AMC HEI Conversion Distributors

[Eagle]

And BTW: AMC did not have a small and big block. The 304/360/401 (and their immediate predecessors ) were all the same physical dimensions.

True.

 

It used to blow the Ford and Chevy guys' minds when they found that AMC was able to build a 401 in the same block that started out as a 290.

[HOrnbrod]

It used to blow the Ford and Chevy guys' minds when they found that AMC was able to build a 401 in the same block that started out as a 290.

That was a matter of cost-saving economics, not stellar engineering. Just like creating the AMX out of a sectioned Javelin. And I DO love the AMX's. 

[omega_rugal]

after reading how the Renix system works, i think is a little too complex for what it does, if the ECU wants to alter the timing there are simpler ways to do so...

[Marine1Texas]

Unless you do a cps mod to push it advanced that is the only way to mess with the timing with the ECU. Even if you turned the dizzy, it will retard it.

 

The only way to get around that is the HEI. There are limits to the HEI, however if your wanting to go out side the specs that the ecu handles that is the only way. They do not make mods for the ecu.

 

I found that in the renix, the best for more power and mpg is; 

1.) the bigger throttle body with the bigger fuel injectors . possible HO intake

2.) a better air filter system, like cold air.

finally the most expensive 3.) the upgraded 4.0 to 4.5-4.6 with the HO head.

 

A better exhaust flow will help as well, but no big gains.

 

In the end it comes down to what you want to use your mj for. Road, offroading, rock climbing, or combo road and offroading. The extra power you gain on any mode only starts to work as the engine revs higher then 2k, unless you do the upgrade in displacement. So it comes down to gearing. If your offroading and want the power you change the differential ratio's. With 3.07/3.08 standard and 3.55 for auto, you can easily put 4.10 or better. This will give you better power at your low end for rock climbing. Then you can change things around by going deeper and adding new larger tires. 

 

I found with the 3.07/3.08 a 29inch is the biggest you want to go before you start loosing at highway speeds. However if you say go to a 4.10 then 31 will do very well for you on the Highway and a nice upgrade for offroading.

 

However once you get over that 29 to 30 inch your brakes are not as good as they once were, and you want to think about upgrading at least the master cylinder booster system. Once you are 32 inch and over you will notice those brakes are not going to cut it!

[Eagle]

Holy thread necromancy, Batman!

 

This thread started in March of 2009, and was last posted in a year and a half ago. Is this a new record for thread resuscitation?

[omega_rugal]

Unless you do a cps mod to push it advanced that is the only way to mess with the timing with the ECU. Even if you turned the dizzy, it will retard it.

 

The only way to get around that is the HEI. There are limits to the HEI, however if your wanting to go out side the specs that the ecu handles that is the only way. They do not make mods for the ecu.

 

I found that in the renix, the best for more power and mpg is; 

1.) the bigger throttle body with the bigger fuel injectors . possible HO intake

2.) a better air filter system, like cold air.

finally the most expensive 3.) the upgraded 4.0 to 4.5-4.6 with the HO head.

 

A better exhaust flow will help as well, but no big gains.

 

 

did you buy the HEI ready for the 4.0 or did you mod it? what model of GM distribuitor can be hacked to fit the 4.0?

 

after cleaning the reducer and some tweaks here and there finally got it to start on LPG but still lacks power under load, it really needs those advance degrees to burn the lpg better...

[Marine1Texas]

they make one for the jeep 4.0/4.2   that just drops right in.  at summit they have them in stock and not bad price SUM-850047 is what I got. you will need the pig tails too.

[cruiser54]

I know this is bring up old thread.

I have a 87 and followed the Renix tips from cruiser. I replaced the computer, every sensor, dizzy, took out the 101 connector and wired straight up, and still get rough idle.

I tried 3 different computers, and even rewired one by one every wire.  I put new cap and rotor with brass terminals, Champion copper NGK plugs and Belden ignition wires. Still rough idle.

I bought a HEI and dropped it in and smooth idle on 1st start. The only problem I had was vacuum advance since there is no right place to connect it. I drove it around with advance off and it was amazing. Only suffer 2 mpg.

For me it seemed to fix the problem however I would like to have the Renix ignition system working right.

 

3 months ago I took out the 4.0 and rebuilt it from bottom up. Replaced everything and every sensor again. I did not hook up the HEI and stuck with the renix. Rough idle on newly rebuilt motor still. Now when I say rough idle it does not shake or anything like that. When it starts from cold it idles around 955 to 1025 rpms for warmup time about 75 secs. Then it gos down to 560 to 815 rpms. it will go up and down from 560 to 815 all day long. It does not bog down on start off or die. It never bogs even when I stomp on it. Just that damn idle is bothering me. Since here in Texas my truck is exempt and only needs to pass visual I have done some mods. It has improved idle a bit. Mods are the cruiser advance timing, spectra intake air filter. Straight exhaust with high flow cat.

 

I may try the HEI again if I can not find what the problem is.

Are you indexing the dizzy per Tip 13?

[Marine1Texas]

before I switched to HEI, I indexed it just like in Cruisers tips. I in fact have index 2 different dizzies one old and a new one neither of them smoothed the idle out. As soon as I put the HEI in and timed it, and set the advance curve I wanted, it idles perfect all the time.

 

I don't take the truck out of state or up real high to worry about the timing. It has never run so smooth in all the years we have had the MJ. Also it does not need the full rotation to stat up, it normally starts on the very next cylinder to fire, or maybe 2nd if it is cold meaning below 32. So I see the starter lasting twice as long.

 

I know people say that HEI is not as good as the computer dizzy, however here on the farm pulling 5k around all the time thru the mud I trust it.

 

For me on this 4.0 I keep the Fuel injection system but with larger injectors, have the large over sized throttle body, capped EGR off, direct cold air intake coming from scoop, and HEI.

 

When it go's out if it does, I will do the 4.5 or 4.6 upgrade like I did on my 88 MJ. I will stay with the fuel injection tho.