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06-14-2019, 08:38 PM | #1 |
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Foundering flathead
Greetings. I haven't posted much but have been reading for several years. I bought a 1951 F1 with a 8BA several years ago out of an estate. The engine appeared to be a new build, clean in and out with many new parts. The entire restoration looked good, but was unfinished as the builder/owner died. It wasn't his first build. I bought without a single wire in the truck, so have been building a wiring harness over time.
This is my first flathead. I finally got around to firing the engine recently. Had 50# oil pressure turning it over. Finally got the fuel pump (new) pumping and put a Holley pressure regulator at 2.5 PSI on it. Went through the Holley 94 and checked everything, fresh rebuild in there too. Has a Pertronix kit in the Loadamatic. It is 12v. It fires up and runs somewhat. I have a very rich condition, some back firing in the exhaust. Vacuum guage shows a steady 12 inches. I checked the power valve and no leaks. Checked the float level. Valves all appear to be opening and closing. I have read that the vacuum should be around 18 inches. Changing the idle mixture screws doesn't have much affect. Next step is checking the intake manifold for leaks. Not sure where to go on the rich fuel problem. Timing is set by ear for now. The only timing mark is the raised dot on the front pulley. It sounds somewhat like it might have a more radical cam than stock, but I really don't know what is inside. |
06-14-2019, 08:45 PM | #2 |
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Re: Foundering flathead
As a point of reference, I have a fresh built 258" 8BA with an Isky MAX-1 cam that makes 20 inches of vacuum. It sounds to me that there is something else wrong besides the carburetor. There was a guy on here a few years ago that had a similar problem and found that the cam had been installed wrong (a tooth or two off as a result of a mis-marked crankshaft or timing gear).
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06-14-2019, 08:49 PM | #3 |
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Re: Foundering flathead
I read that late valve timing could cause low vacuum pressures. I'm hoping I don't have to pull it apart.
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06-14-2019, 08:57 PM | #4 |
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Re: Foundering flathead
It's a real long thread, but if you have some time to spare, you might want to look it over : https://www.fordbarn.com/forum/showthread.php?t=235272
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06-14-2019, 09:32 PM | #5 |
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Re: Foundering flathead
Good read. Tomorrow I'll check the valves in number 1 against the dot on the pulley. That's a start without taking it apart. If it looks off, I'll pull the front cover.
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06-14-2019, 09:46 PM | #6 |
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Re: Foundering flathead
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06-14-2019, 10:17 PM | #7 |
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Re: Foundering flathead
So far they all look black and a little oily (right bank). I'll check the rest. I have watched all the right bank valves through the plug holes.
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06-14-2019, 10:33 PM | #8 |
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Re: Foundering flathead
Is the vacuum fluttery or just low. Rings. Flutter is maybe stuck valves.
Not to say a vacuum leak or other can give the same low readings. Run the heck out of the motor, it's not going to hurt. Fatheads need to be run to really diagnose, problems work them self out. Your not going to harm it if it has oil pressure 99.9 times out of 100. If after something is problematic, stick a vacuum or compression gauge to it. Fuel would be next, then timing/spark. Back fire is too much, pre-fire is to little... granted timing is set right. . Last edited by Tinker; 06-14-2019 at 10:42 PM. |
06-14-2019, 10:44 PM | #9 |
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Re: Foundering flathead
Vacuum is steady, just low. Will check for leaks this weekend. Compression check soon.
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06-14-2019, 10:54 PM | #10 |
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Re: Foundering flathead
Even rings on a new engine will need to run hard to seat. An engine on a stand does not constitute a brake in, it needs load. pour some MMO down the carb and run it. See if it improves. Obviously if you hear metal on metal noises, knock, or other, pull over.
Kinda sounds like timing but.... run it hard underload for a bit. Only thing that will kill it is no oil and high rpms... . Last edited by Tinker; 06-14-2019 at 11:11 PM. |
06-14-2019, 11:11 PM | #11 |
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Re: Foundering flathead
Tinker, he says it appears to be a fresh build. If it is, "run it hard for a bit" might not be the best idea. If it is a fresh build, I'm afraid it will have to be taken apart and everything checked. To the O/P; do you think it is a fresh build or do you know if it had been running well in the past?
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06-14-2019, 11:14 PM | #12 |
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Re: Foundering flathead
Tub not necessarily, New rebuild sitting has never really ran. It needs to run. I'd be really less concerned about low readings if it sat in a garage and never was run? Concern was not about knocking the heads or other. Just my opinion. Probably a good build but it sat, i'm not conditioned to believe the worst.
