# A bigger Carter 4bl. carb



## extinctmake (Feb 8, 2011)

Okay, I have a '65 GTO convertible with a WT code 389 with a four speed transmission, stock 067 cam, 10.75:1 CR, 3.23 axle, and the correct Carter #3895S AFB. The distributor is curved to full advance at 3,000 rpm and I have poly locks on the rocker arm nuts.

It is a 500 cfb carb and while I wait to rebuild my numbers-matching engine (discussed a year or two back with Bear and some other GTO forum friends) I would like to get a little more out of current engine.

I was thinking about an Edelbrock 600 cfm AFB-like carb, but I have been led to believe that this carburetor is not compatible with the OEM pancake air cleaner on my car. 

I want to retain my OEM intake manifold and air cleaner. 

I have some ideas. I have another 500 cfm GTO AFB. I think it is another 3895S model, but the tag is missing. Can this carburetor be modified to flow another 50-100 cfm with different clusters, jets, and metering rods? Or how workable is a 625 cfm Competition series AFB with my stock intake, etc.? 

The worst thing that can happen is I just keep my car as is. This is not a change I just have to make. If it just involves switching carburetors, I would have some fun tinkering to see if my car performs any better, or worse.

Thanks for your input.


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## rickm (Feb 8, 2012)

you cant do too much to that afb for performance. Im pretty sure that edelbrock has the fuel inlet on the wrong side of carb and is designed for rubber hose fuel line. don't know about accepting stock air cleaner.


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## tiger13 (May 4, 2012)

In order for any carburetor to flow more air, you must make the throat larger, just changing jets, or metering rods etc will allow it to have more fuel , but do nothing to allow more CFM, or Cubic Feet of Air. For that you must physically alter the size of the carb throat, or throttle plate. And to just go at it with a dremel tool usually results in poor results unless you have a flow bench and experience.


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## geeteeohguy (Feb 2, 2008)

First off, beautiful car. Nightwatch Blue is one of my favorite '65 colors. Secondly, congrats on not making it yet another tripower clone. That said, a tripower is one of the easiest performance mods with the biggest bang for the buck. The cheapest and probably the best route would be to source a '68-'72 intake and Q-jet and just bolt it on. You can use the '67 base and your current air cleaner upper section. Only Pontiac Purists will know that you have the 'wrong' 4bbl on the car. Your performance will improve measurably. Edelbrock carbs aren't the best choice for these engines.


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## extinctmake (Feb 8, 2011)

Tiger13, you are absolutely right and I should have thought of that right off the bat. I wouldn't take a Dremel tool to my correct AFB anyway.

Thanks for the compliment geeteeohguy. I intended to have my car remain a four barrel car as original when I restored the car back when I started in its once basket-case form.

So nobody knows whether one of those Competition series 625 CFM AFBs would work? Another thought is a Holley. I think I was told a Holley shares the same flange as an AFB. Does anybody have any experience with a Holley in the configuration I am contemplating?

I agree with you geeteohguy about a Quadrajet. Lots of cfms and excellent driveability and economy when running on the primary side of that carb. I just don't want to change my intake manifold. I'm trying to use a larger carb while using my existing intake and aircleaner.

I think if I went ahead and changed manifolds, I'd break the bank and get a Tri-Power set up. I was hoping to find a larger AFB that would allow me to use my existing intake manifold, linkage, fuel line, air cleaner etc. 

Maybe it isn't possible.


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## Jared (Apr 19, 2013)

I have the 600CFM edlebrock on my 400 with what appears to be the stock air cleaner (not completely sure as this was all on the car when I got it). I do not have the stock manifold, mine has an old Holly street dominator painted blue to match the factory engine color. The above comments are correct, you need a rubber fuel line with the edlebrock and it may not be the best choice. Occasionally mine seems to run out of fuel (seems to drain the carb faster than the carb can replenish). 

I put an Edlebrock carb on an 84 Camaro that originally had a quadrajet carb and the stock air cleaner fit. I'm not sure on the Pontiac manifolds, but to use an Edlebrock carb on a Chevy, you need to use an adaptor plate because the holes in the intake do not line up with the ones on the carb, also the intake holes are smaller. Due to hood clearance, I used a performer intake as it was the easiest alternative.

Hope this helps


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## geeteeohguy (Feb 2, 2008)

I have run a Holley 4bbl on the early '65 and '66 4 bbl intakes with good results. A lot more power, and very dependable. Not as good on fuel economy as the Carter AFB and certainly, not as economical as the Q-jet. I'd run a Holley over an Edelbrock any day. A Holley in the 750 cfm range would do well, and bolt right on. Air cleaner fitment with your pancake filter, not certain.


