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Old 4th May 2006, 01:04 PM  
United States
 
Join Date: May 2006
Posts: 4
Gurney Weslake heads

> After some surfing around the Net, I found this on the GW heads. Sounds like
> a completely stock, unported pair of heads.

Those flow numbers you quoted were from me. They were indeed from a completely
stock set of heads, as purchased from Gurney. I also believe they were only
partially finished machined. That step I mentioned looks like a real flow
killer. With that removed and a good bowl porting and valve job, those heads
should do much better. I wouldn't be surprised to see them as good as the
majority of modern Windsor heads but that remains to be seen.

There were a series of Gurney heads. There were the Gurney AAR-designed MK1
heads that were cast by Alcoa and found to have insufficient thickess
is a few spots. The Weslake-designed heads went through several revisions
resulting in MKII, MKIII, and MKIV Gurney-Weslake heads. Most were cast
at William Mills in England. The MKIII was a minor revision of the MKII
race head and the MKIV was a narrowed version made to better fit into
Mustangs and Cougars. The MKIV heads were renamed Gurney-Eagles after
Gurney took over manufacturing responsibilities. That's the version we
tested. There was also a 3 valve pushrod head developed by John Miller
at AAR. The first set suffered from coolant passage problems that allowed
steam pockets to form and were subsequently revised to fix that problem.
I don't know that much about the 3 valve heads but I don't think they were
the success the Gurney-Weslakes were. This wasn't because of anything
fundamentally wrong with the heads (they out-flowed the Weslakes) but
rather there wasn't a racing venue for them (Can Am went big block, Ford
went Boss 302 in Trans Am, Formula 1 went V-12 and Cosworth, Indy was turbo
Offy and Ford 4 cam, Ford pulled out of Endurance racing, etc.) so I don't
think they were developed or raced to any menaingful degree.

Detomaso also had a version of the the Weslake heads prototyped. Some
pictures of the Detomaso heads, along with pictures of the MK-IV heads
we flow tested, can be seen on my website at:

http://www.bacomatic.org/gallery/album18

Notice the modern chamber shape of the Gurney-Weslake heads, along with
the intake runner optimized for independent runner manifolding. BTW, my
buddy Bill had Harland Sharp prototype a set of roller rockers for his
Gurney-Weslake heads. The G-W's have a shaft mounted rockers with
different intake and exhaust rockers.

> I was pretty sure that many of the modern heads would outperform the original
> GW heads. Curiosity getting the better of me, I was wondering if anyone had
> some specifications so that I could compare them.

We're hoping to get a pair of Gurney-Weslake heads to David Vizard for
analysis and a port job. Vizard knew the guy at Weslake who was
responsible for the Gurney head development. According to Vizard, one
of the Alan Mann-prepared Falcon's was making over 500 RWHP from a 302
in the late 1960's. Pretty impressive for the time. Vizard would like to
do an article on the Gurney-Weslakes, comparing them to modern heads to
see just how far we've really come.

> Which is to be expected given 40 years of technology.
> But for their time, the GW heads were awesome.

Just because they are old, doesn't mean they can't make modern power.
I've yet to test a set of Windsor heads that betters the 25 year old Ford
Motorsport high port heads. Those old canted valve heads are still
outstanding. My small port C302B street heads flow 331 CFM intake and
228 CFM exhaust (without the aid of a pipe) at 0.6" lift on a conservative
bench. That's better than the AFR 225cc race Windsor heads in the graph
above despite having smaller port volumes (note the AFR claimed exhaust
flow numbers are quoted with the aid of a pipe, without the pipe expect
to see 20-30 CFM less).

> I'm also curious about the original cam grinds.

I think I may have some information on that in the archives.

Dan Jones
Daniel Jones is offline   Reply With Quote