my77stang

only to a point..... seeing as how ford used holley 600's on low horsepower early 80's mustangs i dont see a 570-625 being too big for any 289/302 especially with vac. secondaries

scuf23

Not being much educated on carbs and intakes ... what is the difference between an original intake on a 289, and a dual plane intake from weiand, edelbrock or holley?

scuf23

Ok - I found this article ... http://www.popularhotrodding.com/tec...ld_comparison/

fast66

And those early 80s mustangs made how much power? As I said, bigger isn't always better, and according to Holley (who want their customers to get the best results from their purchase, a 390 to 570 in a warm 289 is plenty.

my77stang

the early 80's mustangs werent weak because of the carb, they were weak because the intake runners were VERY small (like 255 sized), the cams were tiny, and the compression was low.... and they were bogged down with a crappy generation of emissions equip

too big is the holley 780 the boss 302 came with

my77stang

Carb #
[align=center]Application[/align] [hr] [hr] Part # 1282020
575 Speed Demon

Part # 1282020VE
575 Vacuum-Secondary Speed Demon

Part # 1282020VFE
575 Vacuum-Secondary Speed Demon w/ Ford kickdown linkage [align=center]Stock and mild performance
283 - 390 cid V8 engines[/align] [hr] [hr] Part # 1282010
650 Speed Demon

Part #1282010VE
650 Vacuum-Secondary Speed Demon

Part # 1282010VFE
650 Speed Demon w/Ford kickdown linkage [align=center]Mild 302 to 427 cid engines[/align]note that barry grant specifys a 650 for a *mild* 302 - tell me again how a 600 is too big for a mild 289?

Norm Peterson

302 to 427 is a HUGE range of displacement, and 650 is definitely on the high side for a 302 while being a bit small for that 427. To my way of thinking, it's better suited to engines in the 350-ish displacement range.

Vacuum secondaries help, but with primaries that are overly large for the application, velocity through them will be lazier in the off-idle rpm range (where you're apt tobe while driving in heavy traffic). IOW, it'll tend to be less responsive or even a little cranky down there momentarily until it can digest the pump shot and PV activation.

I'm guessing that BG is primarily drag racing oriented, but I would like to know a bit more accurately what they consider mild, and for what usage.

All those CFM calculators are based on certain assumptions that may or may not fully apply to your application and use. Primarily, they're aimed at daily driveability. You will get slightly more power with a 600 vs a 465. But if a 465 is nearly enough you won't be drawing anywhere near 600 cfm out of that 600 either. So don't expect a power increase that's anywhere near proportional to a comparison of the rated cfm's. 4% HP increase or so? Probably. 25%? File that under wishful thinking/dreaming.

Norm

JohnCalvin

I've had a edelbrock performer 289 (this intake was specifically made for the old 289 that hasn't had a head swap, very torquie!) and a holley 500cfm electric choke... too easy to over carbeurate with anything bigger... I'm actually selling both of these if you or anyone else is interested $250 for them both together... i'll post this under the for sale in a day or two

fast66

Hey my77stang, nice gun gollection. Do you also think a .222 is too small?

my77stang

yeah..... but a .223 isnt

norm i agree 650 = 351ish sized motor, and the 650 vac. sec. i had on my 302 was on the large end of the spectrum, but i dont think it was too big. i was actually leaning towards a 625 but per barry grants site i got the 650 due to my long cam duration and high compression. for my streetable compression 289 (same cam) i will be going with a 570 street avenger or a 625 road demon - depends on what deal i stumble across. i would shoot in the middle and grab a 600 but i want something with the perks (and a plain ol' 4160 doesnt fit that bill..... i have been down that road)