Tunnel ram, vacuum tuning?

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Cope

Cope

Fusing with fire
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I'm getting ready to start tuning the twin 4160s but the 4160 only have vacuum out of the front block and my manifold has no fitting for vacuum.

So.... where do I drill the manifold or should I just tune off the front blocks?

I do have a wide band but I wanna tune for max vacuum before I start tuning for AFR.

or am i totally off base on how to tune twin carbs?

Thanks again.
 
You need manifold vacuum, not necessarily connection to the carbs or to either carb. If you have non-progressive (center squirt) linkage and are trying to obtain some sort of throttle blade sync between the two carbs, you need one of the air horn sync devices used on old side draft sports cars and individual bike carbs. In other words something that will "read" vacuum above the blades



All that will do, tho, is maybe improve off idle/ low speed/ street manners
 
I think we do have a "unisink" for webber's but that's for single barrels not four barrels.
 
:)

Jpar one day I'm gonna drive my bucket up your neck of the wood and I will kick you right in the taint.. or I'll just buy you a squirt and BBQ!

Hope all is well bro!
 
Cope said:
:)

Jpar one day I'm gonna drive my bucket up your neck of the wood and I will kick you right in the taint.. or I'll just buy you a squirt and BBQ!

Hope all is well bro!
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My dad told me what that was when I was 11. Thanks Dad...
 
Anyways I have Edelbrock carbs the correct kind of carburetor to have on Dual quads and I use my wideband O2 to tune them with. Now if I had a couple of junk Holly's I wouldn't know what to do...
 
I was gonna ask your opinion on this but I know you run Chevyedel carbs....and that's ok. I dont judge, what ever makes you happy.

:)

I just wanna play in your end of the pool.
 
Cope said:
I was gonna ask your opinion on this but I know you run Chevyedel carbs....and that's ok. I dont judge, what ever makes you happy.

:)

I just wanna play in your end of the pool.
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You know I'm just bored and messin with ya LOL
 
And have to know what I was doing to have Holley carburetors I just use Edelbrock because they're easy.
 
I know brother.

If you were running twin 4150 750s yellow rose would be running scared.

I'm one 750 short so twin 660 4160 is what we had on the shelf...
 
Honestly it's you, yello rose and young gun that led me into this... so it's all your fault anyways...

:)
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With no provision for a vacuum gauge you can adjust your mixture screws for the highest rpm. Then use idle speed screws to bring rpm to what you want. Adjust mixture screws again and bring it back down again. When you like where it's at then use the unisync.
 
Ok I'm confused. On a single-4, I never use highest vacuum to tune the idle cuz that usually messes up the T-port sync.
Couldn't you just set the syncs on both carbs equally, and then adjust the speed-screws equally after that?
 
Let me explain a little more clearly. Unisync refers to the device used to compare airflow through one carb to another. Or several others. And t port sync is a reference to the transition slot i believe. Adjusting to the highest rpm via the mixture screws and then lowering the idle rpm by closing the throttle blades will make more of the transition slot available to do it's job. Then the unisync is used to ensure equal airflow between carbs.
 
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