The oil for the rockers is indeed "pumped" up there by the rear of cam shaft
bearing area. Assuming that the capacity of this "pump" is sufficient then
there will be a certain amount of back pressure caused by this restricted
area reducing the flow. by opening this up the flow restriction is them
limited by the rocker shaft oilway the same as the external oil feed kit.
However the external oil feed kit does use the main oil galley as its source
possibly reducing pressure to the bearings.
Ralph Jannelli
----- Original Message -----
From: Barry Schwartz <bschwart@pacbell.net>
To: <spitfires@autox.team.net>
Sent: Wednesday, September 22, 1999 3:24 PM
Subject: Re: Oil coolers and rocker feeders
>
> >the oilway that mates to the block and the oilway that
> >comes out on top of the head are one size (I forget the size right now)
but
> >the connecting passage is smaller. If you remove that bolt at the back of
> >the head (the one where the external oil kits connects) and drill out the
> >passageway to the same diameter as the other two connecting passage ways
you
> ********************************************
> Be careful when doing modifications of this nature. This may have been a
> purposely designed restriction, as the factory could have just as easily
> made this passageway bigger if it was deemed a problem with "production"
> engines (not racing engines here which require other mods not intended for
> a street engine) I'm not saying don't do this, just KNOW what it is your
> doing, and the ramifications thereof-
> Chances are opening up this restriction may LOWER your oil pressure all
> other things being equal. (If its in the bleed off from the cam bearing
> then it won't, I haven't looked at these engines in a LONG time, but then
> again you won't get any more oil either. . .) - I'll take a little
> "perceived" increased wear at the rockers rather than at the main /rod
> bearings If however you were to install a higher capacity oil pump, then
> opening this passage *may* be a good thing to do-
>
> Barry Schwartz (San Diego) bschwart@pacbell.net
>
> 72 PI, V6 Spitfire (daily driver)
> 70 GT6+ (when I don't drive the Spit)
> 70 Spitfire (long term project)
>
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