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 4 Barrel for small cube motor. 
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Joined: Wed May 10, 2017 7:39 pm
Posts: 18
I have a 200 cubic inch v6 that i am looling to put a 390hp onto. I picked the carb up years ago and have finally got something that i think would go well on. I have began the de-nascar process by ordering new throttle blades without bleed holes. I have done one before but never got to tune it. On it i looked at a couple different emulsion set ups on 350 holleys and a old 320 economiser sort of carb. I blocked all of the bleeds and just ran it nut as i said never got to play after that. On this one i am going to do the idle restrictions back down low as they are up the top. Emulsions i was thinking of doing the same again and leaving them all blocked to start like the other carbs here for smaller cube motors

I was wondering if i should change the boosters? I have read out there in internet land of good results with annulars on 390s with small displacement motors. I am willing to buy the tool to have a go myself.

Any suggestions on something for a good baseline to get ģoing so i can tune from there?


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Tue May 16, 2017 6:02 am
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Joined: Mon Jul 04, 2016 11:37 pm
Posts: 48
I have this XNascar ford V-6 and it's 270 cid and I have ran twin 660 center squirters with one barrel blocked off,annular booster 9380,a carb shop dogleg booster 850,a QF SSR-780-VS and a single 660 on methanol all have ran pretty decent except so far the 9380 annular booster carb.but I'm still tweaking on it trying to get it to lean out runs really rich with the stock jetting so far this weekend I'll be down to 80's without a power valve, if this helps.


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Tue May 16, 2017 10:42 am
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Joined: Wed May 10, 2017 7:39 pm
Posts: 18
Wow! That v6 is an order of magnitude more hard core than mine. Good ro know big carbs will work. I may meed to look at my engines cool factor now though


Thu May 18, 2017 3:48 am
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Joined: Wed May 10, 2017 7:39 pm
Posts: 18
Stripped down the 390hp today, had to repair some threads, need to order some thread inserts for the throttle plate to the main body. All the emulsion grub screws were seized just enough to strip the allen key drive out so they wouldn't come out, found a left hand drill bit that was the perfect size that worked awesome, they all picked up and screwed themselves out except 2 that I drilled out completely and will re-tap once my spiral taps arrive.

I went out on a limb after ringing around and not finding anyone close who was interested in modifying holleys, so I bought the booster install tooling and some annular booster banjos. I also got some down leg annular style ones from BLP as well, they were really helpful, I'd say they would think I'm crazy for wanting to try annulars in a 390 though. So i started the experiment and here is were I am at.
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They definitely do appear to block the hole but I measured the areas at the points of most restriction and it only looks like it will restrict flow by about 10% fo the booster insert with the large ID and 15% or so for the other one with the .500 ID.

I have had a play on pipemax and even with some optomistic numbers the restricted flow with the different boosters will still be more than enough. On paper...

Anyway this little gem I found in the boot of a car I bought once is what makes me think its not totally stupid
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8)
I had a 45mm weber DCOE on 121in motor that flows more than the 4 barrel and it tuned up real nice so I am sure with perseverance I can get this holley to work.

Thanks for a all the info on this site it is very helpful and reading peoples journeys from noob to expert has helped me not to worry to much and give this stuff a go. Cheers


Thu Jun 15, 2017 7:04 am
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Joined: Wed May 10, 2017 7:39 pm
Posts: 18
So a question, what would be the best booster to start with, .600 ID 12 hole or the .500 ID 16 hole? Looking at around 1hp per cube to start with so roughly 200hp, maybe a bit more if I can afford better cams but NA i think that is probably as good as it gets as it is now. Nissan 3.3lt VG33E, 5 speed manual trans 2200 pound car. 4.33 diff ratio.


Thu Jun 15, 2017 7:10 am
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Joined: Fri Feb 08, 2013 5:50 pm
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.600 16 hole booster. For a carb that small a .435 step down leg will be fine.


Thu Jun 15, 2017 9:47 am
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Joined: Sat Jul 25, 2015 2:31 pm
Posts: 75
1972HO wrote:
I have this XNascar ford V-6 and it's 270 cid and I have ran twin 660 center squirters with one barrel blocked off,annular booster 9380,a carb shop dogleg booster 850,a QF SSR-780-VS and a single 660 on methanol all have ran pretty decent except so far the 9380 annular booster carb.but I'm still tweaking on it trying to get it to lean out runs really rich with the stock jetting so far this weekend I'll be down to 80's without a power valve, if this helps.


So, what were the HP differences between all the carbs you ran?


Thu Jun 15, 2017 1:26 pm
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Joined: Wed May 10, 2017 7:39 pm
Posts: 18
jmarkaudio wrote:
.600 16 hole booster. For a carb that small a .435 step down leg will be fine.


I only have the 12 hole in .600 here. Id have to get some more sent over unless i can find an Aussie seller of BLP inserts?

Do they push back out of the banjo without damage? I could try 12 holes and swap out if needed.

I will measure the downlegs i have here, will they provide as good low down response and drivability as the annulars?

Thanks for the pointers.


Thu Jun 15, 2017 3:24 pm
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Joined: Thu May 14, 2015 8:11 am
Posts: 149
zok race carbs up in capalaba qld uses some blp stuff. no idea if he would have what you want though.


Thu Jun 15, 2017 5:36 pm
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Joined: Mon Jul 04, 2016 11:37 pm
Posts: 48
Not sure on the hp because I only dynoed with the 850 dogleg boosters and that carb went 10:30's at 128 mph,the QF ssr 780 went 10:20's at 131 mph the 660 dual carb set up went 10:05 129 mph really good .60ft 1:34 best and 6:46 1/8 mile and one single 660 went 10:50's 10::60's 125 mph and so far the 9380 hasn't ran to good on the V-6 I won't be trying that carb again until next year.


Thu Jun 15, 2017 5:53 pm
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