BBC Air cleaner base
 

I changed from vacuum secondary Holley to a DP carb. The pvc tube on my factory base hits the secondaries. The factory L88 is the only BB that I'm aware of that had a DP holley. All the repo drop bases look the same and list as fitting all Chevy BBC with a Holley including the L88. What's different about the factory L88 breather that clears the secondary accelerator pump?

Not sure about factory L88 bases, but some of the reproduction bases have a down tube with two 45 degree bends instead of a 90 degree bend, will and work with a double pumper.

I knew I'd find the answer here! Thank you

I didn't know that the L88 had a DP. I thought it was vacuum.

The second design l88 in 1969 went to a 850 double pumper. The list number was 4296. It and the list 4295 carb used on the 1969 z28 crossram were the first double pumpers made by Holley. It was a turning point in Holley performance.

Jason

The 3418 was a vacuum secondary carb, then in 69 they changed to a 4296, which was a double pumper. Just for the record, I have never run across a plain 3418, only 3418-1's. Strange.

Thanks for clearing that up for me guys. Did the ZL1 also get a DP?

Yes, the 69 Camaro aluminum engined ZL1 used the same 4296 carburetor as the 69 L88 iron block Corvette engine.

The AMA specs for the ZL-1 Camaro list the #4296 but none of them were built with it due to the same fitment issue. Vintage photos show the production GE code #4346.