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Old 10-18-2002, 07:52 AM
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Post Tuning Dual Carbs

I cant seem to find anything on how to tune dual carb after they are on the engine. What I have are Holley 1850's. The engine Iam getting has a tunnel ram. I am going to start off with this but will probably change to a regular dual carb manifold. I dont have all of the engine yet and dont have it together just trying to learn as much as I can now. So if some one could walk me thru a procdure for tuning these two buggers it would be great! Thanks!

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Old 10-18-2002, 08:41 AM
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My advice? Put a blank gasket under one cab and ron the other one!!
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Old 10-18-2002, 10:59 AM
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Your probably right on that! My problem is Iam to hard headed when someone tells me something cant be done it makes want to do it even more. Oh well! Guess Ill have to figure it out on my own til I decide for myself its not worth it. That tunnel ram looks to cool to just let sit around. Although it would look kinda cool with one of those viney crawling green plants growing out of the top of it.
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Old 10-18-2002, 11:56 AM
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I run a three deuce tunnel ram 383ci from automotion hotrodcarb in my 54 chevy p/u, It is pretty streetable with loads of bottom end torque and screams on top. It can be done!
Good Luck
Drifter
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Old 10-18-2002, 12:37 PM
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I think two 600s(1850 holley) are a little big for a street small block.I'd use like two 390s or 450s.Also edelbrock makes a low rise duel quad setup 1500-6000rpm range that would prolly be alot more streetable.
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Old 10-18-2002, 01:27 PM
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I was just kidding of course. I never ran a multi-carb setup so would be interested in how it is done. J.C. Whithey and Honest Charlie always sold some sort of tool that allowed tuning of several carbs but I don't know how it worked. Don't recall see the tool advertised for a long time.
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Old 10-18-2002, 01:56 PM
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I knew you were kidding! Yeah I also know the carbs are to big but they are comming with the deal. Its a 400 bored 30 over so may not be to bad if I can jet them down a little. Its also comming with a big ars cam and heads. The guy I got it from built it for his drag car til he get his 502 built. Only ran it a couple times. Just how do you set the Idle and Mixture while its running?? do you turn the same one on each carb at the sametime. or just one at a time. Thanks!
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Old 10-18-2002, 03:51 PM
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If you can find a Unisyn Carb Synchronizer, dealing with this is not as bad. New ones are here; <a href="http://www.storesonline.com/site/256083/product/CP-006-0002." target="_blank">http://www.storesonline.com/site/256083/product/CP-006-0002.</a>

I'm sure someone on e-bay has a used one.

These are set up for tea bagger type cars with S.U. carbs on them and you will have to mickey mouse an adapter from the giant hole on your carburetors to the smaller inlet in the tool. It's basically a vacuum balancing device and maybe when 4Jaw gets in here he will have a simpler answer. We have (my friends and I, not the royal we) used these successfully on up to 6 97's in centuries past.



[ October 18, 2002: Message edited by: slider ]</p>
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Old 10-18-2002, 04:30 PM
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That's it! the Unisyn is the doo-hickey I have seen advertised for decades. Incidentally, the link you show didn't work for me.

Update: just went to eBay and there are two Unisyns listed. One is going for $25 and one is going starting at $15. The appear to be nothing more than a manometer on an adjustable air inlet. To use it, one would adjust the air inlet to achieve just enough resistance to flow to achieve an inch or two of water column pressure drop in the manometer. Without touching the air inlet, the device could be plopped on top of each carb and the idle and mixture screws adjusted until all carbs have the same pressure drop. Actually, you could make your own version wiht some sheet metal, a couple of screws and a big washer and some colored water in a clear plastic hose.

[ October 18, 2002: Message edited by: willys36@aol.com ]</p>
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Old 10-18-2002, 08:05 PM
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Uni-syns, at least the ones I've used, are only good for small throsted carbs not Holleys. All you need to do is to back the idle screws out so the carbs are completely closed( make sure the linkage between them is not on at this time)adjust the rod beytween the carbs so it just fits in the same hole on both carbs, and it's done. You can now adjust the idle with one screw or the other since they are hooked together, I always like to turn the other in until it just touches after the idle is set. On a tunnel ram the mixture isn't being isolated to individual cylinders (nor is it on a regular 2-4 manifold, it just breaks it into 2 paths) so the important thing to remember is to have the carbs open equally. I've run many multi carb set ups and on 2-4s this is the usual way to run, 3-2's can usually be run like this or progressively, but that requires different throttle levers on the carbs.
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