identify these rocker arms

these rockers are installed on a chevy inline 6 Duggan head. i need to get some more and need help identifying them.










the head was developed in australia and i bet these are some type of redily available item from either GM,Chrysler or ford. of course on a earlier engine though. tom

 

They don't look like my Y block or my 270 GMC

 

Possibly Gotha or McGirth?

 

I believe the correct company name was McGirk...in any case both have been gone for 25 years or more.

 

They are either Y Block or early FE Ford .

 

or Mopar

 

Duggan is Australian, he also made SBC heads. I knew a boat racer who used them in the early 80's and he raved about them. You hardly ever hear of them any more though. Sorry can't help with the arm q.

 

The rocker shaft is as interesting as the rockers.You guys searching for the name,McGurk. If you edit stovebolt or inline into the thread title you might get some more help from some of the experts on these engines.Any more info on the Duggan head would be appreciated.

 

http://www.jalopyjournal.com/forum/archive/index.php/t-147333.html

 

Measure the rocker shaft OD.

Compare that with the rocker shaft sizes in Motors Manual.

They're usually in there along with the clearance required between shaft and rocker.

If you find a size that matches that'll give you the brand of rocker vis a vis engine manufacturer.

 

Let's keep trying--It's McGUrk

 

thanks for the replies, still looking for more answers. these have got to be a common type of rocker. how about hearing from the aussies? tom

 

try nick arias jr in gardena , california ,at arias pistons..i beleive they manufactured heads in conjunction with duggan in the seventies..they might shed some light on the original manufacturer..

 

Except for the adejuster lock nut, they do look a lot like my Y block. As best as I can measure my shaf dia. it's .785 although that's also what I am using on my Packard V8 honed out to .812 to fit.

 

At the Div 6 NHRA points meet in Acton Mt today a Duggan head, injected Chevy 6 qualified in J/A at a corrected 7.73 in a prostock like Chevy Cavalier body. Strongest 6 cyl Ive ever seen !

 

I believe Sissel is selling US made Duggan heads now. Call them

 

Early Y-blocks actually used that style of adjuster, with the jam nut. With the ball end on the adjuster screw, I wouldn't be surprised if those were actually Y-block adjusting screws. If they are 7/16-20 thread, then they very well may be.