Re-Curving Mallory Distributor particularly for 4.6l - Defender Source
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  #1  
Old September 30th, 2014, 11:18 AM
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Davis
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Chris Davis
94 NAS D90 6.2LS
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Re-Curving Mallory Distributor particularly for 4.6l

I am running the Mallory Unilte Distributor 4768901. This has a factory preset mechanical advance of 26 degrees. What I did not know is that the 4.6l engine, unlike the original 3.9 that came with the truck, likes a max advance of 28 degrees. So when I am running my idle advance at 10 BTDC and the mechanical advance kicks in, I am up to about 36 BTDC total advance which is too much for the 4.6l.

I decided to finally fix this--as well as to change the springs which give the advance curve based on RPM so that I can get full advance a lot quicker since I am usually running around 2000rpm-3000rpm. This was an easier procedure than I had anticipated.

I purchased the Mallory Advance Curve Change Kit#29014. It came with springs and thickness gauges to set the advance. First I removed the distributor--I didn't want to have to fight any room and it is super simple to remove/reinstall. BTW, I mark the flange of the distributor with a mark right where it hits the block and put another mark on the block so that when I put it back in, I can align it quickly to set the base timing. I also put two marks on the upper lip of the cap--the first mark I put on the lip is right where the rotor is pointing. When you lift up the rotor, the oil pump gear spins it about 45 degrees and I put another mark right there. That way, when I go to put the distributor back in the truck, I align the rotor with this second mark (about 45 degrees counter clockwise from where I want it to line up) and when I drop it back in, it aligns just right. Saves back and forth time.

Remove the rotor. There is a little circlip on the arm from the vacuum advance module--take that off and set it aside. Remove the two screws holding on the vacuum advance and remove it. Next, there are two recessed allen head set screws on the outside of the distributor just to the side of the two clips that hold the cap on. Back these out (you only need to loosen them--don't remove them or you may drop one and they are small). Now the top plate can come out (you don't need to remove the unilte module or unhook the wiring). This exposes the springs and gaps that you will use to set the timing.

Since I run about 10 degrees of initial advance, I wanted to set my mechanical advance to 18 degrees to get about 28 degrees total advance. Using the 18 degree tool that came in the kit, I loosened the torx screws that lock the plate down and inserted the 18 degree key into the slot (flat side against the tab) and carefully equalized both sides. I found that keeping the screws a little tight helped out so the plate didn't flop around.

Next, I changed the springs--super easy. I changed mine to use the purple and pink springs giving me a two stage profile with a quick mechanical advance curve.

Once the truck was running again, I adjusted the vacuum advance--you turn a 2.5mm hex key in the snout (remove the hose) of the vacuum advance counter-clockwise to turn it off--I adjusted it a little clockwise from there to add in some vacuum advance without adding too much to my top advance. I may still tweak things from here.

So now I am running about 28-30 degrees total advance for my 4.6 at 3000 rpm (with mech and vacuum advance)

Truck runs better than ever. Very noticeable for me in both smoothness and sound. I don't know if the power has changed much, but third pulls better without what I now think might have been a slight ping.

For posterity, here are some of the Mallory Parts that I am using:
Distributor Mallory 4768901
Mallory vacuum advance 29332
Mallory eSpark Module 6100M
Ballast resistor mallory 700
Mallory Advance Curve Change Kit: 29014
Mallory High Performance Active Power Filter: 29351
Mallory Cap 209M
Mallory Rotor 322

Now that I know how easy it is to adjust, I may fine tune it from here but honestly don't know how to get it better. Running awesome. But I am still learning so as I learn more about advance curves and fine tuning, I may take it a step further. That said, if you are running a 4.6/Mallory, this is a definite must, IMHO.
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  #2  
Old September 30th, 2014, 11:45 PM
robertf
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Robert F
1995 Discovery
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Location: Dallas, TX USA
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What cam are you running?
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  #3  
Old October 1st, 2014, 12:44 AM
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Davis
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Chris Davis
94 NAS D90 6.2LS
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Join Date: Nov 2003
Location: Colorado
Posts: 2,508
Crower 50227. I tried the 50229, but the load end grunt of the 227 was just too kewl, particularly off road... Love the set up-- running 33", stock diff gears.
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  #4  
Old February 9th, 2015, 06:28 PM
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hoxie173
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Matt Hawkes
1959 S2
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Join Date: Mar 2012
Location: Maine United States
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We did this mod today and it it made a significant difference. The truck pulls much better and no more spark knock. Thanks for posting this thread!
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  #5  
Old February 9th, 2015, 06:52 PM
the rover shop
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shayne young
89,93 & 95 camel trophy 110s 06 130
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Location: ft lauderdale florida
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I just got done doing a 4.6 engine for a customer.. Yet to run it in and drive it in anger on the road yet, but installed the magnaflow exhaust system and it sounds awesome and responds to the revs really quick, I used the crower 50232 cam.. I installed the mallory uni lite dizzy and was having all sorts of problems with overfueling.. Then found with the ignition on, engine not running I was hearing the injectors operating and the fuel pump energizing.. Pulled the ignition wire out and sat it near ground and you could see the coil sparking intermittently....with the engine not running... This was causing the ECU to think the engine was running from the tachymetric pulse and thereby double injecting fuel.. Took a while to sort that one out...at first I thought okay, the shutter is not completely stopping the light to the receiver..put a bit of tape between the optics and it's still doing it... Converted the system back to pain in the lucASS system.. I think I will do the advance curve mod when I change the igniter unit out... This was a brand new mallory dizzy and mallory coil..
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