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Old 05-25-2006, 11:09 AM   #1 (permalink)
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454 tbi on a 350?

Has anyone successfully put 454 throttle body on a 350 and get it running right? The motor is an 89 350. I have used the 350 injectors and the 454 injectors. I believe my problem is i cannot get the fuel pressure low enough for the 454 injectors or high enough for the 350 injectors using the 454 throttle body. Also i am running a hypertech chip. Either way it still runs better than stock ever did. Come on tbi people, i have researched my head off. Somebody help!
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Old 05-25-2006, 01:37 PM   #2 (permalink)
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i swaped a 350 to a fellow for a 454 and he put throttle body and all off the 454 on the 350 and it runs fine. I think he had to use a throttle body spacer so the butterflys wouldn't hit the intake
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Old 05-25-2006, 03:28 PM   #3 (permalink)
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Do you know what all he used? 454 chip? What about sensors? Does his hesitate when he tries to take off fast?
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Old 05-25-2006, 03:59 PM   #4 (permalink)
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he used everthing off the 454. He hasn't had any problems with it hesitating
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Old 05-25-2006, 09:13 PM   #5 (permalink)
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He would have likely had to redo the tables in the ECU chip to tune it, but unlike a carb
that is to large, a TBI (or any injection sytem) should not have the loss of venturie signal bog that to large a big carb will have.

Should be able to reuse all the same sensors as the 350 TBI unit.
I beleive the after market TBI units all are the 454 throttle bore size, that and injector size is the only meaningful differance between the 454 and 350/4.3.


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Old 05-25-2006, 10:22 PM   #6 (permalink)
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My understanding is that 91C (cop package caprice) injectors are the way to go with the 454 TBI on a 350.

I have also heard of people swapping in a vacuum referenced fuel pressure regulator. Doing this will allow you to have lower fuel pressure at idle and more pressure as you open the throttle more.

...however all of these mods should be matched with a custom chip...
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Old 05-26-2006, 11:51 AM   #7 (permalink)
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Triaged, where do i get the regulator you speak of?
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Old 05-26-2006, 12:41 PM   #8 (permalink)
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Take a look at this
http://home.att.net/%7Enotdadsw41/tbi.htm

He says that GM#17113186 is the vacuum referenced regulator. It is however set at about 18psi. He says you can swap the spring with your factory spring.
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Old 05-26-2006, 01:07 PM   #9 (permalink)
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Quote:
Originally Posted by Triaged
Take a look at this
http://home.att.net/%7Enotdadsw41/tbi.htm

He says that GM#17113186 is the vacuum referenced regulator. It is however set at about 18psi. He says you can swap the spring with your factory spring.
Interesting, The only reason I can think of doing that with a TBI unit is to allow better injector pulse width at idle, but that would more than mess up the "normal" pulse width calculation algorithum in the standard 7747 ECU.
May have to do some fancy coding on that setup.

(On a port injected unit, the vaccum regulator is there so there is a constant presure drop across the injector, so the flow rate is only a function of pulse width, for a TBI where the presure drop across the injector is referanced to ambiant, adding a vacume referance would make the flow rate a function of both vacume and pulse width)

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Old 05-26-2006, 01:33 PM   #10 (permalink)
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Quote:
Originally Posted by mdill
May have to do some fancy coding on that setup.

(On a port injected unit, the vaccum regulator is there so there is a constant presure drop across the injector, so the flow rate is only a function of pulse width, for a TBI where the presure drop across the injector is referanced to ambiant, adding a vacume referance would make the flow rate a function of both vacume and pulse width)

Mike D.
I have never tried this myself...I heard about a guy on gm-ecm doing it. He had a high reving engine and couldn't get enough fuel flow at high RPM's and good idle quality without using the vacuum reg. He said no special "coding"...just fudging the Vol. Eff. map. You are right though...it shouldn't be needed on a TBI for the reasons you stated...but with injectors running about $200 he might be able to make the 454 injectors work at idle.
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Old 05-26-2006, 08:09 PM   #11 (permalink)
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Ok, im trying the 454 injectors with the regulator turned all the way down. heading to harlan, ky for a ride so ill get back with you on how this does. thanks so far.
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Old 05-27-2006, 10:41 PM   #12 (permalink)
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I am doing the same set up on my sroker. I chose the 454 because I need the CFM that it offers.
You may have to change the injectors to 350's, they swap out pretty easy.
My experience so far is that the 454 tbi runs to rich even with the fuel pressure dropped down. You will have to have a custom chip made and the best way to do that is plug your laptop into the aldl port and log some data while you drive so you can send it to whoever you use to make your chip. That way they can see exactly how your truck is running.
The program I am using is freeware called winaldl. Pretty straight forward.
Lot's of good info here...http://www.binderbulletin.org/forums...ad.php?t=47254
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