made. could be a week, could be 6 decades. Anyways...here you are doing all this work to get the compression ratio down, and no mention of what the chamber CC is, or what the pistons in the race engine look like, or those in the new engine. Only discussion of displacement. There's more to compression ratio than displacement.
You are right, I just didn't think about. So .. the last time the engine was worked on was sometime between 1963 and the late 1970's when I got it. The head chambers are 51cc with dome top pistons.
reason for my post was maybe the heads were milled and it could be just a head swap to get a little lower comp ratio... maybe even thicker head gaskets???? I don't know anything about race motors, I only raced A/F , and AA/BAD... where as everyone here is top fuel...
Sweet build. Did you ever try running on e85? It can easily handle alot of compression. And it's cheap after putting modern rubber in the fuel system. -rick
No. I can't afford the price of that fuel for running on the street anyway. I don't know anything about racing either and have never driven on a track. I can put this other engine together cheaper than I can buy a new set of aluminum heads.
I didn't mean to run it forever, simply as a tool to diagnose the problem. 100 octane av gas is only about 5 bucks a gallon
The engine came out this afternoon. The engine was lifted out with my portable A-frame hoist and rolled out into the open area beside the car. Then I set it down on my diecart so it is sitting on a solid base for removing the rest of the parts. The water pumps are removed from the front and the head and exhaust are removed from the right side. The engine is turned around on the cart and the other head and exhaust are removed. The transmission adapter and the flexplate are also removed. This leaves a high performance short block.
huh, I bought some 87 for $3.40 a gallon in Indio last week I wonder if he'll put some different heads on it, to drop the compression?
No I don't think so. He showed pic of another engine he was lapping the valves in, first post 4th pic. He maybe jumping from the frying pan into the fire. I would have tried lowering the compression by machining some material in the valve area; probably get some better flow. Block was not relieved, surprised at that. Looks like chevy distributor, maybe some work at advance rate needed. Since it is an auto trans maybe it is just sucking too much power, rear gear too stiff? Car can't weigh too much can it?
Little far to drive for me. Least expensive in town is 3.99? Now. Goes up as I drive further. Issue is we’re too close to the refineries.
Here is a better photo to clarify that. The top of the pistons are .192 above the surface of the block.
My knowledge of flathead engines is very limited. In 1963, when I was 17, I bought this 1950 Ford with a V-8 in it. I fixed it up to look like this. I also put a tri-power intake, aluminum heads and headers on it but the rest of the engine was stock. ( the 56 Pontiac was a car that I fixed up to sell ) Over the years I've had a few flatheads but this engine in the model-T is the first time that I have taken a flathead apart to rebuild it. Being retired, I have limited funds to work with and I'm hoping to be able to sell this first short block to help with that problem. This other stock engine has been sitting for about 30 years. The cylinders look really good without much if any noticeable edge at the top of them. My intention is to just freshen it up by honing the cylinders and lapping the valves. Then putting in new rings, bearings and gaskets. I am putting all new valve springs in simply because the engine has been sitting for a long time with the springs compressed. I'm also going to take the high volume oil pump from the first engine and put it in this stock engine. My thinking is that with it having 1/16 inch smaller bores and 1/4 inch shorter stroke that it will have less compression PSI than the first engine even with me using the same heads. I certainly wouldn't be able to machine 1/4 inch off the inside of the heads. .. Am I wrong in that figuring ?
1/4 inch seems like it would be a lot to take out of the chambers. Maybe a separate post asking about machining off the top of the piston some and some out of the chambers to land you where you’d like to be. On problem though is $$ for the process unless you can do it at home. That much shop time might rival the cost of another set of pistons.
Just an FYI...276 cubic inches with a 51cc chamber head will give approx 9.75:1 compression ratio. The nonsense about chamber cc not affecting ratio is ridiculous-of course it does. Cranking compression pressure is greatly affected by the camshaft's intake valve closing point so pressure will not rely on ratio alone. A set of 71-76 cc chambered heads would put this engine at 7.6-8.0 compression and with a cam swap (probably too radical for low compression now) would make a sweet 276 street engine that runs great on pump gas.
Wouldn't it be easier to do as I planed and just switch engines to the stock block that already has lower compression to start with ?
Sure. But you had mentioned taking out the combustion chambers and showed the pic of the dome, I made the assumption you were trying to make that engine more street-able.
Gotcha .. my misunderstanding. ... I was answering replies from others that were trying to figure out how to make this engine work. My intention all along was to swap engines.
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