Lockdown Ruston restoration

So I've got quite a bit of time on my hands now I'm not going to work. I thought it was time I did some work on the Ruston, it seems to run fast when I get it started, I thought perhaps the governor was stuck but it isn't. Anyway it's full of sludge so I might as well clean it all out and start fresh. Still need to find a way to remove the flywheel gib key hopefully possible now the full crank assembly is out.

To slow them down you need to adjust the governor before refitting the sideplate. Slacken the knurled speed adjutment knob fully, hold the two governor weights together (that is important) and then adjust the screw on the bottom of the fork until it just touches the pushrod in the centre of the gear. Make sure the pushrod is right in. Be VERY carefull with tightening/loosening the adjustment screw as those forks are rather fragile and can break so support it while loosening the locknut! That should still give you a speed range between the high and low hundreds which you can alter via the knurled knob of course. Same adjustment method can be used for the Wolseley WD and Ruston PT's as well.

Pete.

Thank you for that information, I was wondering if the pushrod was worn, but of course it's adjustable as you say, I hadn't noticed.

Pleased to have got the flywheel removed today, found the one and only long series drill I own was a 5mm which was just about perfect. Drilled right through to the back, and then used my home made gib key puller with some minor modification. It couldn't have gone better, now I just need a new key.

I've been cleaning up a few of the bits last week and whilst cleaning the very dirty and clogged up piston, I found a crack in the top oil scraper ring. I think what I'm inclined to do is buy a full set of rings and just change the one that's damaged. I've checked the bore and from my rough measurements there seems to be about 7 thou of wear at the top of the bore whereas it is exactly 3 inches at the bottom. The piston is also a few thou undersize as well, so I think it could be difficult to properly fit a full set of rings with the correct gaps without going down the route of a new over size piston and machining the bore.

Has anyone any advice or suggestions?

I would fit a 10thou oversize set of rings, you should be able to gap them to around the correct figure and for 'our use' should be ok. A Ruston oversize piston isn't going to be easily available if you decide on a rebore, I have never seen any, however I'm assuming that the pistons are similar to the PT engines and I know of several folk who have fitted Lister D pistons to those and they are fairly common in oversizes. Lister D rings fit PT's as well so should fit the PB range, and are readily available in oversize as well, they just need an extra oil ring.

Pete.

Thank you once again for your advice. I'm currently making the new gib key, got it rough shape, now I just need to fit it properly. I will probably make a ring to fit over the crankshaft with a grub screw just to be double sure the key can't come out. It'll be hidden by the flat belt pulley anyway. I made one for the Lister but the pulley on that does the same job.

Is your piston domed?

Personally I'd stick in a standard set and gap for the tightest diameter

I can recommend this crowd in the USA.

http://www.ringspacers.com/

We wanted rings for a pre-war Scottish engine and they supplied to our drawings in a very short time $5 each plus shipping.

Fantastic.

Thank you for the advice. @Villiers yes the piston is domed on the top. I think seeing as the standard rings are easy to get hold of I’ll just order a set of those. Being new, if I fit them properly they’ve got to be better than the original ones as they won’t have any wear.

My next question is though, what should the gap be? As @ListerHA2 I’ll gap them at the bottom of the bore where the wear is least.

A gap of around 12 thou will be fine, I thought my PB had a flat topped piston though? How many rings does it have?

Pete.

matthew92 wrote:Thank you for the advice. @Villiers yes the piston is domed on the top. I think seeing as the standard rings are easy to get hold of I’ll just order a set of those. Being new, if I fit them properly they’ve got to be better than the original ones as they won’t have any wear.

My next question is though, what should the gap be? As @ListerHA2 I’ll gap them at the bottom of the bore where the wear is least.

Assume you will 'glaze bust' the bore if fitting new rings?

Hi Pete, this is the first Pb piston I’ve laid eyes on, so if someone told me it was wrong I wouldn’t know. It’s got 5 rings, 3 compression and 2 oil scrappers. Having seen the job someone did shimming the bearing cap on the big end I’ve no idea what this engine has been through. I know my Grandad wouldn’t have been in there, but unfortunately none of us know where he got it from so sadly it’s history is lost.

I will be giving the cylinder a bit of a scuff up, I borrowed the tool from work when I did the Lister. It’s a vintage tool with 3 stiff rubber flaps with emery paper folded over them. Stick it in a drill, down the bore and have at it but it didn’t work. I’ll probably get the newer type tool for this one.

matthew92 wrote:I will be giving the cylinder a bit of a scuff up, I borrowed the tool from work when I did the Lister. It’s a vintage tool with 3 stiff rubber flaps with emery paper folded over them. Stick it in a drill, down the bore and have at it but it didn’t work. I’ll probably get the newer type tool for this one.

The tool you describe is a device for honing a cylinder after re-boring and is designed to hone out the ridges after boring. What you need for glaze busting is in this video. It will more accurately follow irregular bore wear. The only other decision is whether you need to remove the top wear ridge or fit a 'ridge dodger' top ring.

https://www.youtube.com/watch?v=zvr1bJ9Kjuc

https://www.newmantools.com/flexhone/index.html

Scroll down to ridge dodger. The ring has a machined step to avoid contact with the ridge at TDC.

https://www.thn.nl/en/product-line/piston-rings/piston-ring-types