Carb tuning

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Oct 5, 2011 | 10:05 AM

scraper

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Carb tuning

New to the site. I have 65 Coupe 327/300 auto.
Just had the carb rebuilt, not a holly. How do u tune this carb. Your help is appreciated.

Sioux Falls, SD

Oct 5, 2011 | 10:17 AM

MikeM

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From: Greenville, Indiana

What are you trying to accomplish?

Oct 5, 2011 | 10:43 AM

scraper

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Tune the carb. Fuel/Air mixture.

Thanks for the reply.

Oct 5, 2011 | 11:02 AM

rick charles

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From: AUBURN NY

carb tuning

Use a vacuum gauge to adj. Idle mixture screws ....... Rick

Oct 5, 2011 | 11:55 AM

scraper

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Thanks,

Oct 5, 2011 | 12:31 PM

scraper

Thread Starter

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Joined: Oct 2011

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Likes: 11

Rick,
What would be a good starting set for the screws. One being fuel and the other air.
What is the lbs. I am looking for.

Mike

Oct 5, 2011 | 12:31 PM

scraper

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Should the car idle or higher RPMs

Oct 5, 2011 | 01:16 PM

rick charles

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From: AUBURN NY

carb

Look to get all you can , 15 # at least . Rick

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Oct 5, 2011 | 01:24 PM

RoadKing96

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From: Holly Springs, Nort Cackalacky / Jupiter, Florida

Quote:

Originally Posted by scraper

Rick,
What would be a good starting set for the screws. One being fuel and the other air.
What is the lbs. I am looking for.

Mike

I always start by first bottoming screws (be gentle when bottoming)
Then back them off around 1 1/4 - 1 1/2 turns. Start there

Both screws are for fuel. They are for idle set.

Good Luck,
RK

Oct 5, 2011 | 01:28 PM

#10

KC John

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From: OP Kansas

C2 of Year Finalist (appearance mods) 2019

Gently turn the screws in all the way until they seat. Then back each one out 1.5 turns for your starting point. Connect your vac gauge to manifold vacuum. Turn screws in or out 1/8th turn at a time to get the highest vac possible. Incase you didn't know, both screws are controlling air and fuel, they are not separate.

Oct 5, 2011 | 01:33 PM

#11

scraper

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KC,

Thanks, u guys helped alot. Will let u know how it goes.

Mike
65 Coupe:

Oct 5, 2011 | 01:56 PM

#12

RoadKing96

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From: Holly Springs, Nort Cackalacky / Jupiter, Florida

Quote:

Originally Posted by KC John

Incase you didn't know, both screws are controlling air and fuel, they are not separate.

OK, for my own benefit, and maybe others....

I always thought that "opening" the screws allowed more/less fuel to mix with a relative amount air.

RK

Oct 5, 2011 | 06:27 PM

#13

Karfever

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From: West Tennessee

Kind of along with this topic, on a 65 350HP engine, no options, should the intake manifold had a fitting for a vaccumn source? I just have a solid plug and no manifold vac outlet on the stock holly carb.

Oct 5, 2011 | 07:07 PM

#14

KC John

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From: OP Kansas

C2 of Year Finalist (appearance mods) 2019

Quote:

Originally Posted by RoadKing96

OK, for my own benefit, and maybe others....

I always thought that "opening" the screws allowed more/less fuel to mix with a relative amount air.

RK

RK, I was just trying to point out that one wasn't for fuel and the other for air. That is what I thought the OP meant in his question. You are right, it only controls the fuel, and as you said it's in relationship to the amount of air that is flowing through the carb. You obviously said it better than I did. We were probably typing at the same time, because I basically said exactly what you did.

Oct 5, 2011 | 07:38 PM

#15

JohnZ

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From: Washington Michigan

Quote:

Originally Posted by Karfever

There's a plug in the manifold (for a fitting for power brakes, A/C, Powerglide, etc.), and the manifold vacuum source on the stock 2818 carb is a nipple on the passenger side of the primary metering block, above the idle mixture adjusting screw. What's stamped on the front side of the choke air horn?

Oct 5, 2011 | 09:29 PM

#16

Karfever

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From: West Tennessee

Quote:

Originally Posted by JohnZ

I have the port you decribed, but wouldnt that be 'ported vacuum' verses manifold vacuum?

Oct 5, 2011 | 09:42 PM

#17

65GGvert

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From: Kannapolis NC

scraper, post back how it goes. Looks like your thread has been hijacked. I'd be interested in how the adjustment works out with the vacuum.

Oct 6, 2011 | 07:59 AM

#18

scraper

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Carb Tune

Got a Vacuum guage from work. Turns screws in gently and out 1.5 turns. Ran a (T) for vacuum line. It worked just like you said. Got about
15-16 lbs. vacuum. Going to change plugs next.

Thanks,
Mike
Sioux Falls

Oct 6, 2011 | 01:32 PM

#19

JohnZ

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From: Washington Michigan

Quote:

Originally Posted by Karfever

I have the port you decribed, but wouldnt that be 'ported vacuum' verses manifold vacuum?

Not if it's an original 2818 - "ported" vacuum hadn't been "invented" yet in 1965. If it's a later replacement 2818 (Holley still makes them today), it has a different primary metering block, and that nipple IS a "ported" vacuum source. That's why I asked what the date code is, stamped on the front of the choke air horn.

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