Having had some issues with piston rings over the last few days, I thought I would share this video with you to illustrate some of the problems with making quotes and setting schedules and why we try to avoid this.
The problem illustrated is due to the oil control ring quality and a little due to variation in the piston ring grooves. Most manufacturers call for a nominal 0.008" to 0.012" radial back clearance. That is the clearance between the ring face and the land face of the piston when the ring pushed firmly into the groove. Normally we would consider setting up in the lathe piston jig and machining the groove a little deeper, but with the ring variation on this particular set, I have opted to dress the rings on this occasion. We may also have been able to make a machining jig to correct the rings in the lathe, but that is tempting fate to go experimenting this late in the schedule and with no immediate ring replacement source.
In the commentary I refer to a "pre build inspection sheet" that I have produced to aid me with every engine build to make sure I have peace of mind after the engine has left me (as much as any engine builder has peace of mind). Whilst I always observe the ring and groove condition, this was not actually listed on the sheet. Fortunately, I noticed the issue before fitting the pistons. It will certainly be part of my reminder list in the future, avoiding this sort of correction work late in the build. Despite having built over 75 marques of unusual and rare engines, you never stop learning.
Note to all customers.
Please allow a transition period as we are now hopefully approaching the closing phase of Covid 19 restrictions.
Parts suppliers and Subcontract work will begin to return to a normal service, many items that have been delayed are already becoming available. However, as a very small team, our immediate workload will increase considerably and may cause some delay for a short period as we get all of our projects up to speed simultaneously. We will work hard to avoid long delays and to maintain or return to your pre Covid schedule as soon as we are able.
Thank you for understanding and for your support and patience during this time.
Eric and Jacob.