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## extinctmake (Feb 8, 2011)

Yeah I used an Edelbrock 600 cfm carb on the 350 in my old Nova and it worked well. I figured the fuel line configuration might be an issue on a Pontiac. 

So a Holley will flange up to an AFB intake geeteeohguy? As for mileage, I agree that the AFB is pretty good. Maybe it is because it is a smaller cfm carb too. So what do you think of a 650 double-pumper on a WT-code 389? You say go to 750 cfm? I guess that would be close to what the Tri Power flowed. 

I guess I have some direction with this topic. Thanks. By the way, did your existing linkage for the AFB work with the Holley, or was there some parts/labor involved with retrofitting the Holley to the AFB linkage?


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## geeteeohguy (Feb 2, 2008)

Extinct, this was in 1992, so I can't give you too much detail. I know it bolted onto the carter intake with maybe an adaptor plate, very simple, and that the cable worked just fine with no mods. It was an hour to do, tops. A 650 is on the small side for a 389, IMO. Better off in the 700-750 range. A tripower is rated differently, but flows roughly equivalent to 1000-1100 cfm. I've run them back to back on the same vehicle with a Q-jet, and the tripower trumps the Q-jet easily when it comes to power.


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## extinctmake (Feb 8, 2011)

A Tri Power flows 1000 to 1100 cfm? I wasn't aware it was that much. I always thought it was 750 cfm with each 2bl. carb flowing 250 cfm. 
That's quite a difference and now I can see why it was a popular set up besides the looks and increase in value of a GTO when equipped with it.
I might have to think it over about spending the big bucks to put a Tri Power on my '65.


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## Jared (Apr 19, 2013)

A few years ago the guy on the show Gearz did a Chevy tri power build. He bought a new intake and he rebuilt used carbs. Unfortunately, I don't think anyone makes a tri power manifold for a Pontiac (if they do, I couldn't find one) so you would need to find an old one but you could probably save a bit of money if you're willing to rebuild used carbs yourself. I looked up the rebuild kit from the program and it is available: 

Rochester Tri-Power Base Kit with Linkage - Speedway Motors, America's Oldest Speed Shop

Also, in case you're interested, here are links to the two sections of the show on youtube:


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## geeteeohguy (Feb 2, 2008)

It's been discussed here before, tripower vs Qjet. I've run both on my stock '67 GTO ragtop. The '66 tripower unit I have used changes the personality of the car. It feels like at least 50hp over the 4bbl. Easily. All else being equal, a stock tripower will stomp all over a single stock 4bbl on one of these cars. Someone awhile back posted a reprint of an old car magazine article where a GTO was run back to back with Qjet and tripower....in every case, it ran a full 1/2 second quicker in the 1/4 mile with the tripower, no other changes made. That's a whole bunch.


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## BearGFR (Aug 25, 2008)

FYI, thepartsplaceinc.com (and probably others) carries complete reproduction tripower systems as well as bare manifolds in both iron and aluminum. I've heard that the rough castings need quite a bit of cleanup and port matching before put into service, but at least they're out there.

Bear


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## extinctmake (Feb 8, 2011)

Yeah reproduction Tri Power intake manifolds are available. I found one in an Original Parts Group (OPGI) catalogue for $378 in either cast iron or aluminum. 

I've seen carburetors and even complete, ready-to bolt on Tri Powers (very expensive) offered in several Pontiac reproduction parts catalogues. 

There is no doubt the Tri Powers by far out performed the compariable four barrel cars. I was just hoping to find a larger Carter AFB that would work with my stock intake manifold, linkage, fuel line, air cleaner etc. I was thinking if I went from the stock 500 cfm AFB to a 600-odd cfm AFB, it would liven my 389 a little without having to do more than change carburetors. I guess that is not an option.

A quadrajet set up or biting the bullet and switching to a Tri Power appears to be the best path for higher performance for my GTO.

Thanks again everybody for your input.


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## geeteeohguy (Feb 2, 2008)

Extinctmake, consider this: if you bite the bullet and buy a tripower, it will not devalue the car as long as you keep the original set up. It will add to the value of the car. Also, if you get tired of it, you can sell it for the same as you paid or for more. The last tripower set up I bought was in 1979, and I paid $100-$120 for it, can't remember now which. Still have it on a bench and use it from time to time on my '67. Now it's worth ten times what I paid for it. My point is, Tripowers are like antique Winchester rifles: they never go DOWN in value. So, don't let the $1200-$1800 price scare you off. Check out Mike's Tripowers and similar sites. Q-jets are excellent and a thrifty way to go, but to me just look wrong on a 389 in an early goat.


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