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I've been looking at trying this, and reading through old posts. I still have questions, this is my only vehicle ATM so I want to do it right.

What has to be taken off the 2.8 throttle body and put on the 4.3 besides injectors (my blazer is an 86 2.8 and I know where an 87 astro with 4.3 is)?

Do I use the 2.8 tps or the one on the 4.3? Do I use the 2.8 idle air valve or 4.3? On another site I saw mention of having to make idle adjustments, it was on Isuzus. Will I need to make adjustments idle speed and other things?

Thanks for help.
 

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Both TPS and IAC should be the same. If not, you use the parts that fit the throttle body you are using. The signals/control are the same.
 

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Correct me if I am wrong, but, if what are planning is to put the 4.3 throttle body on top of the stock 2.8 intake, I don't believe it will work because the bores and butterflies on the 4.3 throttle body are bigger than the holes in the 2.8 intake.
 

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Awww..you ain't got shit!
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Despite what I read I believe that it wouldn't open all the way, I remember sitting the 4.3 TBI on the 2.8 intake stock and it did open all the way, but without the plenum being bored it's a waste of time. It cost me like $70 I think to do mine.

Cut the gaskets when you replace them...not worth the time to pull the rods. People will say not to do it, but I've done it plenty of times without issues. Just make sure to use a little RTV to keep them in place.
 

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You need to enlarge the intake bores to 4.3 size,mark it using a 4.3 tb gasket.As I recall the the Astro and Safari van 4.3 TBI fits without throttle bracket / linkage needs no mods.
 
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