I have a 454 that is for the most part "stock". What are the pros and cons of a carb with a vacuum or mechanical secondary. All inf will help.
I have a 454 that is for the most part "stock". What are the pros and cons of a carb with a vacuum or mechanical secondary. All inf will help.
depends on your cam...most Marine cam profiles do not produce much vacuum so mechanical secondaries are the preferred choice....try a edelbrock 750 marine for your motor P/N EDL-1410
If its in a jetboat go mechanical. There is no need for a vacuum secondary carb in a jet boat. Oh yeah, for performance reasons, go holley. There is a reason they have been around so long. If you need tuning advice post something in gear Heads.
Im not saying don't go with the mechanical secondaries. But I have a pretty stock 460, and the boat CAME iwht a 750 vacuum secondary and so far I have NO issues with it. I don't have any reasons why no double pumper. I know that once I get a little more HP I'll be going mechanical.
What carb was on your boat?
Its a rebuilt 454 .30 over with 396 heads with about 10.5 to 1 comp, ported heads and bigger valves.
I had a 670 on my olds that i am told will be to small for the bbc. Im looking at the holley 80537 marine carb.
Its a rebuilt 454 .30 over with 396 heads with about 10.5 to 1 comp, ported heads and bigger valves.
I had a 670 on my olds that i am told will be to small for the bbc. Im looking at the holley 80537 marine carb.
I think you can buy a kit from Summit to change the main body and get more CFM.... cause carbs are expensive! Or go used. 750dp sounds adequate, or possible an 800
found one used in spam today for 200.
If its in a jetboat go mechanical. There is no need for a vacuum secondary carb in a jet boat. Oh yeah, for performance reasons, go holley. There is a reason they have been around so long. If you need tuning advice post something in gear Heads.
I agree. Mechanical on a jetboat is the way to go. You want instant rpm and you get more of that this route.
I changed from a vac to a mechanical carb on a 454. The difference was impressive. Especially in low to midrange acceleration.
I recommend a Holley 800cfm model 9022 marine carb. Its the same carb that came stock on Merc 500HP 502 ci motors before EFI.
http://www.holley.com/HiOctn/ProdLin...rb/0-9022.html
this is all great info thanks
depends on your cam...most Marine cam profiles do not produce much vacuum so mechanical secondaries are the preferred choice....
Karl, MANIFOLD vacuum has nothing to do with how the vacuum secondaries of a Holley function. They open based on a VENTURI vacuum signal generated in one of the primary venturies. More airflow through primaries = more venturi vacuum = secondaries open.
Posting Permissions
Reply With Quote