HEI questions

dewfamily

New Member
Joined
Nov 4, 2011
Location
Clarendon,NC 28432
Hello, this is my first post. In fact, this is my first jeep. I am truly a newbie. My question is this. I have a 1988 Wrangler with the 258. I have read about changing the distributor out for a HEI. What type of spark plugs and wires will I need? What about the timing? Any help would be greatly appreciated. thanks
 
dewfamily said:
Hello, this is my first post. In fact, this is my first jeep. I am truly a newbie. My question is this. I have a 1988 Wrangler with the 258. I have read about changing the distributor out for a HEI. What type of spark plugs and wires will I need? What about the timing? Any help would be greatly appreciated. thanks
Click to expand...
If you have a pull it yourself junkyard nearby you can do this on the cheap. Find a Chevy/GMC truck or van with a 250 or 292 straight 6. Remove the distributor and take as much of the wire that is plugged into the side of it as you can get (if you don't get the wire you can buy the terminals at NAPA). If you want a tach feed make sure to get an extra terminal/wire. If the donor does not have a tach you can use the feed wire and terminal from another HEI donor. Go find a mid 70s or newer full size Jeep waggy or truck with a V8. Pull the distributor and remove the gear by tapping out the roll pin. Remove the gear from the HEI unit, put the Jeep V8 gear on the HEI distributor, and replace the roll pin. Go find a nice heavy relay (early 90s caddies have nice ones with brackets) to run the HEI. Pay the boneyard and go to the parts store. Buy some wires for an 82 Ford Fairmont with a 6 cyl. Open the gap on your plugs to about .045 (you don't really need new plugs unless your are shot). Mark the wire numbers on the old cap for easy reference. Bring the motor to #1 TDC and pull the old cap. Note the rotor position and pull the old distributor. Install the HEI with the rotor in the same position. Install the cap and new wires (firing order should be on the manifold if you didn't mark the cap) one cylinder at a time using the old cap as a reference. Run a fused wire (use a 15 amp fues and the same gauge wire as the feed wire you pulled from the donor) from the battery to the relay input and from the relay output to the feed wire on the HEI. You can run your tach feed from the old coil to the tach output on the HEI if you want. Run a key on hot wire to the trigger of the relay and hook up the relay ground. Fire it up and set the timing to 8-9 degrees. The timing may vary a few degrees either way and you will have to adjust it a bit to get it to run good. Make sure you unplug the vacuum advance when you adjust it and plug the hose then plug it back into the distributor when you are done.

Since you have an 88 you may want to consider doing the carb portion of the nutter bypass when you do this. There are tons of write ups on the net about this. In a nutshell you are going to turn an adjusting screw while looking at the metering pin in the carb and when it is all the way adjusted you are going to unplug the control harness from the carb. I also suggest you replace or eliminate the mile of old rotted vacuum lines under your hood. Vacuum leaks will make the 258 run like crap. You need a feed for the front axle (4wd), the vacuum advance, the trigger for the canister to dump the bowl vent and tank vent fumes into the carb, and the feed to the power brakes. The rest is the air system garbage. You can leave it all in place dead since you will just have a visual inspection 9if you ar ein an emissions county).

Good Luck

Bob
 
HEI Set ups are WAY cheap on EBAY. I am running one now in a 258 and am very impressed with it. Just be careful not to get one with a hardened gear. $65 shipped for billet distributor and all new everything.
 
I took your advice on the relay. I got to thinking about it using the heavier gauge wire. I used the exisiting yellow wire to turn relay on, but problem is the motor won't shut off. I have to pull the yellow wire off for the engine to shut off. I checked voltage and with the key turned off I still have close to 9v. Any ideas.
 
Yep use a different source to trigger the relay. Lol

How about the trigger wire for the electric choke. Use a test light to see if it dies when you turn the key off. The relay wont use much juice so it can run off most any key hot trigger that does not drop out during start.
 
BB535 seems to know his carb junk, so .......

My magnetic pickup in my stock CJ7 distributor got smashed so I put in one of the ebay HEI distributors. The only way I can get it to run right is to keep the vacuum advance disconnected. Runs great disconnected. With the vac plugged into the distributor it backfires and runs crappy at all timing settings I have tried. Is the distributor a tooth or so off maybe?
 
JC said:
BB535 seems to know his carb junk, so .......
My magnetic pickup in my stock CJ7 distributor got smashed so I put in one of the ebay HEI distributors. The only way I can get it to run right is to keep the vacuum advance disconnected. Runs great disconnected. With the vac plugged into the distributor it backfires and runs crappy at all timing settings I have tried. Is the distributor a tooth or so off maybe?
Click to expand...
My first guesses without seeing it would be a tooth off or bad vacuum advance. Is your carb stock, do you have a cto that switches between ported and manifold vacuum, if not which is feeding the advance? If the old distributor advanced ok then it is likely a bad advance module or a tooth off. I would reset it a tooth back before I spent money.
I never bought a 258 hei. I always built them from gm 292s and jeep 360 drive gears. The curve wasnt perfect but it was close enough not to spend $300 on the dui.
Bob
 
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