Compression
New User
Joined: Oct 2002
Posts: 15
Likes: 0
From: Moreno Valley USA
Compression
Anybody know what the compression (psi) for a 1972 F250 camper special with a 390 all stock 
I put in a Pertronix Ignition system but I guess it was to much for my motor. The motor has about 157000 miles on it. I did a check and #' 5 and 7 are at 110psi and the other very from 120 to 130 psi. I took it for a ride around the block and man it was popping pretty good. Any Ideas, you think just redueing the heads would work. Need to do the low budget fixer being the holidays and all. Any help would be appreciated :-X12
I put in a Pertronix Ignition system but I guess it was to much for my motor. The motor has about 157000 miles on it. I did a check and #' 5 and 7 are at 110psi and the other very from 120 to 130 psi. I took it for a ride around the block and man it was popping pretty good. Any Ideas, you think just redueing the heads would work. Need to do the low budget fixer being the holidays and all. Any help would be appreciated :-X12 
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
Compression
John, I don't think the pertronix will cause your engine to do that if properly installed. The compression sounds about right for a tired ol FE. 
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John
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John
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In the cool still quiet of night, you can hear chevies rusting away.
Post Fiend
Joined: Jun 2002
Posts: 13,873
Likes: 3
From: Atlanta GA
Compression
I would look at what might have been damaged during the install.
I would suspect cross firing or a bad spark plug wire. Make sure all the wires are seated at the dist. cap and spark plugs and that the rotor is making good contact with the cap and that the tabs are securing the cap. Then check the timing. Check for arcing from plug to manifold (in the dark)
If that does not work, put an ohm meter on the plug and dist. wires, they should read about 15-20 depending on age and length.
I would suspect cross firing or a bad spark plug wire. Make sure all the wires are seated at the dist. cap and spark plugs and that the rotor is making good contact with the cap and that the tabs are securing the cap. Then check the timing. Check for arcing from plug to manifold (in the dark)
If that does not work, put an ohm meter on the plug and dist. wires, they should read about 15-20 depending on age and length.
Logistics Pro
Joined: Feb 2000
Posts: 3,565
Likes: 9
From: Sun River St. George
Compression
If it ran OKAY prior to the Pertronix install and poorly immediately afterwards and even with the points reinstalled, look for something you screwed up. I am overly cautious whenever working on these engines I do one thing at a time and test it to be sure there are no problems. For example I install a new cap, rotor, and plug wires and then start the engine. If every thing checks out, install the Pertronix and test again, then do the coil and test again. This way you are not chasing your tail. So put the Pertronix back in. Be sure the point plate ground wire is installed. Double check the air gap between the sensor and pickup. Pertronix likes 12 volts in the run mode, (you already have 12 in start). Then double check your connections on the coil. Go to www.galaxieclub.com/petronix.html for detailed instructions. Post back! This story should have a happy ending.
William in Atlanta
William in Atlanta
