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4BBL and intake design


Guest nikko74z

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Guest nikko74z

Who has pics of their 4bbl intakes. I have a 4bbl intake that bolts to the SU intake. This automatically gives me equal length runners with fuel coming from a central location. My Holley 600 was built by Precision Racing Carbs. These guys are great. The guys in NHRA Pro-Stock run these carbs. The car runs great. It runs the strongest it has ever run. I had Weber 40's on it. They ran strong as well. I would like to get a set of 45's. I have read that the 40's are to small on a stroker. With the holley on my street car, I ran a 12.79. I ran a 12.91 with the webers. I will take a picture of the intake and post it by this weekend. I have an Arizona Z intake on another stroker. I have not been able to get number 1 and 6 to burn as nice as the other cylinders. They run lean when the others are on the money. I have a couple of ideas for a single carb intake. Someone mentioned a dual plane design for BMW. Is that right? I am even considering running two 352 carbs. The idea was suggested by Chris at PRC. Any of you guys have any ideas?

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I am using the AZ 4bbl manifold with a Holly 390 cfm on a stock 2.8 with flat top pistons. It works well. I live at 2800 ft so I had to go down two jet sizes and change the accelerator pump cam to get rid of a bad stumble. The benefits of the 4V are electric choke (no choke cables), no dampener oil to refill, tidier engine bay, and easy to find parts. There are NO cylinder distribution issues with the AZ set-up. I could not tell any power difference over my home rebuilt SU's with the tricks shown in the Z Therapy video. I never had problems with either SU's or 4 bbl once set up properly. Jetting the SU's spot on is a little harder because needle profile is more difficult to modify compared to changing jets, cams, and power valves. BTW, the small main jets needed are not in the standard Holly jet package, they have to be bought in seperate pairs. MPG was unchanged between the two. My case is comparing good SU's to good 4V set-up, not the usual situation. Just my .02.

Will Piatt

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  • 1 month later...
Guest 305240

WHP, I've got the same setup in my 77. I also have a complete Monza exhaust. What size jets do you need for the 390? The PO told me they needed to be jetted down. He already did the Acelorater pump mod.

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I would really like to see any pictures that you have.

SU intakes kinda of puzzle me.

77_1_b.jpg

This is equal length runners? :confused2

 

4barrel.jpg

But this is not? :confused2

From the pictures, I would say the SU intake is closer to equal length than the 4bbl by quite a bit.
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Nikko..youur manifold adaptation may have been offered by a company called Car Tech. I have found the following companies offered 4 BBL and usually for Holley 390 CFM application for the Z.. Clifford Research 6=8, Cannon, Offenhauser and of course Car Tech. Arizona Z and MSA may be the only company (s) offering the 4 BBl adaptation. I would like to find the Car Tech 4 BBL adaptation on eBay or a classified forum. As for equal length...I will flip a quarter over that since both appear to be an attempt at equal length... Arizona Z won !!! (this time)

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Guest 305240

Thanks. I live around the 1000 foot mark. I was having troubles with mine backfiring when under a slight load, but ran good when the 4 bbl opened. First, I had to undo the PO's screwups and got rid of that huge vacume leak. He had the valve cover hose just hanging, and a PCV valve going to the crankcase. I read the post from ArizonaZ and did it their way. Still had the poping. I got rid of those junk Bosch plugs and put in a new set of NGKs, dropped the fuel pressure down to 3 1/2 from 4, adjusted the floats and the air mixture. All I can say is WOW! This has to be by far the most easiest, and the most reliable szetup on the market today. I'm not going to be in a hurry to tease the twin turbos just yet.

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