What is the difference in the TB's between the 85-88years and the 89-92years...

thanks
larry

 

Hope this helps...


Induction

The 1985-86 intake manifolds will fit the older small block heads without modification. In 1987 and up, the heads were designed with vertical bolt taps for the two center bolts on both sides of the intake manifold. With a little drilling the newer manifolds will fit the older style heads. The intake manifolds are therefore interchangeable for all small engines. The plenum is interchangeable for all model years thru 1990. The 1990 and up have tapped holes for the mounting of a MAP sensor (right rear of plenum). The throttle body is different on 90 and later models, modifications can be made to the plenum to use the 90+ Throttle Body by drillling a hole in the front of the plenum. Intake tubes (runners) are interchangeable for all model years, however the left intake tube through 1988 has a mounting for the cold start injector, for 89 and up this mounting is deleted.
NOTE: Throttlebodies 85-88 are the same and must be matched to plenums 85-88. To work properly on 90 and up plenums a hole (1/2") must be drilled, between the intake openings where the throttle body mounts, to allow for passage of idle air from the IACV to the plenum. 89 and up throttlebodies will work on earlier plenums without modifications. The fuel rails have a few differences. If the left side fuel rail has a fitting at the end close to the firewall it is from a 1985-88system. The fitting is for connection of the cold start injector fuel line. The left side fuel rail is stamped at the factory to identify same with the engine. The Fuel Rail Identification Table above will assist you in identifying your system as a 5.0L / 5.7L and the injectors furnished with those systems.

 

Very well put there Captain, however there is one thing that is not mentioned there. And that is the fact that the 85-88 throttle bodies use a different throttle cable than the 89 & up throttle bodies.

 

Thank you very much for the info.

later
larry

 

Correct as usual King Friday....