Hello everyone

I am using Pertronix 3 flame thrower and my current timing on my 455 is as follows:
Initial 16 w/o VA
Initial 32 with VA
with the VA plugged I only get to 24 degrees total (initial and mechanical) at 1700rpm
Total is 47 all in also at 1700rpm
I'm running a 224 degree cam, 2000 stall and 3.23's
Idle and cruise is decent but when I go WOT and loose the vacuum advance there is some hesitation.

Am I correct in thinking I need more mechanical and less vacuum and if so what changes are recommended with my current weights and springs?

 

With 16* initial and vac adv disconnected, what is the rpm that the mechanical adv stops and how many degrees is it? You do know there is an rpm limiter built into the pertronix 3 and is it adjusted correctly?

 

Is your vacuum advance hooked to ported or manifold vacuum? And those springs look heavy.
In addition how do you you know your problem is in the dist/timing? Could be accelerator pump issues as well. Buy a wideband and see what it does during that activity. I’ll bet it spikes lean.

 

You probably ought to reread the OP's post.

 

24 degrees of mechanical advance is the most I can get and no increase past 1700rpm. I'm aware of the rev limited with Pertronix and I believe the factory setting is 5500rpm and i'm not aware of any impact on the mechanical advance?

I am using manifold vacuum as it really helps with closing the primary throttle plates at idle.

I am using a wideban which is showing a tad lean through most circumstances. The jets/rods are factory 70/49B and I haven't played with them yet. Carb has been rebuilt well including replacing the accelerator pump

the springs do look thick so I was wondering what the consensus was with lighter springs. Will I get more mechanical advance or just earlier advance?

 

Your math does not add up or you don't understand the terms. Initial is what you set the timing to at idle, mechanical is how much advance is built into the distributor. With no vac adv connected, 16* initial and 24* mechanical would make your total 40*. Will the engine rev past 4500?

 

there may be some confusion from my latest post but my original post is accurate.

initial is 16
total w/o VA is 24 so 16 Initial + 8 mechanical with no increase past 1700rpm.
With the manifold vacuum I am getting 32 degrees total at idle (16 initial 0 mechanical and 16 vacuum) but in the higher rpm ranges with more vacuum total is 47 degrees (16 initial 8 mechanical and 23 from vacuum)

Is 8 degrees of mechanical normal with stock weights and springs, this seems low and not seeing it increase past 1700rpm seems odd.

 

No 8* is not normal, you may have advance plate binding issues. There should be around 25* of mechanical advance built into your distributor.

 

Ok that makes sense. Knowing that 25 degrees is possible then the 8 degrees is the problem and I will focus on freeing up the advance plate

Thanks for the help

 

I did, and the rev limiter has nothing to do with advance. It limits rpm, not advance unless it won’t let it run to the desired RPM.