As mentioned in another post, I'll be buying a Holley 4150 (1966 vintage, new in the box carb) for use on my 427 BBC for the wagon. The carb is LIST 9188, 780cfm, vacuum secondary, single pumper carb. I'm very pleased with the price and the choice for my purposes.

I actually want a carb with vacuum secondaries, but if it does not have center hung floats is the upgrade simply a matter of swapping fuel bowls and related float/needle valve parts? If I do change my mind, can a 4150 be upgraded to a mechancial secondary double pumper with bolt on parts?

The only modification I PLAN to make with the carb is to add a vacuum secondaries spring quick change kit. It may already have center hung floats, I won't really know until I lay my hands on it myself.

The bowl swap is pretty easy, but the swap to mechanical secondaries isn't. It's not worth your time. You'd need a DP baseplate, DP rear bowl, squirter, spring, etc., and then have to figure out how to drill the body for a secondary accelerator pump, block the diaphram passages, etc. Even then it won't really work right. The quick change spring kit is definitly a plus.

Makes sense. If I ever feel the need for mechanical secondaries and DP I'll simply upgrade to a new carb.

Makes sense. If I ever feel the need for mechanical secondaries and DP I'll simply upgrade to a new carb. Or you could just put a screw in the linkage to tie the seocondaries to the primary, crude but effective.

Originally posted by rthlc:
Or you could just put a screw in the linkage to tie the seocondaries to the primary, crude but effective. When i got my junk yard carb it was like that and I quickly took it off before I installed it. Wouldn't that cause a serious lean condition every time the secondaries are opened because there is no secondary squirter?

Originally posted by Fried_Guy:
</font><blockquote>quote:</font><hr />Originally posted by rthlc:
Or you could just put a screw in the linkage to tie the seocondaries to the primary, crude but effective. When i got my junk yard carb it was like that and I quickly took it off before I installed it. Wouldn't that cause a serious lean condition every time the secondaries are opened because there is no secondary squirter? </font>[/QUOTE]yes, with no accelerater pump in the secondaries, snapping the secondaries open would cause a lean bog until the boosters can catch up with the extra airflow.

the 3310-1 on my 66 was like this when i bought it. out on the street it would bog until it got into the power band. i took the screw out and put in the second to lightest spring in the vacuum pod and no more bog.

nowadays with the quick change spring kit and the spring assortment there is no need to use the old screw in the linkage trick.

Mine was already set when I got the car but I never had it bog. Maybe the trick is to set the screw is set where the secondaries won't come in until the primaries are already partially open. The screw was set start opening the secondaries when the primaries were aleady open about 1/4 thrrottle.