258
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".

Steve 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".

The 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?".

Jeff Swann 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".

David Boniface noted "remember itis the inlet manifold, please grease the drill bit first to stop the swarf going into the engine".

Stuart 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?"
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Note updated on 11.5.07