Timing Q's Please Help

[69chargerdad]

       After spending some time looking up old posts I have a couple of questions about timing. I am running a fresh 440 with Mopar Performance electronic ignition. From what I understand to set the initial timing I need to disconnect vacuum hose from the distributor and plug the hose. Then advance the timing by rotating the distributor at idle (700-800) rpm until then engine rpm stops increasing which should roughly be around 15 degrees btdc. Then lock down the distributer hold down.
       What I don't understand is that my total advance should be around 34-38 degrees without vacuum and 38-42 degrees with vacuum. At what rpm should this be achieved (2000?) and if it is not correct how do I adjust my mechanical advance. I know that I can adjust the vacuum advance with an allen key through the vacuum hole. But i am unsure of how to set my total advance correctly. Any help or corrections will be much appreciated. Thank you

             Marcus

[chargerbr549]

There are alot of different variables on what to set your timing at depending on what your engine likes, as a general guideline on stock to modified engines I like to set intial timing (with vacuum advance plugged) from about 10 to around 18 degress and total timing (mechanical) around 36 to 40 degrees and with vacuum advance hooked up the advance will probably be around 50 to 55 degrees. Depending on your gear ratio, converter, weight etc. etc. you probably want total timing in around 2400 to 3200 rpms, you can get different strength springs to taylor when your mechanical advance comes in, I think I used Mr Gasket ones. As far as adjusting total timing, after you have intial timing set you can swap different plates that your weights slide in, or you can elongate the slots in the plate or weld them up depending on where you want to set your advance. Since most of us don't have access to dynos it may take some trial and error to dial in what your car wants, sometimes what your engine likes the best you may run into some detonation, you either need to get better fuel or take some aggressiveness out of your timing, just take your time and enjoy the process after all isn't that all part of hotrodding?

[firefighter3931]

Hey Marc, you're on the right path. The total should be in by 2500-3000 rpm. The speed of the advance curve is controlled by the springs on the advance weights. Get the light out and map the advance from idle to say 4000 rpm and see what you've got. Report back with the results and we can proceed...

You can limit the mechanical advance by welding the slots in the plate or if you've got a newer MP distributor the Mallory kit will work. All of the newer MP distributors are made by Mallory. How old is your electronic conversion kit ?

Ron

[69chargerdad]

thanks chargerbr549 and firefighter3931

to answer your questions firefighter the mopar electric ignition kit is fairly new I purchased it about a month or two ago from mancini but who knows how long they may have had it. Is there an easy way to tell whether it is a Mallory unit.

Right now we are having carb troubles but the new carb should come in on thursday and I should be able to install it and check the timing on friday. So I will probably have the info by Friday night.

The reason I posted this was before when it was running I set the intial timing at 7 degrees btdc and at 2000 rpm with the vacuum plugged the advance was only around 28 degrees. But after reading some posts my intitial timing was probably to low, so friday I will set it by listening to the engine and then mapp out the advance curve.

thanks again

marcus

if it is the mallory unit they make kits. does this mean weights and springs? or only springs?

[firefighter3931]

Hi Marcus, yours will be the Mallory distributor....everything sold in the last 3 years has been the "mallory built" distributor. Check out the advance curve first before ordering the kit. If you had 7* base timing and 28* total then you've got around 21* mechanical advance built into the distributor. Advancing the idle (base) timing to 15*-16* should put you in at 35*-36* total which is pretty close to where you want to be.

The kit will have springs for a quicker advance and screws that go into the plate which are used to limit mechanical advance. The more initial you dial in...the more you have to limit the mechanical advance. Yours might end up being real close without any modifications. You might need to swap out the springs to quicken or slow down the advance curve....depending on what the engine likes.

Once you get the carb sorted out, try bumping the initial up to 15* and map out the advance curve in 200rpm increments to see how fast it's advancing and how far it's advancing. Record the #'s and post them.

Ron

[69chargerdad]

well i picked up my carb yesterday and after school i will go out and see what I can accomplish hopefully I will have some numbers to post if not today than tomorrow. Thanks again

Marcus