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Johnball
United Kingdom
98 Posts |
 Posted - 01/06/2021 : 22:38:43
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I did on my earlier posts say I would ask some silly questions as a new boy to Prewar MG’s.
I have some new NGK B7HS plugs that out of the box are gapped at 025, but I believe from what I have read they should be near 018-020 ?
Also on the blow off valve, I can see a slight gap at the bottom through the round exit hole. Is this correct of is it slightly jammed. I ask the question as car hard to start when cold and even harder when hot after I have stalled it !!! Would it be sucking in air rather than from carb via supercharger, being a long tract.
Slowly getting car road ready, have installed indicators and electric cooling fan.
Next job is to look at cable brakes !! |
Edited by - Johnball on 01/06/2021 22:40:26 |
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Simon Johnston
United Kingdom
6168 Posts |
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Tim Luffingham
United Kingdom
342 Posts |
Posted - 02/06/2021 : 07:11:42
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John - it was good to meet you last weekend at a friends get together.
Simon's thread is a good one. I also use NGK B7HS on a supercharged engine - gap .025 in.
Regarding your starting issues do you have a Ki-gas pump fitted? It's a long way from the front mounted carb and blower to the combustion chamber and I know of others who have difficulty starting from cold without one.
The blow off valve should be airtight and only open to relieve excess pressure. If you think it is incorrectly set then I'd suggest trying to seal it with masking tape and observe when starting and / or engine running.
As discussed I'll try to visit you in the next week or two. Do drop me a line on timluffingham@gmail.com
Very best
Tim |
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Johnball
United Kingdom
98 Posts |
Posted - 02/06/2021 : 11:02:17
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Simon, thanks for the reminder to look at old posts. There certainly seems to be several opinions. I guess I will try the different gaps, but a bit worried about my head threads as they seem very soft compared to my XK and Healey. So am being very cautious about not tightening too much !
Tim, yes it was great to meet up with someone who is local to me. Looking forward to meeting up here any time you are available. I now have a feeling that maybe the starting problem could be air going in via blow off. So, next Minor job of the many on this relatively new car to me is to examine it, but will try the tape as suggested. You have my mobile so will leave to you to call me for dates. |
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Johnball
United Kingdom
98 Posts |
Posted - 02/06/2021 : 20:38:24
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Blow off valve looked quite sooted up, so cleaned and put back together.
Interesting, that when I tried 20K ohm setting on multi meter with all the plugs I took out,
5 plugs gave 0.00 and 1 plug gave 1, showing a short. But car seemed to run ok.
As a precaution, have put in 6 new plugs.
Tim, forgot to answer your question about Ki-Gas. Yes it does have the large version as fitted to the Spitfire and Centurion Tank !! I have been told to be careful as can flood engine fairly easily. I had the whole thing apart a few weeks ago and put in new graphite string, then discovered that the two jet holes on the manifold were totally blocked. |
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