4.9L EFI - CARB Conversion
 

Ok, before everyone jumps up and down, I know going "Backwards" to a Carb is losing some Horsepower.... BUT Mileage doesn't bother me.... Trucks have gotten pretty much between 14 - 22 MPG (smaller rangers) for 30 years... the new trucks, with all their technology can't seem to improve on it.... so 14-20 mpg is fine. That said, My project truck will not be my daily driver, I commute 85 miles/day I will drive it, I like old trucks, but if it isn't a race horse that is fine by me. Someday when I have a garage again and all my tools.... (don't get divorced) I will build something really pretty...
With all this said, I am going to convert my EFI over to a Carb set up. What I have found out so far is that I will probably use the DURASPARK 2 set up, requiring the new Intake manifold, Carburator (a Holley 390 has been suggested), a distributor with Vaccum advance, the coil and the wiring harness.
Questions I have:
I have read that the in tank pump on an 87-89 was designed for a Carb anyway so I should be able to hook that straight up. No regulator, lose the High pressure pump, etc... Is that a true statement?
I am looking for a Duraspark 2 from anything running a 4.9L, or does it need to be more specific?
I planned to use the Vaccum Diagram from an 80-86 F150 to set up my vaccum with the carb? Any pointers?
I have played with my EFI wiring enough to know what my constant hot and switched hots are so that shouldn't be a problem?
As far as guages goes... Any Issues there? The speedo isn't hooked up right now, but it is the old cable type, going to a C-6... so that shouldn't be a big deal.
Anything I am forgetting?
And of course? Anyone have any of this stuff lying around?
I apprecite all the pointers tips ya'll give.

o_0?
 

I thought we answered your questions in your last thread on your whole carb conversion deal.

Just jump in, get a carb and Duraspark distributor in place. If it runs, I'm sure there are folks here that will walk you through making the gauges and speedo work.

The 390 cfm Holley List #0-8007 has an electric choke. Follow the instructions to the letter as far as hooking it up. You might have to use a universal throttle cable from Lokar or some other co. to get it hooked up.

Get the Clifford Research intake manifold #43-4502WH as it is the best for your app. It's water heated to help atomization. You tee in the water lines to your heater. Not cheap but it works. Be sure to get the 4bbl adaptor that is offered for it.

Clifford makes the headers, too. Again, not cheap but well worth it.

For an air cleaner, find a closed element stock style housing that will fit. There are heat riser kits to get hot air to the snorkel when the truck is cold, and the thermostat in the snorkel will draw in outside air when the engine warms up. Open element units look good but contribute to poor cold driveability.

That's my $0.02 USD worth.

I would keep the EFI if it were me.

You list Maryland in your profile. Do you have an emissions exemption for the truck and/or know the inspector at the local station?

Yeah, right!
 

After some searching, it would seem your truck is still subject to a bi-annual
tailpipe sniffer test (VEIP), since it seems like you live in Washington county. Just so you know, that little Holley 390 4bbl is probably gonna fail that test big time.

Have you given this any thought? You are not exempt from smog testing, according to your state website.

Oh well, better get ready to fix your EFI.

That is why I asked about the emissions exemption. They used to issue them years ago. I friend had one for his Mustang. A guy I currently work with has been fighting the emissions test for years. Can't get his '83 F150 Custom (he bought it new) to pass.

4.9L EFI to carb conversion
 

Alrighty then, I know this is an old thread, but I just completed my 4.9L EFI to carb conversion on my 1990 F150 Shortbed 5 speed Custom 2wd. I absolutely had to because the thing would stall right at the wrong time (a serious hazard), and THAT was with all new EFI things (including computer, distributor, injectors, blah, blah, blah).
In detail:
1. Weber 32/36 Carburetor adapted to a 86 and pre-EFI manifold. Weber kit from Piercemanifolds.com #K617 (I wanted a K616 manual choke but mistakenly ordered a K617 electric choke. Didn't want the hassle and expense of returning it, so I adapted a manual choke kit to it). The #K616 and #K617 kits have the adapter that fits that old cast iron manifold (with some finagling). I used the original EFI accelerator cable bracket and tack-welded the cable ball joint from the EFI throttle body swing-arm? to the Weber swing arm. Surprisingly that all worked without much pain and anguish. And it has the "original look".
2. Kept the EFI exhaust manifolds - you need to grind off the square-ish casting boss on the rear manifold #4 port, and do some other grinding adjustments to make it fit, but, dang, it worked! Please note that the cast iron grinds REALLY easily.
3. Used a new, Amazon supplied GM HEI one wire distributor made for the FORD 4.9L 6 banger (surprised?). That sucker works BEAUTIFULLY! Powered it with the now under-used EFI relay. Ran the vacuum for it up to the port on the vacuum advance port on the Weber. Set timing to 11 BTDC.
4. Ran the breather to the fitting supplied in the #K617 kit air cleaner simply by shortening the original hose. No air cleaner hassles. Ran the PCV to the old PCV port on the carb manifold. Super clean.
5. Fuel. This was the most difficult sweaty dirty task because I had to remove the fuel tank, and modify the fuel pickup by gutting the EFI fuel pump and adding a take-up hose to reach the bottom of the tank. I had to reinforce the fuel sending unit bracket with an extra holding screw because the original holding bracket was the no-longer-used and no-longer-there plastic fuel pump housing. Put all the back in place and installed a Carter P4070 fuel pump (powered off the old EFI Fuel Pump Relay) forward of the original fuel filter. The pump is self priming, but on first start up it take a LONG TIME to prime. No problem after its primed, but it is noisy (until the wind noise cancels it out at about 25 mph). Ran the fuel supply to a Redline Weber regulator 31800.063 because those Webers will flood with pressures above say 4 psi. Bypassed the EFI Fuel relay ground-through-the-EFI-EEC and took it right to ground - that way the EFI-EEC is OUT of the picture. Fuel sending unit works and the fuel gage works.
6. Removed the old EFI fuel lines forward of the Carter, and removed the old EFI injector harness - a massive birds-nest of wires, but kept track of the oil pressure wire (left side of engine below and behind the distributor) and the water temperature wire (way back of the engine on the lower right). Ran just those two wires back to their sensors after cutting everything else off (literally) and taping the cut ends off). Oil pressure and water temp gages work.

