GM HEI dizzy swap in 4.2l how to
#1
Posted 18 May 2005 - 01:44 PM
Unlike the Ford conversion with the GM dizzy you replace the entire unit and discard the Motorcraft ignition system that gave Jeeps so much trouble in the past. The GM unit has the ignition coil in the top of the cap and the module inside the dizzy. It is just a 1 wire hook up to the side of the cap for keyed up power. The whole conversion only takes about an hour with hand tools and you will need a chop saw or something to cut the dizzy gear. I'll try to describe in detail and any questions please feel free to call me, I'm sorry I didn't get any pics but my camera was broken.
Before you start make sure that #1 cylinder is at top dead center, the rotor points at the #1 spot on the distributor cap.
1-disconnect the battery
2-remove spark plug wires and sell them (or throw the away)
3-remove the distributor, and the drive gear from the bottom of the Jeep dizzy, you do this by removing the roll pin that goes through the gear, you tap it out with a small punch or finish nail if you don't have a punch, and save the pin for re-use.
4- remove the gear from the GM dizzy (the same way as the Jeep dizzy)and discard---you won't be using it.
5-cut a 1/4" off of the bottom of the Jeep drive gear, try to keep the cut as straight as possible.
6-with a small grinder or cut-off wheel, bevel the edges of the gear very slightly for easier installation and less wear on the camshaft gear. This only has to be slight and only on the very edges.
7-purchae a small roll of metal tape (used for air conditioning vents found in your house, any good hardware store will sell this.
8-put the GM dizzy in a vise upside down, (I left the cap on as to prevent the shaft from falling out), take metal tape and make exactly one wrap on the distributor shaft where the gear mounts. If you test fit the gear you'll see why you have to install the wrap of tape. this will allow the gear to fit tightly over the shaft. trim the tape so no tape sticks out of the bottom of the gear, install the gear and the roll pin. you will have punch a hole through the tape where the pin goes through, you can do that with the punch or nail.
9-install the dizzy like you would any other dizzy, find a keyed power source (one of the wires from the
factory ignition system should be keyed power) and hook it to the terminal on the side of the dizzy cap
marked positive and hook up the vacuum advance.
10-purchase a good quality set of spark plugs and ignition wires (wires I used are for a 96 Jeep Cherokee with a 4.0 litre engine (the terminals will slide right onto the GM cap terminals and the wires are the same length as the factory 4.2l wires) set gap on plugs and install wires a nd your ready to set base timing.
11- remove entire Ford/Jeep factory system and tape up any loose wires and secure
Remember to set base timing with the vacuum hose for the advance disconnected!
Good luck
I can tell you from experience that the GM dizzy holds up to water intrusion alot better than the factory dizzy! My Jeep starts on the very first crank and seems to have a little better throttle response.
[ ]IIIIIII[ ]
It's hip 2b SQUARE
89-YJ 454/TH350/D300/Rockwells/full cage/44 Boggers
#2
Posted 19 May 2005 - 07:15 AM
One question, what model vehicle did you install this in
El Niņo
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#3
Posted 19 May 2005 - 08:41 AM
[ ]IIIIIII[ ]
It's hip 2b SQUARE
89-YJ 454/TH350/D300/Rockwells/full cage/44 Boggers
#4
Posted 20 May 2005 - 06:38 AM
#5
Posted 20 May 2005 - 09:44 AM
[ ]IIIIIII[ ]
It's hip 2b SQUARE
89-YJ 454/TH350/D300/Rockwells/full cage/44 Boggers
#6
Posted 20 May 2005 - 09:52 AM
#7
Posted 20 May 2005 - 09:58 AM
[ ]IIIIIII[ ]
It's hip 2b SQUARE
89-YJ 454/TH350/D300/Rockwells/full cage/44 Boggers
#8
Posted 20 May 2005 - 10:56 AM
#9
Posted 20 May 2005 - 01:28 PM
hiway, on May 20 2005, 10:57 AM, said:
IIRC, most engines run the oil pump off the dist. The older Jeep V-8's w/ the pump on the front of the engine are an oddball.
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"War is an ugly thing, but not the ugliest of things. The decayed and degraded state of moral and patriotic feeling that thinks that nothing is worth war is much worse. The person who has nothing for which he is willing to fight, nothing which is more important than his own personal safety, is a miserable creature and has no chance of being free unless made and kept so by the exertions of better men than himself." ....
John Stuart Mill
#10
Posted 20 May 2005 - 05:38 PM
#11
Posted 07 June 2005 - 11:31 PM
#12
Posted 19 July 2005 - 03:48 PM
Well at least I'm man enuf to admit it......hehehehehehehehe
[ ]IIIIIII[ ]
It's hip 2b SQUARE
89-YJ 454/TH350/D300/Rockwells/full cage/44 Boggers