Hey guys, just curious as to what kind of carbs you all are running on your big blocks. i have a 73 429 with a cam and ported heads in a truck and am thinking about a new carb. while power is at the top of my list, reliability and fuel economy follow close behind. one thought was a holley double pumper of some sort...would that be overkill and would it also kill mileage? how much more power would you get out of a double pumper? another more serious thought was an edelbrock...more than likely a 750. would the 650 work well with a big block or is it too small, and what would the mileage differce be between a 650 and 750?

 

I'd say a 750 cfm with vacuum secondaries, whether it be a Holley or an Edlebrock, should do the trick.

Todd
BB79RANCH

 

I agree with Todd...750 Holley w/vacuum secondarys...stay away from the double pumpers unless your racing only.


Deen Hylton
Ford F250 460 C-6, K&N, Headers, Dual Exh.,Comp. Cams,Shift Kit
Pioneer CD w/Bose Speakers.
Other Passion: Blown 77 Corvette (Sorry Guys/Gals)
How I can afford to Drive the above: 93 GEO Metro

 

carb size will depend on use....if you are going to be mainly in low-rpm's, go with a 600 cfm edelbrock...i have 2 bb's...one has the 600, the other has the 750....600 is enough for a conservative use, but 750 is definitely recommended for bb use....i think that my 429 with the 600 cfm runs perfectly, but the one with the 750 is more versatile

 

deen,

Why the warning on double pumpers? Just put an 850 on my pumped 429. Any info would be appreciated.

dennis
55f100

 

>deen,
>
>Why the warning on double pumpers?
> Just put an 850
>on my pumped 429.
>Any info would be appreciated.
>
>
>dennis
>55f100

Dennis, double pumpers were designed for competition use and are not jetted to give the best fuel mileage Here are a few quotes from "Holley Carburetors" by SA Design: "Vacuum control offers potentially smoother operation and minimizes the effect of a carburetor that is too large, because it has the ability to "size" the carb to the needs of the engine." Also "vacuum control
is typically advised for street, R.V. and recreational boat use, while mechanical secondaries are found in virtually all forms of competition use, the notable exception being off-road racing."
I don't have time this morning to look for more reasons not to use a double pumper but I can find them next week for you when I get back from out of town. I can say that I have been drag racing and off road 4 wheeling and racing for the past 30 years. I used both vacuum operated and double pumped carbs...I've found you'll normally be faster/quicker with a vacuum operated secondary EXCEPT for the following example: Low gearing like 4:10's-4:56's (even steeper gearing if tires are over 31-32" diameter) as a minimum PLUS a manual transmission AND a fairly low body weight...say under 3200-3500 lbs for a truck. When you get right down to it, the double pumper was designed to operate best at WOT, any other throttle position is a compromise.

Deen Hylton
Ford F250 460 C-6, K&N, Headers, Dual Exh.,Comp. Cams,Shift Kit
Pioneer CD w/Bose Speakers.
Other Passion: Blown 77 Corvette (Sorry Guys/Gals)
How I can afford to Drive the above: 93 GEO Metro

 

I would also suggest a 750 vacuum secondaries. You never want to over carburete, but that's kinda hard to do on larger motors. I have a Holley 750 on top of my 460 and it runs great. I would personally suggest a Holley over an Edelbrock. I can't talk from personal experience, but from I've been from everyone that has an Edelbrock on top of their motor are disappointed with there performance.

TBirdGuy

"Stuck with a m*par, Settle for a ch*vy, Happy with a Ford!!!!"

 

Thanks for the great info guys. Looks like I need to add a Street Demonor different Holley to my wish list? Didn't like the Edlebrock 750 I had on it. No problems, I just didn't feel it was performing well.

Dennis

 

so would you guys all agree that the edelbrocks arent that great? it's funny, an edelbrock\carter was actually at the top of my list just because ive heard a lot of good things about them. plus ive run a carter 600 on a 400 and it idled awsome, was easy to tune, got decent mileage and had smooth acceleration too. what kind of a power difference would there be between comparable holley and edelbrock 750 vacuum secondary carbs? if the power difference is minimal, then ill go with the reliability that ive experienced in the past using the carter style...however, i must admit that power IS at the top of the list and if it would make a large difference i would consider the holley instead. thoughts?

 

I've always ran Holleys, but I'm not saying the other brands are bad. Holleys are extremely tunable but there are some folks out there that have had bad luck with them. If your sold on Edlebrock/Carter you may not be satisfied with anything else. I'd say unless your racing in some form of competition where a hundreth or thousandth of a second determines if you win or lose...I'd stick with what your comfortable with. Myself I dragrace, there is probably a 90% use of Holleys over any other brand in that form of competition.



Deen Hylton
Ford F250 460 C-6, K&N, Headers, Dual Exh.,Comp. Cams,Shift Kit
Pioneer CD w/Bose Speakers.
Other Passion: Blown 77 Corvette (Sorry Guys/Gals)
How I can afford to Drive the above: 93 GEO Metro

 

Got a fairly mild cam, ported/polished heads, and a couple other mods on my 460.. runnin about 390 horsepower.
Used an Edelbrock 750cfm. Got about 12-13 miles/gallon.
Threw a properly tuned Holley 750/vac. secondaries on there. dropped 2/10 on my e/t AND gained 1 mpg (average) on the street..
Personally, I like Holleys.. I think they are the best carbs in the world, IF they are tuned right. Ill admit that Carter/Edel has a much simpler tuning system than the Holley, but hey.. Whatever floats your submarine, man. Good luck.

J/.c

1965 Ford Galaxie 500 (okay, so not quite a truck)
460/C6 transplant @ 389hp/491 lb.ft.
14.29@103.8, 13-14 mpg heheheheheh