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Thread: Throttle Body

  1. #1

    Default Throttle Body

    Hey guys hope everyone is having a great Holiday season. I was wondering, what do you guys think about switching my 85 454 burb over to a throttle body? Will a newer carb swap right in? Are there kits? Is it worth it?

    Thanks!
    Last edited by crane557; 12-15-2010 at 10:33 AM. Reason: mispell
    1985 c20 Suburban "Amtrack"
    7.4 liter project

  2. #2

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    It's currently carb, and you want to go to TBI, right? Well, you may gain some fuel mileage. You'd have to install a computer, the TBI (TPS sensor, 2 injectors, and I think another sensor on the TBI), an oxygen sensor, coolant temp sensor, and possibly a new intake manifold. It's really relatively simple. All the mods are on the intake with the exception of the exhaust. If you can pull a TBI, intake manifold, oxygen sensor, wiring harness, and computer off a truck for cheap, it might be worth it. Otherwise, I'd consider staying with the carb, and possibly switching to a 4-barrel with a light foot on the accelerator if this isn't already the case. TBI vs carb for performance, the 4-barrel carb would win any day because the TBI is only a 2-barrel.
    Christopher

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  3. #3
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    In addition to everything Crawdaddy mentioned, you'll also need a c.c. distributor & a knock sensor, & possibly a half dozen other things we forgot lol. I went the other way & switched my '88 TBI over to 4 bbl carbed with an HEI distributor for the simplicity, & more power & it actually gets better mpg than the TBI did. 11.9 vs. 8.1.. I would stick with what you have. It is easier for you to work on, & the wiring harness alone will make you wish you hadn't ever thought about TBI.
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    One word from me if you want to "Donor" getting a donor truck will make the switch very simple. Oh and stephan the wiring harness on the TBis really isnt to bad in my opinion. (i had to go thru 3 harnesses before i got the right one). But as mentioned for peroformance a 4bbl will beat the TBi becasue the TBi just isnt designed to flow as well.
    I am personally a fan of EFI. I can work on and repair an EFI system way easier than a carb (this is just because of the era that i grew up in) so it all boils down to personal preference.
    Mike

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  5. #5

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    WOW thanks for all the great replies! It sounds like I may have to stick with the current setup for now, besides who doesnt want more horsepower lol.

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    Quote Originally Posted by murdog94 View Post
    One word from me if you want to "Donor" getting a donor truck will make the switch very simple. Oh and stephan the wiring harness on the TBis really isnt to bad in my opinion. (i had to go thru 3 harnesses before i got the right one). But as mentioned for peroformance a 4bbl will beat the TBi becasue the TBi just isnt designed to flow as well.
    Good point Mike, (3 wiring harnesses before you got the right one)<-- This is only one reason I would talk a novice out of doing this swap.
    The donor rig would be a BIG plus..

    BTW Crane, I thought of a few more things you'll need. A new fuel pump 12-15 psi, & new style f.i. fuel filter & fittings, new fuel lines (2) either a "hard" pressure line, or one of the plastic with the woven metal covering circa 1988-up, & a return line to run the extra fuel back to the tank. You'll probably also have to fit a new fuel tank, as the attachment fittings for the top ring (stock tank) won't suit the new pump installation..

  7. #7

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    Oh...Yeah. The common conversion is going from TBI to carb. You almost never see it go the other way around. I totally forgot about the rest of the fuel system.

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    Well i did go thru the three wiring harnesses because i wanted one that had the tach signal to the dash... it took three because GM isnt exactly forthcoming about information about these trucks and what you are looking for. And it wasnt something someone else had done before. So i had to wing it and be the guinea pig.
    And X2 on the fuel system needing to be updated to accept all of that.

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    "because GM isnt exactly forthcoming about information about these trucks" <--- You're right about that Mike. GM doesn't want us modifying ANYTHING on their vehicles, whether it be upgrading old to new or retro-fitting back to earlier days.

  10. #10

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    I'll take a EFI over a carb any day, especially for a daily driver.

    The easiest way to do this swap is to get a donor vehicle. GM offered TBI 454 started in 87. The one tons and suburbans kept the body style through 91. Find one of those vehicles that have (or had) a TBI 454 and you have the majority of what you need.
    When you hear hoofbeats, look for horses not zebras.

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