Post by dave1800 on Nov 3, 2014 0:42:19 GMT
Hi Tommy
I wonder if the fibre/plastic heel on the nos stock has possibly degraded over the years since it was made and wears down faster - just a thought, no evidence.
Why are you using the single chain? The first thing I did with both my Mk111 cars was to fit duplex chains as they stretch far less. I also preferred the double valve springs and if you are using them with a single chain it may stretch a little bit more.
IMOH I don't think it's worth trying to set the dynamic timing at 600rpm on a worn engine with backlash in the timing gear. The 14 degrees at 1,000 rpm quoted for Mk111 HC cars fitted with the same 25D4 or 45D4 distributor should be more reliable. Or you could use the John Twist method and set the maximum timing (no vacuum) to around 36 degrees at 4,400 rpm and let the idle sort itself out on the basis no engine damage occurs at idle from an incorrect setting whereas at high rpm and load excessive advance is definitely not good.
Hi Chris!
Glad to hear you sorted it! Have you found the reason why the points keep closing up? In fact I've just experienced this on mine too. Didn't really notice any misfire or anything, but during a check I found the dwell angle to be well above 70 % and the points gap was very small, couldn't even get a 0.014 feeler gauge in.
Tommy
I wonder if the fibre/plastic heel on the nos stock has possibly degraded over the years since it was made and wears down faster - just a thought, no evidence.
Why are you using the single chain? The first thing I did with both my Mk111 cars was to fit duplex chains as they stretch far less. I also preferred the double valve springs and if you are using them with a single chain it may stretch a little bit more.
IMOH I don't think it's worth trying to set the dynamic timing at 600rpm on a worn engine with backlash in the timing gear. The 14 degrees at 1,000 rpm quoted for Mk111 HC cars fitted with the same 25D4 or 45D4 distributor should be more reliable. Or you could use the John Twist method and set the maximum timing (no vacuum) to around 36 degrees at 4,400 rpm and let the idle sort itself out on the basis no engine damage occurs at idle from an incorrect setting whereas at high rpm and load excessive advance is definitely not good.
Glad to hear you sorted it! Have you found the reason why the points keep closing up? In fact I've just experienced this on mine too. Didn't really notice any misfire or anything, but during a check I found the dwell angle to be well above 70 % and the points gap was very small, couldn't even get a 0.014 feeler gauge in.
Tommy
. Bad fuse contact, always start with the obvious!