Ok here's the deal. The previous owner of my truck ripped the smog pump, bracket and I'm sure other smog pump related components off the 4.9. I didn't know at the the time I bought the truck, but from what I've read recently the feedback system needs the pump to run correctly. The truck seems to run ok, but it's idles rough and shakes a bit when stopped while in gear. I'm hoping it's just a misfire and the plugs, wires and distributor cap I just bought fix it.

I had to replace the carburetor, which set me back quite a bit, so the cheap side of me just wants to replace the pump and it's components. Problem is, I'm not even sure what's missing from the smog system and some of the parts like the bracket just aren't available. I'm getting that bad feeling that it'll be more expensive than it's worth. I'll take a pic of the engine bay in a bit, maybe there's not much missing for the smog pump and it'll be cheap to fix for now.

The do it once and do it right side of me just wants to spend the $1000+, do the Duraspark conversion and get some more horsepower with a better intake manifold and bigger carb. I'm leaning on saving up and hunting down all the components for Duraspark conversion over the winter and beefing up the engine and exhaust system in the spring.

Will my truck be ok for 6 months driving it without the pump until I'm able to find all the stuff needed for the conversion? I assume yes, but most of you know way more about this truck than I do. Any help would be most appreciated.

 

I didn't know the computer system needed the smog pump to work correctly? People take the pump off fuel injected trucks all the time and it does nothing except throw some codes, which are not serious as far as the computer is concerned.

A duraspark II conversion should not cost $1000. You can buy the duraspark components or just put a aftermarket HEI in place for less than $100.

I would do some research on a manifold swap and carb swap. Go down to the six forum and see what they say. That is expensive, and you may need to run water underneath the carb to keep it warm enough to run in RI winters. You could run it with your computerized carb for now, with the duraspark II dist.

If your system is all hooked up and working properly(except the smog pump) you have one of the better systems ever put on the 300 for fuel mileage. But keeping it going can be a problem unless you know all about the system.

 

Hi Franklin, I've read that not having the pump on screws up the timing and it runs rich. However, this is the internet so who knows if that's correct information. I'm hoping for my sake it's incorrect lol. The $1000 I want to spend on the conversion includes the Duraspark components, new intake manifold and new carburetor. If I can get all that stuff for less than a $1000, that would be awesome.

Everything does seem to work good now, it runs down the road great, it's just the rough idle 'a little shaky' while in gear and stopped. Out of gear the engine runs smooth as silk. Another question, will the painless duraspark wire harness work on our trucks? The original harnesses seem to be rarer than leprechauns.

 

The smog pump adds air downstream in the exhaust system, the computer does not know anything about it unless it would mess with the oxygen sensor.

I think if you are contemplating this conversion, I would do it one step at a time. First, I would try to fix the rough idle problem you have now. The only thing the computer has control of is the timing and the cruise air to fuel mixture in the carb. So if at idle you hook your timing light up and the timing is rock steady, you can eliminate the computer causing the problem.

Look for the normal things like vacuum leaks. You can put a solid piece of metal under the egr valve temporarily to see if it might be leaking a little bit. There is a mixture adjustment on your new carb correct? Turn it and see if it makes a different. You can gently put the truck up against a tree and leave it in gear if you want to adjust it while in gear. Or get someone to hold the brake while you adjust it.

 

You think these parts are going to be cheap?! Take a look-see at the parts catalog pic to see all the involved parts, most of which are obsolete and difficult to find.

 

Oh yeah I know the parts can get a bit expensive and finding them is very hard. I was hoping most of the smog stuff was still there and I would only have to replace just a few parts which would be cheaper than the conversion. After looking at those very helpful diagrams you posted, I can already tell that going the duraspark route is going to be the better path. I want more horsepower anyways, so doing the duraspark would give me more choices with that.

 

I would have to agree with Gary.
"Cheap" is going to be an HEI distributor and a relay to run it, for under $100.

 

MrFord619,

For your consideration [from forum stickies]: https://www.ford-trucks.com/forums/9...-86-i-6-a.html

 

Thank you, I read that one and it seems pretty straightforward. The only problem I'm having is finding the wire harness. Would anyone know if the Painless wire harness would work? It's expensive, but if it'll work I may go that route.

 

See if this might interest you? NOS 1975 FORD E150 E250 E350 300 CI 6 CYL DASH PANEL TO ENGINE GAUGE FEED | eBay

 

Would that be one I need? I've honestly never seen a good picture of one.

 

Wow, that's nice!

​​​​​​​If I had a 4.9 I-6 I would be all over that DSII harness in a heartbeat.

 

I'll assume it is then, buying it now!

 

Thank you so much 1986f150six! I kept searching duraspark harness, I would've never found it! I just bought it. A major piece of the puzzle has been found. My feedback days are numbered lol.

 

Glad to be of help! That is what this forum is all about.