Morning All,
after all my adulation about the 4hp Bamford going so well, it's become a very grumpy starter. So going through the divine checklist, fuel - tick, spark - tick, compression-hmm, blowing out through the moving contact on the igniter. I fiddled with that and stopped the blowing.
Still no start, this engine has gone from being a prime mover to an exercise machine (Lots of cranking, while adjusting fuel settings).
It's alway been relatively easy to turn over compression, but it started, so I assumed the rings to be satisfactory. So out with the piston and happily, there are no obvious horrors, such as a broken or stuck ring or a holed piston crown. I can get a 12 thou feeler gauge in with the ring in the first groove. The other three rings (all plain with 45 degree gap) are slightly tighter in their grooves but not much. The piston is 4.75" maximum outer diameter (though it's a bit less at the crown end) and the rings are 0.25" wide and 0.155" deep. The piston is stamped -007 on it's crown (James Bond strikes again in Uttoxeter). The bore feels quite good, something of a lipat the head end , bit I've felt much worse. At the crank end, a lip is just discernible for about
90 degrees of the 360 ( from five o' clock to about 11 o' clock).I can get replacement rings relatively cheaply and quickly, the question is, with that sort of slop in the groove, should I buy
3/16" wide rings and machine the grooves (or should I say get them machined as I'm too chicken) true, or is it not that critical.Could I get away with just plonking in 4 3/4" x 1/4" rings and eliminate the wear on the circumference of the ring.
What clearance should be allowed if machining the grooves?
Any other ringlore or advice on this matter would be gratefully received.
Regards, Arthur G