Rob,
Stick with the 16BTDC at idle.
Confirm you do not have more than 31 BTDC at 4,000 rpm
with vacuum disconnected.
TWO ADDITIONAL COMMENTS:
Tom - How does 16 + 7.5 = 31?
Uh good point. 16 degrees is at the CRANKSHAFT.
The distributor rotates only ONCE for every two
crankshaft rotations, so the distributor advance
cam is in "distributor degrees, so you have to
double it to change is to crankshaft degrees"
So 16 + (7.5 * 2+ = 16 + 15 = 31
Tom - If I set my "smog distributor" with a 17.5 cam to
a maximum of 30 degrees at 4,000.... doesn't that
mean my idle setting would be around 5 degrees
ATDC (AFTER TOP DEAD CENTER) and not at TDC?
Correct! This will also cause the engine to run
much hotter in stop and go traffic... I'd recommend
changing to the "early" cam, weights, and springs.
Problem with setting it to TDC, and having worn slots
is the distributor may actually advance a total of 40
degrees. Running that much advance while charging up
hills may do some damage.
It is NOT UNCOMMON to find all sorts of problems in the
older distributors. Hence putting a dial back light to
good use.
Cheers,
Tom
>
> Thanks for the in depth info. I know I have a
> "non-smog" 7.5 distributor however I will also be
> installing a Pertronix unit. Should I look to do
> anything different or just stick with the 16 BTDC?
>
> Rob
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