ZL2 Flat Bottom AC Base

[L78 steve]

Im told that after April 69 the ZL2 Air cleaner base changed to the ribbed design. When exactly was the change over? I'm trying to figure out what my 04C came with. Ideas?

[william]

It was later than that; June-July '69?

[L78 steve]

OK, Thanks william.

[L78 steve]

Next question. What is the correct 2 letter code on the decal applied to the base. Ive seen DG on the re-pops and a CA on a real base.

[william]

The ducted hood base was also used for '70-'72 Chevelles.

Known '69 Camaro codes are DE for L48/manual trans, DF for L48/auto, DG for 302, 396, 427.

[69Z28-RS]

My 09C (September '69) Z28 has the flat bottom cowl air cleaner base...

Gary  /  69Z28-RS

[william]

Is the vent tube 1 90º bend or 2 45º bends?

[69Z28-RS]

Hi Bill,

I went down and took a photo; it appears to be a continuous 90 deg bend to me.    What is the significance of the 90 versus 2 45 deg bends??  My car is an 09C (Sept 69).   This is the ac that was on the car in '76 when I purchased it..  didn't appear to have been added on (all original components).. so I believe it is original to the car...

Gary

[KevinW]

Gary, can you give is the diameter of the metal tube?  thx!

[william]

The bend has significance because the original flat-bottom base with 90º tube won't clear the rear pump on a Holley DP carb. It wasn't an issue until ZL-1s went into production. They were supposed to be built with the #4296 850 DP but were built with the #4346 780, same as an L72/L78. NHRA wouldn't allow it as it did not match AMA specs so Chevy had to retrofit many if not all of the ZL-1 Camaros. Was this because of the interference?

All the service ZL2 air cleaners I have seen had the 2 bend tube and the rib. I've never seen or heard of an NOS service flat-bottom. Wondering if both the tube and rib were changed at the same time. I don't know that it has been positively established that the service unit was used in production-this was only a problem on the very few ZL-1s built. I've heard of fairly original cars having the service unit but that doesn't mean it was OE. Back in the day it was common to cut off the snorkel; ducted hood air cleaners were also regiularly stolen. Many were added during restoration. I worked at a Camaro parts business; we stocked and sold many ZL2 air cleaners.

[69Z28-RS]

It's interesting that you mention 'cut off snorkel'..  Mine has that (was cut off about an inch away from the housing) when I bought it in '76.   In '76, Z28's with cowl were so 'rare' (unlike today), I thought that it might have been 'original'..       NOW I'm looking for a full snorkel so I can 'fix' that cut off one.. 

[L78 steve]

I have a snorkel only. But it came from a later service replacement and has 2 notches in the crimp. What is the reason for the notch?

[69Z28-RS]

Steve,  If your snorkel is the same as 'original', and you want to sell it..  I'm interested..

Kevin:   I measured the vent tube diameter of my A/C...   it is 1 inch in diameter....

[KevinW]

Hmm, I thought 1" was for BB and 3/4" was for small blocks.  William, Kurt? shouldn't a 302 be 3/4"?

[william]

Z/28 and BB used the same base; BB did not use the extension.

Exactly what the difference is between an SS350 manual base [6485233] and the Z/28-BB base [6485235] I do not know. I looked at a survivor Festival Z11 last year and the vent tube looked the same as the 235 unit. May have been clocked differently. The AIM shows both use the same vent hose: 3951632. I had thought they were 3/4" also.

Remember that '70-'72 Chevelles also had ZL2. Those units may have other differences; I believe some had an angled snout.