Which Carb?

[WelldoneCJ7]

Hey guys I was just looking for some help with carbs. I know there have prob been quite a few other posts like this one but your help is appreciated.

I have a Jeep CJ7, with a crate vortec 330 deluxe, with a turbo 350 with a slightly higher then stock stall about 1900rpm, with 3.73s. It currently has a Holley 600cfm vacuum secondary carb that is needing some help. I am looking at getting a new carb.

I have been looking into the holley truck avenger 670 and was wondering how it compairs to other CARBS, now i know its not going to be as good as injection but I dont have the money to do this. The jeep is primarly driven on street, some off road, snow, and sand dunes, as well as occasional drag race.

Which carb would you guys reccomend for best all around performance as well as ecconomy (if at all possible) with gas prices the way they are. I currently only get about 9mpg with a mixture of highway and city.

Any help is appreciated thanks a lot.

[Home Built]

Put a Quadrajet on it.. I have a couple of friends with the truck avenger and I am not impressed and they are not either..
Quatdrajet is simple and reliable.
Not bad on milage if you keep your foot out of the secondaries..

[dannnthemann]

Use junkyard parts and go efi.

Same price if not cheaper than a new carb.

[GMCTruxrule]

I got a 670 TA on my 454, and the second one I put on there works great.
The first one was a POS.

[odin544]

a vortec 330? is that 330 CI? i think a 670 is a little large for that.

[WelldoneCJ7]

No its a 350ci, sorry about that, they just call it the 330 deluxe crate motor cause its rated at 330hp. I was looking into possibly getting a truck avenger.

Fuel injection would be nice but seems expensive, even if i got junkyard parts wouldn't it still end up being more by the time you get the computer and harness? What type of fuel injection are you talking about MPI or TBI or what?

Thanks for the input guys.

[noface]

I've got a Holley Truck Avenger 670 on top of a 300hp 327. Works great for me.

It was a little tough to tune the idle not to be so rich, but once I got the timing, mix screws set, she'll run at some amazing angles for a carb.

I like Q-jets too, but finding a good one these days if difficult.

[chewingum]

I've got a 750 vac secondary truck avenger on my 383, works great

I'm far from a tuning genious, I just got it out of the box, bolted it on, set the floats and it works.

[dannnthemann]

Originally Posted by WelldoneCJ7

Fuel injection would be nice but seems expensive, even if i got junkyard parts wouldn't it still end up being more by the time you get the computer and harness? What type of fuel injection are you talking about MPI or TBI or what?

TBI is going to be the simplest way to go. Go to the JY and pull EVERYTHING including the harness and cpu. Its gonna take a while to pull but you will be happy.

[T-Bolt]

I have a 670 Truck Avenger and I was happy with it on my maiden voyage. I didn't tune it at all, installed and set the idle speed. It works better than the old q-jet I used to have. The same angles that would flood out my qjet have no effect on the holley.

But you are right, it is not FI. It still has it's limits. It crapped out on me on a few steep ascents (well over 45*, more like 70* on white knuckle hill it died) but never on any descents. I am going to have it tuned and see if that helps.

[florida4x4]

look for a 90's grand am with a v6. the computer can be programed with a AUJP chip for a 350... seach there is lots info posted here.

[Grumpy_old_fart]

Im running an 800 double pumper (list 4780) on my daily driver 350.

its not too big, either. throttle response is twice what the 600 cfm vac secondary (list 1850) was..

if someone is telling you that a 670 is too big, then they just need to realize that they are limiting fuel mileage by making the carb richer with the smaller venturi pulling more fuel over...the same jets in a larger carb wont use as much fuel because it wont have as much signal. makes for a softer bottom end, but a lot more response in the cruise rpm, where the smaller carbs suck.

[gmc4cw]

I have the truck avenger on my 350, same horsepower rating as yours. bolted it on, set the idle, floats and electric choke and have not messed with it for years. it only stalls on really steep descents, you have to have the truck pointed at the ground. I had a quadrajet before that and it would stall on any descent.

[aaronr10]

Originally Posted by dannnthemann

Use junkyard parts and go efi.

Same price if not cheaper than a new carb.

I know you said you want to go carb for $$ reasons, but I agree with this quote. Been there done that! Go EFI, better power and fuel milage.

[Grumpy_old_fart]

Originally Posted by aaronr10

Go EFI, better power and fuel milage.

not true.

maybe the fuel mileage part...

Definitely NOT the power part.

Can it get close? yes. getting close is spendy. carbs arent as spendy for being more powerful.

Sure, a carb wont run upside down. Generally, your tires arent touching anything when youre upside down, anyway, so that probably wont help ya.

Even the drag race guys know this. You think they would run a carb if it could be outperformed?

[WelldoneCJ7]

Thanks for all the input guys, I really appreciate it. So what is the lowest anyone knows a new 670 truck avenger going for (and where) the lowest i have found reciently is 400.

