Convert from ECM to carb w/points...

Hello all,

I live in Galveston, and just replaced the long block on our 1989 B350 service van. When we had it smogged last fall, we were informed that we will no longer ever have to have the vehicle smogged due it's age. FINE BY ME!

Question: looking for broad suggestions as to how to go about removing all electronic controls from the engine and reverting to a carbuerated, points-type distributor engine. We're not looking for high performance, but simplicity. I have a decent grasp of tuning and maintaining carbuerated, non-electronically controlled engines so no worries there.

Any serious caveats from the Dodge world?

I remember I had an 87 Fifth Avenue and the Fellow that built it converted to the earlier distributor wire harness and all the accompanying boxes, ballist resistor as it was a more reliable sety-up than the crappy 87's. Its been a long time since I dabbled in that but I think it was the up to 1983 set-up and you would probably need the intake w/carb/choke and air cleaner set-up as well. A good donour car like an old Cop 360 from that era might do it. I remember having literature on the subject. Mopar Police Cars and Fifth Avenue Haynes books are a good place to look. I got rid of all that stuff after my car was ruined in storage when I came back from a 3 year overseas tour. It was a shame. Not sure if this helps. Danny

if the thing runs fine as is you should probably leave it. converting from TBI to carb can get kind of expensive unless you have most of the parts sitting around or buy a parts vehicle. you will need a carb, intake, voltage regulator, fuel pressure regulator, ignition system. now i don't have exact numbers but i guess it would cost you about $700 for these parts new and you would not gain anything.

My concerns on this situation - is there anything electronic on the transmission that needs the TBI system to operate? How does the trans linkage compare between a carb and a throttle body?

the easiest way to do this (and i know from experience)is to find a wiring harness from an 85 or older ( to easily get rid of the smog and ecm), find a gas tank from a carbed old dodge, buy a mechanical fuel pump, a carb, run your lines. you should probably look into getting an electronic ignition type distributor (summit has a mopar performance brand kit for like 230) as it has a more reliable spark and youll never have to worry about aggravating points. and modify the linkage for the transmission and carb as needed. this is not a conversion for the lighthearted. but it is what I did and my truck runs better than it did with that crappy tbi.

Now it's not running fine anymore.

It started by surging and stalling a bit at red lights, etc. I checked all vacuum lines, etc. I replaced the guts of the distributor. Plugs and plug wires are practically brand new. The problem got progressively worse until now the vehicle is undrivable. I found some remanufactured ECMs online, but if I'm going to go through the headache of solving this problem, I'd just as soon do it all in one go. I don't mind doing modifications of linkage and etc. I can also 3D print any brackets or stuff like that I need. I'll give this a go and see how it goes, and report back here.

It's amazing to me that people have gotten so that they don't appreciate the simplicity and satisfaction of tuning an non-ecm engine. I used to do it on saturdays just for relaxation. Having the control the old style setup gives you is important to me, and a well tuned engine will burn just as cleanly and efficiently as a "modern" computer controlled engine, imo.

carb engine are simple and cheap to fix but i still like my fuel injected engine as long as things work properly.

do you have a tach? could try adjusting the idle speed adjustment. it can sometimes cause small issues.

Thanks a lot for this. I have actually tried this, and I thought it solved my problem for a little while. But now, the engine actually cuts out at driving speed, and sometimes barely runs even when I mash down the gas. It cuts out on the freeway at 60 mph, etc. I was lucky to get it back to the shop. This is something that is affecting the engine at all rpm ranges, in other words.

might want to check fuel pressure. could have a fuel pump that is going bad.

I will do that, thx. I'm also told the map sensor may be going bad. Easy to test that, or so the guy says -- just unplug it and the ecm will generate its own default (albeit wrong) voltage.

crazzywolfie said:

if the thing runs fine as is you should probably leave it. converting from TBI to carb can get kind of expensive unless you have most of the parts sitting around or buy a parts vehicle. you will need a carb, intake, voltage regulator, fuel pressure regulator, ignition system. now i don't have exact numbers but i guess it would cost you about $700 for these parts new and you would not gain anything.

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I agree with you on leaving it as it is & fixing it.
But the last time I bought a new 4bbl carb for my 88 D250 it was close to $450. A two bbl new isn't much cheaper. Now wrecking yard parts I would say your price is closer to.