Hi:
I have a 99 regal V6 FI with a seized engine due to coolant loss thru the plastic intake manifold. I bought a 2004 assembly-line replacement engine. The 2004 engine has an aluminum intake manifold. The problem is that the throttle body controls on the 2004 are electronic while on the 99 the throttle body is cable controlled. The throttle body housings do not interchange. My question is, is it posible to adapt the plastic 99 throttle body to the 2004 aluminum intake? Has anyone done this successfully? Thanks

I do not know of anyone that has made that conversion. The problem will be adapting the plastic UIM from the SII 3800 to the SIII 3800 lower intake manifold. I am quite sure there are differences. The purpose of the SIII 3800 and the aluminum upper intake was to get rid of the problems associated with the plastic UIM. If you figure out a way let us know. Good luck.

Welcome to AF.

I was hunting an aluminum intake for my 5.3L Silverado and observed many 3.8 intakes and parts on ebay. You might be able to find something you can use off a newer 3.8L.

I don't believe he will have any success. Reviewing his question I guess he was wondering whether the older throttle body from the SII 3800 would adapt to the newer SIII 3800 he appears to have purchased. I don't see how he is going to get the IAC, TPS and linkage system to work.

You cannot retrofit a plastic UIM from a SII 3800 to the newer SIII 3800. The lower intake manifold is different.

He might have to find an aluminum manifold for his year computer controls if it will fit the engine. So far the closest thing I've found is an aluminum intake for a 2000 to 2004 camaro and one for a corvette for $599.00 since it was a little more than I want to pay I didn't check if it would fit my 5.3L silverado. But if mine starts leaking I will check a lot further.

Thanks for the replies. I want to keep the aluminum intake plenum to avoid the problems of the plastic plenums, if possible. It appears there is no bolt-on aluminum upper intake plenum for the series II engine available anywhere. Since the throttle body housing bolts-on to the intake plenums on both the series II and the series III engines, my thinking was that it might be possible to machine an adaptor plate so the throttle body assembly from the series II could simply be bolted-on on to the aluminum plenum of the series III engine. Is this only wishful thinking? Thanks

Check this adapter plate http://www.mpefab.com I'm not 100% sure what you want but this looks like what I think you want.

Is this only wishful thinking? Thanks

Probably so. How do you plan on getting the accelerator linkage setup? Also, the SII Throttle body is heated. Coolant flows through it so any adapter would have to be fabricated to consider this. Also, the TB on a SII is only 65mm as far as bore size. The SIII TB is 70mm and 75mm for the supercharged version.

There is a guy on this forum that did the very thing you are asking about. (look at the picture)

http://theoildrop.server101.com/forums/showflat.php?Cat=0&Board=UBB24&Number=576838&Searchpage=2&Main=576822&Words=lght1&topic=&Search=true#Post576838

http://theoildrop.server101.com/forums/showflat.php?Cat=0&Board=UBB24&Number=576310&Searchpage=3&Main=576300&Words=lght1&topic=&Search=true#Post576310

I'd contact him... Suppossedly there is a throttle body conversion bracket.

Also, you could use your new engine, take off the aluminum manifold, and put a plastic DORMAN manifold on it. That might solve your problem.

Thank you so much JmLangeveld, this is exactly what I was looking for.
Thanks again!