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What would be the best carb set up to to run for my 186 soon to be 192. i calculated it would need at least 420 CFM, but i'm tossing up whether to run triple strommies, twin strommies, or a 465 holley. I know the holley is easier to tune, but i'm looking for power. I dont quite know whether the twin setup would feed the engine properly because i don't know the carbs CFM rating.
Fcuk Psi
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How did you get 420cfm? I worked it out to be 280cfm max, for a 186 at 6500rpm and 80% volumetric efficiency (both being generous).
Calc is (3.625/(12x2))^2 x pi x 0.25 x 6 x rpm, then divide by 2 as it's a 4 stroke and then multiply by the volumetric ef |
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equation as given by street machine: 192 x 6500 (forged pistons all balanced etc) divided by 3456 divided by 0.9 VE = 400 CFM (fine i made a small mistake) This engine won't be standard at all, the only part that will be standard will be the crank. other Edited by user Wednesday, 28 February 2007 3:00:07 AM(UTC)
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Hi Guys.
boom, that ve figure of 0.9 is the problem. Engine designers, the world only dream of a 90% volumetric effeiciency. In Byrons calculations he uses 80% & that is generous.
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what would a realistic ve figure be for a 186 with the following specs:
bored to 192
Forged pistons
Hei dizzy
Worked head
Triple Carbs or a 4 barrell holley
33/73 billet cam
matching valve springs
straight cut timing gear
Blue 202 rods
Steel For
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Be careful of what you read, and make sure you apply it correctly. Street Machine make mistakes, and they have here or you are applying wrong.
By my calculations (someone please correct me if i'm wrong) cfm of an engine goes like this:
cfm = (bore/2x1 |
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While considering all this maths, something else comes into play. Holleys Use different pressure drops on 2 & 4 barrels carbs when they are rating the flow. They use 3"hg to rate 2 bbls and 1.5"hg to rate 4 bbls. Which makes it hard to compare 2 bbl carbs
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Out of interest, what size carb did the 4BBL Hemi Pacer run? And was it rotated.
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Gotta agree with Sandman here...in my experience, the 465 is an EXCELLENT carb for the larger Holden 6's and light years ahead of a 350 Holley...
I have heard of people running Quaddies on 202's quite happily...but they'd only be using a small fraction
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Boom
I think your carby choice may be clearer now.
I did successfully run a 390 4BBL on a 202 in an LX hatch many years ago, using an old CAIN manifold with the big square runners, which are hard to find today. Most 4BBL manifolds nowadays look like the |
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Boom, I have for sale a set of triple SUs on a Cain manifold, also have twin strommies (matching) on a Cain manifold. http://cgi.ebay.com.au/w...=170085162646&rd=1&rd=1
Also have twi
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Well Boom, there's your answer. A set od triple SUs will outperform a Holley in my opinion. BUT only if they're running properly, so if your good at tuning or know someone that is,. plus can find parts for SUs. I had some 1 3/4'SUs and they were get.
I g
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BTW. I'm not sure what size a std 4 bbl 265 ran but i have seen a 600 vac sec Holley running real well on one. Also I saw a quadrajet tried unsuccessfully. Perhaps more time tuning might have got a better result.
From what I have seen, most spreadbore
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I use a modded Q Jet on my worked 202 powered HR and it is mint great throttle response, great fuel economy (For what it is)and heaps of power when the secondarys open,no lag or hesitation at all.My son drove it for a year and he and his mates said that
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well, that's half of the answer complete. 465 or Q jet? what needs to be modified on the q jet to work?
Fcuk Psi
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My preferce would be a 465 Holley.
1. It will bolt to most manifolds as they are usually square bore.
2. Plenty of parts easily available for Holleys.
3. Closer suited to your engine size.
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Boom here is a bit of imfo on Q jets and modding them http://www.geocities.com...ures/quadrajetTech.html and http://www.florida4x4.com/tech/quadrajet/ There are a few other pages out there as well if you want them if you need to ask any que Edited by user Monday, 5 March 2007 8:31:37 AM(UTC)
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Sandman all of my 6cyl red 4 barrel manifolds have been duel pattern and I have just swapped the studs to suit the various carbs I have fitted.?? Holden V8 4 barrel std manifolds are spreadbore and have to have a addapter to suit squarebore carbs dont the Edited by user Monday, 5 March 2007 5:48:56 PM(UTC)
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When working out the V/E of a engine I was told and have read to use about 70%V/E for std pollution production engines. A full race engine may get 95% V/E and the only way to get over that is to forced induction ie turbo, supercharging or N2O.One of the p
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