Timing curve question

[astat1]

I just place in a new MP electronic distributor. I have an all stock 440 with a stock 4:10 rear end. My initial timing is set a 15 BTC. I am only getting 31 all in at about 2600 rpm. When I hook up my vaccum at idle I am not seeing any change in initial timing. It is a ported source and I do have vacuum here at idle.  I am still getting pinging under hard/heavy acceleration. I am getting 41 degrees with vacuum attatched at 2600. Any recommendations? THANKS

[firefighter3931]

I allways tune with the vac advance disabled....works better for me that way. The base timing is fine but you should be getting more total timing. The newer MP distributors have adjustable stops built into the advance plate which allows you to adjust the mechanical advance. You need another 3-4* of mechanical advance so it's time to open up the distributor and start adjusting. You might have to slow the curve down with heavier springs depending on what the engine will tolerate. 


Ron

[frederick]

I just place in a new MP electronic distributor. I have an all stock 440 with a stock 4:10 rear end. My initial timing is set a 15 BTC. I am only getting 31 all in at about 2600 rpm. When I hook up my vaccum at idle I am not seeing any change in initial timing. It is a ported source and I do have vacuum here at idle.  I am still getting pinging under hard/heavy acceleration. I am getting 41 degrees with vacuum attatched at 2600. Any recommendations? THANKS

This is normal for ported vacuum. You will only get vacuum advance under decelleration and light to medium acceleration. At full throttle the vacuum advance will be zero(no vacuum).
It is strange though that you're getting vacuum at idle, are you sure it's not manifold vacuum?
If you're getting pinging under heavy load, I'd say the mechanical advance comes in to early and you need heavier springs, like firefighter said.
At what rpm is it pinging?

Frederick

[astat1]

I'll have to check the rpm's when the ping starts. I have a 4:10 so I'm in the higher range quickly. Wouldn't tightening the vacuum advance have the same effect, to delay the mechanical advance response? Thanks