So I just purchased an 86' GT It's in good shape, with 115,000 miles and is totaly stock other than a C4 trannsmission and 87-93 GT rear spoiler. It just needs a little bit of a tune up and of course some go fast goodies. I've done a little searching but haven't had much luck finding the info I'm looking for. I know there are some differences between the 86' and latter fox mustangs that require a little different approach to working on them, so any more info or help you guys can give would be much appreciated.

Here's what I know:
Flat top pistons with higher compression
Low performance lower intake and 58 mm throttle body
Low performance heads
Speed Density
Different shocks and struts

After I get it running well I am going to start improving the performance. First, I am changing over to a mass air setup.

I'll then be going with a completely new exhaust from headers to tail pipes. Because of the auto tranny are my choices for exhaust components limited?

Finally, I would like to do a head cam and intake swap, but because of the flat top pistons I am unsure what to go with. Will GT 40 heads work? What is a safe lift for a cam?

Also will 87-93 shocks, struts and springs work on the 86? With or without modifications.

 

GT40 heads will work, but i think u might need different headers to go with them, might wanna check on that. Most all 79-93 Suspension pieces are interchangable. I would prefer a cobra or GT40 intake. The auto does not limit what exhaust components u can use.

 

I have BBK shorty headers on my 86, but it has an 88 motor in it. Pretty much the same i do beleive. It runs real good and sounds great with bbk shorty headers and an offroad exhaust

 

Standard gt40 heads do not require specific headers. You are thinking of gt40 P heads which do require different headers. Now, I am not sure if he would be able to use the stock headers from the 86 (I think they had e5 heads) but standard fox 5.0 headers should work.

 

Kool, Thanks for the insight Joker. I was confused.

 

piston to valve clearance is going to be a problem with the 86. thats why when i had the motor replaced in my 86 i went with a rotating assembly from an 87 to get away from those pistons. almost all heads even the E7TE i believe will need valve reliefs cut into the piston

 

I assume that the piston will have to come out for reliefs to be cut?

 

no, my dad put heads off a 90 GT on his 86 Gt and had no issues. but u cant go to far with the cam with those heads due to the clearence issues.

 

I was thinking that a used set of later model heads might be my best bet. If they are ported and have roller rockers it will be better than nothing. At least until I can afford a new rotating assembley.