djd2392

So i did alot of research as to why my spark plugs didnt fit, as it would turn out the motor in it is actually from a 86.. now from what Ive read the only real difference is the heads, which is why they made less power from the factory compared to the 87-93..is this true?

Mike T

Here's the history of the 5.0, 82-93...http://phystutor.tripod.com/stang/engines/50.html

capri debris

The heads are not the only difference... the pistons are true flat tops with no valve reliefs.

djd2392

also i notice the compression ratio is different, I mean it's really not a big deal, its the same block and aftermarket parts are gonna be the same haha

Js88lx

Waw.., well atleast you know why the plugs didnt fit..LOL

tinman

If I remember right '86 has a positive deck hieght, meaning the pistons at TDC are above the deck of the block.........

djd2392

lol yeah i found out last night, the previous owner texted me and said that either the heads are off an 86 or that the whole motor is, as far as im concerned its not a big deal, the extra 25 hp i lose from the factory is becoming negligible at this point haha

capri debris

Don't make the mistake of thinking you can put any head on an '86 stock block and pistons... you'll without a doubt have piston to valve clearance problems. The piston valve reliefs in the '87 and up engines are there for a reason. Pretty much the only heads you can use on a stock '86 bottom end are the stock heads... or Trick Flow Twisted Wedge heads, designed specifically for true flat top pistons.

I own 3 '86 Capris and have done extensive research on this. Some will tell you they got away with installing GT40 heads, etc... but they are the ones who got very lucky with P to V clearance due to manufacturing differences and can physically only have a few millimeters of clearance and are only a blink away from detroying their engines if they float the valves even once.

djd2392

where is the serial number for the motor? I kinda wanna get total closure on this haha