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post #1 of (permalink) Old 09-15-2003, 06:12 PM Thread Starter
 
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Small vs Big Block TBI

I was wondering if there is a difference between the 350 and 454 Chevy TBI setups? My concern is that I know I can buy an adapter plate from summit to allow me to bolt on the TBI but I don't know if one's larger than the other. I wanted to bolt on the 454 TBI, brainbox, wiring, sensors, ect so I could easilly accomodate engine modifications in the future. (I've heard that the 350 TBI doesn't like flowing much more than the 350 cubes and I may be going with a stroker kit in the future). Anyway any help you can provide will be much appreciated. Thank you. NORM
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post #2 of (permalink) Old 09-15-2003, 06:32 PM
 
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Re: Small vs Big Block TBI

There is a difference between the two TBIs. I don't know what the CFM is rated at. My old truck had a 406 in it that wasn't close to stock, and I did nada to the computer and the TBI. It had killer low end torque, kept you pinned in the seat till you let off. I'm pretty sure the computers and harnesses are the same, the chip is definitely different, and heard that some of the connectors are. Don't think you will see very high R's in a 4wd, inless pushing 6k.
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post #3 of (permalink) Old 09-15-2003, 06:46 PM
 
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Re: Small vs Big Block TBI

The 454 TB unit has 2" bores and larger injectors, compared to the 350 unit's 1 11/16 bores. The prom is also going to be different. The 454 unit is definately the way to go, but some chip work is going to be needed to get it to run on a SB. Third gen BBS has lots of info in the TBI and PROM sections.
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post #4 of (permalink) Old 09-16-2003, 04:32 AM Thread Starter
 
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Re: Small vs Big Block TBI

I guess what I'm trying to ask is will the 454 TBI bolt up to a 350 TBI intake? I saw an adapter from summit but it didn't specify what kind of tbi only that it was for GM TBI. I don't want to source all the stuff then not be able to find an adapter for my square bore intake. Thanks alot for the link. I'll be in the background there with my frankenstein plans. The admin there doesn't look like there up for helping anybody except folks with the camaros, ect Thanx again for all your help. NORM
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post #5 of (permalink) Old 09-16-2003, 01:28 PM
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Re: Small vs Big Block TBI

I dont think the big TBI unit is the way to go.
Im not sure why it just doesnt clickn in my head for some reason.

check out turbocity.com for worked over tbi units

http://www.turbocity.com/TBIPowerMain.htm

and other tbi junk
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post #6 of (permalink) Old 09-16-2003, 02:36 PM
 
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Re: Small vs Big Block TBI

The 2" bore TB units will bolt onto a small bore manifold, but the increased flow will be negated because of the intake restriction. If you install a larger TB you will need to either port your stock manifold out to 2", or install an aftermarket manifold. The stock manifolds flow like crap, and there is a good amount of power to be had in going aftermarket. When I build my motor, I'm going to use an edelbrock performer (or EPS) manifold with a 4BBL to TBI adapter plate. The only problem with going this route is that if you eliminate the EGR you are going to trigger the SES light until you retune the PROM. As far as the TB unit is concerned, I plan on using the stock unit at first, but when funds allow I am going to go with a holley replacement unit. Holley TBI It has the bigger bores, and is completely new and won't have to be rebuilt. GM TBI upgrades will fit, such as the injector spacer, and larger injectors. The 454 unit is also a good choice, but by the time you change the injectors and rebuild it, it's going to be the same price as the Holley. Used 454 TB's go for around $200+ on e-bay, 3 times that at a yard, while the Holley unit goes for around $330 mail order. Is this going on a GM motor? [img]images/graemlins/burnout.gif[/img]
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post #7 of (permalink) Old 09-16-2003, 09:04 PM Thread Starter
 
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Re: Small vs Big Block TBI

I'm going to be installing this on my 351W. I've heard the 454 TBI would allow me to perform future engine mods. ie: 390 stroker. I'll be using holley's adapter plate so I'm hoping it will flow the 454 TBI. My motor is currently carbed and I'm hoping that this upgrade will make considerable improvement. I chose this route over Ford's because the amount of crap involved in Ford's swap. I like GM's alternative because it is relatively simple and easy to work with from what I've read. Also the TBI wires into the Ford ignition box relatively easilly. Thank you for all your replies and don't hessitate to comment if you can think of anything that may help. Thanx, NORM
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