Carburator Compatibility

johnejo · Apr 3, 2015

Hello. I am looking to put a 4bbl carburetor on my '67 289 using a 302 4bbl intake manifold. I am also selling a '74 Mercury Cougar XR7 that came factory equipped with a 460 and a 4bbl Carter TQ carburetor. I am wondering, and hopefully someone will know, whether or not I should hold onto that Carter carburetor and if it would fit my '67, or if I should just let it go with the Cougar.

Thanks in advance for any input/help you can give me with this.

rbohm · Apr 4, 2015

that depends, if the carb in question is a square bore carb, meaning that all bores are the same size, then yes you can use the carb on the 289. if the carb is a spread bore carb, meaning the primary bores are smaller than the secondary bores, then no you cant use it without an adapter.

johnejo · Apr 4, 2015

rbohm said:
that depends, if the carb in question is a square bore carb, meaning that all bores are the same size, then yes you can use the carb on the 289. if the carb is a spread bore carb, meaning the primary bores are smaller than the secondary bores, then no you cant use it without an adapter.

Okay. Thank you. Yes, the carb in the Cougar is a "spread bore" carburetor, and now I know it definitely will not fit on it. Thanks, again.

7991LXnSHO · Apr 7, 2015

You can bolt it on with an adaptor, but that should not be the main issue. A carb that runs on a 460 will have too many CFM for a 289. If it has vac. secondsries, you may be able to keep the it running on mostly the primaries, but that is not ideal. You will be happier with A 600 CFM Holley. That will be plenty for the little motor.

johnejo · Apr 7, 2015

That's good to know. Thank you. I'll look into that. Is there a reason why people generally talk about Holley's versus Edlebrock, etc.?

rbohm · Apr 8, 2015

7991LXnSHO said:
You can bolt it on with an adaptor, but that should not be the main issue. A carb that runs on a 460 will have too many CFM for a 289. If it has vac. secondsries, you may be able to keep the it running on mostly the primaries, but that is not ideal. You will be happier with A 600 CFM Holley. That will be plenty for the little motor.

actually the airflow isnt the problem, the jetting is. take a carb from a 460 and drop it on a 289, and you have to change the fuel low curves, and that entails more than just the main jets and power valve to get teh fuel curve right.

johnejo said:
That's good to know. Thank you. I'll look into that. Is there a reason why people generally talk about Holley's versus Edlebrock, etc.?

understand that holleys have been a performance carb option since late 50s. as such they have a huge following, and many variants from companies, like barry grant, that started out as holley carb tuners.

when edelbrock got into the carb game, they jumped in with both feet and hit the ground running. they started by buying weber carbs and carter carbs, and combining the best of both carbs to create the edelbrock performer carb.

once again barry grant got into the act and started tuning edelbrock carbs, and now has his own line of demon carbs based on the edelbrock design.

but the reason these carbs are generally the ones recommended by enthusiasts is that;

1: they flat out work well out of the box generally

2: there is solid aftermarket support for these carbs

3: they are easy to tune

4: they are reliable

johnejo · Apr 8, 2015

rbohm said:
actually the airflow isnt the problem, the jetting is. take a carb from a 460 and drop it on a 289, and you have to change the fuel low curves, and that entails more than just the main jets and power valve to get teh fuel curve right.

understand that holleys have been a performance carb option since late 50s. as such they have a huge following, and many variants from companies, like barry grant, that started out as holley carb tuners.

when edelbrock got into the carb game, they jumped in with both feet and hit the ground running. they started by buying weber carbs and carter carbs, and combining the best of both carbs to create the edelbrock performer carb.

once again barry grant got into the act and started tuning edelbrock carbs, and now has his own line of demon carbs based on the edelbrock design.

but the reason these carbs are generally the ones recommended by enthusiasts is that;

1: they flat out work well out of the box generally

2: there is solid aftermarket support for these carbs

3: they are easy to tune

4: they are reliable

Okay. Thank you. Holley has both the experience and reputation for reliability and relative ease of use compared to the others? Then Holley it will be! Thank you!

7991LXnSHO · Apr 8, 2015

Holley makes a square bore carb that is just the right size and is the right price (check out the 1850-? For a vac secondary, manual choke for the cheapest that will run great. Step up with an electric choke and a quick change spring housing to make it better), they are simple, and Ford has a long history of using Holley or Motorcraft made Holley copies, as since 1903! Demon Carbs are now owned by Holley as is one of the other innovators.

But any brand's 600 cfm square bore new carb will be a better choice than one for a 460.

rbohm · Apr 8, 2015

johnejo said:
Okay. Thank you. Holley has both the experience and reputation for reliability and relative ease of use compared to the others? Then Holley it will be! Thank you!

the holley is a fine choice, i have used them in many applications over the years. that said, i would push you towards the barry grant demon carb line, especially the ones based on the holley carb. these are improved versions of the basic holley carb, though a bit more expensive since tehy have more development work done on them.

7991LXnSHO · Apr 8, 2015

As far as jetting vs. cfm, the whole truth is more complicated than anyone wants to type with one or two fingers on the phone. But both are part of the full answer. My answer was just enough to get it to run, @rbohm wants it to run right. I do not see the work being worth the effort.

rbohm · Apr 8, 2015

7991LXnSHO said:
As far as jetting vs. cfm, the whole truth is more complicated than anyone wants to type with one or two fingers on the phone. But both are part of the full answer. My answer was just enough to get it to run, @rbohm wants it to run right. I do not see the work being worth the effort.

just getting an engine to run really isnt enough. anyone can do that. the real artistry is getting to run right. where you have good power, solid reliability and the best efficiency you can drag out of the motor. for instance back when i first started driving, i got to use the family station wagon. it had the 429 two barrel engine. from the factory it got about 9mpg, but with some creative tuning, i managed to drag both more performance, AND 12 mpg from that car.

johnejo · Apr 8, 2015

Wow! Thanks for all the great input! I greatly appreciate it! I'm just now getting into car restorations with Mustangs my focus, and this is going to help me avoid some headaches in the future I'm sure.

Thanks again!!

rbohm · Apr 8, 2015

johnejo said:
Wow! Thanks for all the great input! I greatly appreciate it! I'm just now getting into car restorations with Mustangs my focus, and this is going to help me avoid some headaches in the future I'm sure.

Thanks again!!

one thing to remember is that from the manufacturer, all these cards are jetted a bit rich, up to about 15% depending on who builds the carb. this is done for two reasons, one is safety for a new motor, the other is because the manufacturer does not know what mods you have made to the engine(goes back to the safety thing).

so you are going to want to learn to read your plugs and listen and feel what your motor wants as you tune it. the better feel your get from your motor, the better you can tune it and give it what it wants.

johnejo · Apr 8, 2015

rbohm said:
one thing to remember is that from the manufacturer, all these cards are jetted a bit rich, up to about 15% depending on who builds the carb. this is done for two reasons, one is safety for a new motor, the other is because the manufacturer does not know what mods you have made to the engine(goes back to the safety thing).

so you are going to want to learn to read your plugs and listen and feel what your motor wants as you tune it. the better feel your get from your motor, the better you can tune it and give it what it wants.

Oh, good to know. Thank you!

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