Is there a new replacement carburetor for the AFB that fits a 327 engine on a 63 car. Not a Edelbrock but some other make. I would like to use the original air cleaner and can adapt to the fuel location.
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Re: New replacement carburetor for 63 300 HP
Chester;
Of course you know that there are a lot of physically exact replacements out there in the form of the 3720/21 series AFB's. I bought a new one, I believe, in 1989 (a 3721SB). They traditionally can be bought used or rebuilt for about half of the cost for a 3460/61S used originally on a 1963. There are, of course, differences in the jetting (particularly those in the primary clusters which are hard to change), but I used the 3721SB on my L-76 (340hp) both stock and with slight jetting changes for many years.
I don't blame you for wanting to pass on the use of an Edelbrock carb on your 63. I bent over backwards to avoid this same situation and waited about 15 years to find a correctly dated 3461S for my car. And then, it took me a whole year to sort it out and correct all the mistakes that previous owners and rebuilders did to it. That carb is very unique and has a number of small features that neither the Edelbrocks or the 3720/21 series have. Finding one was well worth the wait. It is the best performer of the bunch.
Stu Fox -
Re: New replacement carburetor for 63 300 HP
Buying a rebuilt or used is just buying more problems. That's why I would like to purchase a new carb that will work. Hard to believe there are none available.Comment
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Re: New replacement carburetor for 63 300 HP
The air horns of a new Edelbrock Performer and an old Carter AFB will interchange. Just swap the tops of the two carbs. I've done this, and it works fine. By using a 62-65 Carter AFB air horn in your car, everything bolts right up - air cleaner, fuel line, etc. By using a new Edelbrock Performer base, you have the benefit of a new carb. When I did mine, I used the metering rods, floats, accelerator pump, and other parts that came with the Performer. The only old part I used was the air horn itself. For the base, I used the Edelbrock Performer 1406, which gave me an electric choke.Comment
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Re: New replacement carburetor for 63 300 HP
Didn't you find that the accelerator pump on the 1406 was of a larger diameter? That has been my experience. Then there is the pump stroke and squirter. How did you rectify those differences? There are a number of differences in the jetting of the Venturi clusters (fuel and air) as well, but perhaps it wouldn't matter much on an L- 75 engine. How about the linkages (choke, fast idle and accelerator pump)? All compatible? Then there is the venting and variances in top plate gaskets. How did they work out for you?
Sounds like an interesting approach. I'd like to learn more.
Stu FoxComment
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Re: New replacement carburetor for 63 300 HP
Yes, if you buy a worn out carb somebody has just thrown a kit in and cleaned up it may still have problems. A properly restored carb should work as new. I have 5 restored carbs; the restored dual quads and single carb currently on my '61 and '63 run flawlessly. Now, the air horn swap is interesting and I've never heard of that before. Just be advised swapping an old Carter air horn on to a new body will require some inspection. Older air horns get worn at the guide lugs where the accelerator pump shaft goes up and down in the air horn and can cause sticky operation and inconsistent idle.Comment
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Re: New replacement carburetor for 63 300 HP
Having been a journeyman working in the trade in the 70's 80's when there was nothing but carbs I can tell yo that there is 0 advantage to a new carb over a properly rebuilt one. There are relatively few moving parts that wear out, and those that do (throttle shafts) are rebushed to give them an as new or better fit. The rest is castings. What wears out on them? Back in the day the only time you ever saw a "new" carb was when someone went out a bought a Holley to put on their Torker or Tarantula (remember those) manifolds. Otherwise, everything was rebuilt.
More often than not what was blamed on a poor carb rebuild was in fact a problem external to the carb that the carb was being blamed for. Poor diagnosis was/is the biggest problem.
I think that the heat soak tends to be one of those things that gets blamed for problems that can not otherwise be explained by the technician/diagnostician. With the exception perhaps of ethanol, fuels have not changed enough in their volatility to cause this rash of "heat soak" problems. I can say with great certainty that heat soak was not an issue on these cars back in the day. I had a 63 340 all stock with a fuel system that worked perfectly. No hot start issues, cold engine driveability issues (what I hear referred to today as being cold blooded).
