Anyone ever dyno test stock GM BB 3 carb set up ?

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amcenthusiast
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Re: Anyone ever dyno test stock GM BB 3 carb set up ?

Post by amcenthusiast » Sun Oct 15, 2017 10:29 am

Part of this discussion could be on how the two 'secondary carburetors' effectively shorten intake runner length making 'six pack' induction system function as a variable length runner manifold.
XRV8 Race Parts > for AM's '56-'67 Rambler V8: http://amcramblermarlin.1colony.com/favorite_links.html

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Re: Anyone ever dyno test stock GM BB 3 carb set up ?

Post by ZEOHSIX » Sun Oct 15, 2017 5:37 pm

mag2555 wrote:
Thu Oct 12, 2017 12:15 pm
If it where not for GMs foresight and getting there hands on the new Rochester 750 cfm Q-jet in mid 67,GM lines would have had a hard time in keeping there hp numbers up after 1970 when the emissions / fuel mileage crap kicked in.
GM may have been forced into trying to keep some multi Carb set ups I think!
The Qjet was such a great carb that Ford even used them on the 429CJ motor.....the SCJ got the Holley of course.

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Re: Anyone ever dyno test stock GM BB 3 carb set up ?

Post by Schurkey » Mon Oct 16, 2017 10:22 pm

amcenthusiast wrote:
Sun Oct 15, 2017 10:29 am
Part of this discussion could be on how the two 'secondary carburetors' effectively shorten intake runner length making 'six pack' induction system function as a variable length runner manifold.
While true, I suspect it's a matter of going from "too short" runner length to WAY too short runner length.

I never noticed a dip in the torque when the secondaries kicked-in, but then my 3x2 system is vacuum-operated. Chrysler 440+6 carbs installed over the years on various Chevy small-blocks--283, 350, 400. I have always assumed that I was giving-up horsepower compared to a modern manifold and a single-four carb.

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Re: Anyone ever dyno test stock GM BB 3 carb set up ?

Post by Krooser » Tue Oct 17, 2017 5:06 am

I worked at two different Chevy shops in '67.... at Humprey Chevrolet in Milwaukee I had the only twin post lift that would take a Vette with side pipes. I did new car set-up at Holz Motors in Hales Corners... drove too many tri carbed big blocks to remember. My butt dyno never felt any loss of tq.

Set up and drove the first Z-28 in Wisconsin and my "test drive" was done on a county road with a '66 360 hp Chevelle right beside me up to 80 mph... would have done better but that darn frame mounted Muncie shifter wouldn't let me power shift.
Last place in the B-main is better than anyplace in the grandstands...

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