4.3 TBI on a 2.8 - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 03-25-2000, 09:36 PM
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4.3 TBI on a 2.8

Well, I went out and got a '89 4.3 TBI for my 2.8. It came with the linkage on the throttle shaft that the cables (throttle, cruise control and tranny) attach to, but did not have the bracket that would hold these. On the 2.8, the bracket bolts to the side of the TBI. Apparently on the 4.3 the bracket bolts in front the TBI, on the manifold, and comes back to it.

How has anyone else solved this dilemma? I'm thinking of pulling the throttle shaft out of the 4.3 and putting the 2.8 lever on it, then drilling and tapping the TBI for the 2.8 bracket.

Also, the posts mention that the TPS sensor may need to be re-wired. On the '89 TBI I got, I'm just going to try to swap out the TPS from my 2.8. The IAC comes in two flavors though, one with a collar and one without. The '89 4.3 TBI has the same one as on my '86 2.8, with a collar.

Once I get this done, I'll let you guys know how it works, including the wiring.

Would like some input on the bracket dilemma though... I think I'll take my truck apart next weekend (if the wife doesn't have any plans for me).

Any input is appreciated.

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post #2 of (permalink) Old 03-25-2000, 10:09 PM
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Re: 4.3 TBI on a 2.8

over at http://www.itog.com at there discusion group they
have gone pretty deep into this and I think the bracketry was
part of it (don't rember)run 4.3 tbi through there search engine
hope this helps

<font color=red> ALL THOSE WHO WANDER ARE NOT NECESSARLY LOST </font color=red> [img]/wwwthreads_images/icons/cool.gif[/img]
post #3 of (permalink) Old 03-26-2000, 12:08 AM
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Re: 4.3 TBI on a 2.8

Went to the ITOG group, although they've done a few of these conversions, no one has mentioned brackets.

Still need some help.

Another question: How much does swapping out the stock rockers with 1.6:1 ones help with power/torque?

Thanks guys.

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post #4 of (permalink) Old 03-26-2000, 09:00 PM
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Re: 4.3 TBI on a 2.8

Ok, here is the original post from John G. I found it in the ITOG GID Archive 2:

"he problem: The stock 2.8L TBI on my 3.4L was not adequate. After hearing
the Holley ProJection uses a 4.3L TBI base gasket, the wheels in my mind
started turning. I got a 4.3L TBI for only $45 delivered off the 'net
(thanks to my fellow ITOGgers for the website). After a thorough cleaning
with carburator cleaner, I put it on. IT WORKS GREAT!!! No more surge
during the open-loop and it allows my 3.4L to breath to it's full potential.
No high-tech tweeking or anything. It gets to redline and beyond in a hurry.
Best of all....160 HP with a total GM install, not one aftermarket part
(Actually the best part is the 270 bucks I saved with the 4.3L TBI).
I am sure the stock 2.8L V6 would benefit from this larger CFM too.
The Details:
It was not a direct bolt on, but very close. The four main TBI wires plug
right in. The Throttle Position Sensor (TPS) did not. In 1991, GM changed
the standard TPS style on all of it autos. Therefor the 1992 4.3L TBI I
bought had a different TPS plug-in (but still 3 wires). I simply went to a
local salvage yard and got the male pigtail for the 4.3L TBI. With my trusty
multimeter, I figured out which wire went where. Here is the conversion:
Trooper Black to New Black (Ground)
Trooper Blue to New Blue (Position signal 0-5V)
Trooper Green to New Grey (5.0V source)
Second issue: The accelerator cable linkage. I had to use the shorter S-10
cable bracket that happen to still be on the TBI (thank god). Then I took
the Trooper throttle cable off and ground the end down flatter until it fit
the new style linkage. The 4.3L linkage is a lot different because it kinda
wraps around a pulley thing. I like the throttle "feel" better now. I don't
have cruise control. If you do, good luck.
Thats it...proverbial piece o' cake...$47 and a couple of hours at the most.
Now everybody hurry on over to www.car-part.com before the cheap 4.3L TBI's
are gone!"

Hope that info helps, it may not directly apply to an S-10 but maybe......

Regarding the rocker arms, I put a set of Comp Cams Magnum 1.6:1 rollers on my '90 Trooper (it also has a Holley TBI and exhaust mods). The rockers made a noticeable difference in power, I think mostly in the mid-to-upper range. Still best power is at 3000 and up, but the Holley, rockers,and exhaust made it a lot more tractable between 2000 and 3000. Of course the only solution to more torque after all that is a 3.4! At least all the parts will transfer over. The rockers are a good way to go if you're really not up to a cam change; a lot easier to pull valve covers and replace the rockers.

"Keep On Troopin''......."Blazer'n"?........ed

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