But what has changed is the number of technicians familiar enough with carburated fuel systems to be able to properly diagnose and repair the problems. Given that back in the day probably 7 out of 10 mechanics couldn't do it properly then, it's not surprising that so few can do it today.
I have a friend that restored an early 70's Chev pu. He's like most here, not a mechanic but did what he was able to and subbed out the rest. When I asked how his resto turned out he remarked that all was good except this hot start problem. He had had it back to the shop that rebuilt the carb several times and they had not been able to rectify the problem. I know the shop. Back in the day they were THE carb shop. That was all they did, specificqlly a carb shop with drive in bay facilities. So trying to helped I asked if they had checked that the heat riser valve was working properly and the intake cross over clear. He told me he hadn't put a heat riser in it, wanting to reduce exhaust restriction. Well of course he would have hot start problems. The choke was never coming off completely, Installed a heat riser and it worked like a new truck. The point is the generation now working in that carb shop know nothing about heat risers and their purpose and obviously don't have a good understanding of the theory of operation of the complete system. Heat risers haven't been used for 30 years.
Long post, I know, but with the number of threads I read about wired back heat risers, electric choke conversions, and heat soak, it appears to be something poorly understood.
SteveComment
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Re: New replacement carburetor for 63 300 HP
Its easy enough to measure -- get one of those Harbor Freight I/R temp guns and take a reading at the carb bowl after a long hot run...anything 140* or higher is bordering on percolation.Comment
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Re: New replacement carburetor for 63 300 HP
Normally it doesn't of course. If you look at the picture above you can see that the shaft of the pump can get cocked between the guide lugs and not always return to the full rest position...Comment
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Re: New replacement carburetor for 63 300 HP
I believe we old guys from back in the day have all dealt with hot soak conditions, specially those of us who did week end racing at the strip in the heat of the summer. Today, however, the situation is exasberated by the ethanol laced gas and the problem rears it's ugly head when the wife complains about the gas stink in the attached garage. I've managed probably as best that can be done.
Stu FoxComment
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Re: New replacement carburetor for 63 300 HP
Steve------
I've had the opposite experience. I have NEVER, EVER purchased a commercially rebuilt carburetor that ran as well as a new carburetor. I have had good experience when I've rebuilt a carburetor from my own core but NEVER with a commercially rebuilt carburetor.
I believe the problem stems from the fact that many of the cores used for commercially rebuilt carburetors have serious deficiencies. Yes, there are few moving parts in a carburetor. However, cores can be damaged from abuse (e.g. some klutz running the idle mixture screws in with gusto and damaging the seats) or deterioration, especially from the scavengers used in leaded gas (most of the carbs of interest here ran for years on leaded gas). Another problem relates to air horn, float bowl, or throttle body warpage due to excessive heat, especially that resulting from the intake manifold heat slot used on some pre-1969 applications. None of these problems can be easily seen.
Another problem could be just sheer incompetence or carelessness in the rebuilding process. High volume, rebuilding "sweatshops" in some foreign country doesn't bode well for a quality job.
The best rebuilt carburetor I ever had was a Q-Jet rebuilt by Holley carburetor and it only ran OK, not at all like a new carburetor. For me, nothing runs like a NEW carburetor. NOTHING!In Appreciation of John HinckleyComment
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Re: New replacement carburetor for 63 300 HP
If you experienced heat soak back in the day, you had a mis adjusted/poorly rebuilt carb. I was there too. I worked on this stuff every day. And I currently have numerous carbed cars and none suffer from the issue with today's fuels. I drove my 64 300 slushbox to Bloomington in 1979 then did some touring from there. Temps were 110 in the shade. No evidence of heat soak. My buddy was with me in his 66 425 and he had no such problems in spite of having difficulty keeping eng temp under 210.
