Carburetor
Thread Starter
Cruising
Joined: Mar 2013
Posts: 10
Likes: 0
From: Bayville NY
Carburetor
My 70 LT-1 has a Holley double feed on it. No auto choke mech which starting a little bit of a chore. As part of the spare parts that came with it, I was told the original carb was included. The spare looks freshly rebuilt. I can not find the proper number on it. The one installed is a mechanical secondary car. The spare "original " has vacuum secondaries. The Original has the number 6335 and 6145. Neither has the correct 4150 number. Any suggestions? Did the factory Holley LT-1 have vacuum or mechanical actuated secondaries?
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
My 70 LT-1 has a Holley double feed on it. No auto choke mech which starting a little bit of a chore. As part of the spare parts that came with it, I was told the original carb was included. The spare looks freshly rebuilt. I can not find the proper number on it. The one installed is a mechanical secondary car. The spare "original " has vacuum secondaries. The Original has the number 6335 and 6145. Neither has the correct 4150 number. Any suggestions? Did the factory Holley LT-1 have vacuum or mechanical actuated secondaries?
The 6335 stamp is not on the airhorn - it's on the metering block, and is a metering block designator for a 1970 LT-1. The carb list number is likely to be 4555, stamped into the airhorn. It's a vacuum secondary 4150 flowing 780 cfm.
Lars
Last edited by lars; Jan 19, 2014 at 07:53 PM.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
A mechanical secondary carb, properly set up, will run exceptionally well if it's the right size for the engine's requirements. It can outperfom the vacuum secondary carb if it is set up right. Badly set up, the mechanical carb can produce severe bogs going into the secondaries. The vacuum carb, badly set up, can fail to open the secondaries at the correct time, limiting the carb's actual airflow capability. Use whichever carb you are best at tuning and setting up, assuming both carbs are the correct cfm size.
Lars
Lars
