Holley 670?

[rikubot]

Sup dudes,

I have a stock built 440, except for the edelbrock 600 carb. My buddy has a Holley 670 double pumper with a vacuum secondary, and is wanting to do a trade with me. I like that my car fires up right quick if it hasn't sat very long. Seems when He had the Holley on his 350 crate, he'd have to do a lil pumpin even if he had just been driving it. My car is a weekend cruiser. Let me know what you guys think. He usually gives me good deals so I'm thinking he'll prob want 100 or so bucks

[XH29N0G]

A quick clarification for me.  I usually think of double pumper with a mechanical secondary because there is a (second) accelerator pump circuit on the secondaries that is needed to compensate for them being jammed open.  My understanding is that the vacuum secondaries (which have an accelerator pump circuit on the primaries) do not need a second accelerator pump because the vacuum mechanism opens them as fast as possible without needing this shot of fuel. 

So, I would double check on the type of carburetor.  I think it could be a vacuum secondary (or a double pumper) but not both.  I don't think it should necessarily make a difference in start up; I could be wrong, but my guess with the starting up when warm, or cold, is that it is more related to how the ignition and carburetor are working together and properly than what type of carburetor is on there, so I think you will be able to get the same start/run characteristics with a different carburetor.

If it seems like another size or type carburetor will work better for you, then you can try the switch.  From my own experience you will want to optimize the tuning of the new (and old) carburetors to make a valid comparison of any differences in performance. I find that part enjoyable tinkering.  Satisfying when done.

[rikubot]

I must have confused myself. The carb he just bought was a double-pumper, so that must have stuck in my head for no reason.  I know it's got vacuum secondaries because he said we may have to change out the spring to a stronger one because my motor makes more vacuum than his did. Sorry about that. It's hard to help someone who doesn't know what they are talking about (me). But yeah, for sure vacuum secondaries. He tells me my 600cfm is not a big enough carb for my 440.

[XH29N0G]

My guess is that your engine could handle the larger carburetor (and maybe even larger yet - like a 750)  but, it depends on the other parts of the set up (automatic or manual transmission, gears, and how the engine is set up).  I do not know if you will notice a huge difference between the carburetors.  I ran a 670 Holley Avenger on my 383 and it worked well, but I had to work with it (jets change) because it was lean out of the box.  If I were you, I would wait to see what others say, and also search around on this list (if the search doesn't work - it isn't working for me as well as it was before - search on google and put the forum name in, you will pull up many of the discussions).