I cant afford Fuel Injection. I have a 500hp BBC 468. It has a pretty large cam . Right now I have an old holley carb that sucks offroad. I need something above 750 cfm. Has anybody had any luck with the edelbrock or holley offroad carbs?

http://www.off-road.com/isuzu/gifs/throttlebody/studioTB.jpg

http://www.florida4x4.com/tech/quadrajet/index.php

I cant afford Fuel Injection. I have a 500hp BBC 468. It has a pretty large cam . Right now I have an old holley carb that sucks offroad. I need something above 750 cfm. Has anybody had any luck with the edelbrock or holley offroad carbs?

I put a new holley 750 dp on mine with spring loaded needle and seats and it work good

http://www.off-road.com/isuzu/gifs/throttlebody/studioTB.jpg

What kind of throttle body is that and how much do they cost.

I have an Eldebrock 650 4 pumper with the 4x4 package(spring loaded needle and seats) also took my floats and bent the 7/16" up so when it wiggles its constanly dumping liquid gold.

really have a lick of trouble, and my front end has been off the ground more times than I realy wanted.

jack

for off road ability on the cheap, i'm talking 20 to 50 bucks including a rebuild kit from napa, a quadrajet is hard to beat. most of them are 750 cfm's already. some of the 500 cubic inch caddy's came with 850 cfm quadra's.
i have also heard from other guys running the truck avengers that they are good off road carbs. i have seen one guy in a flatty fall on it's side and still kept idling, when we pushed his jeep back to all four's i was shocked to see that he had a truck avenger. only drawback to this carb is the entry fee, 440 for the big cfm version, which your bb will probably need.

If you can spend the money on a truck avenger then I would contact someone like Jet or the carb shop to build a custom q-jet for your application. If you aint got no money, learning to tune one takes a lot of effort but is well worth it in the long run. read the documents on the site I posted (especially the troubleshooting doc) and you'll be far ahead of the pack.

caddy's had a 800 CFM version which is the biggest of em all. I think the 1978/79 are the best caddy years but I'd try to get a 1980 or newer q-jet off a truck because it has the newer body with the APT adjuster for part throttle mix.

What the hell, I love mine :)

me too

What kind of throttle body is that and how much do they cost.

It's just a random pic of a throttle body. TBI is your friend, and will feed your rat just fine with some tuning.

You most likely don't need more than 600 cfm to run your rat, either.

I am with Tim. TBI.

That or go Q-jet, and then upgrade to propane injection later.............

I talked with the propane guy. he said that I would probably run out of air-volume with my application. I will look into a quadrajet. I have one sitting around. Not sure of the cfm rating though it came off my 350. But I will probably save up for a Holly TBI 950 unit. Its around 1400 thats not too bad. but the multiport units are way beyond what I want to pay.

http://www.pirate4x4.com/forum/showthread.php?t=486402

d00d if you're really going to go efi anyway then collect factory parts and put on a TBI. GM engineered that stuff right and you can customize the eprom with free software. still the q-jet is the way to go

90% of chevy truck q-jets are 795cfm. which by the math is plenty of cfm, in actuality you will most liky starve the motor.







DO NOT RUN AN EDLEBROCK, they are a great drag/road carb but the they are not made for 4x4ing. [this will inevitably start the holley v eddy war but its true]

I run a quadrajet on my 383 and absolutely love it. It took me awhile to get it the way I wanted,but it was worth the trouble.

d00d if you're really going to go efi anyway then collect factory parts and put on a TBI. GM engineered that stuff right and you can customize the eprom with free software. still the q-jet is the way to go

I heard that stuff doesnt work right when you have a radical cam, which I do have.

I heard that stuff doesnt work right when you have a radical cam, which I do have.

That's not entirely true, there are ways around that if you're running a really crazy cam.

Mine is 216/223 @ .050" and there are people running much larger cams than me successfully with TBI.

The best way to avoid problems is to get a cam ground for FI. The general rules is to stay in the 112-115* overlap.

The best way to avoid problems is to get a cam ground for FI. The general rules is to stay in the 112-115* overlap.

Perhaps you mean 112-115* lobe seperation angle.

With 112-115 degrees of overlap, I doubt an engine would even run.

Thanks guys,My engine is already built and solid Im not changing my cam. Current cam specs are as follows Top RPM is 6200 and the cam is advertised 311 exhaust duration and 636 lift.

If I save up I will go with the holly 4di for the 450-600 hp power range. Dont really feel like running a 2 barrel TBI.

Im going to look into finding a big q-jet for now.

Perhaps you mean 112-115* lobe seperation angle.

With 112-115 degrees of overlap, I doubt an engine would even run.


:emb2: yep!

I have an extra 795 cfm Q-Jet w/electric choke and factory throttle bracket that came on my 454. I dropped down to 700 cfm carb for better throttle response and fuel economy.

I talked with the propane guy. he said that I would probably run out of air-volume with my application. I will look into a quadrajet. I have one sitting around. Not sure of the cfm rating though it came off my 350. But I will probably save up for a Holly TBI 950 unit. Its around 1400 thats not too bad. but the multiport units are way beyond what I want to pay.


That's kinda wierd the propane guy told you that. I have a 510cub BB full roller motor 10.5:1 compression and he told me it would work fine?

I've tried several carbs after my old Q-jet needed a rebuild. I tried the Edelbrock Performer Q-Jet, Holly Truck Avenger(both sizes, 670 & 770), and the AVS or whatever that Edelbrock makes, and a Holly 750. All of them were pieces of crap and none of them would run right at an angle but flat. The Truck Avengers did the best, especially the 770, but still ran worse than my old worn out Q-jet. I rebuilt the old Q-jet and have been running it since then and I would never try any of the others again.

What are your cam specs. Mine are pretty radical. It's like a 6200 max rpm cam. I shift at like 6000-6500 when im racing up the sand hills.He said it would run fine but at the upper rpm range I might run out of air volume or something like that.

What are your cam specs. Mine are pretty radical. It's like a 6200 max rpm cam. I shift at like 6000-6500 when im racing up the sand hills.He said it would run fine but at the upper rpm range I might run out of air volume or something like that.

I have a lunati roller cam 1500-6000 rpm. I don't know the specs off hand as far as lift and duration. My truck shifts at 6k

My cam is advertised 311 exhaust duration and 636 lift.
Range is 3000-6200.

Here is what he wrote.

Dear Art,
That is definitely pushing the limits. I can't honestly say how it will do.
It will do great until it runs out of air volume.
Thanks,
Cary

My cam is advertised 311 exhaust duration and 636 lift.
Range is 3000-6200.

Here is what he wrote.

Dear Art,
That is definitely pushing the limits. I can't honestly say how it will do.
It will do great until it runs out of air volume.
Thanks,
Cary

Hmmm...I would be curious to see how it would do on your motor. I am going to be making the conversion soon I'm fed up with carbs:shaking: I'll let ya know how it goes.