Another "which carb" question

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03-18-2008, 11:26 AM

#11

silverblue66

2nd Gear Member

Join Date: Sep 2006

Location: Ca

Posts: 318

RE: Another "which carb" question

Quote:

ORIGINAL: my77stang

silver the problem is most of the time driving your running on the front two barrels so your 500 is now a 250. add in a dual plane intake and each cylinder is only drawing from a 125 cfm barrel when its sucking air. this is why you can get away with a slightly larger carb than mathmatically required when using a dual plane intake with a vacuum secondaries carb (which is the combo MOST of us have).

not to mention even ford was using holley 600's on underpowered 302's in a variety of applications for years and years..... that should tell you something.

True enought that you are driving on two bbls most of the time, but you are also cruising at around 2-3k, 250 is about right for that rpm, when you are under acceleration and your rpm goes up to 4500-5000the secondaries kick in at higher rpm when you need them. the point of primaries and secpondaries is to eliminate waste. efficciency and power when you need it. yes it is true they put 600s on 302s and the also put 3502bblson 390s. just cause ford did it doesn't mean it was or is a good idea. I am not trying to be rude, but I am just presenting an alternate opinion that has worked for me. plus I am looking at the whole package power and fuel economy. in theroy I get around 20-21 mpgs highway

in theory mind you

Kip

03-18-2008, 11:45 AM

#12

kalli

6th Gear Member

Join Date: Oct 2006

Location: Cork, Ireland

Posts: 6,417

RE: Another "which carb" question

vacuum secondaries are not opening in relation to rpm, they open in relation to vacuum in primary booster,
so for that a 600cfm carb with vac secondary should be ok, shouldn't it?
but yes I believe a 500cfm carb should be sufficient as well ?!