Holley 660 dual quads set up

jg33replica · Jul 22, 2018

Hi has anyone had some experience setting up Holley 660 dual quads. I have a reco pair on my tunnel rammed 351 windsor in a Ford falcon . My problem is with the 1:1 linkage set up , when you press accelerator pedal down it will go so far nice and smooth and then as the primarys linkage start to push the secondaries open , the linkage gets to a certain point where it just slams all four open almost instantly. This just bogs the thing down to a near stall. I was wondering if it was wise to grind the slot out on the carb that the linkage runns through to make it a bit more progressive. Ihope someone can understand what I am trying to explain . I cant think of the words to use. If it is helpfull I can supply video or pictures

Grumpy · Jul 22, 2018

Id suggest you start by reading these linked threads,
keep in mind a tunnel ram intake is designed to run in the 3500 rpm-7000 plus rpm power band,
its an intake designed to maximize power and its generally not the best choice for a street car.
and that generally requires a cam with about a 240 @ .050 lift or greater duration, usually a reasonably tight 106-109 LSA,
open headers, at least 10.5:1 compression ratio,
and rear gears in the 3.73:1-4.56:1 range and a 3500 rpm stall speed or higher converter,
or a manual transmission to maximize the dual quad/tunnel ram intakes designed power curve potential.
yeah you can have a different basic combo, but the further you get from the design parameters,
the more difficult it becomes to tune and get it to run with a brisk crisp throttle responce, and no other issues.
and yes the larger the displacement , the higher the compression ratio, and closer the cam, duration,compression and exhaust header tune match
, the drive train gear ratios and the lighter the car is,
so the engine can maximize that intended upper rpm power band,
all the time the better that tunnel ram intake design, will tend to run

Throttle Linkage

I have an Edelbrock 1406 carburetor (might need to be rebuilt), it came with the LM1 350 I bought for my 64 El Camino. The el camino originally came with a throttle rod lever that attaches to the carburetor from the gas pedal, it's not in good shape. I also have a bracket for a throttle cable...

garage.grumpysperformance.com

Loves302Chevy · Jul 22, 2018

What you are describing is progressive throttle linkage. Here is one.
https://www.summitracing.com/parts/lok-tcbplr3/overview/
The linkage you have now might be able to be set up as progressive.

Loves302Chevy · Jul 22, 2018

From an older Grumpy's post: YOU DON'T SET THE THROTTLE LINKAGE UP OR TUNE A TYPICAL LOW RISE DUAL QUADS LIKE A TUNNEL RAM IS SET UP OR TUNED. On the low rise dual quads many guys have the rear carb primaries open about 1/4 before the front carb primaries start to open, and the rear secondaries open before the front secondaries do.
That's all wrong on a tunnel ram.
Transition means that few instants between holding it at about 2000 rpm just before your launch and rapidly depressing the pedal to WOT, and the engines running up close to the rev limiter, in a few heart beats, tunnel rams are MAX EFFORT intakes, and not really designed for a daily driver.
BUT if you're good at tuning you'll get by on the street remarkably well.

Post a picture of your current setup.

Holley 660 dual quads set up

jg33replica

New Member

Grumpy

The Grumpy Grease Monkey mechanical engineer.

Throttle Linkage

Loves302Chevy

"One test is worth a thousand expert opinions."

Loves302Chevy

"One test is worth a thousand expert opinions."