'86 5.0L upper vs '88 5.0L upper questions???
 

I tried to install a 65mm TB/EGR plate on my '88 GT this weekend with endless problems. Upon removing the originals, I sheered off the studs holding them all to the upper intake manifold. I had a spare upper from an '86 5.0L I decided to use rather than get the studs machined out. I tried the "Easy-Out" route and broke them too!!! The '86 upper looked slightly smaller at the mouth, but otherwise identical. I ported the mouth of the '86 upper to match the 65mm TB/EGR spacer and installed it to the '88 lower, hooked everything back up, adjusted the TPS, and it ran like crap! There's idle surging, black smoke, and it sounds like it's missing a cylinder (all plugs/wires are good). It smooths out at high RPMs, but there is still the sound of a miss or something. I thought it might be a gasket leak, so I pulled it all back off and reinstalled again with new gaskets and RTV with the same horrible results. Could it be the upper from the '86 5.0L causing the issue? I thought 86-93 intakes were the same with exception of the 58mm TB on the '86, and the 60mm TB on '87+. HELP!!!

RE: '86 5.0L upper vs '88 5.0L upper questions???
 

no regard to teh forum, but what rims are those? are those the black cobra r's?

RE: '86 5.0L upper vs '88 5.0L upper questions???
 

Black89GT: They're Dynamic Racing's Anthrocite wheels.


I figured out my intake issue. The vaccum line running to the MAP sensor was split open in the back. That'll do it!!!

RE: '86 5.0L upper vs '88 5.0L upper questions???
 

Hey,
If i were you i would take that 86 upper off and replace it with one from 87 or better. The reason is that the 86 intake is smaller once you get past the throttle body. If you take it off and compare it to the other ones you can see the track leading into it from the under side. I found this out when replacing mine on my 86GT.