OK, so here are my comments on how well this conversion works. On first start, the timing was way off, but surprisingly the thing started (after the long fuel pump prime). Having set the timing, and learning to work that manual choke, the thing starts WAY FASTER than the EFI ever did. I mean it cold-starts on the first 1/2 of a revolution (that NEVER happened with the EFI). The thing runs beautifully, and at this point, I am realizing no loss of power and no reduction in mileage. No stalling. No missing. Smooth running. Plenty of power. Now look - I am an old geezer (63), and my lead-foot days are past, so I am not running this thing around at WOT all the time. I do realize that the Weber is about 270 cfm and the original Autolite probably did 300 cfm, so there is some de-tuning. But I don't run it at those power levels, ever. If you wanted to, you could probably use a Weber 38/38 and get the 300 cfm if you needed it (or even more).

Drawbacks: There is a lot more lifter/rocker noise making it into the cab, especially at a certain throttle position. Sometimes it sounds like an old Dodge Cummins diesel under full power. I chalk that up to: less things in the way to prevent the sound from getting in there, AND, my old rockers are probably worn a bit much.

So, I have only had this for a few weeks, but overall, I am very happy with this conversion. Reminds me of my days with my 64 F100 and the old 223 - good times. If only I had the three-on-the-tree ...

Congratulations on a job well done!

Looks like you dealt with nearly every concern that I normally have about these conversions. I do have a couple questions/suggestions.

1) I would add a safety relay operated by an engine dependent function like an oil pressure switch to shut off your electric fuel pump when the engine is not turning.

2) I can only imagine this is not subject to an emissions inspection.

3) How much did this conversion actually cost?

Enjoy your truck!

Thank you.

1. On the safety switch, that make sense ... I'll look into that.
2. I live in a no-smog-check county, so yes, Blanca is not subject to emissions inspection. No car in this county is (that's right I said NO CAR).
3. I'd say the conversion cost about $700 (I paid too much for the intake manifold). Might make some back on the almost-new injectors, and EFI lower intake.

And yes, I am enjoying my truck, thanks!

Thanks for the write-up. Every now and then when I have stumbled across a pre-'87 4.9 F-150 at the junkyard I think about grabbing the carb stuff, but as of yet I've never bothered. Even though I'm 60, I actually understand Ford EFI stuff better than carbs, so for me I'd do the swap more as a novelty to understand the old way better.

Did you consider using the factory carb rather than the Weber? I imagine that could have made the swap easier and less costly. I imagine I could get the carb and intake for $50 at the U-pull.

Yes, I considered a factory carb, but I wanted a new one, and NOT one made in China. So I did a Google search on "the best carburetor" and saw that the Webers were popular, tunable, had lots of followers, could be had new, and were not made in China (made in Spain). The clincher was that the 32/36 was 2 barrel progressive with a mechanical secondary and flowed close to the original Autolite. I saw that guys were putting Holley 650s on their conversions, and I thought that idling might be a problem, AND to put a 4 barrel on there would require an aluminum aftermarket intake (an extra $400 to $500). Now, with that little Weber performing so well, I would not put anything bigger on there than an Autolite 2150 2 barrel, or a Weber 38/38. I think that those Holley 650s are overkill unless you cam the engine, and I liked my engine the way it is (stock cam). Right now, I am very happy with that little Weber 32/36 - most of my driving is city driving, so I don't need the performance of say the Autolite 2150.

This morning, it was a cold 23F out and the truck had sat out all night - stone cold. It started right up on a full choke with two pumps of the accelerator. I stalled it right away like an idiot, and struggled to start it again, but it started nonetheless. That is one of the good things about EFI - dependable cold starts.

So yeah, if you can pick up a manifold set for $50, that is a good price. Mine was $200 when it was all said and done. I paid too much, but couldn't wait for the right deal.

Here's an article (with lots of pics) on rebuilding an Autolite 2150...
https://www.motortrend.com/how-to/re...50-carburetor/

Just in case myself or someone else wants to go down this path one day.

no offense to ford fans but I would not do duraspark II I would do an HEI like a GM style.. if it exists for a 300... because
https://cimg6.ibsrv.net/gimg/www.for...e1672cdabd.png
unless duraspark ii got better since the 70s the modules are absolute jokes for reliability and didnt they do the crossfire on the tower thing

AuroraGirl, That post was from May 2016. The thread was brought back from the dead by BRBR549.

Aha you are correct
BRBR549, youre making me commune with the dead. we should let them rest in PEACE. Here I am shouting at it to show me its private parts and I look like a fool

This forum isnt as easy as the buick forums to see the dates and as obvious when things were posted lol..

Not dead, but MOSTLY DEAD. And I DID use a one wire GM HEI distributor for my conversion (works GREAT!). I think these EFI to Carb conversions will be around for a LONG time, especially since you can't get a new computer for these old EFIs (I think). And I am so happy with this conversion because it doesn't randomly stall (SO DANGEROUS)! I just saw an ad for a 93 Jeep Cherokee that "starts, runs a bit, then stalls". I'm thinkin "Hmmm, I wonder if I could convert THAT one over?" I'm basking in the glow of this success ...