MSD distributor timing issue
started a new thread based on post from carb tuning thread, hoping i can get some help or advice with timing issues
i intended to start getting deep into the carb tuning this weekend. well, like the responsible sane person i pretend to be sometimes, i decided to do the right thing and re-check / confirm timing before i got into the carb tuning.
for reference, I'm running an MSD 8361 distributor , it's the pro billet dealy with vacuum advnace, an adjustable vacuum advance can hooked to manifold vacuum with a limiter plate for 10* additional advance, an MSD 6AL box and blaster 2 coil.
the beginning set up in the distributor was the 2 lightest silver springs to bring all advance in by 2,000 with the green limiter bushing to limit mechanical advance to 23*. initial set at 12*
disconnected the vacuum can, plugged the port on carb base and hooked my light up. once at full operating temp (175*) i read my stated 12* initial advance.
this is where things get weird.
with the light on the balancer, i bring the RPM's up to watch the mechanical advance. as the rpm's reached 2,500 or so the advance quickly ran up to right at 30* then just as quickly settled back down to 20* and remained there regardless of how much rpm input i added. maybe I'm missing something but shouldn't the advance get to around 34-36* with this set up and stay there with added rpm's?
so i confirmed what i just listed above a couple times and check with three different timing lights. (2 dial back style, 1 fixed style) got the same reading each time.
at this point i was figuring i had the wrong mechanical stop bushing in the dizzy and wasn't allowing it to get the full advance timing. I pulled the distributor, found the green bushing in there that i had in my notes. i replaced it with the silver bushing that should have added 25* or so and replaced one of the springs with the light blue spring that would make it come in a little higher, around 2,500.
replaced distributor, reset initial to 12*, ran it up and got the exact same readings as before. pegged to 30* then quickly came down and settled at 20* no matter of added rpm even with the smaller stop bushing. goes right back to 12* at idle.
i tried adding initial timing up to about 18-20* then brought the rpm's up again. same thing, initial would be right where i set it, mechanical advance spikes to 30* then drops back to 20* and stays there.
what am i missing here? called MSD tech line but they are closed on saturdays. may try another call today if someone here can not add some clarity.