27-02-2020, 12:50 PM
Thank you so much for these two very prompt and most helpful replies.
Jim's brilliant thought of different bearing widths and the possibility of a shim in the wrong place had never occurred to me (despite lying awake at night for hours considering the problem from all angles!).
However, Chris' mention of the issue with early Phoenix cranks may indeed be what I am up against. I have had a quick look and the front web is so close to the new front lip that I doubt now that I would be able to move the crank forward even 1/16". Also, I can see that someone has removed some metal from the centre cam web which suggests that there was a clearance problem in that area too. My dream discovery of a Phoenix crank is fast becoming a nightmare!
I reckon that this must be an early crank and I may have to live with these issues, so long as there is indeed at least a fag paper's clearance between little ends and gudgeon pin bosses. If there isn't, I should have thought that I could safely remove enough metal from the two bosses at risk to provide a definite clearance without compromising the pistons' strength.
This in turn raises another question. Should I now drill the gudgeon pin bosses from below, as seems to have been done with earlier pistons, to improve gudgeon pin lubrication in case not enough oil is reaching the pins because of the small gap between little end and boss?
What a wonderful source of invaluable information Forums like this are.
Thank you both again,
John.
Jim's brilliant thought of different bearing widths and the possibility of a shim in the wrong place had never occurred to me (despite lying awake at night for hours considering the problem from all angles!).
However, Chris' mention of the issue with early Phoenix cranks may indeed be what I am up against. I have had a quick look and the front web is so close to the new front lip that I doubt now that I would be able to move the crank forward even 1/16". Also, I can see that someone has removed some metal from the centre cam web which suggests that there was a clearance problem in that area too. My dream discovery of a Phoenix crank is fast becoming a nightmare!
I reckon that this must be an early crank and I may have to live with these issues, so long as there is indeed at least a fag paper's clearance between little ends and gudgeon pin bosses. If there isn't, I should have thought that I could safely remove enough metal from the two bosses at risk to provide a definite clearance without compromising the pistons' strength.
This in turn raises another question. Should I now drill the gudgeon pin bosses from below, as seems to have been done with earlier pistons, to improve gudgeon pin lubrication in case not enough oil is reaching the pins because of the small gap between little end and boss?
What a wonderful source of invaluable information Forums like this are.
Thank you both again,
John.