Upgrading from original 2 barrel on 287

625 Carter on a 232 and a Dodge 225 here.
Both were a LOT more powerful after the change.
The Offy manifolds obviously helped.

If they could open the secondary air valve a 287 obviously can.

Hello sir? ...are you still there?

Since you don't seem to have much mechanical experience, you need to arm yourself with knowledge first.

 

Buy 'all the books' = educate yourself about your car:

1) AMC Technical Service Manual

2) Chilton's Repair Manual

3) ...buy a book on carburetors? (how to rebuild modify etc?)



Welcome to 2018.

It's not 1966 anymore.

Your car was made to run on 'regular gasoline'. (leaded fuel)

E10 gasohol conversion is your main concern because your car was originally made to run regular gasoline which is now outlawed.

Judging by how you asked your question, forget about carb swapping for now.

Fortunately, your stock Holley 2bbl carb as described is your best choice (never mind if it looks like a one barrel)

Forget about carb swapping and do websearches on on 'running ethanol gas in old cars'.

(don't waste your money of fuel additives!)

Is your car currently in good running condition?

Does it have vacuum operated windshield wipers and do they work?

You should be concerned about the old fuel pump in your car also. Cutting straight to the point, 'further on down the road' you need to consider install electric wipers and a 'new school' mini-electric fuel pump for future compatibility with the new fuel.



Do another websearch and contact your nearest AMC club for more help with your car. Maybe joining an AMC car club will be best choice for you; there should be someone in the club who can guide you in the 'right' direction* with your car...

*E10 compatibility is your main concern for now.


This in not merely my opinion, it's US Federal Law:

https://www.epa.gov/renewable-fuel-standard-program/overview-renewable-fuel-standard

There are some concerns with ethanol added fuels, but not a lot. Any rubber parts that would be affected have usually been replaced with something made over the last 30 years, which is fine with ethanol added fuels. I keep saying "ehtanol added" because straight ethanol is a different story... E10 (which is regular fuel now) and a little more will be fine, even E85 should be.

If you have a 40-50 year old fuel pump it might be a different story. Gas lines and carb accelerator pump too. The rebuild kits for the fuel/vac booster pump you have now are ethanol capable, but an old pump might have issues. Typically the rubber parts get hard and don't do their job so well any more, in the worst case they may break or tear, but most quit delivering enough fuel for the engine to run well before then. Chances are that since yours is running well and the vac wipers work well that the fuel pump has been rebuilt in the last 20 years. For some old carbs this is a real serious issue, as you can't get accelerator pumps for them any more, just NOS (New Old Stock -- meaning it might be a brand New part, but it's Old Stock -- been sitting in a shelf 40 years...). Using NOS rubber parts is circumspect at best, using it with ethanol is worse... it won't last long.

Modern fuel also atomizes easier than fuel form the 60s and 70s. That's better for EFI, but it also mean it will evaporate faster. Not uncommon to leave an old carb car sitting in a garage for a couple weeks only to find there is no (or not enough) gas in the carb. It evaporated out! So pour a little down the carb (about 1/4 cup) before starting. Always try starting normal first... how much evaporates out depends on weather conditions. Might do it during the hot summer in an uninsulated garage, might not during cooler conditions.

You can run a little more timing with modern fuel, and an electric fuel pump will pump it better, but the old original type rebuilt with newer parts should still work adequately. There are alternatives to running electric wipers also, but if you're building this car as a daily driver, not just an occasionally driven fun car, then you probably want electric wipers, and can then properly install an electric fuel pump as well. If a restoration or just a weekend/fun car, seldom sees bad weather? Don't know that I'd worry much about it...

Be aware that 2 barrel and 4 barrel carburetors are rated differently. The CFM numbers can't be directly compared. Long story short, a 500 CFM 2bbl is equivalent to a 353 CFM 4bbl. A 500 cfm 4bbl is equivalent to a 707 cfm 2bbl.

Despite the lower comparative CFM, the 500 and larger CFM 2bbl carburetors have poor street manners due to the large venturi size.

An equivalent CFM 4bbl will have smaller venturi. This means a greater differential in air pressure. This makes it generally easier for the carburetor control fuel release from the boosters.


Edited by akimmet - Jan/14/2018 at 11:11pm