[Cobraman1024]

so back to the idea of the late-model 8-plug head swap............has anyone done it?

EDIT> after looking up the years for a Ranger dual plug head, there doesn't seem to be much of a power difference stock for stock. I guess thats where the portwork/milling comes in to make a later dual plug head better than an ealier one.

[free2.3]

how about this screw 8 plugs there junk the one i had ported and milled fucking cracked the first time i put the nuts to it right from the valve to the intake runner there goes 400 bucks rrr run a dport theres more meat for milling and porting without having to worry about cracking my recommendation is if your looking for quick easy power swap in a milled ported dport head youll be glad you did. 8 plugs heads are like turds you can polish them but there still shit

[OHC230]

“ It stands to reason; it will need less material removal to obtain good numbers because the flow is already pretty good.”

Unfortunately, this just doesn't apply here
“For the truly incapable, just milling and doing a 95-01 head swap on a 91-93 mustang looks like it will yield promising results.

Unfortunately, I don't think it will help as much as you might think

It looks like a late dual plug head (95-01?) would be a great starting point for porting since it doesn't need as much compared to a stock d port or early 8 plug (91-94?)
My observations regarding the flow capacity of the late dual plug head: most of the gains in gas flows came from the use of re-profiled valves with smaller valve stems, coupled with better valve seat work. There are some easy tricks you can do to the 4 plug D-port heads, which push them well over the flow capacity of the stock, late model, dual plug designs.

At the risk of oversimplifying this; simply cleaning up the area below the valve seats and performing a quality multi angle valve job, can improve things dramatically on the 4 plug D-port heads. After this point, dollar/time wise, you would be hitting a steep hill in terms of work to remove the offset in the intake port of the dual plug head.

The bottom line here is power and the dual plug just doesn’t produce much more than a stock 4 plug D-port head, despite having a better fuel system + 4 more plugs and more "compression" which I have proven numerous times, can make up the difference at the dyno.

8.9:1 90hp @ 4000 RPM (1986 - 1988) Single plug
9.2:1 100hp @ 4600 RPM (1989 - 1995) Dual early
9.4:1 112hp @ 4800 RPM (1996 - 1997) Dual late