Hi All - I am looking for some inputs as a sort out my '66 L79 ignition /fuel system.
I just determined that my Distributor is a 1111490 out of a '69-70 350/350 and not the 1111156, 1111196 that would have been original on my June '66 built L79.

Can anyone help me identify differences in Mech/Vac Advance Plates and any incompatibilities bertween these 2 distributors ?

• How do i determine if there are any differences in the Total Advance available between them?
• How do i identify whether the Advance Plate, Football and Weights are same or different between these and use that info in timing ?

Obviously they are somewhat compatible as the car runs OK and even pretty well @ 2500 rpm & above

Because I know someone will ask:
I've used posts / papers from Duke and Lars to sort out several items and have it running strong at 2200 and above but still chasing Hard Start & Poor Idle.
Idle is 16.5" Hg at 900-950, Will stall if i try to lower idle, Doesnt overheat but doesnt idle well and wants to stall at stop lights when hot (170-180*F)
Timing is 36* All In at 3250ish but that leaves timing at idle at about 24* BTDC (seems high), football and weights move freely
Smells like it runs rich and sounds flat on acceleration between 1000 - 2500 rpm

Thanks in advance

 

A later model distributor might not be the only non original thing. A previous owner may have already changed weights and springs. The football is the same for most Delco V8 distributors. It's the advance cam/plate, weights and springs that determine the advance curve. You seem to have only 12 deg of centrifugal advance. That seems too small by half. 20 to 24 is more like it. The cam/plate slot for the pin on the underside of the football may be obstructed, someone put a too big bushing on the pin, or the weights are too "fat" and won't let the pin return all the way in the slot. Get that sorted out first so the initial timing is about 10 to 16. If by hard starting hot you mean slow cranking, the problem is likely too much initial timing. Rich mixture smell, you have some carb issues to sort out. Your idle vacuum seems ok, but you should be able to get the idle to 800 to 850. Possible dirt in idle and transition slots in the carb base plate.

 

Dizzys and internal parts for those are completely interchangeable.

You can built whatever you want from about anything. Cast iron, aluminum, doesn't matter. Except for the tach drive thing, thgts Corvette only

Only the number on the housing won't match if that is important to you.

Note the "football" ( top of distributor shaft) is diff on reg perf vs SHP motors on at least some years. Doesn't make a huge diff, but it does affect the cent adv curve to some extent, with equal springs

 

Thanks for the reply @AZDoug Not so much concerned with Numbers Matching but seem to only get about 16* Mech advance. I thought 20* - 24* was norm for Mech Advance and was wondering if it was:

• Wrong Dizzy,
• Wrong Internals, or
• Just had wrong understanding on my part.

The Adv is all in at 3000-3100 but to get 36* total, or 51-52* With VAC, Idle is quite rough and the initial timing seems awfully high to me. When i found it was later model Dizzy, I began to wonder if the Dizzy setup was limiting factor.
Any reference you can point me to or more info on which direction to take this investigation ?
Thx in advance