random questions
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random questions
sorry about the newb questions guys but
is it possible/normal for ignition control modals to fail (1975 f-100)
and also wat is a healthy compression pressure for that old of a motor mine is 115psi the book say 75% of the highest cylinder pressure
mine has also been punched 0.60 over if it makes a difference
is it possible/normal for ignition control modals to fail (1975 f-100)
and also wat is a healthy compression pressure for that old of a motor mine is 115psi the book say 75% of the highest cylinder pressure
mine has also been punched 0.60 over if it makes a difference
Senior User
Joined: Jun 2009
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From: Hudson,Michigan
It is very possible,and when they quit,they usually don't give any warning.If I'm right,I think these are color coded (blue,red,yellow) on the plastic part of it,if so,you can use any module of the same color (used like one out of a salvage yard) .If you don't have spark all of a sudden,there's are real good chance that it's the module on these.I don't think that pressure is too bad,the big thing is that all cylinders are close to the same reading,you wouldn't want to have others reading,say 90# and especially next to each other.If you replace that module,slip a little coat of dielectric grease in the plug-ins,keeps moisture out.
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Joined: Jun 2009
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From: Hudson,Michigan
I had one shut off for a second and come back on,blowing a baffle out of the muffler on a '77 LTD,then a couple days later it just never started and I had to replace the module.If you tapped on it while it was running and it cleared up,I've never heard of that.If you shut off and tapped on it,then restarted and it was ok,the tapping may not have had anything to do with it.At any rate I wouldn't trust it.I would at least locate another module and keep it in your truck so you don't get stranded,it's nice to have a spare anyway,I always carried one in any vehicle that had duraspark,which is a great ignition by the way.I would also be checking all my connections and ground.If it loses ground it will shut down,may be corroded where it mounts to metal.
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From: Lebanon
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From: Boise, Idaho
Most automotive parts stores will test your control module for free if you bring it in. That'll eliminate a lot of the guess work.
I wouldn't say that 115 is necessarily a good strong engine. The fact that they're all really close does mean it's healthy, but it sounds like it may be showing some age. I think a good strong, healthy engine is generally around 140 - 160. However, who knows, you may not be getting a very good spark if your control module is dying. I'd get the control module taken care of, and then test compression again.
I wouldn't say that 115 is necessarily a good strong engine. The fact that they're all really close does mean it's healthy, but it sounds like it may be showing some age. I think a good strong, healthy engine is generally around 140 - 160. However, who knows, you may not be getting a very good spark if your control module is dying. I'd get the control module taken care of, and then test compression again.
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Joined: Jun 2003
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From: Brunswick, Maryland
Most automotive parts stores will test your control module for free if you bring it in. That'll eliminate a lot of the guess work.
I wouldn't say that 115 is necessarily a good strong engine. The fact that they're all really close does mean it's healthy, but it sounds like it may be showing some age. I think a good strong, healthy engine is generally around 140 - 160. However, who knows, you may not be getting a very good spark if your control module is dying. I'd get the control module taken care of, and then test compression again.
I wouldn't say that 115 is necessarily a good strong engine. The fact that they're all really close does mean it's healthy, but it sounds like it may be showing some age. I think a good strong, healthy engine is generally around 140 - 160. However, who knows, you may not be getting a very good spark if your control module is dying. I'd get the control module taken care of, and then test compression again.
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From: Boise, Idaho
I've heard a weak/dying battery can even lower your compression test readings.
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