ZL1 correct carburetor

[Hillbilly]

I am currently working on a original ZL1 motor, and I am having issues with the carb not wanting to idle.(carb has been rebuilt) Im thinking that it isnt the correct carb for this particular motor. What would be the best way to find out which one is correct for this car? Thank you for youre time.

[SuperNovaSS]

They are available new. An original is alot of money. The list number is 4296. Many other carbs should work for it though. The ZL1 is meant to have a high idle. Maybe VintageMuscleCar can chime in. Eric is a wealth of knowledge not to mention a cool dude.



Jason

[VintageMusclecar]

David;

The "correct" carburetor for a ZL1 is a Holley LIST 4296.

re: idling issue--is it idling too lean and doesn't want to idle at all? Have all the basic adjustments been set (float levels, trim screws, etc.)?

How many turns out are the idle trim screws?

Eric

p.s.
Thank you Jason http://www.yenko.net/ubbthreads/images/graemlins/beers.gif

[Alss]

Funny how this post is here..a buddy just brought me a gift for my Malibu project..could it be??

L 3955205
list 4296
912

???is it real??

ALbert

[Fast67VelleN2O]

They are now available new from Holley I believe. 912 sounds like a real ZL1 carburetor to me. I recently sold a May of 1969 L88 4296.

[SuperNovaSS]

Is it old and crusty or new and shiny?



Jason

[Alss]

[ QUOTE ]
Is it old and crusty or new and shiny?



Jason

[/ QUOTE ]

new and shiny

[SuperNovaSS]

There are plenty of guys stamping the new ones that do not come with a date. Either way, it should work great for your application.


Jason

[Alss]

Thats what I figured, but its a new ZL-1 carb and thats OK with me

[William]

When discussing ZL-1 Camaro carbs "correct" and "how they were built" are different.

Perhaps due to the ducted hood air cleaner interfering with the rear pump on the #4296 many if not all were built with the L72/L78 #4346 carb. Fred Gibb stated this in an interview many years ago and photos of the #3 Berger ZL-1 confirm it. The #1 ZL-1 flunked Tech at the Phoenix AHRA meet because the AMA specs listed the #4296 and the car still had the OE carb.

Which carb should a properly restored ZL-1 Camaro have? You decide.

[SuperNovaSS]

The ones build with the 4346 carbs has the correct 4296 carbs serviced installed on them.



Jason

[Hillbilly]

What would be the acceptable RPM range without going too high? Thanks again for the help.

[nuch_ss396]

[ QUOTE ]
When discussing ZL-1 Camaro carbs "correct" and "how they were built" are different.

Perhaps due to the ducted hood air cleaner interfering with the rear pump on the #4296 many if not all were built with the L72/L78 #4346 carb. Fred Gibb stated this in an interview many years ago and photos of the #3 Berger ZL-1 confirm it. The #1 ZL-1 flunked Tech at the Phoenix AHRA meet because the AMA specs listed the #4296 and the car still had the OE carb.

Which carb should a properly restored ZL-1 Camaro have? You decide.

[/ QUOTE ]

This brings about a great point. I remember hearing this
4346 vs. 4296 carb controversy here on this site years ago. I was amazed!

Why would GM spec a carb ( i.e 4296 ) that clearly did not operate
with the ZL/2 induction system for the reason you mentioned.
For the purists here ( I'm one too ), I'd have to go with
the 4346 because that is the carb the engines came factory
equipped with. What have the ZL-1 owners done to their
air cleaner bases to allow the secondary pump assembly to
operate properly? I'd like to hear from some owners..... http://www.yenko.net/ubbthreads/images/graemlins/hmmm.gif

Nuch

[William]

Using a thick gasket on the carb is one solution.

The problem is not all that obvious. The 90º tube may compress the rear pump lever somewhat resulting in a constant trickle of fuel. The poor idle and fouled plugs are written off to "that's how they were." Another ZL-1 restoration error is to run a heat riser.

We ran the #4296 with the 2nd design air cleaner and the car started right up and idled smoothly.

[nuch_ss396]

William,

What differentiated the 2nd generation air cleaner assy from
the 1st generation assy? Was this modified specifically for the ZL-1 issue?

Nuch

[William]

The 2nd design has a vent tube with 2 45º bends and a raised bead stamped in the base to elevate or better seal the element. Chevy began using it in production during the model year; June-July or so. Some service units were provided with chrome lids. Every service ducted hood air cleaner I have seen is the 2nd design; never heard of an NOS flat bottom.

I do not know what motivated Chevy to change the design but the #4296 carb issue is a plausible theory. The change was done to accomodate a Holley double-pumper carb and that was the only application to use one.