Why won't they find a EFI 351 with a C6? I owned one for many years.

 

In what truck ?

 

In an 88 f150.

 

You could get a C6 behind any engine in a pickup truck until 1996. They became less common as the E4OD became the standard heavy duty automatic transmission but they are not rare.

 

I know they're listed, but I've never run across one that late. Like I said, good luck finding one now. If it was there, it would have been ordered that way, not a regular production run item.

 

The C6 was the only heavy duty automatic available until 89/90 when the E4OD was introduced. EFI was introduced in the trucks on the 302 in 87 and the rest of the fleet in 88. So 2 years of production EFI trucks with the C6. The 4.9 and 5.0 could have the AOD/AODE? or the C6 but 5.8 and larger only came with the C6 (for automatics).

After 89/90 they definitely get more scarce, but people still ordered them.

 

Not disagreeing with you, only that they're not as common as you think. Especially now, thirty years after the fact.

 

you think it would work to run a efi 351 with a manual behind it if you used the 351 efi computer that was designed for a c6 since its not electronic?

 

What you need is a 351 (preferably 94+ to get roller lifters and better cam, but watch out for differences in cam shaft gear and distributor gear compatibility issues when sourcing parts) and stand alone harness from a 302 or 351 with C6 or manual transmission, and a computer for a 351 with a manual or C6. Not to mention intake manifold, sensors and plumbing. I would think the part trucks to look for would be 87-90 for a minimal harness. Or just rock a carburetor and forget about it. You can install EFI down the road as the block doesn't care so long as it is fed.

 

Ok, good info on the tranny. So, lets talk carb. What would be a good combo, as in not always adjusting, for a stock ex FI 351? Intake and Carb. electric choke? Right now, I got a masters 2300 electric fuel pump installed and a regulator I can go from 12psi to 40psi.

 

12psi is too high for a carb. The excess pressure will be something the floats in the bowls will be fighting against to keep the needle/seat valves closed when they're supposed to be. 5-7 psi is plenty. It's a carb, not fuel injection. What pulls the fuel into the airstream in the throats is the vacuum generated by the pistons sucking air through the throttle bores. As for intake ? Performer RPM or something similar (high rise dual plane) These will work from idle on up to your upper rpm limit despite what the advertising says. Stay on the small side for carb size. No bigger than 650 cfm will give you EFI-like throttle response. I like Holley carbs. As for your question about having to "always adjusting it" That's BS. You should never have to adjust it, once you've tuned it to the engine. If you are, then you're either never satisfied with something, or there's something going on with the ignition causing erratic performance. Once you adjust a carb it will stay that way for years. The only parts that will wear are the throttle shaft bushings, and that only if the return spring is too stiff. Only other advice is to feed it clean, quality fuel and use two fuel filters.

 

theres a small fuel pressure regulator you can buy thats made by mr gasket i believe ad put it before the carb then itll adjust that pressure down to what you need for carbs

 

Agreed. I don't know why everyone thinks having a carburetor means "always having to adjust it." Once it is tuned to the motor, and the stock thermostatic air cleaner is in place, the carburetor shouldn't need any adjustments - no matter the season.

The other rumor that won't die is difficult "cold starts." As long as the choke is hooked up and functioning correctly, there shouldn't be any problem - no matter the season. The reality is, with the proper size carburetor tuned correctly (for a 5.8/351 in a truck, I would suggest a 600 cfm), a thermostatic air cleaner, and a working choke, there is very little difference between an engine with a carburetor compared to one with EFI.


Throttle shaft bushings:
I addition to the throttle cable, I have a Lokar transmission kickdown cable attached to my throttle lever, in lieu of a kickdown rod. Which means I have two return springs closing the throttle lever. The throttle return spring is part of the throttle cable, which pushes the throttle lever closed from the back. At the same time, the Lokar kickdown cable has a return spring that is part of the transmission cable, which pulls the the throttle lever closed from the back.

Is this bad for the throttle shaft bushings? It is set up like this, and 1:30 shows the motion:


Now that I have located the correct throttle linkage for my carburetor, I was thinking about going back to a simple kickdown rod. But if the Lokar kickdown cable isn't any worse on the throttle shaft bushings, I will leave it.


Two fuel filters:
My Autolite 4100 carburetor has a screw-in fuel filter attached to it, which means it filters after the fuel pump. Can I run an additional fuel filter before the fuel pump as well? Or will that create a restriction?

 

Yes you can run a filter before the pump. If it does cause a restriction, thatll tell you it needs to be changed. You don't want a lot of spring pull that the throttle shaft has to fight against, that'll wear the bushings prematurely. Cold starts ? Run a wide LSA efi can and enough timing to allow easy starts and you won't need a choke or anything else. I ran an explorer 5.0 in an 89 Ranger without a choke on a Holley 570. With the timing at 12-14* All I had to do on 25*F mornings was crank it a few seconds. It would fire off and idle with only a couple of pump shots with the go pedal

 

Throttle shaft wear is exacerbated by the normal action of the throttle cable (and TV cable/rod) acting on the lever above the shaft, and the return spring acting on the lever below; they're both applying force toward the back, causing wear in that direction.. One way to reduce wear is to install the return spring above the shaft, and anchor it in front of the shaft somewhere. This way, most of the fore-aft forces balance out.

It may be difficult to find a spring anchor in front and above the throttle shaft, but you can probably fabricate a small bracket.