Too much total timing

[Baconbird]

Never had this issue before…
Just rebuild my 440 .030 over very mild cam performer intake w/ Holley 750
Dizzy is Summit Electronic Billet w/ ICU
Seems to like 10* initial which puts the total at 42*. The total timing is 34* with the VAC Adv off. I have adj the dizzy advancement plate back but still have to much total. Is this to much total? I don’t why I have such a big swing from initial to total. If I go 13*+ initial it wants to diesel over when I turn it off after it is at temp. I’m missing something. Probably going to swap out for HEI tomorrow just to see.

 

[MoparLeo]

Go back to stock ignition and don't start chasing your tail. The factory ignition is an excellent one. Been used for decades on millions of cars.
Was the racers choice for years before all the HEI and different electronic ignition stuff hit the markets.
There is no horsepweer in ignition.
If you are concerned with the ignition curve, there are experts who do that. One of them is on this site. @HALIFAX SHOPS

 

[Baconbird]

Thanks.
Not really looking for horsepower…just want it to run good.
By factory do you mean points?

 

[HawkRod]

Never had this issue before…
Just rebuild my 440 .030 over very mild cam performer intake w/ Holley 750
Dizzy is Summit Electronic Billet w/ ICU
Seems to like 10* initial which puts the total at 42*. The total timing is 34* with the VAC Adv off. I have adj the dizzy advancement plate back but still have to much total. Is this to much total? I don’t why I have such a big swing from initial to total. If I go 13*+ initial it wants to diesel over when I turn it off after it is at temp. I’m missing something. Probably going to swap out for HEI tomorrow just to see.

I'm not sure I understand your timing numbers...

But to be very basic, there is initial (static) timing, centrifugal advance (from the distributor), and vacuum advance (from the vacuum pot on the side of the distributor.

If we ignore vacuum advance (assume it is unplugged), and very generally (there are a lot of variables), most old Mopar's run well with about 36*-38* of total timing. This is the static plus centrifugal. Centrifugal timing often adds about 11* of distributor timing, which is 22* at the crank. So to get 36* total timing you would need 14* - 16* static plus 22* centrifugal which = 36* - 38*. I say again, these are very rough numbers and there are many cases where they may be different.
Centrifugal timing should start to come in about 1000 RPM, and by about 3000 RPM should be "all in". So you need to check that your centrifugal advance is working properly. It sounds like from your description that the centrifugal advance is not working right? It should be adding essentially zero timing at 1000 RPM. If it is adding timing below 1000 RPM, then your springs are too weak or something else is not set right in the distributor.

 

[BeepBeepRR]

If your car is dieseling Watch this video has nothing to do with your timing. I know its a lincoln but the point is the same.

 

[Crackedback]

Poor or inadequate initial timing setting can contribute to dieseling because the throttle plates may be open too far at idle to maintain idle. Remember those throttle solenoids they put on the cars in the early 70's when the engines started being timed at TDC.

Same as cars that smell like a fuel truck dumping raw fuel out the pipes.

 

[Geoff 2]

First thing you need to do is get the idle timing correct for THAT engine. Engine idling [ in gear if auto ], start with about 10* BTDC [ not critical ] & slowly advance the dist until you get the highest idle rpm. Then, check to see what the timing is. Do not be surprised if it is 30* [ or more!! ]. Come back with the results & we can go from there.

The claim that there is no hp in ign is NONSENSE.

Below is an extreme example but demonstrates the point.

 

[451Mopar]

Need to re-curve the mechanical advance. Need to limit the amount of mechanical advance.
Not sure how it is done on the distributor you have.
The vacuum advance might also need adjusting, but I would just leave it disconnected until the mechanical advance is fixed.

 

[Don Frelier]

What is your compression ratio?
How much cylinder pressure are you getting?

 

[Baconbird]

Thanks everyone.
Not sure on the comp ratio. 1968 .030 over flat top pistons w/ 906 heads.
Pistons & rings are new.
Goin out to work on it now. Will report back.

 

[twecomm]

Here is a good article on tuning.. Tuning Tips

 

[Don selleck]

I installed a msd stand alone, had the same issue. kit came with stop bushings, of course the largest one was still allowing 18 degrees of advance ended up buying a bushing larger from another manufacturer and filing it down to get 14 degrees, your going to have to stop the advance sooner by what ever means it will allow, or scrap it and go back to orange boxes and ballast resistors. google the part you need more that likely someone makes it.

 

[HALIFAXHOPS]

It is really all about the curve. Points or electronic basically give the same output, electronic is a bit crisper. Tons of ways to skin this cat. JFYI the Mopar vac advances can only be adjusted for the vacuum rate not total advance with the adjustment screw.

 

[Baconbird]

The transfer slots were open to far. Adj the mech advance plates again and this is where I’m at.
With no vac it’s at 13* & 38*
With vac it’s at 15* & 55*
I will adj the Mech advance more and work my way through trecoms tips next.

 

[Some Car Guy]

Stock heads on a big block with today’s fuel like 33-35. I found 34 was the ticket just playing around with it, then read that spread in Mopar Action.