1969 351W 4V mustang engine build up

Hello

As I understand in 69 and 70, 351W engine had heads with beast flow, but could anyone realy tell me how much potencial this heads realy has. With some porting, maybe larger valves, where is the HP limit for this heads.
I would like to stroke this engine, put new cam, intake, carb, but I would like to keep the heads if possible, with some work on it off course.

Thank you for you answer

Filko
Slovenia-Europe

There is a great article in the tech section comparing small block ford heads..The 351 heads with porting and bigger valves can flow similar numbers to some of the smaller sized aftermarket heads....They will be a choke point on a 351 based stroker though.

Go here and there is at least one 351w stroker with ported 351w heads making good power. If it's enough for you, then use those heads.

302w.com - Ford Windsor Engine Horsepower Database

Early 351W heads can be ported to work fairly well - not as good as the best aftermarket heads - but pretty well. These folks do CNC porting on heads and have their flow numbers posted on-line:
Small Block Ford 289 - 302 - 351W "Early"

The biggest restriction is on the exhaust side where there's a ruddy great thermactor hump in the middle of the port. I'm in the midst of porting a set now. A few hours of grinder work makes a huge difference.

I will give you an example. The best ported 351 Windsor castings will be 60 to 70 HP LESS than an out of the box AFR 165 Alumuinum CNC ported head. Unless you just want to do the work for fun--- dont waste your time, The flow numbers the other guys are talking about are NOT the only thing that makes horsepower. They just dont know that.

JOE SHERMAN RACING ENGINES

Thank you all for your answers. I'll do this for fun and try it first, and then maybe I'll buy aftermarket.

Originally Posted by BIGJOE

I will give you an example. The best ported 351 Windsor castings will be 60 to 70 HP LESS than an out of the box AFR 165 Alumuinum CNC ported head. Unless you just want to do the work for fun--- dont waste your time, The flow numbers the other guys are talking about are NOT the only thing that makes horsepower. They just dont know that.

JOE SHERMAN RACING ENGINES

Joe, beyond flow numbers - which are admitedly one part of the power equation - what are some of the other head design characteristics that add hp? I would assume combustion chamber design, spark plug location, and the head material. What else?

Regarding head material, I saw an article on a 351W build up years ago where they dynoed identical castings on the engine, except one set was cast iron and one pair was aluminum. The aluminum heads made 20-30 more hp. Popular wisdom is that aluminum heads also allow one to run a higher compression ratio. Has that been your experience as well?

In my case, I'm building a '69 351W to replace the tired 302 in an '82 F250 pickup - Comp Cams XE250, Stealth manifold, 600cfm carb. It has been kind of fun porting the heads, and I just can't rationalize spending $1,000 above what it's costing to rework the D0OE heads I've got for a pair of AFRs. If I was building a hot rod, no doubt about it. But not for my lumber hauler.

Thanks.

You can make in the neighborhood of 375-425 hp if your a decent porter, but the aftermarket stuff will blow the ported factory castings away out of the box

I always try to run more compression when I am using aluminum heads. If the iron and alu were truly the same, if you did NOT raise the compression. the iron SHOULD make a few more HP. BUT I have never seen it work out that way. There might be something about the water jackets in the alu heads, and the shape of the chambers, But I dont really know what makes one head better than another. All I know is there is more to it than the flow bench numbers.

JOE SHERMAN RACING ENGINES

just port out the exh. bump and clean up the bowls.
Just clean up the bowls and smooth out some of the intake hump at the push rod interface. Be careful there tho.. just smooth out the transistion. do not want to break thru the wall.
I would say by my times on my 351w that the dooe heads made me about 50 hp more.