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Just finished installing a HEI and....

362 Views 4 Replies 2 Participants Last post by  **DONOTDELETE**
I just installed an HEI into my 78CJ and to be honest I don't notice any improvement. Did I miss something here? I would hate to say that I wasted alomst $100 on something that doesn't really work! Any ideas?

Alec (New HEI)

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Well, you didn't waste the dough, you could sell it to someone if you're not happy with it. What you've got now is a completely non-computer controlled Jeep. What do you have for a carb?

I did have to play with the advacne curve, though, to liven things up. I found that the 2 heavy springs wouldn't let the advance come in soon enough. I now have one light spring and one heavy spring (from the crane kit) and that seems to have flattened out the advance curve a bit, bringing it in early in the rpm band (she was kinda doggish with the 2 heavy springs) and still having some for the higher RPMs (i've got an auto, so she runs into 3000 on the highway with the 4.10s.)

Maybe it's just time to play with it a little. Everyone's setup seems to be a little different.

Good luck

88YJ,4"susp,33"BFGMTs,9000#winch, hm swing out TC/HL mount ,258,999,4.10,weber32/36,GMHEI.
Ok here's the deal....Once iget over 2000rpm it really takes off, but between about 900 and 1800 it hesitates real bad. I assume it has
something to do with the advance. I saw the two springs in there when I was cleaning it up are those the two I need to change. I have
seen the crane curve kit is that what I need to get? What color springs should I start with? By the way I have a carter carb one barrel
on my 78CJ



See, that's the problem I had. When I would advance it to cure that exact problem, she would ping on the highway at the higher RPMs. Then, when I'd retard it to stop the ping at the high end, she'd be real doggish at the low end. The stock GM springs are fairly stiff, and I figured resulted in a pretty steep advance curve. I bought the crane adjustable advance kit (about $24 from summit) and it comes with an adjustable vacuum can, and 3 different spring weights. I have since taken the crane adj. vacuum can out (too much adjustment to play with). See if you can find a tension spring similar in size to what's on there, maybe not so stiff, and replace one of the springs, and see if that helps the lower end, by getting some advance there. Or, spend the $24. Again, just my opinion, I'm not the all-knowing. Also, I advanced it until it was pinging, then backed it off some. I know, not the most technical approach, but I think you want to run as advanced as you can without detonation for the most power.

Good luck

88YJ,4"susp,33"BFGMTs,9000#winch, hm swing out TC/HL mount ,258,999,4.10,weber32/36,GMHEI.
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check your vacuum advance, make sure it works properly and is hooked to the proper port. what ignition was on there before? if it was a motorcraft you didnt gain too much IMO. what was the hei out of? it may need recurved.


I do not intend to offend,I offend with my intent
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