Huh. It seems reasonable to expect that lack of a ground in the distributor could cause the issue at high speed, under load.

An intermittent or variable ground will make the electronic chip in a Pertronix go nuts. Simply having resistance in the grounding - like through the point plate bearing is enough to have a low voltage problem. On the systems I have built using the Ford Duraspark II system there are old service reports concerning the grounding (black) wire - which returns from the silver box - all the way back to the distributor - and then through the dizzy base to the block. The service lit on the subject - says try a grounding wire on the distributor body.  On the systems I build - I put a grounding wire on the housing - and run it to the block. 


 
 Steve Metzger       Tucson, Arizona

Somebody claimed they saw 2 to 3 hp gain or somesuch on the dyno simply by running a ground strap from distributor housing to block. Not a lot, though measurable.

Re 57-58 Ford Distibutors; Don't know if this has any bearing on this posting, but according to J. Mummert, most of these units were intended to be operated with about 3 degrees of intial advance  & had about 34 degrees centrifical. If a modified engine has a fairly hi.po. cam & needs initial at idle set at up to 12-14 degrees, now the engine may "detonate" because  the total is well above 35 degrees.. He recommends for basic retro fits 1960-64 distributors.. and notes the vacuum units are more readily available then the earlier ones..


Paul

Don't know if this has any bearing on this posting, but according to J. Mummert, most of these units were intended to be operated with about 3 degrees of intial advance  & had about 34 degrees centrifical. If a modified engine has a fairly hi.po. cam & needs initial at idle set at up to 12-14 degrees, now the engine may "detonate" because  the total is well above 35 degrees..

It certainly does.

Depending on the DIST source (ID'd by Stamping Nos) the timing curve will most likely be inadequate for a performance engine.

____________________________

The distributor cams in the older style have different length slots that determines the amount of centrifugal advance, finding the correct OEM part would likely prove difficult as they are getting to be rare as hen's teeth. It's tedious, but the slots can be brazed up and filed to the correct length and the mechanical advance tailored that way. Using latter year distributors, there was the whole debacle with counterfeit "remanufactured" units in circulation in the last few years. I'm not sure how that ever shook out. I'm afraid to look.

The Problem Distributors from Cardone were no longer available from the usual Sources (Ebay, Rock Auto, Auto Parts Suppliers) last Time I checked.
Maybe Cardone has finally owned up about them being Garbage. Some of the Repo Parts Sellers are offering Distributors but unless they are sourced from someone besides Cardone I wouldn't get my Hopes up about being useable.

  

FYI  I have a totally stock 1957 Ford distributor in my engine that came out of a 272 station wagon with 40,000 miles on it.   I also have an Isky RPM 300 cam (301333), which is pretty mild.  When I degreed the cam and it was right on spec. My engine runs best at 10 degrees on the balancer. Without the vacuum line, this engine has about 36 degrees total timing according to my timing light.  My engine has about 9/1 compression.  I run Florida pump high test fuel.  My car has a standard transmission and a 3.89 rear gear.  It never detonates.  My problem was bad fuel. I have not had any problems since.

If it is a totally stock '57 distributor, then it should provide more than 36 degrees of total advance, closer to 45 degrees with 10 initial.  It's either not stock or there is a problem with the timing light.
However, I agree, if this is the way it's been and nothing has changed and it has not been a problem, then it is not the cause.


Lawrenceville, GA

Here is how I am determining the timing.  Maybe I don't understand how this works, but it seems right to me.  I have a newer Craftsman timing light, the kind where you can set the timing on the back with a dial.  If I disconnect the vacuum advance line and dial in 10 degrees, at idle the TDC mark is right on the pointer. If I dial in 35-36 degrees and rev the engine to about 4000 RPM, the TDC mark is right on the pointer.   This distributor is totally stock and has never been modified.    I know that because I took it out of the lady's car.  It has the points back in it now.