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Big-block timing backing up #2457645
02/26/18 12:25 AM
02/26/18 12:25 AM
Joined: Jan 2005
Posts: 222
California
70Drop Offline OP
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California
I just checked timing on my 440/500. I have an MSD distributor set to bring in all timing by 3,000 rpm, which it does. But if I keep accelerating beyond 4K or so, the timing starts retarding, ultimately by about 7-10 degrees. The timing is steady, not erratic. It advances steadily, then retards steadily with increasing RPM.

I have a collar on the distributor shaft to keep the distributor drive from "walking up". It's a solid roller cam, and I have a bronze gear that's showing some wear. But I can't see how this might solve the problem.

I think I'll now pull out the distributor and try to replicate the issue on the bench with a drill, but thought someone might have seen a similar problem before

Re: Big-block timing backing up [Re: 70Drop] #2457671
02/26/18 01:08 AM
02/26/18 01:08 AM
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Bend,OR USA
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Cab_Burge Offline
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Bend,OR USA
Which ignition control box are you using? Does it have a automatic retard option? If so, look there first up

Last edited by Cab_Burge; 02/26/18 01:09 AM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Big-block timing backing up [Re: 70Drop] #2457677
02/26/18 01:14 AM
02/26/18 01:14 AM
Joined: Jan 2005
Posts: 222
California
70Drop Offline OP
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I have an MSD Digital 6 Plus. I think it has a timing retard function. I'll check that. Everything else looks good so far.

Thanks!

Re: Big-block timing backing up [Re: 70Drop] #2457691
02/26/18 01:30 AM
02/26/18 01:30 AM
Joined: Jan 2005
Posts: 222
California
70Drop Offline OP
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California
I don't think it's the retard function of the box. It's a single-stage retard that's not hooked up. Plus, the timing retard I'm observing is a steady thing, not sudden.

Re: Big-block timing backing up [Re: 70Drop] #2457692
02/26/18 01:31 AM
02/26/18 01:31 AM
Joined: Dec 2007
Posts: 12,587
Great Neck,LI,new york
hemi-itis Offline
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Great Neck,LI,new york
How can you tell past 4k rpm that it is retarding?


HEMI-ITIS has no cure.
My condition is fully BLOWN!!
Re: Big-block timing backing up [Re: hemi-itis] #2457696
02/26/18 01:40 AM
02/26/18 01:40 AM
Joined: Jan 2005
Posts: 222
California
70Drop Offline OP
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California
I set my timing light to my total timing and read directly from the balancer while revving the engine

Re: Big-block timing backing up [Re: 70Drop] #2457705
02/26/18 02:08 AM
02/26/18 02:08 AM
Joined: Jan 2005
Posts: 222
California
70Drop Offline OP
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California
I checked the backlash of my dizzy drive gear, and it seems like a lot to me. It moves probably 1/4-inch back and forth. I'm thinking maybe that's the problem (worn bronze gear), even though the timing seems to move pretty steadily up, then down, not erratically like I'd normally expect with a worn distributor gear.

Re: Big-block timing backing up [Re: 70Drop] #2457720
02/26/18 02:51 AM
02/26/18 02:51 AM
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Australia
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ozymaxwedge Offline
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Australia
Yeah replace that gear first, hope it fixes the problem.


1963 Plymouth Max Wedge
1971 Barracuda
Re: Big-block timing backing up [Re: 70Drop] #2457732
02/26/18 03:21 AM
02/26/18 03:21 AM
Joined: Jul 2006
Posts: 4,319
Puyallup, WA
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StealthWedge67 Offline
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Puyallup, WA
If that doesn’t fix it, I’d put the timing light on another car just to make sure it’s not in the light.


