Holley Carburetor Identification help needed

[Gerald C.]

I have this carburetor with #4781-5 with a 2146 code below. Can anyone help me ID this carburetor?

Thanks

Jerry

[Joe L.]

Re: Holly Carburetor Identification help needed

I have this carburetor with #4781-5 with a 2146 code below. Can anyone help me ID this carburetor?

Thanks

Jerry

Jerry-------


Holley 4781 is an aftermarket-only carburetor. It was never used for any original application and, certainly, no Corvette application. It is an 850 CFM, model 4150 carburetor with dual fuel inlets. It is a mechanical secondary carburetor with a manual choke. Personally, I would not recommend this carburetor for street operation.

[Gerald C.]

Re: Holly Carburetor Identification help needed

Thanks Joe! Much appreciated. I have a 396 two bolt main with a standard bore of 4" + or-. the casting # is 3855961. It looks like a 396/325 engine. If I want to keep it as stated, what Holly carburetor would you recommend and can I use it in an intake # 3866948?

Thanks for your help

Jerry

[Joe L.]

Re: Holly Carburetor Identification help needed

Thanks Joe! Much appreciated. I have a 396 two bolt main with a standard bore of 4" + or-. the casting # is 3855961. It looks like a 396/325 engine. If I want to keep it as stated, what Holly carburetor would you recommend and can I use it in an intake # 3866948?

Thanks for your help

Jerry

Jerry------


Yes, you can definitely use intake manifold casting #3866948. This assumes, though, that you have oval port heads (whether of original casting number or not).

Unless the engine has been built up into some very high performance internal configuration, I would recommend going with Holley R-3139, R-3370, or R-3811. The latter two can be purchased NEW in reproduction. They're expensive but nothing makes a car run like a NEW carburetor-----NOTHING!

[Gerald C.]

Re: Holly Carburetor Identification help needed

Thanks for the advice Joe. It is a standard bore 396 with nothing else done to it. I'm not going to enhance anything other than to build it as stock.

Jerry

[Joe L.]

Re: Holly Carburetor Identification help needed

Thanks for the advice Joe. It is a standard bore 396 with nothing else done to it. I'm not going to enhance anything other than to build it as stock.

Jerry

Jerry------


The carbs I suggested will work fine for your application. The most important attribute they'll provide is that you'll require a minimum, if any, mods to make the installation. As often occurs with aftermarket items, there ends up being a "cascade" of installation problems requiring mods. The carbs I mentioned, as OEM, should be "plug-and-play".

[Gerald C.]

Re: Holly Carburetor Identification help needed

Joe,

Thanks again! I'll go searching for the intake and the carburetors you suggest. I assume they're all pretty equal as to performance.

Jerry

[Gerald C.]

Re: Holly Carburetor Identification help needed

Joe,

One other thing. I think I'm going to use exhaust manifolds # 3856301 and 3856302 on this motor, so everything should go together pretty well.

Jerry

[Joe L.]

Re: Holly Carburetor Identification help needed

Joe,

Thanks again! I'll go searching for the intake and the carburetors you suggest. I assume they're all pretty equal as to performance.

Jerry

Jerry------


Yes, they are all essentially equal in performance. As far as the manifold goes, you're pretty much stuck with using the cast iron casting you mentioned if you want to use an original GM manifold. The only aluminum, oval port ,manifolds ever offered by GM were the 1968-69 Corvette L-36 manifolds but these have a spread-bore (Q-Jet) carburetor flange.

[Joe L.]

Re: Holly Carburetor Identification help needed

Joe,

One other thing. I think I'm going to use exhaust manifolds # 3856301 and 3856302 on this motor, so everything should go together pretty well.

Jerry

Jerry-----


These will work fine. The only thing is that the 3856302 has provisions for a hot air choke tube. You won't use this as the 3866948 and the carburetors I suggested are designed for a divorced style choke.

[Gerald C.]

Re: Holly Carburetor Identification help needed

Joe,

I'm looking for these carburetors I can't find the numbers you mention on the Holly website, Summit Racing or the internet in general. Is there a crocss reference number I should be looking for.

Jerry

[Leif A.]

Re: Holly Carburetor Identification help needed

Gerald,

Try these folks. This is the 3370. I bought my Holley from them.

http://specialtypartsdirect.com/HOLLEY-CarbC2-Corvette1966427390HP_p_48.html

[Joe L.]

Re: Holly Carburetor Identification help needed

Joe,

I'm looking for these carburetors I can't find the numbers you mention on the Holly website, Summit Racing or the internet in general. Is there a crocss reference number I should be looking for.

Jerry

Jerry------


No cross reference. You can find these carbs under these numbers used/rebuilt on eBay. The NEW carbs are available from Specialty Parts as Leif indicated.

[Gerald C.]

Re: Holly Carburetor Identification help needed

Joe,

Did the Holly company go from putting letters for the month of build to numbers begin in 1967? My 3906631 List 3810 is dated 6B1 which tells me it was bulit the first week of February 1966. However, my 67 was built on 2/9/67 and I see one on EBay dated 721 which seems to mean the first week of February 1967. Am I correct in my assumption going from letters to numbers in 1967?

Thanks,

Jerry

[Joe L.]

Re: Holly Carburetor Identification help needed

Joe,

Did the Holly company go from putting letters for the month of build to numbers begin in 1967? My 3906631 List 3810 is dated 6B1 which tells me it was bulit the first week of February 1966. However, my 67 was built on 2/9/67 and I see one on EBay dated 721 which seems to mean the first week of February 1967. Am I correct in my assumption going from letters to numbers in 1967?

Thanks,

Jerry

Jerry------


No, the dating system was the same from 1963-72. The first digit represents the year of manufacture. The second digit represents the month. It's 1 through 0 for January through October. Then, A for November and B for December. The last digit is the week of the month. So, your 3810 is December, 1966, first week. The eBay carb would be February, 1967, first week.

Holley carbs with 4 digit, partial julian date codes were in use from 1973+. Of course, there were no Corvettes that used a Holley carb after 1972. However, SERVICE carbs for earlier applications manufactured from 1973+ would used the 4 digit date codes.