Are Holley base plates stamped with PN#'s?

[Dan Pepper]

I'm trying to find a correct replacement for a 4555 Holley (date correct '70 LT1 application). Is there any way to cross-reference to find if other carbs used this identical base?

[Joe L.]

Re: Are Holley base plates stamped with PN#'s?

Dan------

The base for the Holley list 4555 carb was known as GM #3979534, although that number appears nowhere on the part. As far as I can tell, no other Holley carb used this exact same base. That's not to say that other carbs might have used VERY similar bases. But, none used this exact same base.

[Mark #28455]

many share the same casting

Holley was very good about only having a few castings that were machined to different specs. Things to look at when buying a baseplate from a donor carb:

Throttle bore size
Throttle linkage
PCV tube and location
ported and manifold vacuum tubes

Typically, you'll have the best luck using a Holley donor that came from a different Chevrolet car of similar vintage (ie: Camaro, Chevelle, Impala). Unfortunately, all those are bringing more $$$ since the whole collector car market has taken off. You can still get lucky on e-bay. As far as I know, most of the carbs used the same throttle bore sizes except the L88 3418, 4054, 4296 carbs.

Good luck,
Mark

[Gerard F.]

Re: Are Holley base plates stamped with PN#'s?

Dan,

Are you sure you are looking for a 4555? The Holley parts book lists this carb for a 70 Camaro Z28, 302 engine.

It lists the 4558 4558-1 and 4559 for a 70 Corvette 454 engine 465 HP,
depending upon AIR, and transmission.

I am not familiar with a 70 LT-1 but the above is what the current Holley book says. All the carbs above are 4150's with the same base plate, but with differences in ports and linkage depending upon the transmission and engine options.

Jerry Fuccillo
#42179

[Joe L.]

Re: Are Holley base plates stamped with PN#'s?

Jerry----

The Holley list 4555 was used for BOTH 1970 Corvettes with LT-1 (and, without EEC)as well as 1970 Camaro Z-28 (and, without EEC). The Holley reference which says that the 1970 Camaro Z-28 used a 302 cid engine is incorrect. ALL 1970 Camaro Z-28's used the 350 cid LT-1 engine. The 302 cid engine was last used for the 1969 model year in Z-28's.

[Gerard F.]

I guess you can't trust the Holley book

Dan/Joe,

Here's a 4555 on ebay right now:

http://cgi.ebay.com/ebaymotors/1970-Holley-4555-Chevelle-LS6-Camaro-Z28-Corvette-LT1_W0QQcmdZViewItemQQcategoryZ33550QQitemZ330097251778QQrdZ1QQsspagenameZWDVW

Wonder if it is the same part number for a Corvette. I remember the older Holley's having an application code after the part number.

Jerry Fuccillo
#42179

[Joe L.]

Re: I guess you can't trust the Holley book

Jerry-----

The GM part number for the Holley list 4555 carb for Corvette and Camaros was the same----GM #3972121.

By the way, the seller of the eBay carb is incorrect about its usage for 1970 Chevelle LS-6. It was not used for that application. 1970 Chevelle LS-6 used Holley #4491 or 4492, depending upon transmission.