My proposal will probably strike horror into the technically minded who grace the forum. I've a nice set of new pistons perfectly matched to a cylinder block and I'm wondering if there is a way of using them without the pinch bolt. Why ? Because I've also got a nice new Phoenix Crank and matching Rods with no facility for using a pinch bolt. Obviously I'm suggesting a floating gudgeon pin arrangement with either Teflon or soft metal caps on the ends of the gudgeon pin (I've got some examples of these)or a similar material plugged into the piston to prevent the gudgeon pins scoring the cylinder bore. Is this a mad proposal or has someone got an alternative ? Look forward to any views. James

Fully-floating gudgeons were used by Austin themselves, so no horror at all.
The original Nippy / 65 engine as one example used them with, as I recall, aluminium end caps.
Go ahead!

Location: Richmond, Texas, United States

Fully floating gudgeon pins are still available from the usual A7 suppliers.

As usual, a quick and very useful response from Forum members. Thank you all. I'll be getting in touch with one of the Cherished Suppliers once the May Bank Holiday is over. James

Location: Ferring, West Sussex.

James
I just did the same but chose to machine circlip grooves in the gudgeon pin holes.

Martin

Martin, interestingly enough, the location of the gudgeon pins or lack of it with the use of ordinary pistons was one of the questions that was 'floating' about in my brain. I think your solution is far better than depending on capped ends that must make frequent contact with the cylinder bores. Obviously this impact is cushioned by the oily bath or mist created in the crankcase that in turn would discourage the use of baffles. I've checked through the catalogues of several suppliers and don't see any reference to floating gudgeon pins but a phone call or two will hopefully lead to a solution in that respect but if I had the skill, I'd be doing exactly what you're doing. I suppose you can just use ordinary gudgeon pins or are they weakened at the 'pinch point' ? It does raise the point of why aren't all gudgeon pins designed to be floating as it looks as if its an easier way than pinching them with a bolt ? James

Location: Ferring, West Sussex.

If you make the end caps from brass or perhaps bronze(as I think Austin did) or aluminium and you make them too tight they will split the gudgeon pin when they heat up and expand. This I have seen. I will have to ask elsewhere to find out how tight is too tight. Memory says there may be a problem with nylon-like material and I will see if I can confirm this.
Regards,
Stuart

Doesn't nylon swell when in contact with mineral oil?

Location: Devon

Teflon Buttons have been used for years in racing engines, I have seen them for sale off the shelf for some engines, I have never used them, In my engineers brain there is something inherently wrong with doing this,(although probably it is not) I would be machining the pistons for circlip or spirolocks

Location: Deep south of sussex

James,

the Pistons available from the Seven Workshop are already machined for C-clips (provided), so that they can be used with both types of gudgeon pins, I would suggest you look at these and machine yours similarly if they do not already exist

Were it my engine, I would use use gudgeon pins designed for bushed little ends, not the pinch-type you propose above, as stated the correct ones are readily available at minimal cost.