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12v heads

1071 Views 9 Replies 7 Participants Last post by  BC847
Are the heads on the 89-93 12v not the same as 94-98 12v?
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The heads are almost the same. The 2nd gen has a little different port configuration on the intake side. It flows a little more air. Around 5% is the number I have read on the subject.

The early nonintercooled engine has a different size injector bore. It is a 9MM tip size. They were known for cracking. Stay away from them.

The head from the 91.5 to 93's were the 7MM injector tip size like the 2nd gen's.
so what is needed to put the 9.1+ head on a 89-91.5 motor? Just the head and injectors, or ?????
All you need is just the head and the correct size injector to fit a 91.5 + head.
so could the 94-98 head bolt up to a 1st gen?
The 94/98 heads will fit with no problems on a 91.5 +.
The 94/98 heads will fit with no problems on a 91.5 +.

Only 91.5 up or 89 to 93?? Im sure some day my head may give up. How do you know when the 9 mm head cracks. Where do they crack and what is the symptoms.
The crack between the injector bore and the valve and will have the same symptoms of a blown hg

The four front cylinders on my head are cracked but not leaking yet
Be aware that the 2nd gen head may not have the bolt holes for the 1st gen throttle bracket drilled and tapped.

It's no big thing. The boss for the mounting of the throttle bracket is there. Just position the bracket where it should be, drill the holes, and tap as usual. :thumbsup
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