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post #1 of (permalink) Old 02-20-2000, 12:52 PM
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4.3 TBI on a 2.8

Has anyone with an S-10 put the 4.3 tbi on their 2.8, like the guys over at ITOG have done? If so, did it make enough of a difference to warrant the effort? I need to pull the intake manifold to fix a minor oil leak, and thought I'd go ahead and have the machine work done to open up the manifold at the same time...

I'm also kicking around the 3.4 swap. Anyone out there done one? Was it as plug and play as reported? Any problems with emissions? I'm concerned over emissions tests as I live in Southern Cal.

I would do both at the same time, but even with 253,000 miles, my 2.8 still will break my 235s loose in a corner, and still goes up the mountains at it's original (blistering fast) 35-45 mph. Maybe when the bottom end goes...

'86 S-10 Blazer, 4wd, 700R-4, Accel coil, K N, new cat and 2.25in exhaust....

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post #2 of (permalink) Old 02-20-2000, 01:33 PM
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Re: 4.3 TBI on a 2.8

Not sure about your question, but my little 2.8L in my '85 with a limited slip rear would smoke up the 235's very nicely! [img]/wwwthreads_images/icons/wink.gif[/img] Still probably will, but with the brand new tires I got on there, I certainly can't afford doin' that anymore...

(I bet you'd like a 383cubic inch V8 much better than the 3.4L.. [img]/wwwthreads_images/icons/wink.gif[/img] Get a dummy truck that has crappy body and put the same vin # on it and keep the small engine, and drop the stroker into your good truck with the same vin#, then put the emissions certification in your good truck... [img]/wwwthreads_images/icons/wink.gif[/img])

And of course, here's my disclaimer of the day:

We all know that The_Sandman_454 would never recommend or endorse anything that isn't legal, however, unless it's in a joking way...


[img]/wwwthreads_images/icons/cool.gif[/img] '79 Suburban 4x4 454, 6" lift, 35x12.5s & '85 GMC S15 4x4
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post #3 of (permalink) Old 02-21-2000, 11:35 AM
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Re: 4.3 TBI on a 2.8

Sounds like my 2.8! I don't do burnouts though, just gravel peelouts.[img]/wwwthreads_images/icons/wink.gif[/img]

83 S10 Ext Cab
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post #4 of (permalink) Old 02-21-2000, 11:56 AM
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Re: 4.3 TBI on a 2.8

I asked the same question about a month ago and this is the response I got:

"I know a number of guys who have done the 3.4 swap using the stock 2.8 manifold, bored out to match the larger Holley or 4.3 TBI. All have passed emissions with flying colors, in CA and WA.

The later 4.3 TBI's have a slightly diff plug on the TPS, which can be adapted to the 2.8 harness. Or, supposedly a pre-'90 or so 4.3 TBI is a good matchup with little or no mods. At around $50 used at www.car-part.com, a lot cheaper than the $314.99 Holley.

The S-10 TBI EFI seems to work just fine, as long as you use the larger TBI. The computer doesn't seem to have any problems adapting to the larger-displacement motor.

If you strip all the extra stuff off the Camaro Long-block, you just swap all the appropriate 2.8 S-10 parts over and off you go.

Depending on the year of your 2.8, it may or may not have a "zero-balance" flywheel. Later model 2.8's already have the right one.
The Camaro flywheel has a different setback and apparently can't be used in an S-10 application."

This is hearsay, sorry I can't be more help. I'm even more sorry I'm still stuck with the 2.8. The only time I can spin a tire is on ice or wet grass. [img]/wwwthreads_images/icons/laugh.gif[/img]

Did the coil, K&N, and exhaust help the 2.8 any?

post #5 of (permalink) Old 02-23-2000, 10:43 PM
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Re: 4.3 TBI on a 2.8

Hi Guys: Thanks for all the info. Looks like I'll do the 4.3 TBI and manifold mods first, and then do the engine in a bit. I'm looking at what the price difference is between a re-built long block or a used engine from a local yard.

