Locking out timing on a street car

[morgan]

Vacuum advance is handy for pulling in lots of extra idle advance but given the small diameter caps mopars use, if you already have a lot of initial timing it can actually cause a misfire by firing on the next adjacent post. My thinking is vacuum advance on a mildly tuned street car but mechanical only on something a bit lively that gets raced and needs a lot of initial timing.

My lovely new engine doesnt seem to care - which is really odd.
Fixed mechanical ~16deg initial and 34 all in - seems happy - runs LOVELY.
Vacuum on - pulls it right in (like 40 degrees or so) - and seems just as happy.

I was hoping the vac would make the idle cleaner - but it doesnt really seem to mind.
Now I've sorted the cooling and its all run in I am not even sure I need the lower heat. Its just a happy car now

[Blue]

Good to hear Morgan, not every combination wants setting up the same way, the bottom line is whatever the engine responds to is the correct appraoch.

[David Walker]

So driving it to brooklands today seems fine, throttle response certainly is very crisp.
However hot starting seemed to need to crank and crank and crank before firing. I'm not sure if it's timing related or I'm just not pumping enough fuel in to get it going.

Got a bit more playing to do I think to see what works best. But I was enjoying the crispness of having it locked at 34' that's for sure!

The hindhead tunnel also appreciated it

[Blue]

I don’t think the timing is causing a hot start issue, I’ve had locked out timing for years and have done the same on other cars without issue. I do use a start retard these days that knocks out 20 degrees during cranking to ease the load on the starter. My old big block Dart was locked out at 34 and would easily start hot or cold without any start retard. My Barracuda has a tall single plane intake with a fair sized plenum, it does need a fair amount of fuel down its neck before cranking for a quick start, less so when its hot.

[David Walker]

Yeah the more I think about it, it's probably fuel evaporation or something similar from sitting for a few minutes.
I've got a 1" carb spacer which helps. The motor was running a bit warmer than usual but not super hot.