Heat soak does not cause carbs to drip. Period. If the fuel expands in the line enough to open the needle and allow fuel into the bowl, how much will that be? 10% of the volume in the line? If that's enough to raise the bowl level to be above the highest point the fuel travels to spill into the throat, then the fuel level in the bowl is already way too high. Today's fuels don't expand by volume anymore than those of yesteryear and that was never an identified issue in the field or the dealerships.
Heat soak and hard hot starting was a problem with the fuel vaporizing in the bowl and that vapor venting into the throat causing a rich idle and a hard hot start. Long before 1963 carbs were equipped with hot idle compensators. The fuel bowl has an additional vent hole that is covered by a plug. It has a bi-metallic spring and is also connected to the throttle by a mechanical linkage. With the throttle off idle the external vent is always closed. In the idle position the valve is normally closed but the bimetalic spring (more like a lever) will open the vent if the temp is above the preset. So if underhood temps are high enough at idle or shut-off the fuel vapor vents to atmosphere and not into the throat. Took care of the problem experienced in the older vehicles.
I suspect if you have confirmed heat soak issues your hot idle compensater may not be properly adjusted. However, if you had hard hot start issues that were not confirmed to be fuel vapour out the bowl vent I would look at an incorrectly adjusted choke, a non op or stuck heat riser valve or a plugged exhaust crossover in the intake.
I can't see how you can possibly keep fuel temp below 140. On a 100 degree day the fuel entering the pump is already 100 degrees. The air pouring through the rad is at least 180 degrees. Add that to the 1000 degree exhaust temps the manifolds deal with. Where does that put your underhood temps? And the design of the manifold routes exhaust gas under the base of the carb, heating the whole thing up. On the old Rochecster 2GC's there was actually an exhaust passage in the base plate of the carb. Hot exhaust circulating right through the base, immediately below the fuel bowl. Now picture the rate of fuel flow through the carb. A bowlful lasts a long time and as such the fuel in the line and the pump gets plenty of time to heat up. The engineers anticipated all these things and they did not leave the factory with these flaws.
And why is it that some cars experience this "heat soak" and the rest don't?
Those are the reasons I believe "heat soak" is a misdiagnosis.
SteveComment
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Re: New replacement carburetor for 63 300 HP
Our experiences are actually very similar. The commercially rebuilt carbs were of poor and inconsistent quality. That's why I always did them in-house. It's not a matter of the quality of the cores as much as a matter of the quality of the rebuilder.
Not that many years ago when I was restoring my 442 I sent the Q-jet to Autoline, a major rebuilder that's been around since I worked in the trade. I did so because it was cheaper to have them replate it as part of their custom rebuild program than to find a plater to refinish the body correctly. The carb came back looking great. They really have the dichromate thing down right. But otherwise, the quality was as poor as it was back in the day when I worked in the trade. I had to go through it completely to correct all the adjustment.
SteveComment
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Re: New replacement carburetor for 63 300 HP
Accelerator pump diameter: I probably used the old Carter AFB accelerator pump plunger because it was already in place. I don't remember any differences in diameters. But if there were, you can buy accelerator pump plungers in the aftermarket. At some point when I was running this carb, I installed a Carter marine accelerator pump. The marine accelerator pump has a rubber or Viton skirt rather than the leather usually found on the automotive ones. See http://www.carburetor-parts.com/Cart...mps_c_578.html
Pump stroke, squirter: See above. I probably used whatever plunger that fit. The lever on the Edelbrock has holes in different places to adjust the stroke. I believe you can adjust the stroke on the Carter by bending the "S" linkage.
Jetting: I used whatever was already in the Edelbrock. I didn't change them. I believe I used the Edelbrock metering rods too.
Linkages: I believe all the linkages matched up with the possible exception of the old choke. But I switched to the electric choke from the Edelbrock 1406, and used that linkage.
Gaskets: I don't remember any differences in the gaskets. The only gasket I used was the air horn gasket.Comment
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