FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: preaction on August 08, 2015, 04:21:51 PM
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Im working on a 67 390 which I was told was rebuilt and most likely .030 over bore. This engine is otherwise factory in its parts except a very mild replacement cam. I have the initial timing at 16* and total at 38* with the distributor vacuum plugged. With the vacuum put back to the distributor and a rev of the engine the timing goes way past the 38* easily to what looks like 44 to 46* this is about 3000 RPM. Im not sure if this is correct. The engine starts well and runs well with much low torque everywhere and stays at 180 to 200* but at highway speed 70MPH which is 3000RPM for this car the engine starts running much hotter-220 to some times 230* is the over heating a symptom of the timing ? The carb is fresh 68 jet in front and 72 in back. Any ideas, thanks Paul.
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Pretty sure that you can have around 15 degrees vacuum advance in the distributor, so timing in excess of 50 degrees BTDC at higher speeds and high vacuum levels is not uncommon. On the overheating issue, my experience has been that more timing reduces the tendency to overheat, so I'm somewhat puzzled by your issue. You could certainly disconnect the vacuum line and go for a cruise, and see what the temperature does...
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Thanks Jay that's a easy and good idea.
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Sounds more like blocked or not enough radiator to me.
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The radiator was just removed and cleaned (oxalic acid ) but no rust or sediment was found, also checked hoses and bottom hose spring was in place. Also this is an A/C car so the radiator is a extra cooling package with a shroud in place.
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There was one recently where the fan was on backwards, but you would think at highway speed it wouldn't matter. Usually the old rule of thumb, overheat at idle = airflow, overheat at speed = radiator, is pretty good. Is the balancer verified as reading correctly?
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Have you got a big spring in the hose going from the bottom of your radiator to the inlet of the water pump? Also make sure your fan belt isn't hard, usually the alternator discharges when that happens also.
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The balancer has been checked for movement and its good. There is one thing I have seen with a vacuum gage on the engine at idle it reads 15 to 16 moving slowly between the two, could this be something with the valves causing the high RPM heating ?
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The balancer has been checked for movement and its good. There is one thing I have seen with a vacuum gage on the engine at idle it reads 15 to 16 moving slowly between the two, could this be something with the valves causing the high RPM heating ?
Doubt it. Fan type? Solid, flex fan, OEM later Ford type clutch fan? Is the top radiator hose (expansion tank to the radiator) nice and stiff.....or squishee?
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don't overlook the obvious, thermostat or lack of one.
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The fan is factory ford with new clutch for a 390 GT with A/C. All parts are factory with the exception of parts replaced for a rebuild. I checked the balancer with a piston stop and zero was right in the center of my two marks. The bottom hose has a new spring and the top hose is in very good condition. We thought it might have been running lean so we took out the 64 front jets and put in 68's and it does run with more power and torque but highway speeds ( 3000 RPM ) it runs hot but never boiling over hot, usually to 220-230*.