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Engine photos: What do I have? (Feedback Carb related)
After reading through many, many of the 4.9 Feedback Carb/Duraspark/HEI conversion threads, I'm pretty certain that I'm headed down a similar path. I have a 4.9L 300 i6 that is an absolute dog at higher speeds/RPMs. To put it lightly - it runs like crap down the highway. Either my truck is stuck in a limp mode or some various layers of issues. Before throwing parts at it, I wanted to upload some images of what things look like under the hood.
I'm hoping FTE members can help me determine the following:
1) Do I have the feedback style carb?
2) Anything else under the hood I can remove if going HEI (I dont need to pass emissions - TX truck)
- This was a Utah/CA truck, and so I assume I have emission crap that can go away too?
3) HEI vs Duraspark II. Warm weather truck, very little need to cold start. Not a daily driver.
It has a reman feedback carb.
The distributor looks like a feedback TFI, computer controlled unit; it is not a points distributor.
Most folks with that unreliable system are prone to revert back to a non feedback carb and DS II distributor and delete the computer.
Yes, that's the feedback carb setup.
It's a system that runs great when it's working, but they rarely do anymore.
As for what you can remove, pull the old ECU from under the dash (it's behind the dash up above the gas pedal). Just note that if you have cruise control, there will be two modules. Don't remove the cruise control module.
The ECU is the one with the big plug that has a bolt holding the plug in. The cruise control module is the one with two small plugs.
Remove the ECU, and then feed the big plug of wires through the firewall into the engine bay. From there, you can follow those wires, unplug them from everything they go to, and remove all those wires from the engine bay.
Near the firewall on the driver's side, there are a couple modules that are bolted to the valve cover. You can trace these and unplug them from everything.
DuraSpark II vs HEI won't matter for cold weather. Most of your cold weather starting will depend on the carb setup and if you supply heat to the underside.
Are you still planning on staying with a 1bbl carb? (If you do, you'll probably need a non-feedback one).
As said it is a feed back system and Abandon did a great job os going about removing said system.
Being the carb is new looking and others have run a feed back carb with a non-feed back dist. and that helped a lot.
So do the non- feed back dist. swap first and see how it runs. If the system is in "limp mode" the timing could be locked and why it is a dog.
You also did not say what year the truck is, the model 4x2 or 4x4, gear ratio(s), transmission and tire size?
If running 2.75 gear in the axle, 37" tire and over drive trans then most of what you do may not help a lot LOL
Dave ----
Tires: 31's on stock rims
4x4 Truck
300 i6 manual trans with 4 speed. No OD at the top, so the low power situation leaves me running 60 or under.
I'll have to look for the gear ration. I'm sure its whatever came standard. Truck is very original.
Tires: 31's on stock rims
4x4 Truck
300 i6 manual trans with 4 speed. No OD at the top, so the low power situation leaves me running 60 or under.
I'll have to look for the gear ration. I'm sure its whatever came standard. Truck is very original.
If the timing is locked in limp mode that could be most of why it may not go faster.
The 31's dont help as stock were 29 I believe. Match it to a 3.08 gear I think the 4x4's came with and it would be a dog.
But I got to say if you check timing you may find it is not advancing like it should, timing locked.
I say this based on my 81 F100 4x2 non-feed back 300 with EFI manifolds and 94 complete exh system less cat. 4sp with granny first, 2.75 rear and stock 235 / 75 / 15 tires,
I also run a Advance Adapter over drive and the truck will cruise at 70 MPH in OD with out trouble, may slow down a little on a hill but a little more throttle and it stays at 70 MPH.
It will also cruise at 80 - 85 in OD and only turning 2200 - 2500 RPM shocks some of the newer trucks running that speed.
Check the timing or just replace that feed back one for a HEI and see what happens as it cant hurt and you are half way to removing the rest (carb) of the feed back system.
Dave ----
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