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GM HEI Swap #711770 04/01/06 05:15 AM
Joined: Jul 2005
Posts: 75
Boulder, Colorado
G
Greg2000 Offline OP
Getting the Wheeling Fever
Is it possible to swap in a HEI distributor without replacing the Carter bbd carb. Or do they need to be done together? <img src="/forums/images/graemlins/cheers.gif" alt="" />
Re: GM HEI Swap [Re: Greg2000] #711771 04/01/06 03:57 PM
Joined: Jun 2004
Posts: 1,904
W
wyleone Offline
Body Damage is Cool
It may cause some ill effects with the carb operation. I have not heard of anyone replacing the ign and not the Carb too.
I did a search on this recently and there is a ton of info.
Search like this: +HEI and click on the Jeep header on the left. There are mixed feeling about swapping to the GM HEI on this board as you will find out.

Last edited by wyleone; 04/01/06 04:00 PM.
Re: GM HEI Swap [Re: Greg2000] #711772 04/01/06 05:31 PM
Joined: Oct 2003
Posts: 7,768
Central Texas
BigJim Offline
Web Wheeler
Greg in good repair your dist will run JUST as good as an HEI in your Jeep! You will have no gain! Simply making a spark will burn all the fuel in the cylinder.. no matter what it is that makes the spark.
Now will it work without changing the carb.. YES if you disconnect all electric connections to the carb..
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

professional bovine relocation specialist
Re: GM HEI Swap [Re: BigJim] #711773 04/01/06 05:37 PM
Joined: Apr 2004
Posts: 77
Massachusetts
D
DRCYCLOPS Offline
Getting the Wheeling Fever
Just an opinion I love the Hei you do however have to perform some computer magic,(nutter bypass) Hei will provide a hotter spark you can increase spark plug gap to .45 your tach will work too providing you find the right wire( I forget the color) hei also works great with FI kits
Re: GM HEI Swap [Re: DRCYCLOPS] #711774 04/01/06 05:49 PM
Joined: Oct 2003
Posts: 7,768
Central Texas
BigJim Offline
Web Wheeler
Cyclops.. No you do not have to do the nutter... THAT wire is not used with the HEI!
So what if it makes a spark at .045? If .030 is all needed in a carbed system why make it jump an .045 gap? No gain there.. What does "hotter" mean? A simple ORANGE spark will ignite the fuel mixture.. No need to advertise for the scammers here.. tell the truth about spark.. NONE of the aftermarket gadget dists will improve performance over a good running stock dist..
It is all about the COIL being used. What coils do is to BUILD voltage until enough is built up to JUMP the gap on the plug. At which time the spark occurs. The reason modern fuelies have a 045 gap is because the mixture is so lean a spark in an 030 gap may not have enough combustible fuel in it to ignite the cylinder..misfires may occur.
Carbed engines run a much richer mixture and this mixture can be ignited in a 030 gap.. WHY put extra strain on the coil for NO REASON?
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

professional bovine relocation specialist
Re: GM HEI Swap [Re: BigJim] #711775 04/02/06 01:07 AM
Joined: May 2002
Posts: 337
Hawaii
80CJ Offline
Mudrunner
Quote
Cyclops.. No you do not have to do the nutter... THAT wire is not used with the HEI!
So what if it makes a spark at .045? If .030 is all needed in a carbed system why make it jump an .045 gap? No gain there.. What does "hotter" mean? A simple ORANGE spark will ignite the fuel mixture.. No need to advertise for the scammers here.. tell the truth about spark.. NONE of the aftermarket gadget dists will improve performance over a good running stock dist..
It is all about the COIL being used. What coils do is to BUILD voltage until enough is built up to JUMP the gap on the plug. At which time the spark occurs. The reason modern fuelies have a 045 gap is because the mixture is so lean a spark in an 030 gap may not have enough combustible fuel in it to ignite the cylinder..misfires may occur.
Carbed engines run a much richer mixture and this mixture can be ignited in a 030 gap.. WHY put extra strain on the coil for NO REASON?
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />
I know we've gone thru this before, but I put a DUI HEI distributor on my 80 CJ-5 with stock Carter BBD and it starts and runs noticeably better. <img src="/forums/images/graemlins/rolleyes.gif" alt="" />
Re: GM HEI Swap [Re: 80CJ] #711776 04/02/06 03:58 AM
Joined: Oct 2003
Posts: 7,768
Central Texas
BigJim Offline
Web Wheeler
Quote
[quote]Cyclops.. No you do not have to do the nutter... THAT wire is not used with the HEI!
So what if it makes a spark at .045? If .030 is all needed in a carbed system why make it jump an .045 gap? No gain there.. What does "hotter" mean? A simple ORANGE spark will ignite the fuel mixture.. No need to advertise for the scammers here.. tell the truth about spark.. NONE of the aftermarket gadget dists will improve performance over a good running stock dist..
It is all about the COIL being used. What coils do is to BUILD voltage until enough is built up to JUMP the gap on the plug. At which time the spark occurs. The reason modern fuelies have a 045 gap is because the mixture is so lean a spark in an 030 gap may not have enough combustible fuel in it to ignite the cylinder..misfires may occur.
Carbed engines run a much richer mixture and this mixture can be ignited in a 030 gap.. WHY put extra strain on the coil for NO REASON?
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />
I know we've gone thru this before, but I put a DUI HEI distributor on my 80 CJ-5 with stock Carter BBD and it starts and runs noticeably better. <img src="/forums/images/graemlins/rolleyes.gif" alt="" /> [/quote}


Well yes.. Now you have timing you did not have but you still have the variable fuel from the carb. You have zackly what you would have had if you had put 8 feet of wire in there and done the nutter bypass.. There would be no difference at all. The HEI is designed to do something that is not needed and does not help our little guys.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

professional bovine relocation specialist
Re: GM HEI Swap [Re: 80CJ] #711777 04/02/06 04:03 AM
Anonymous
Unregistered
I think Big Jim is correct, I didn't really notice a big difference from the properly working stock distributor when I installed the HEI.
However, when I started having trouble with the distributor advance not working properly and ignition module failing intermittantly, I wanted to simplify things so I switched to an HEI (all ignition components in distributor, and 1 wire hookup)and removed the computer.
That was before the MC2100 swap (still had the BBD), and the two worked together with no problems.
Right or wrong, my distributor advance is connected to manifold vacuum, and runs great. <img src="/forums/images/graemlins/patriot.gif" alt="" />
Re: GM HEI Swap #711778 04/02/06 03:44 PM
Joined: Apr 2004
Posts: 77
Massachusetts
D
DRCYCLOPS Offline
Getting the Wheeling Fever
just a thought but doesnt that bbd system run leaner so that vehicles form the late 80s and early 90s can pass inspection.I said just an opinion.do you run hei I do and thats just an opinion Im sharing nice banter though
Re: GM HEI Swap [Re: DRCYCLOPS] #711779 04/02/06 05:03 PM
Joined: Oct 2003
Posts: 7,768
Central Texas
BigJim Offline
Web Wheeler
Cyclops it is a variable carb.. It runs as the computer directs. However it NEVER gets as lean as a fuelie. It was an attempt, however feeble, at getting inside the standards of the day.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

professional bovine relocation specialist
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