Converting the Japanese advance & retard setup to UK spec
Dave Batten popped a note on the V8BB noting he has had his RV8 (a Japanese reimport)
for some years now and when he first brought it back from Japan he changed over
the vacuum advance to UK spec as recommended in RV8 Workshop Note 60, and thought
nothing more of it. "Recently I accidentally stumbled across Steve Newton's
note of 9 December 2004 in the V8BB archives and thought I would check the plenum.
Sure enough the male intake on the upper side of the plenum chamber has never
been drilled out, and for the last few years, without knowing it, I have been
driving around with no vacuum at all! Just thought I would post this note in case
anyone else out there might be in the same boat. RV8NOTE60 needs a footnote to
bring this to members' attention". (8.5.07)
Roger Davies posted a message on the V8BB in December 2004 saying "having
recently bought my RV8 (a Japanese import), I thought that I would select a simple
maintenance job as my first task under the bonnet. I have read Bryan Ditchman's
note about converting the Japanese advance and retard setup to UK spec and this
seems like a good start. I phoned my local MG Rover dealer to try to get the part
suggested but they said it is NLA. I decided to call Clive Wheatley and fortunately
he had a little kit in stock to do just the job. Can anyone who has done this
conversion let me know if there is
anything I need to do/check/change/be careful of, other than that described
in Bryan's note? Clive has already said I may need to drill out the male intake
on the plenum top which was not done on the Japanese cars".
Newton at Clive Wheatley V8 Parts posted a further note saying "we
have changed many vacuum pipes over to UK spec but we have found that the small
male intake on the upper side of the plenum chamber, outside of the butterfly
valve, on many occasions needs to be drilled out to the same internal
diameter as the male intake. This is necessary as sometimes the casting has not
been drilled out. Then the ignition timing needs to be reset to UK spec which
is at 800 rev/min maximum 5 degrees plus or minus 1deg. BTDC with the vacuum pipe
disconnected as stated in the RV8 Repair Manual AKM7153ENG".
next day Gavin Brown in Tasmania added "it won't make any difference
to power output at all, as all the Japanese set-up allows for is full vacuum advance
pretty much straight away. It is purely an emissions thing. The factory did not
hook up 1,500 odd cars incorrectly so do the green thing and leave it as it is".
Jim Dolbel raised
two queries with members who had completed this modification: "when drilling
the obstruction, is the blockage in the base of the male intake or is it the plenum
casting and can the male intake spike be removed to carry out this procedure?".
replied: "it is just a very thin 'membrane' at the bottom of the intake.
There is no need to remove anything, just find a drill that fits the diameter
of the intake and drill it out in situ, very little pressure needed. I used a
Dremel hand tool - it took about 5 seconds to sort it".
Boniface noted "remember itis the inlet
please grease the drill bit first to stop the swarf going into the engine".|
Middlemiss was grateful that Dave Batten had brought this to everybody's attention
and also to Jeff Swann and David Boniface for the further clarifications. "Mine
was undrilled too. A 1.5mm drill fits nicely. Take the air induction ducting off
the plenum, wedge the throttle linkage just behind the plenum so that the butterfly
flap is held open and carefully place a piece of greased (but otherwise clean)
rag on top of the open flap to catch any swarfe that might drop down. Grease on
the drill bit as David suggested; there's very little metal to go through. Make
sure afterwards that there is no swarfe left in the hole and no rough edge to
the hole inside the plenum, as it is very close to the top edge of the butterfly
flap when the throttle is closed. Carefully remove the rag and the wedge on the
throttle linkage, replace vacuum pipe and air induction ducting (check this is
air tight and has no splits in the ducting) and job done".
John Cumming spotted
RV8NOTE258 on the V8 website and checked his RV8 and noted "I put the
smallest drill I had, 1mm, into the vacuum advance intake in the top of the plenum
and found it would not go through. Ah, I thought, I have got the same problem.
I then thought about it and could not believe that Rover would have had two types
of plenum for the engines. So, I then used a piece of locking wire instead, of
diameter 0.62mm, and promptly located the very small hole drilled into the plenum
casing. I wonder if Dave Batten had a hole in the plenum but didn't use a fine
enough piece of wire to locate it?"