Posted By: dfsmopars
MSD Electronic Distributor 8504 - 04/21/14 03:38 AM
Who is an expert on the MSD E-Curve distributor? If you have a good understanding of mechanical distributors (which I don't) it helps probably. I have an 8504 on my 5.9 Magnum and the options are too numerous. It would be nice to have them whittled down to a few. Who knows where this engine timing base should be using the dials in the dist and perhaps I can tweak from there. A dyno would be nice but that is not an option at the moment.
Specs:
Street (Spirited driving)
.04" over flat top pistons
Hughes .544 lift, 218°/228° roller cam (degreed)
Roller rockers
Iron X heads
9.5:1 compression
625 cfm carb
SB Hooker headers
2.5" exhaust
AT w/OD
3.55:1 gears
28.5" tires
4000+ lb b-body
Posted By: RobX4406
Re: MSD Electronic Distributor 8504 - 04/21/14 04:23 AM
It's pretty simple really.
Using vacuum advance? Pick which one from the graph. See number on the vertical side of dial settings chart. If not using vac adv, just use the #1 line.
Find the curve you want in the charts, I'd think 15 or 20*, all in at 2500, 20* is G and 15* is K. Go across the top and find those letters. Set dials to the setting it shows, G = 0,7 K = 1,1.
Initial should be anywhere from 14-20 depending on how much total the engine will handle and ease of starting when hot. You may have to compromise the total or initial timing number to get a happy spot that the 5* split in curves will provide.
You need to find what the engine likes for initial and total timing. Then it's finding the curve that fits best. Either of the two suggested should get you in the ballpark to start.
Posted By: RapidRobert
Re: MSD Electronic Distributor 8504 - 04/21/14 04:49 AM
Set initial with the vac gauge method. then set the total (checked with vac adv capped) to 35 (initial + mech), Then mix/match springs staying just under the pinging point up thru the gears on your hottest/driest day with the adv starting no less than 200 RPM above your hot in gear idle speed which is what the eng will see from stoplight to stoplight. Then plug in/adj the vac adv. CCW with a 3/32" allen wrench gives less adv at a given in hg vac amount & stay just under the pinging point in everyday driving under varying vac levels (load) on your hottest/driest day. #1 is do em IN ORDER
Posted By: dfsmopars
Re: MSD Electronic Distributor 8504 - 04/21/14 04:58 AM
I am running vacuum because it being a street car and fuel economy is somewhat important on the Hot Rod Power Tour and such. Do I choose the vacuum advance curve or does the engine itself dictate that? If I choose curve 3 vacuum then that will limit the vacuum advance to 10°?
What you are saying about the graph (which I have studied many times) makes good sense but curious why you say all in at 2500 rpm? Are you just getting me in the ballpark with that or is it just best to advance the timing really quick in this case?
The cam comes in around 1800 to 2000 rpm. The stall is slightly more than that at around 2500.
Based on your reply 4,7 or 5,1 would be a good start? That is 10° vacuum advance, with either 15° or 20° electronic advance.
I know that once I grasp the concept of this thing like you have I will be able to utilize its benefits.
Posted By: dfsmopars
Re: MSD Electronic Distributor 8504 - 04/25/14 03:42 AM
Robx, got it about where I think it wants to be. Started with 15* electronic plus 10* vacuum at 37* total timing. It ran good with the quick curve you recommended. Bumped it down to 10* advanced and set the total at 42* and it perhaps performed a little better on the top end but it certainly did not hurt it. So with the vacuum and electronic advance the initial is at 22*. Starts quick, no detonation and the dead spot at initial WOT is gone. Understanding this thing a little better. Thanks for the direction.
