69 Holley Carbs

[Don_Lightfoot]

Would like to confirm the correct CFM on the 4053 Z/28 and 4346 L78/L89/L72 carbs. Seems everybody refers to these as 780's which is what Holley is advertising for their reproductions as well. I've always respected anything in print by Jerry MacNeish and he refers to both of them as 800 CFM. What is the real scoop? Appreciate it.

[JoeC]

Holley used different methods to determine the CFM rating. The same bore diameter carb can be rated between 750 CFM and 800 CFM.

[Keith Tedford]

The 780 and 800 designation seemed to be interchangeable on this carb back in the day. Some called it one and some the other. It was THE carb to have until the double pumpers came out.

[T Billigen]

They were double pumpers. In 68 or 69 they came out with the three barrel, I had one on my 68 Camaro, I think they were 1000 cfm? They had a nasty habit of sticking and flooding the carb, caused me a lot of money when my car caught on fire when it backfired threw the carb.

[William]

In their '68 Z/28 magazine ads Chevy refered to it as an 800 cfm carb. The '75 Power Manual calls it a 780.

Guess that makes it a 790 :-)

[Don_Lightfoot]

Good one William /ubbthreads/images/icons/laugh.gif

Thanks for the responses guys. Guess I don't know any more than when I started /ubbthreads/images/icons/confused.gif

[Keith Tedford]

I think you will find that the carbs on the Z/28, L72, and L78 engines all had vacuum secondaries. The double pumper carbs were just starting to come out around this time. Some of the ZL1 cars were shipped with the vacuum secondary carbs while the proper double pumper carbs were shipped to the dealers later when GM got the carbs from Holley.