- Dec 24, 2006
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i just pick up a stock 86 5.0 h0 motor only, can someone advise me on the internals on these motors?........such as pistons,heads and cam spec's compared to 87-93 ho's.
86 302 HO Q's????
- Thread starter justintx75
- Start date
- Dec 24, 2006
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skunk21
Active Member
The 1 and only year for true flat top pistons. The pistons them selves are the same forged aluminum casting used until1993. The motor shares the same crank and rods. The 86 has the worts flowing stocks heads like already stated E6's, cam is pretty close to the same save for minor varations in duration and events. The upper intake has a smaller opening changed in 87 the lower intake is carry over. The 86 had a 58mm TB. The 86 also had different stock headers vs the 87 up motors.
skunk21
Active Member
stang&2Birds
Founding Member
If you want a stock daily driver engine, the '86 is fine. Plus, it produces less emissions, especially at idle. However, if you want to add heads, then you don't want an '86 shorty block. The '86 setup has better low-end and mid-range power and torque. So, for a daily driver, it's great.
For the quarter mile, you get very limited in heads and cams because of the flat top pistons. In fact, the only other head that meets spec for valve to piston clearance is a TW head.
As mentioned, the upper and TB are different (targeted for low-end and mid-range response and power). The heads are E6 high swirl heads (better idle quality and lower idle emissions). The pistons are flat tops (less likely to cause pre-detonation, but limit the head/cam choices).
It's called real-life trade-offs in any engine design or setup.
For the quarter mile, you get very limited in heads and cams because of the flat top pistons. In fact, the only other head that meets spec for valve to piston clearance is a TW head.
As mentioned, the upper and TB are different (targeted for low-end and mid-range response and power). The heads are E6 high swirl heads (better idle quality and lower idle emissions). The pistons are flat tops (less likely to cause pre-detonation, but limit the head/cam choices).
It's called real-life trade-offs in any engine design or setup.
If you want a stock daily driver engine, the '86 is fine. Plus, it produces less emissions, especially at idle. However, if you want to add heads, then you don't want an '86 shorty block. The '86 setup has better low-end and mid-range power and torque. So, for a daily driver, it's great.
For the quarter mile, you get very limited in heads and cams because of the flat top pistons. In fact, the only other head that meets spec for valve to piston clearance is a TW head.
As mentioned, the upper and TB are different (targeted for low-end and mid-range response and power). The heads are E6 high swirl heads (better idle quality and lower idle emissions). The pistons are flat tops (less likely to cause pre-detonation, but limit the head/cam choices).
It's called real-life trade-offs in any engine design or setup.
So do you still have the good 'ol E6 heads on your car? You sound like me; a little resentful, trying to point out the positives about the '86 engine while everybody else gets to use whatever cylinder head combinations they want, haha. It sucks, but oh well. I'll keep saving up for that Dart-based build.
To the OP: IF you have the resources, rebuild the motor with aftermarket pistons with valve reliefs. The flat top pistons really do limit your choices on heads/cam. If not, at least throw on a better intake and TB, better flowing exhaust/headers, and the engine will pull crazy hard to about 5K. After that, it'll fall flat on its face, haha. But under 5K, SOTP feel is awesome, and I'd say that my car feels better than some E7 headed cars I've ridden in.
