Distributor conversion for timing control.

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Bill usn-1
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Distributor conversion for timing control.

Post by Bill usn-1 »

I will try to address the distr setup to clear up some of the misinformation, mostly being spread around the Jeep forums.
There are a couple guys that started spreading the rumor that a distributor does not require to be properly phased to work with EFI timing control.
This is normally from ignorance of what is really happening in the distr and the computer.
But because someone did a conversion to GM TBI and did not properly phase the distr and it ran, they then posted all over the web that it was not required.
THIS IS FALSE.
The reluctor/rotor phasing must be properly changed for timing control.
The Holley system has different phasing requirements.
I have have converted hundreds of distributors for GM timing control and have already done many for the Holley system.
They are different. But both require changes from a factory mech adv distr.

Here's the bottom line TRUTH.
The factory distributor will work fine for timing control if you DO NOT listen to the experts on the web and properly convert it.
A system will only work if it is correctly set up.

I'm running 7 days a week to keep up so I don't get a lot of time to check other forums.
Either check and post on binderplanet in the injection forum, where correct information is posted, or call.
But check the info on BP first or I will be forced to get a 1 900 number!
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babywag
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Re: Distributor conversion for timing control.

Post by babywag »

These folks are being told by vendors that stock and certain other distributors won't work either or that is their troubles.
Easily fixed of course by spending hundreds of dollars on their products.

They're also being told that certain or crazy high lph fuel pumps are required.

Neither of course is accurate information.
-Tony
'88 GW (aka Babywag)

rocklaurence
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Re: Distributor conversion for timing control.

Post by rocklaurence »

Bill, thanks for the Heads-Up

acct21
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Re: Distributor conversion for timing control.

Post by acct21 »

Bill,

Have searched the Injector Tech forum over at Binder Planet. Under the 'Start Here' have found the detailed write up for phasing the Motorcraft/Duraspark for TBI -- but you say the Holley system requires different phasing? I have not been successful finding that information.

I have a Holley Sniper on my 360, and would like to convert to timing control through the Sniper. Can you touch on the differences required to phase the Motorcraft for use with the Holley system -- or point us to the link?
1990 GW with HD towing package -- everything works! (today, anyway)
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Bill usn-1
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Re: Distributor conversion for timing control.

Post by Bill usn-1 »

As mentioned, I don't check all the boards regularly.
I replied to your post on binderplanet.
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Stuka
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Re: Distributor conversion for timing control.

Post by Stuka »

Thanks for being such a huge source of knowledge Bill, you posts are always a great addition to the forum.
2017 JKU Rubicon
Pevious Jeeps: 1981 J10, 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

ScramblerCJ8
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Re: Distributor conversion for timing control.

Post by ScramblerCJ8 »

Hi guys, I'm new to the site, so I'm late catching up with all this tech threads.
My 2 cents on the distributor for TBI saga.
I have done two stock GM TBI conversions to amc engines. Modified the stock chevy 350 TBI distributor, buy shorting/machining the base of the housing, also machine the shaft and made an adaptor shaft that fits over the GM shaft, witch is smaller than the AMC shaft, secured it with a roll pin and installed the AMC drive gear on it.
It works just fine, only hiccup was timing. GM timing specs call for 0 degrees with the brown/black wire disconnected and check engine light blinking like a GM vehicle. Did not run well. Set the base timing at 8 degrees like the AMC 304 specs it and then shut engine off, reconnect brown wire and you are good to go.
I think I have an extra distributor already modified in my work shop, will look for it and post some pics.
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Bill usn-1
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Re: Distributor conversion for timing control.

Post by Bill usn-1 »

Scrambler.....
Your talking apples and oranges and really your trying to use a work around just to get it to run instead of correctly setting up the system.
There is a distr conversion provided on binderplanet that grafts the lower stock distr to the factory GM small cap HEI.
A machinist named Marlow has been doing these for people for almost 20yrs.
I still run the first one he did for me..... after a couple mods to prevent them from burning up the upper bushing!

Timing is very misunderstood.
A lot of people confuse base timing to running timing.
That's why so many make the wrong leap that the base timing needs to be something other than 0*.
This is just not true.
There is not a single AMC system I have built that uses anything other then 0*.

The key to proper timing is to make sure you have a correct timing table for the AMC engine.
The basics are provided on BP.

A lower base timing allows an engine to start cranking easier.
At 400rpm the ECM takes control of the timing and the timing table is applied.
This happens before the engine is at idle speed.
So Base timing has absolutely nothing to do with how the engine runs or idles.

Most of this is covered in the tuning threads on BP.
Just not in detail.
If a setting doesn't 'NEED" to be changed, I don't include it in the instructions.

We are way off topic from distributor phasing but all affects timing.

ScramblerCJ8
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Re: Distributor conversion for timing control.

Post by ScramblerCJ8 »

Bill, you are right and I apologize if i roughed some fetters. I,m just an old retired auto mechanic, had my own repair shop and tinker with jeeps as a hobby. I just figure out how to make it work for mine and my son's jeeps.
Basically took a donor 1988 chevy truck 350 TBI system and adapted it to the 304 AMC engine. When I got to the distributor segment of the conversion, I just use some cowboy logic and some Macgyver ingenuity. So I took both, GM and AMC distributors apart, and machined the GM housing to match the Amc one, build an slive, cut down the AMC shaft and matted to the GM with the AMC gear installed.
I installed it on the engine and timed it to 0 degrees like a GM car, but sputtered an pinged under acceleration, so I set it to 8 degrees BTDC, what the specs are for the 304 engine and run fine. Is it the right way to do it ? I don't know, but it has been about 16 years and both still run fine.
BTW, they are both 1978 models and every two years pass the state of Oregon emission test.
Like I said before, I think I have an old converted distributor for that application in my work shop.I will dig it out and post some pics.
It is old technology and have move away from it.
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Bill usn-1
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Re: Distributor conversion for timing control.

Post by Bill usn-1 »

No feathers ruffled.
I did the same thing over 20yrs ago for my IH.
I documented everything so others could duplicate it.
Then when i retired from naval Service, i started building complete systems for those who didn't have time to do what i did .
It's all just a click away in my sig below.

The reason you have timing issues is because the GM engine is a lean burn engine and the timing table isn't even close to what's needed.
As you found, even wrong, it runs better than a carb.
Here's a couple examples of the timing tables you are using.
Note WOT is only about 16* by adding 8* you are still only at 24*.
Most engines run about 30-32*
If you have knock sensor issues or don't run it, you lose 9^
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ScramblerCJ8
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Re: Distributor conversion for timing control.

Post by ScramblerCJ8 »

8-) Bill, first thank you for your service and for clarifying the timing issue. Our jeeps are not daily drivers, just fun off road machines, legally licence.
The most we drive is to and from the trails here in the PNW, anything further than 60 miles, we just tow them.
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