FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Riderjeff on June 24, 2024, 06:12:53 PM
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I have a distributor pulled from a '74 (?) pickup and rebuilt for use in my mild 390. I told the shop what the application was, and on delivery I think he said it had 15 degrees centrifugal and 12 degrees vacuum advance (I may have those turned around...)
Anyway, he provided no testing documentation and I'm concerned the advance curve may be inappropriate for my car and engine combo. '65 Thunderbird, .040 over 390 at around 9.5 static comp, C4-G heads, streetmaster, Lykins custom cam, 735 Holley. I've tried to decipher the distributor ID: C5TF 12127, 4KD, but am only ASSUMING it's a truck dizzy. Were the advance curves customized from Ford for each application? What springs/weights would be the closest match to my needs?
TIA, Jeff
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Yes the curve would have been different for different engines. Short of taking it apart to see what the limits are (the weight plate is stamped), disconnect the vacuum advance, and put a timing light on it and record the readings every. 500 rpm up to 3500 or so. That will give you an idea of the mechanical curve. As for the vacuum, put the timing light on it, see what it is at idle, then connect the vacuum can to full manifold vacuum and see what the timing jumps to. It won’t be exact because the increase in rpm will give some mechanical advance, but you’ll have a general idea at that point…..
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Not a lot of info there, but you say "rebuilt" not "recurved" did they do a performance curve to it?
With stock distributors you don't change weights and springs like a Chevy, they change slots in the main shaft that limit travel and springs, or weld the slots to limit travel. It makes sense that yours could be in a 15L slot, which provides 30 degrees of ignition advance, which you'd likely set the initial around 8-10. Vacuum seems to make sense too at 12, but overall, that is designed like a stocker. A performance curve would have limited centrifugal and given you a rate after testing too.
I'd ask them to spin it on a distributor machine, and if they didn't or can't, it depends on the cam, gears, and where it is now in terms of springs if you need to do anything
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If you want to be sure it's correct for your combination, you can send it to Faron Rhoads, he is The Man with Ford distributors, many years of skill and experience. Give him your vehicle info and he will let it be all it can be- accept no impostors lol. totalperfentofpa@aol.com
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Thanks for the feedback. I didn't ask for any modifications during the rebuild, so likely it's "stock" for the part number. My trouble is there doesn't seem to be a database anywhere where I could look up whatever specs apply. This was done in advance of installing a fresh engine, the bird currently has a non-running 360 truck motor (ugh)! So no way to test right now.
My immediate goal is to insure that the engine will fire up properly for break-in. For now I'll just plug it in and hope for the best. Optimal performance can wait, Faron Rhoads sounds like a real resource.
Thanks again!
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Although you maybe found it in a later pickup, your distributor appears to originally from a 1965 Ford pickup, and there should probably be a letter or letters after the “-12127-“ that would denote the exact application. The 1965 Ford Truck shop manual should have the exact stock “curve” specs, and they can also be found on the old Sun tune-up spec cards. The Ford Truck Parts book will list which advance slots it should have, although you should be able to see those numbers through the adjustment hole on the point plate. The Ford Parts book will list which springs it should have, but just by part number, and not by the tension they have.
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I have a distributor pulled from a '74 (?) pickup and rebuilt for use in my mild 390. I told the shop what the application was, and on delivery I think he said it had 15 degrees centrifugal and 12 degrees vacuum advance (I may have those turned around...)
Anyway, he provided no testing documentation and I'm concerned the advance curve may be inappropriate for my car and engine combo. '65 Thunderbird, .040 over 390 at around 9.5 static comp, C4-G heads, streetmaster, Lykins custom cam, 735 Holley. I've tried to decipher the distributor ID: C5TF 12127, 4KD, but am only ASSUMING it's a truck dizzy. Were the advance curves customized from Ford for each application? What springs/weights would be the closest match to my needs?
TIA, Jeff
There is an Advance Rate for each and certain engine. No matter what brand. Sun Spec cards gives the advance rate for that particular engine. Great info to have, especially on setting up custom curved distributor for the engines needs and wants.