As to what has made the most difference, I'd say the exhaust work and the coil. The cat and back exhaust work did make a difference. It firmed up the bottom end a bit, and it does rev a bit quicker. The coil, an Accel unit, was a plug and play unit. I opened up the plug gap .010 and bumped the timing a degree or so. My '86 idled a whole lot better, and, once again, ran better. Note that when you change the coil you'll have to drill out the rivets on the bracket, and then use machine screws with lockwashers to bolt the bracket back up. The K&N just doesn't have a chance to work as the engine, even with 4.11s, just doesn't get up to revs that often, although I do take it up to 6 grand sometimes (when I'm feeling lucky and am only a mile or so from home!)

post #6 of (permalink) Old 02-26-2000, 12:50 PM
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Re: 4.3 TBI on a 2.8

A couple of things. First of all, I may have missunderstood your question but if you are trying to fit the intake manifold from a 4.3 onto a 2.8 it simply won't fit. The 4.3 is a 90 degree vee and the 2.8 is a 60 degree motor. Not sure if that's what you meant. Also, sandman may have missled you a bit. Swapping vin numbers is illegal, so why break the law when you don't have to. Last time I looked, in every where but calif. where they change daly the emmission laws are not too harsh. As long as any modifications you make to you emmissions system are with stock parts from other trucks of your model year anf newer, and all factory emmissions equipment is used, you should have no problem. For example, if your 2.8 is an 86 and you swapped parts from a 90 4.3, as long as all the emmissions stuff was hooked up, you should get the blessing of the DOT. You should check before you do anything but I think that how it works.
Aslo, if you really want power in your S-truck, pit in a V-8. I chucked the 2.8 in my 85 4X4 for a 305 about a year ago and the change is incredable. It's pretty much a stock motor too. Wasn't all that hard to do if you like to work on things. To really boost performance, consider that.
Good luck

post #7 of (permalink) Old 02-26-2000, 01:31 PM
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Re: 4.3 TBI on a 2.8

Just to clarify form the most part what canadagmc said.

In CA at least, you can swap in a motor that's the same or newer year as the truck. You must maintain all smog equipment for the motor you put in. Once you get all that put in, your best bet would be to go straight to a referee because it won't pass the visual test (hmmm, this doesn't look like a v6... how did you shoe horn a 454 in there? [img]/wwwthreads_images/icons/smile.gif[/img]).

Take it straight to the referee and get what is basically a waiver for the visual. When you get your smog check, which should do better than your original motor anyway (is also why they don't mind the motor swaps), you'll be ready for {CA} Bear.

I did a lot of research when I was going swap a 4.3 in my old Toy, and there are NO clear references on what to do in the rules. Your best bet is to go to the smog stations or referees directly to find out the scoop in your area.

Hope that helps...

[img]/wwwthreads_images/icons/shocked.gif[/img]- <font color=purple>J.R.</font color=purple> -[img]/wwwthreads_images/icons/shocked.gif[/img]
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post #8 of (permalink) Old 02-26-2000, 10:56 PM
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Re: 4.3 TBI on a 2.8

In case there is any confusion, here is the link to John Gough's post at ITOG about bolting the 4.3 TBI to the 2.8/3.4 manifold:$WEBMSG.Read.ITOG-2.6783

Here is the text of the post if you don't care to go to the link:

"The 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!"

BTW we definitely are not talking about putting a 4.3 manifold on a 2.8, we're talking about bolting a 4.3 TBI to a 2.8 manifold.
And the post that was quoted here about the 3.4 swap/4.3 TBI was a previous one of mine, it's no B.S. Dudes, just what has already been done and known to work. The folks over at ITOG have been very busy!!

Hope this helps clear things up.....ed

post #9 of (permalink) Old 02-29-2000, 06:10 PM
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Re: 4.3 TBI on a 2.8

I am going to do the same 2.8 to 305 swap.
What transmission did you use?
What bellhousing did you use?
Any help/advice would be appreciated.

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