400 vs 700 trans

[Treverreed]

I have an 89 Jeep Wrangler outfitted with a 350 dual feed carb, 400 turbo trans, 38" mud tires. It gets horrible fuel mileage. I have a 700 trans and debating on swapping it out for better fuel mileage. I don't plan on doing a lot of mud riding. What are your thoughts.

[AnotherWs6]

What gears do you have? And what is your cruising highway rpm? Those tall tires are going to calm your gear ratio down quite a bit, and if your not screaming on the highway it might not help much. Though I believe -and please someone correct me if I'm wrong - the 700 has a numerically higher 1st gear which would help you from a stop since you'd need less throttle to get moving.

Not sure what jeeps come with gearing wise, but a 3.55 combined with 38's would put you right at 2,000rpm at 65. Which is pretty good.

[Treverreed]

Just bought the vehicle last week from someone. Not sure what gears I have. I do know that the guy he got it from was using it as a rock climber. I will check and see if he knows what gears are in it. It has been highly modified.
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[GASoline71]

Fuel mileage is probably gonna suck no matter what.

Gary

[Treverreed]

Yea. I figured it would. Not looking for great fuel mileage but right now it's getting about 5 mpg
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[MalibuSSwagon]

That seems exceptionally bad for a small block. Maybe look into getting it properly tuned and everything. Carb might be overkill for the application too. People usually slap on a "double pumper" cause it sounds cool, but really it's just blowing smoke like a brodozer diesel.

[Treverreed]

I was thinking the same. Didn't see a need for that dual feed. I'm no mechanic so just trying to figure it out and get some ideas on what to do. I bought it drive and have fun with. Won't be rock climbing but may take it in the mud occasionally.
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[MalibuSSwagon]

Could be would depend on how the engine was built as well. Could be you just need a smaller carb like an Edelbrock. There's also a new fuel injection system out called FITech, seems simple for anyone with basic wrenching skills to install and setup, plus it's cheap! It's self learning from what I understand so no need to pay a tuner. Maybe a better investment rather than tracking down a tuner that knows carbs these days.

[GASoline71]

Originally Posted by Treverreed

I was thinking the same. Didn't see a need for that dual feed. I'm no mechanic so just trying to figure it out and get some ideas on what to do. I bought it drive and have fun with. Won't be rock climbing but may take it in the mud occasionally.
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A "dual feed" Holley doesn't mean double pumper. There are dual feed Holley carbs (like a 3310) that have vacuum secondaries and can be had between 650cfm to around 850cfm.

Double pumper is referring to the rear accelerator pump and mechanical secondary linkage.

You could get by with just a "single feed" Holley such as an 1850 that is 600cfm.

You couldn't pay me to bolt on an Edelbrock.

Gary

[Treverreed]

Eric that injection conversion sound interesting. If you have more info please send it to me.
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[MalibuSSwagon]

Here ya go take a look.

http://fitechefi.com/products/

They have the "fuel command center" for an additional $400 but it's really just a "swirlpot" which your mechanical pump on the engine feeds and has an EFI pump inside to feed the EFI. Being an 89 you should already have a baffled tank stock and you should be able to drop in a stock fuel sender with a high pressure GM EFI pump and plumb directly to the throttle body. Lot of reviews and installs of this system out there.

[AnotherWs6]

I know that there are a couple of other systems out there, I've never heard of this one. It's fairly reasoanbly priced. Wish I would have known before I bought a new carb a few months ago. I am keeping this on my radar. Between the cost of the new carb and the the two O2 wide-bands I bought to tune the carb I could have just about bought this system. Think I might actually sell it all now. I've been DDing my burb and getting less than 10 mpg, going about 400 miles a week. Probably would pay for itself in a short amount of time.

Can you see you AFR on the hand held thing? Can you use it while driving? One or two O2 sensors?