ZL1 correct carburetor

[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.....

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.