Tearing an engine apart that has never left a garage or run a mile seems premature. or not. Good luck . Last edited by Tinker; 06-14-2019 at 11:37 PM. |
06-14-2019, 11:51 PM | #13 |
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Re: Foundering flathead
It appeared new from looking at the valves through the spark plug holes. It sat before I got it for an undetermined length of time, and for 5 years after I got it. No strange noises from the block, oil pressure is still around 50#. All run time is static right now as the rest of the truck is still in work.
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06-14-2019, 11:54 PM | #14 |
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Re: Foundering flathead
Get some load on it. There are conditions that run great at idle and fail under load.
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06-15-2019, 12:20 AM | #15 |
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Re: Foundering flathead
Tinker, I guess we'll have to agree to disagree. With the cost of building a flathead what it is today, I'd probably go to great lengths to make sure that no damage would be done to a fresh engine.
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06-15-2019, 12:41 AM | #16 |
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Re: Foundering flathead
If the powervalve in the carburetor is old...it may be stiff as--- and not close giving you a rich condition...
It still donīt leak but carb runs rich all the time. Put in a good powervalve and check timing with a strobelight to start with. |
06-15-2019, 06:24 AM | #17 |
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Re: Foundering flathead
What exhaust ? A blocked exhaut could result in low vacuum. Just another place to look that's easy .
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06-15-2019, 10:21 AM | #18 |
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Re: Foundering flathead
New exhaust, stainless pipe and straight mufflers, pretty loud.
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06-15-2019, 11:58 AM | #19 |
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Re: Foundering flathead
MOT, you mentioned that the timing is set "by ear" and that the loadamatic distributor is equipped with the Pertronix ignition. I am presuming that the vacuum connection between the port on the carb and the distributor is in place. You have not mentioned the idle speed, i.e., fast or slow or how the engine reacts when you "goose" the accelerator. Is there hesitation/stumble or a quick run-up? Have you measured the vacuum while rotating the distributor to advance/retard the timing? This will have an effect on the vacuum.
Richard
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06-15-2019, 12:49 PM | #20 |
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Re: Foundering flathead
I may have missed it but what port are you using for the vacuum gauge ?
What's your location , I'm in lake worth , fl. If your close I'll help ! |
06-15-2019, 04:08 PM | #21 |
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Re: Foundering flathead
I'm near Tyler, Tx. I' m using a manifold port, small one. I have had the ported carb vacuum hooked up and not hooked up to the Loadamatic. I just picked up a compression guage, some MMO, and some other odds and ends. I'll be trying several things this weekend.
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06-15-2019, 04:29 PM | #22 |
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Re: Foundering flathead
If the vacuum is not connected to the loadamatic then it is not going to work. The loadamatic is totally dependent on that connection and will not function without it. This would have a major impact on how the engine is performing. The loadamatic does not have any other method for advance other than the vacuum ports in the carburetor (manifold vacuum will not work!).
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06-15-2019, 06:30 PM | #23 |
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Re: Foundering flathead
I got my car as an unfinished project with a motor in the same condition as yours. I could see nice shiny valves through the spark plug holes. My car ran, but not the best. I had sticking valves, it farted, backfired every now and then and ran rich like yours. We can't get MM oil here is NZ but I poured some Moreys upper cylinder lube down the sparky holes and put some in with the gas. Overtime it freed up and I would say the rings bedded in. I have done 2k miles on it now, the more I drive it the better it gets. I have even backed the idle off now where I had to have it up a bit to get it to run ok.
The other thing is to get your distributor properly set up and run a good coil. I got one of Skips rebuilds and this made a diferrence the way it ran and started GB
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06-16-2019, 12:09 PM | #24 |
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Re: Foundering flathead
All cylinders are between 90#-100#, engine cold, cylinders dry, throttle open, 450 feet msl. But, while cranking number 3 cylinder is steady spraying fuel mist out the spark plug hole. I assume that indicates a carb leaking internally. Also found the plugs are wrong, Autolite 75 is a bit short. I picked up some Autolite 216 to replace them.
Last edited by My Old Tools; 06-16-2019 at 12:54 PM. |
06-16-2019, 12:54 PM | #25 |
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Re: Foundering flathead
Starts right up. Takes throttle pretty well. Timing with the light is pretty close, maybe a bit retarded. No marks on the flywheel other than TDC. Half a bottle of MMO down the carb didn't change much but really fogged the garage.
Last edited by My Old Tools; 06-16-2019 at 01:49 PM. |
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