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A tuning nightmare!
#1418491 Wed Jul 28 2021 01:02 PM
Joined: Feb 2000
Posts: 4,373
J
Joe H Offline OP
'Bolter

Last edited by Joe H; Wed Jul 28 2021 01:04 PM.
Re: A tuning nightmare!
Joe H #1418494 Wed Jul 28 2021 01:35 PM
Joined: Mar 2014
Posts: 2,520
J
'Bolter
Wow! 3 Rochester Bs, pulleys that might or might not line up, a belt tensioner with a different pulley width and a thermostat housing about 20% corroded inside with what looks like a spider's nest in there. This guy is well on the way to creating a very special engine. When he gets it started it will be time to buy stock in Chevron.


Jon

1952 1/2 ton with 1959 235
T5 with 3.07 rear end
Re: A tuning nightmare!
Joe H #1418511 Wed Jul 28 2021 04:10 PM
Joined: Feb 2004
Posts: 23,018
H
'Bolter
Now I know what Forrest Gump's Mama was talking about, and I don't mean "a box of chocolates"! At least when Ford did that with the 312 engine, they built a pressure box around the carburetor!
Jerry


The murder victim was drowned in a bathtub full of Rice Krispies and milk.
The coroner blamed the crime on a cereal killer!

Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
Re: A tuning nightmare!
Joe H #1418544 Wed Jul 28 2021 08:24 PM
Joined: Dec 2008
Posts: 1,636
P
'Bolter
IIRC all of the Paxton (fixed drive ratio) & McCullough (variable ratio) blowers used that method in aftermarket kits, and factory Packard and Studebaker V8.
John Erb (of K-B Silvolite) wrote extensively about these, websearch "John Erb supercharger" for a long list.

Re: A tuning nightmare!
Joe H #1418883 Sat Jul 31 2021 04:18 PM
Joined: Dec 2018
Posts: 792
F
'Bolter
JoeH Do you think they are going to hold that with 4 little main bearings and those little skinny rods ???

Re: A tuning nightmare!
Hotrod Lincoln #1418903 Sat Jul 31 2021 07:45 PM
Joined: Jul 2008
Posts: 363
S
'Bolter
The early T-Bird 312 V8s were blow through. I think they even used that weird "tea pot" Holley.

SimS

Re: A tuning nightmare!
Joe H #1418923 Sat Jul 31 2021 10:24 PM
Joined: Nov 2002
Posts: 2,233
C
Carburetion specialist
Ford used two different "Holley type 4000" carburetors on the 312 with the blowers.

Neither were made by Holley, but they were sold by Holley.

Good luck on finding any information on these in the Holley books.

Jon.


Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify
If you truly believe "one size fits all" try walking a mile in your spouse's shoes!
[image]http://www.thecarburetorshop.com/Avatar.jpg[/image]
Re: A tuning nightmare!
Joe H #1418983 Sun Aug 01 2021 12:46 PM
Joined: Feb 2000
Posts: 4,373
J
Joe H Offline OP
'Bolter
I put together a Macho-TA for a local fellow, 1979 Trans Am with a turbo charger (1 of 9 dealer made cars ). The Quadrajet had a special plate under it that provided boost to the outer ends of the throttle blades via small holes drilled in the base plate. This was their way to seal the throttle shafts so pressurized fuel mixtures were not blown into the engine compartment. It also had a special vacuum advance unit which retarded the timing under boost ( Turbo Corvair I believe ). On top of that it had a boost line going into the top of the fuel pump so fuel pressure would rise as the boost went up. I am not sure what was done to the inside of the Quadrajet, it was rebuilt by the guys that designed to turbo system back in the late '70s.
I wouldn't know where to start on the three carburetors, what happens inside them under boost? Where is it likely to leak from? How much boost will the floats take? Lots of questions need to addressed. The Macho-TA didn't have any boost control, it went full boost, as much as the turbo could make, no blow off, or waste gate. I think what kept it alive was the small turbo size didn't make much more then 7 -8 lbs of boost. A modern turbo would blow the crank out of the block!

Last edited by Joe H; Sun Aug 01 2021 12:47 PM.
Re: A tuning nightmare!
Joe H #1419000 Sun Aug 01 2021 02:29 PM
Joined: Nov 2002
Posts: 2,233
C
Carburetion specialist
Where there is a "will", there is generally a "$way$".

Have done a number of "blow-through" genuine Carter AFB carbs, and also a few Holley 4000 carbs.

The Rochester B (opinion) has enough issues without pressure; don't think I would want to be trying these.

Listing modifications REQUIRED for the Carter AFB:

(1) Throttle shaft vacuum seals
(2) Idle mixture control screws pressure seal
(3) Accelerator pump shaft pressure seal
(4) Fabricate aluminum baffles for INSIDE the brass float pontoons (no, Virginia, foam floats do NOT work!)
(5) Boost reference for the fuel pump (depending on boost)

"Pull-through" carbs are MUCH easier!

Jon.


Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify
If you truly believe "one size fits all" try walking a mile in your spouse's shoes!
[image]http://www.thecarburetorshop.com/Avatar.jpg[/image]
Re: A tuning nightmare!
Joe H #1419006 Sun Aug 01 2021 03:01 PM
Joined: Dec 2008
Posts: 1,636
P
'Bolter
"4 little main bearings"?

#1: 2.684” (front)
#2: 2.715” (2nd)
#3: 2.746” (3rd)
#4: 2.777” (rear)

By comparison:
Chrysler 426 (gen 2) hemi 2.75"
Chrysler 392 (gen 1) hemi 2.6875"
Chevy LS 2.65"
Chevy 427 2.75"
Ford FE 427 2.75"
GMC Atlas 2.756"

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