Slow progress on the engine rebuild has me ready to put the pistons back. I had the machine shop measure and they found that the bores and pistons were still within specs, so I am reusing the original pistons. I believe that the engine had been rebuilt but never run by the owner in 1978/9, before the car was laid up, and it looks to me like the rings are new. I removed the compression rings from a piston and put them into the bore to measure last night. The gap was 0.021" for both rings. This is higher than the numbers in the workshop manual (0.013-0.018" top, 0.010 to 0,015" bottom), but I wasn't too surprised - the block has been honed, so even if only half a thousandth was removed, that would add a couple of thousandths to the diameter, increasing the ring gap accordingly.
Over the course of my ownership and very slow rebuild, I have purchased lots of parts, some twice. I have somehow managed to have two new sets of rings. One is a STD size by Deves, looks to be old stock. The other is a white box (County?) set from Rimmer Bros at +0.020". I tried the Deves STD rings in the block last night, and found the gap to be comparable with the ones already installed - 0.020" or more.
I bought the +0.020" rings with the thought that I would hone the block and find myself unable to use STD rings, which is where I find myself. My thinking was that I could use the piston ring grinding tool (late night ebay purchase years ago, still in its box) to get every ring to exactly the right gap. Looking at it now, I wonder whether I am being an idiot with this approach. The oversize rings will be under more tension than STD size, and I worry that I will wind up breaking the rings shortly after start-up.
So, my options are:
1. reuse the rings currently installed - no risk of me breaking a ring! but with somewhat oversize gaps
2. use the NOS Deves rings, with larger than desirable gap
3. use County +0.020" rings ground to the right gap
I would welcome any thoughts on this - maybe I should stop worrying and just get the thing put back together!
Cheers
Alistair
Over the course of my ownership and very slow rebuild, I have purchased lots of parts, some twice. I have somehow managed to have two new sets of rings. One is a STD size by Deves, looks to be old stock. The other is a white box (County?) set from Rimmer Bros at +0.020". I tried the Deves STD rings in the block last night, and found the gap to be comparable with the ones already installed - 0.020" or more.
I bought the +0.020" rings with the thought that I would hone the block and find myself unable to use STD rings, which is where I find myself. My thinking was that I could use the piston ring grinding tool (late night ebay purchase years ago, still in its box) to get every ring to exactly the right gap. Looking at it now, I wonder whether I am being an idiot with this approach. The oversize rings will be under more tension than STD size, and I worry that I will wind up breaking the rings shortly after start-up.
So, my options are:
1. reuse the rings currently installed - no risk of me breaking a ring! but with somewhat oversize gaps
2. use the NOS Deves rings, with larger than desirable gap
3. use County +0.020" rings ground to the right gap
I would welcome any thoughts on this - maybe I should stop worrying and just get the thing put back together!
Cheers
Alistair
