'66 Holley Carb Question

[Mark W.]

I have a '66, 327/350 hp with the original intake and holley carb, which is a pain in the neck to keep running well. Since I use my car as a weekend driver, I'm more interested in reliability and perhaps a little better performance. I'm looking for suggestions for a replacement carb ( new holley?) that will bolt right on the original intake. Also, should I go with an electric choke and is it difficult to make the switch or just a matter of running a wire?

[Joe L.]

Re: '66 Holley Carb Question

Mark-----

A new Holley replacement carb might overcome some of the problems which your older carb suffers from. However, it won't solve the basic problems which ALL Holley carbs inherently suffer from. So, while there may be some marginal improvement, I don't think that they'll be any quantum improvement in ease-of-operation. Also, I don't think that the electric choke will, by itself, give you any better choke operation than the divorced-style choke used for your application on the original carb. However, installing a carb with an electric choke is simply a matter of adding the wire.

A considerable departure from originality but a change that will give you a better running carb would be to change the manifold and carb to a Q-Jet. A Q-Jet will provide an 800-850 CFM carb that will have near-perfect "street manners". I've got about 200,000 miles of personal experience with Holley carbs and about 200,000 miles personal experience with Q-Jets. The Q-Jet is, by far, the better street carb. GM invested megabucks in the design and development of the Q-Jet; far more than was ever invested by Holley in their carbs. GM-Rochester got it right. These carbs have a few weaknesses, but the weaknesses can be field-modified out of the carburetor. The Holley weaknesses you're pretty much stuck with if you use a Holley.

There is NOTHING that I dread more about my "ZL-1" project than having to live with a Holley carb again. Absolutely NOTHING!

[jordan grant]

Re: '66 Holley Carb Question

I happen to have the setup that you are headed for,and am in the process of converting back to the original Holley carb/non electric choke setup because "it" was difficult to keep running well for extended periods of time.I believe(and anybody can chime in here!)the Holley carb is in general a high maintenence item in that it needs constant "fettle".

Anybody got any tips for the user friendly "driver"setup?.

[G B.]

Pay your dues

Old Holley carbs are a high maintenance item. If you use your car regularly and crave reliability, you ought to just buy a new one.

The List #3367 Holley for a '66 small block is still available new for about $420 from Jeg's and Summit. A new one will run right for several years. Just consider the money to be dues paid to the Holley Fan Club.

[jordan grant]

Re: Pay your dues

Is there a more user friendly carb that will fit on the stock 3890490 intake?And what exactly is it that makes the Holley so temperamental?I know there is only one filter at the carb,wouldnt it help to add a filter somewhere else in the fuel system?

The thread from Jerry says the car will run right for a couple of years.how many miles of use is two years?.

It sounds like,if youre not going to have your car judged.loose the Holley!! Yes?.

[Patrick H.]

Re: '66 Holley Carb Question

I know it deviates from the norm, but I'd consider one of the newer Demon carbs for your motor. Sure, it won't have a GM-assigned part number, but I think it may help your "issues" somewhat.

I've often thought of installing an LT-1 intake on the 71. If I ever do, it won't have a Holley, but a Demon. Maybe that's some "Summit Racing" influence. Who knows.

Patrick

[Verle R.]

Re: '66 Holley Carb Question

Joe,

You could consider one of the throttle body fuel injection.

I helped build a ZL1 engine about ten years ago that was installed in a 65 Corvette. We used a Holley TB and it worked very well.

Verle

[G B.]

Holley replacements

I know of only two carburetor designs available new that will bolt up to your intake. One is the modern Edelbrock version of the AFB. This is a very reliable carburetor, but it has an electric choke that interferes with a stock Corvette air cleaner base.

The other design that will bolt up directly is the Barry Grant Demon series. I haven't tried one of these myself.

Holley made two big mistakes in the original design of the 4150 and 4160 series 4-barrels. There are several vertical and horizontal seals that pass vent air, vacuum signals, and gasoline. Holley also made most carburetor castings from a material much like pot metal. This relatively soft body/block metal always warps over time. This warpage causes the critical vertical (and baseplate-to-body horizontal) seals to start leaking.

[jordan grant]

Re: '66 Holley Carb Question

I have a totally rebuilt correct Holley carb for my 66.and have too much dough in it to not use it!.Can anyone tell me specifically where to periodically adjust this carb for optimum reliability?.If they are prone to warping due to the type of metal used to make them,shouldnt there be screws that should be checked on a regular basis other than the normal fuel/air settings(or do they "all"need to be checked periodically??)

I'll give the Holley a season under the hood, and try to live with it.Any help is appreciated.

[Clem Z.]

most all holley problems on older carbs

can be cured with careful machining if you want to keep the orignal carb. a new holley will work fine as a direct replacement. one of the big problems with holleys is caused by owners over tightening the bowl screws causing the bowls,metering bodies and the main body to warp,when they see a leak rather than installing new gaskets. the same thing happens with Qjets carbs when the owners over tighten the top screws and the front carb to manifold bolts and distort the top cover.

[John Walker]

Re: most all holley problems on older carbs

Clem; I had a street Demon on my wife's 454 powered 73 coupe, I could not get the carb to operate properly! I had a 15 year old 3310 that I put a kit in and now the car starts beutifully and runs very well. The problem is this, fuel pours out of the rear vent tube, I have changed the needle/seat assembly and checked the float all to no avail, with the rear float bowl fuel line blocked off the engine performs flawlessly, I don't know what else to do.

Thanks in advance John

[Clem Z.]

Re: most all holley problems on older carbs

the way i check for problems like this,i remove the float bowl,invert it so the float is putting pressure on the needle/seat and apply about 6/8 PSI air pressure to the fuel inlet and use soap solution to check for internal leaks.

[Paul L.]

Does Anyone Say OK for Holleys?

I have not had a problem with a 4160/3810.

[Wayne W.]

Re: Does Anyone Say OK for Holleys?

Paul, Holleys are OK. No matter what anyone says, Q-Jets have their share of problems too. Some people just dont know how to fix Holleys so that they are dependable. I personally like the Holley better than the Q-Jet for early Corvette applications.

[Jim T.]

Re: Does Anyone Say OK for Holleys?

Wayne I think Holleys are okay. I have been using Holleys on the 68 and 70 Corvettes since about 1974. Bought two new spreadbore Holley 6210 650 douple pumpers to replace leaking or its going to leak Q-Jet.
Not driving my cars often enough I use a syringe to inject gas into the fuel bowls through the vertical vent tube to keep gas in the fuel bowls while they are not being used and again before driving. The cars start very quick after non use because the fuel is available. Keeping fuel in the Holleys is probably a benefit for the gaskets.
I learned a long time ago about how to test the Holley for a bad power valve real quick and had changed several through the years. When I put a ZZ1 crate engine in my 70 I bought a new square bore Holley 650 double pumper.