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Dr. Hamman
Dr. Hamman, Technician
Category: Classic Car
Satisfied Customers: 2436
Experience:  I have 30 years experience repairing, restoring, and customizing cars, and pickup trucks.
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Mercury truck-same as Ford: . I have a 1966 F100 with a 352

Customer Question

Hi. I have a 1966 F100 with a 352 4 speed. I have the timing at 6 degrees BTDC and dwell at 27 degrees. When I speed up the engine from 500 RPM to 900 RPM. my timing advances more than 24 degrees. I suspect the previous owner tampered with the centrifigal advance, since the springs do not look right. So, Which weight is primary and which one is secondary? I have new springs on order to hopefully correct this.
Thanks. Terry
Submitted: 2 years ago.
Category: Classic Car
Expert:  Roy Belding replied 2 years ago.
good morning my nme is roy and I will assist was this done with the vacuum advance connected??? the weights work together. I have never done a set of weights and springs that were marked primary and secondary. is there a driveability issue with the timing this way??? does it ping??? Roy
Customer: replied 2 years ago.
Hello Roy.
Yes, the vacuum advance was connected. Yes, there is a drivability issue- it pings.
From what I have gathered, a total of 30 degrees of advancement should happen at 3500 RPM, not 1000 or less.
My factory Ford parts book from 1966 identifies a primary and secondary distributor weight spring. My Ford manual identifies which is primary and secondary on a LOADMATIC distributor, but doesn't identify which is which on a dual advance distributor, which is what is on this 352.
It seems that there is a lighter and heavier spring in this application.
Is that what it should be? If it is, where should the lighter spring be?
If both springs are to be equal, that is my problem.
Thanks for your time on this.
Let me know what you think or what your thoughts are on this.
Expert:  Roy Belding replied 2 years ago.
good morning just got home from work. got my old books out and you are absolutely correct. there are different weights. I never paid attention when I replaced them as the ones I installed were the same, not OEM parts. the springs were different tensions. there were light weight and heavy.I would install the heavier weight to the front. do you have different tension springs?? f you do, use the heavier ones so the timing will advance at later rpm.Roy