Carb Upgrade Recommendations

[Bigcalhoun]

Fellas,
I have a 70 F100 302. It’s almost entirely stock except for a Flamethrower Coil and Pertronix upgrade. I’m considering a carb upgrade and would appreciate any good suggestions on one that will improve performance but be appropriately sized for the truck.

If I go with an electric choke, what’s the best spot for connecting it to some juice?

Thanks y’all.

[Ford-f100-1972]

I have '72 with a 302 bored .030 over and a mild RV cam. Put on a Demon 625 five years ago and the truck runs and starts great.My son has '71 Comet GT with a 302 and this same carb. All original, never rebuilt and he has had the same experience as I have. Great carb for a stock to mild 302.

Hope this helps.

[Bigcalhoun]

Much appreciated. I’ll check it out.

[zgerbic]

About 550 to 600cfm would be the right size for that engine and the fact that the truck is heavy. Too many people make the mistake that bigger is better. I run a 650 holley on my F250 400CID with an RV cam. It runs good but probably also would with a 600.

The 625 recommendation sounds good as well but I would not go bigger.

The electric choke will require an ignition switched 12V source. Cannot get from the coil power since it has a resistance in the wire. If there is a throttle positioning solenoid you could get the power from there. Another option, which I had to use, was to run a wire from the ignition through the firewall, bundled with the wire that powers the coil, and use that for switched power when I changed from manual to electric choke. I would also run a second wire and use it to run the tach if you don't already have a tach wire.

Another thing to consider is to use a toggle switch under the dash somewhere with one side to the switched ignition power connection and the other to the electric choke. In this case leave the switch open when the truck is parked. If someone steals the truck the choke will remain closed causing the engine to tend to flood out at idle making it really difficult to drive the truck any real distance.

[Bigcalhoun]

Thank you. That is extremely helpful. I was concerned about going too big with the carb. You both put aside the fear that something in the 600 range would be overboard.

[Fraser]

I'm guessing you will be changing the intake manifold, it is also important to get a dual plane unit, Offy. dual port works well on a small block, but expensive. Do not use a single plane manifold on a street driven truck (my opinion).
My '77 was pre-wired for an electric choke. Weird, because the factory didn't offer one, but look for an unused wire in the area that is hot only in run. otherwise, you can run a wire off the alternator, (field, I think, but the carb instructions should say, if new) it will heat anytime the engine is running.

[Bigcalhoun]

Still pondering the manifold swap. I have a soft spot in my heart for old, heavy, original Ford parts. If I can paint it blue I’ll likely get over that however.

I found a great YouTube video this morning re: wiring the electric choke. They used a relay attached to the solenoid with an inline fuse on the positive side. I may take that approach.

One more thought, would gains in power or efficiency justify a 4 barrel?

[sparky72]

For a stock engine I personally wouldn’t bother with upgrading to a four-barrel manifold and carb. I doubt the rest of the engine would breathe well enough to make much use of it.

[Ford-f100-1972]

I initially was hesitant to put the 625 on my 302 but it ended up being just fine. It does have some pretty good performance when the secondary kicks in. I've driven my son's Comet with this carb and it works just as well on a stock original engine.

I found that I get better mileage with the 625 vs the old 2 barrel as long as I keep my foot out of it.

Good luck with whichever way you decide go. You'll never get large.power out of a basically stock 302 but a little extra power for passing or just for fun is a good thing.

[cep62]

I know some people don't like them but I've had good luck with a Holley 500 cfm 2BBL.
then you don't have to change intakes.
Also the factory ran the choke off the alternator , so When it stalls it won't keep heating and it opens before
the engine is ready.

[Fraser]

It will be an improvement. But Once the intake is upgraded, the exhaust will still be a little restrictive. You can do a lot or a little with a smallblock, lots of options there, stock is good, more is better.
Edit; I also like the Holly 2V cep mentioned, and super easy.

[Bigcalhoun]

Thanks for the advice. Just ponied up for a Holley 500 cfm. I plan on pulling off the intake manifold while I'm at it to install fresh gaskets, but will keep the original part. Also a great opportunity to degrease and repaint the manifold that beautiful Ford blue. I'll start out with the alt for a power source.