Carbs... Not just for nutrition

HDTony · Nov 23, 2010

Alright here comes tony's question of the week. Im doing some more shopping and im moving up the engine from top to bottom.

347
Afr 185 comp heads
Edelbrock intake
Comp cams 1.6 rockers
One of fti's badass custom cams

Yada yada yada

Im shopping for a carb, looking at hollys 770 or edelbroke, anyone have any input on carbs? The more i read, the more i realize theres just too much information on the web and i dont know who to believe

blown65 · Nov 23, 2010

Well, I love my Prosystems carb on mine. Runs great and they have great customer service.
Demon's are good carbs too, but I wont give BG a dime of my money after all the BS with their leaky fuel pumps.

Actually have 3 of their carbs on different cars. Never had luck with the edelbrock carb, but I know a few ppl that seem to like them.

woodsnake · Nov 24, 2010

I prefer Holley's myself. What kind of transmission and rear end gear ratio are you running? I think for what you've described, a good old Holley vacuum secondary 750 would fit the bill. However, there is something to be said for custom carb work, like custm cam work, custom head work, etc...

D.Hearne · Nov 24, 2010

Carbs ? Nothing like multiple Holleys on the same engine. Love my tripower on my 331. No muss, no fuss, just dead on reliable for 6 years now.

HDTony · Nov 24, 2010

T-5 trans and i have a 9" with a 3.70 gear on its way. I'm partial to holleys, but only because its what has been on other cars ive owned. I've never actually purchased a new carb before.

So a 750 vacume secondary would provide the proper volume for this motor?

68RCodeConv · Nov 24, 2010

I've got a 347 with worked Dart Pro 1 heads, Cobra intake.

I've run both a VS 750 Holley and a VS Edelbrock 750. I liked the Holley just fine but I kept having idle problems with it and I just got tired of fiddling with it. I got the Edelbrock and maybe lost a few HP (like I care on the street) but all I had to do was make one metering rod change and it runs great.

Holley will make more power with some tuning but an Edelbrock is pretty much set and forget.

coolblue65 · Nov 24, 2010

I have the 650 mighty demon and really like it. I had a edel. 750, and i liked it for most driving, but it just didn't seem to have the punch the might demon does.

robbz28 · Nov 24, 2010

A holley 750 vaccum secondary would be a good carb, but if gas mileage is no issue something like a 650 double pumper would really liven things up. Something about that mechanical secondary and that Instant gratification you get when you smash your foot into the floorboard always made it worth it to me, but whatever carb you get make sure you have it tuned, makes all the difference in the world. But in fairness I have never used an edelbrock, but have heard good things.

HDTony · Nov 24, 2010

Ya know that is a question i had, what is the difference of a mechanical secondary?

D.Hearne · Nov 24, 2010

HDTony said:
Ya know that is a question i had, what is the difference of a mechanical secondary?

Mechanical secondarys open all the way when you nail the go pedal. Vacuum secs open with engine demand, but can be tuned to open early or late as you like (on Holleys) And as robbz298 suggested, if you go with a mech carb, go smaller on cfms.

HDTony · Nov 24, 2010

D.Hearne said:
Mechanical secondarys open all the way when you nail the go pedal. Vacuum secs open with engine demand, but can be tuned to open early or late as you like (on Holleys) And as robbz298 suggested, if you go with a mech carb, go smaller on cfms.

Gotcha, thanks for the explanation

robbz28 · Nov 24, 2010

A vaccum secondary is better on fuel because you run around on the rear two barrels (approx 350 cfm) only pulling fuel out of that side of the carburetor, until you nail it, then the rear barrels will slowly open (usually around 4000 rpm) and the car kind of eases into the power. On a mechanical secondary you can run around at around 1/3 throttle with the front barrels only, but then the rears open the further u press, but when you press they all 4 slam open and if everything is tuned right that baby will go! Anyway, since you asked about vaccum and mechanical, D did a fine job I just wanted to tell you a little more, its late and im bored.

65FBE2 · Nov 27, 2010

I have a 347 that is very close to what you have described. I ran both a Mighty Demon 650 DP and a Holley 750 HP carb during a recent dyno session and the Demon made the most HP by just a hair (about 3-4 hp different) I don't know what these dyno guys all look at but during the testing the fellow running the dyno said that the motor was not carb limited even with the 650. I have gotten 19 mpg with it with 3.55 gears and a T5 with a .74 custom 5th gear. The motor made 465 hp. I would buy the Demon again in a heart beat. Depends on the cam duration as to which Demon you should select.

jcp123 · Nov 27, 2010

For performance, your Edelbrocks probably won't be the ticket...Holley and Demon are better any day of the week.

Having said that, I ran an Edelbrock on my ol '68 and loved it, and currently run a Carter AFB (upon which the Edelbrock is based) on my 'vert and love both. Great response, easy to swap metering rods, good mileage, and both seem to hold a tune perfectly. Probably a better day-to-day carburetor for the daily driver/cruiser.

HDTony · Nov 28, 2010

Thanks for all the help guys! Very informative.

PoppyMod · Nov 30, 2010

HDTony said:
Alright here comes tony's question of the week. Im doing some more shopping and im moving up the engine from top to bottom.

347
Afr 185 comp heads
Edelbrock intake
Comp cams 1.6 rockers
One of fti's badass custom cams

Yada yada yada

Im shopping for a carb, looking at hollys 770 or edelbroke, anyone have any input on carbs? The more i read, the more i realize theres just too much information on the web and i dont know who to believe

I believe in a custom build. After all, you provide the specs, and you get an out-of-the-box that's closer to "right" than off the shelf and 6 months of tuning. Previous to these Webers, I ran a ProSystem 680 Holly XE. It was perfect OTB! But, I do love my Webers too!
Go Custom!

Carbs... Not just for nutrition

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