Holley Replacement, '66 300hp Powerglide

[Ron Miller]

I've messed with this darned Holley long enough, between the inferior quality replacement choke coils and the leaking bowls. When it's right, it runs fine, but it's frequently wrong more often than right. Conversely, I haven't had to do a thing to the Carter AFB on my '65 in the past 20 years. I'm considering a replacement Edelbrock, manufactured similarly to the Carter AFB on my '65 300 hp 4-speed.

Does anybody know if Edelbrock makes a direct bolt-on replacement that will allow use of my existing throttle and transmission linkage, manifold, and breather? I know I'll have to abandon the manifold heated choke and go to electric, but no big loss to me at this point.

Any thoughts on this conversion, or suggestions regarding this or other carburetors?

 

[JohnZ]

There are few things simpler than a Holley, although after 40 years they usually need some help; this is aggravated by the "hot-slot" design of the 783 intake, which puts hot exhaust crossover gases directly under the baseplate - this can warp the baseplate AND the main body, which causes metering block and/or bowl leaks. This "hot-slot" design was abandoned by GM in 1970, after the biggest carburetor (fire) recall in history on cars with this feature and Q-Jets.

The cure is to plug the two passages in the carb mounting pad that feed the hot gases (7/16" cup plugs work well - see pic), and have the carb rebuilt by a professional who will mill the main body seal surfaces flat so the gaskets will seal. I've had countless Holleys over the years, and have never had one leak.

The current Holley "Universal" 1850 is a direct bolt-on replacement with an electric choke (about $230 at Jeg's) if you want a brand-new carburetor, or you can have a pro rebuild/restore your original 3367 for about the same price.

 

[Ron Miller]

JohnZ, I appreciate the information and the comments. I've read in an earlier post about the "hot slot", but haven't plugged the one on my manifold yet. I concur that few carburetors are simpler than a Holley, but I believe that one of the few that is simpler is the Carter AFB. Also, in my opinion, a better design with no place to leak fuel, since the bottom is a one-piece casting.

This isn't a 40 year old carburetor I'm dealing with, it's more like 8-10 years old with very few miles on it, a new reproduction of the original Holley. And, as I've said, when it's right, it's OK. But, I've had my problems keeping it right, thus, the interest in going to something that for me at least has proven to be more trouble free.

Another question, I don't see in the manuals where a heat insulator is used on the original Holley between the manifold and the carb, did I miss something here?

I'm gonna give it one more chance, plug the "hot slot", go back thru the carb again to get it "right", then the next time . . . . .

Thanks, John, for the info. Appreciate it much!!

Ron

 

[JohnZ]

Another question, I don't see in the manuals where a heat insulator is used on the original Holley between the manifold and the carb, did I miss something here? Ron

A stainless steel heat baffle plate was used on all Holley applications on intakes that had the "hot-slot" feature; the conventional gasket went on the intake first, then the stainless baffle, then the carb. Omitting the stainless baffle is an early death sentence for the carb. No phenolic insulator was used.

 

[Ron Miller]

A stainless steel heat baffle plate was used on all Holley applications on intakes that had the "hot-slot" feature; the conventional gasket went on the intake first, then the stainless baffle, then the carb. Omitting the stainless baffle is an early death sentence for the carb. No phenolic insulator was used.

Thanks John, that's the way mine was installed.