blower carbs ?
Thread Starter
Melting Slicks
Joined: Dec 2000
Posts: 2,130
Likes: 1
From: mesa,az
blower carbs ?
holley tech line tells me my dual 660 setup wont be enough for my 871/496 engine. they suggest 750s. now when i read the holley books they have a series of modifications they tell you needed to be done. holley will sell you special made blower carbs but when i talk to a few guys i run into at the local shows they tell me they just a running reguler old carbs. Then the guys at the speed shop just say replace the power valves and call it a day. i'm a little confused.
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
It might depend on the type of blower setup you choose. There is one where the high pressure tube from the blower is bolted onto the carb intake and uses the carb bolt. I would think you need the high pressure carb setup for this because the inside of the carb will be at a much higher pressure than the surrounding air - therefore you can blow power valves, gaskets, etc.
The other type of blower setup consists of a "box" that fits entirely over the carb itself. This results in the high pressure inside AND outside the carb being the same. In that case, you might be able to use a regular carb.
Just guessing...
The other type of blower setup consists of a "box" that fits entirely over the carb itself. This results in the high pressure inside AND outside the carb being the same. In that case, you might be able to use a regular carb.
Just guessing...
Burning Brakes
Joined: Feb 2003
Posts: 1,246
Likes: 1
From: SouthBend IN
My friend runs 2 750 VS carbs on his blown 468 with 12 lbs boost. He put a 50CC accel pump on them , other than that their stock. The local engins shop just dynoed a 509/871 with stock 750DP's on it 1100 HP@ 18 lbs and 870 HP @ 3 lbs.
Blow through carbs are tricker than the roots type carbs.
Blow through carbs are tricker than the roots type carbs.
Drifting
Joined: Jul 2001
Posts: 1,418
Likes: 1
Just a suggestion . Run 800's with the power valves blocked . Jets squared up with 80's in all 8 corners will be a good baseline .
If you use the 660's , give a dedicated fuel line to each bowl or you'll lean it out up top and kill parts . A blower motor will suck fuel , will be worse with the 660's due to the 1.1 linkage .
I run a regulator to each carb with or without a blower when I used dual carbs with enough pump and large enough fuel line to feed a methanol motor .
Grenades are for war
If you use the 660's , give a dedicated fuel line to each bowl or you'll lean it out up top and kill parts . A blower motor will suck fuel , will be worse with the 660's due to the 1.1 linkage .
I run a regulator to each carb with or without a blower when I used dual carbs with enough pump and large enough fuel line to feed a methanol motor .
Grenades are for war
Thread Starter
Melting Slicks
Joined: Dec 2000
Posts: 2,130
Likes: 1
From: mesa,az
660s going on the shelf. everything says they are to small. i'm doing some research. holley tech says 750s, BDS formula says 800CFM+ each. so you block secondery AND primary power valves on your blower carbs. you don't think i need to reference to the manifold vacum on them even on a street setting?
Drifting
Joined: Jul 2001
Posts: 1,418
Likes: 1
You can try but the motor will sneeze and pop the power valves when your firing it up and getting initial timing set and stuff of the likes .
I'd say block them , use the baseline until the motor is run in and tuned up then play with the power valves .
Some of the 800's and 850's come w/o a power valve in the rear metering block anyway . Depends on what carb(s) you wind up purchasing .
I was thinking boat motor using good fuel on the jetting above. You'll probably need to compensate for smaller tube headers /mufflers and type fuel and whtaever carb size you use .
I'd say block them , use the baseline until the motor is run in and tuned up then play with the power valves .
Some of the 800's and 850's come w/o a power valve in the rear metering block anyway . Depends on what carb(s) you wind up purchasing .
I was thinking boat motor using good fuel on the jetting above. You'll probably need to compensate for smaller tube headers /mufflers and type fuel and whtaever carb size you use .