[WelldoneCJ7]

So one other thing i forgot about, the mpg about 9mpg in a jeep with the mild 350, does it seem about like what it should be getting? What do some of you guys get? Any advice on tuning my carb for better ecconomy or is that about what i should be accepting?

Thanks a lot for all the help guys.

[florida4x4]

My bet is on EFI but you have to reprogram it to make it have OMG WOW performance. Due to the complexity learning how to use all the computerized tools, wideband 02, etc, it is a lot to ask for some (me included to some extent). Most people get it running and leave it at that never knowing how very, very flexible, tunable and reliable EFI is.

The second best choice is the trusty old quadrajet IF you don't mind a fairly steep learning and high parts expense ($200 in parts) to tune it. I have collected some very good documentation and have it posted HERE. If you decide to go this route then be sure NOT to buy anything that was remanufactured. Try to get a vintage edelbrock 1904 (350ci), 1906 (454ci) or 1910 (race). If searching the JY look for big block caddy's and later model trucks. Get the specs on the carb number and be sure before you try to tune that you verify the needles and jets are what the OEM specified. If you try to tune with ANYTHING other than the original calibration, you're bound to find only frustration unless you're VERY lucky.

Read and understand the instructions at my link you can tune it to do anything.

[Nskeeter99]

If you are planning on around 400, then you can get a complete tpi from the 85 to 92 vets commaros and firebirds for about 400. That will get you every thing you need and if you get the MAS system there wont be any need to program it.

Skeeter

[florida4x4]

Offroad is no place for a MAF. IMHO. Get a TBI from a late 80's truck or TPI from a 90-92 camaro. The later TPI does not have the 9th injector to fool with and is very durable with the SD (speed density) sensor only. Yeah you gotta tune (or build the engine like a stock GTA transam) it but damn it will rock. The "best" TPI chip for any hot rod project with an auto is PN 16151348.

[44boggers]

all i have to sya is do not use a quardajunk, i had one specially built to my engine specs and i thought it ran ok maybe a little slugish, then i got a 670 truck venger and it felt like i gained about 100 hp, i coudl not be happier with it. and for the price you cant beat it, and setting up a holly is so easy.

[44boggers]

i have one its a 750 just about brand new, probly (mayeb ) 100 miles on it. blue printed carb

[aaronr10]

Originally Posted by Grumpy_old_fart

not true.

maybe the fuel mileage part...

Definitely NOT the power part.

Can it get close? yes. getting close is spendy. carbs arent as spendy for being more powerful.

Sure, a carb wont run upside down. Generally, your tires arent touching anything when youre upside down, anyway, so that probably wont help ya.

Even the drag race guys know this. You think they would run a carb if it could be outperformed?

Okay, I'll agree with you on one point. All out WOT a carb can outperform an EFI system. Just so you know an EFI system will not run upside down, the fuel pick up tube runs dry upside down, you need propane for upside down. EFI will run at any angle as long as there is fuel at the pick up tube. I owned a quadrajet and a Holley truck avenger. I didn't care for the truck avenger at all. I change altitude wheelin to much to bother with constant holley carb tuning. I noticed that once I went to GM factory TBI on my modified 350 with a custom prom, both my milage and power went up. Not the best carb tuner in the world and I know that is the main reason but IMO on average with offroading EFI is the ONLY way to go. Can't really apply drag racing to offroading. It's like comparing apples to oranges. But I do understand you point of view. Just sharing my point of view.

[florida4x4]

Yep that's right all. EFI don't make as much power as a carb (NOT).

I think the main reason anyone runs a carb in drag racing is the rules. Think about it. You have sophisticated electronics that take thousands of measurements per second on a variety of inputs such as Barometric pressure, fuel pressure, Intake air temp, detonation, MAP, O2, knock sensors, etc and then looks up fuel and timing values, averages everything to create the perfect mixture of air, fuel and spark. The ONLY limitation to what EFI can do is solely based on the knowlege and capabilities of the tuner and the power of the computer. How do you think those 6 second 200 mph + single turbo Mustangs get down the track time and time again. With a demon or holley? Damn thing would blow up more than it would cross the 60 foot mark!

EFI is here to stay and will only get better. The fact that the late 80's GM stuff works so well is a testimony to that. It's PERFECT for the off roader because it is cheap and reliable. You just need to invest a little time to learn how to wire it up and what you need to adjust things in software.

[redbeast]

Forget EFI with all the stupid programmers, chips and expenses dude!
Stupid chips and computers trying to do all the thinking and tuning for you.
Leave the computer at the office where it belongs!
I've got a Holley 750 double pumper on my 350. Like someone else said, a little softer on the low end but when it comes to mid range and high end - look out! A lot less expense and a lot more options for high performance builds!
"The only limitation to what EFI can do" is how much money you have in your wallet! Peddle that crap somewhere else!