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Posted By: Joe H A tuning nightmare! - Wed Jul 28 2021 01:02 PM
How about this, https://www.jalopyjournal.com/forum/attachments/0c9bb400-6296-4b2d-871c-5d9e7a4529f9-jpeg.5124402/
https://www.jalopyjournal.com/forum/attachments/984162f9-1864-46da-897b-ca2898d9992b-jpeg.5124403/
I don't see it working very well, those carbs are not going to like boost!
Posted By: Jon G Re: A tuning nightmare! - Wed Jul 28 2021 01:35 PM
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.
Posted By: Hotrod Lincoln Re: A tuning nightmare! - Wed Jul 28 2021 04:10 PM
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
Posted By: panic Re: A tuning nightmare! - Wed Jul 28 2021 08:24 PM
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.
Posted By: fixite7 Re: A tuning nightmare! - Sat Jul 31 2021 04:18 PM
JoeH Do you think they are going to hold that with 4 little main bearings and those little skinny rods ???
Posted By: SimS Re: A tuning nightmare! - Sat Jul 31 2021 07:45 PM
The early T-Bird 312 V8s were blow through. I think they even used that weird "tea pot" Holley.

SimS
Posted By: carbking Re: A tuning nightmare! - Sat Jul 31 2021 10:24 PM
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.
Posted By: Joe H Re: A tuning nightmare! - Sun Aug 01 2021 12:46 PM
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!
Posted By: carbking Re: A tuning nightmare! - Sun Aug 01 2021 02:29 PM
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.
Posted By: panic Re: A tuning nightmare! - Sun Aug 01 2021 03:01 PM
"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"
Posted By: fixite7 Re: A tuning nightmare! - Mon Aug 02 2021 04:41 PM
PANIC I suppose your right,makes me feel a little better about doing one of those rear main seals. That million dollar CNC machine looked like over-kill to me.Can do it with a Qwik Way boring bar.
Posted By: fixite7 Re: A tuning nightmare! - Mon Aug 02 2021 05:12 PM
panic sorry my posts go hide
Posted By: fixite7 Re: A tuning nightmare! - Mon Aug 02 2021 09:44 PM
panic trying
Posted By: fixite7 Re: A tuning nightmare! - Wed Aug 04 2021 06:48 PM
panic Agree, forged shaft too !
Posted By: fixite7 Re: A tuning nightmare! - Wed Aug 11 2021 05:13 PM
panic your right
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