LemonWedge - Street heavy / Strip ready - 11.07 @ 120
Re: Big-block timing backing up [Re: 70Drop] #2457738
02/26/18 03:54 AM
02/26/18 03:54 AM
Joined: Jan 2008
Posts: 2,363
Cotati, CA
Dave Hall Offline
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Cotati, CA
FWIW, the bronze gear lasts about 300 passes on my 493. I don't know what that equates to in street miles. Probably not 10,000??? It gets worn until it's sharp on the edges.

Re: Big-block timing backing up [Re: 70Drop] #2457744
02/26/18 04:22 AM
02/26/18 04:22 AM
Joined: Jan 2005
Posts: 222
California
70Drop Offline OP
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California
Thanks. I will check my timing light, but I think it's good. The gear isn't sharp on the edges yet, but I can definitely see the wear. I've probably got 50 passes and 100 street miles. Think I might try one of the Crane steel gears that are supposed to be compatible. I'm also starting to think a crank trigger could be a good idea

Re: Big-block timing backing up [Re: 70Drop] #2457850
02/26/18 01:32 PM
02/26/18 01:32 PM
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Posts: 14,479
So. Burlington, Vt.
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fast68plymouth Offline
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So. Burlington, Vt.
Step one...... Retest with a timing light that has no dial back type circuits in it.

Ran into this years ago with a motor on the dyno using a dial back light that had never exhibited the issue before.
Tried a non-dial back light...... Problem gone.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Big-block timing backing up [Re: 70Drop] #2457900
02/26/18 03:28 PM
02/26/18 03:28 PM
Joined: Dec 2007
Posts: 12,587
Great Neck,LI,new york
hemi-itis Offline
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Posts: 12,587
Great Neck,LI,new york
Would like to know how we know if the MSD does what it's programmed to do.With programmable timing and a map sensor to take out timing with boost,how can we tell??


HEMI-ITIS has no cure.
My condition is fully BLOWN!!
Re: Big-block timing backing up [Re: 70Drop] #2457934
02/26/18 04:34 PM
02/26/18 04:34 PM
Joined: Jan 2005
Posts: 2,540
Milwaukee WI
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TRENDZ Offline
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Milwaukee WI
I agree with the dial back timing light being suspect. The multi spark goes away real close to where you are seeing a timing change. That multiple spark transition to single spark will confuse the calculation of the strobe.


"use it 'till it breaks, replace as needed"
Re: Big-block timing backing up [Re: 70Drop] #2457952
02/26/18 05:14 PM
02/26/18 05:14 PM
Joined: Jan 2007
Posts: 8,027
Mt Morris Michigan
mopar dave Offline
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Mt Morris Michigan
A crank trigger will fix your issue. I had the same problem with my billet msd dist. on a sb. Installed a crank trigger, problem solved. I now have the same issue with another msd billet dist. In my 511. Timing goes backward about 3 or possibly 4 degrees as rpm is increased. Did not have this issue with the firecore dist. i removed because of a different issue with it . I use a timing light that takes 2 d cell batterys.

Re: Big-block timing backing up [Re: 70Drop] #2457972
02/26/18 05:52 PM
02/26/18 05:52 PM
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Posts: 481
Cheswick, PA
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Bob_Spelic Offline
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Posts: 481
Cheswick, PA
Same problem on my 572. On the dyno we saw about 4 degree retard between 6500 and 7500. MSD billet distributor. Since my application was drag only and I ran a 6200 stall converter, we set timing at 6500 on the dyno.

Last edited by Bob_Spelic; 02/26/18 05:53 PM.
Re: Big-block timing backing up [Re: 70Drop] #2458001
02/26/18 06:48 PM
02/26/18 06:48 PM
Joined: Jan 2007
Posts: 8,027
Mt Morris Michigan
mopar dave Offline
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Mt Morris Michigan
Msd will not acknowledge there is an issue with there distributors. I called them before and after the fix with the crank trigger and still refused to admit there was any issues with the billet distributor. Because i use a Ice Ignition box, im thinking about getting there distributor and new box that has severeral preprogramed electronic timing curves.







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