Ruston Hornsby 4 AP

This won't be the first time this engine has been recommissioned, it looks to have had a mild restoration in the past, possibly only paint though. I bought the engine from the second owner about 17 years ago, the seller is believed to have bought it from his place of work. I'd seen it outside under an oil tank exposed to the elements for a couple of years before i went and asked if it could be for sale. After getting it home we made an attempt to run it, which it did, but it ran too fast and we struggled to stop it, after that (knowing it did run) we never touched it again. Until, a few months ago i got a friend to help me lift it into the van to bring to my house so i could work on it. I only got started on it a few weeks ago. So after some cleaning and fettling, and being too scared to start it again, i got it to run, this was a sunday after spending all saturday with zero results. I must admit to pulling the HT lead off as soon as it started. This went on for several start's as i found out how to shut it off with the HT lead trick and to shut it down by the butterfly. So it's been running a few times over the last three weeks and i'v slowed it down a bit by the butterfly governor linkage, see pic. But it still goes too fast for me. I'v got used to starting it by only two good swings of the flywheels and not using the starting handle. Starting on low comp and switching over to high once it's turning over nicely. I made a peg for the high / low cam as it was missing. I have the original tank for it but it's holed, so i'v made a Petter one fit for now. I'v cleaned out all the bearings and oiler points and found the main bearing broken, since the engine runns and it's getting oil i'm leaving this alone, the cost of repair set against the amount of use it will get don't add up. To get the shaft side bearing off i had to remove the flywheel, i am slightly allarmed at how easy it came off, but at least it came off ! As well as the peg, i had to make a drain tap for the oil catch in the bed. Also had to make a tape repair to the hot air manifold intake for the carb, i held back from putting zip ties round it aswell, i was happy with the tape.















If anyone has any knowledge they would like to express upon to me i'd appreciate it, regarding the slowing down of the engine. Also, info on how to set the carb cold / warm air intake when the engine is starting and run up to temperature.

Nice and easy restoration I think, looks great sounds like your having fun.
Thank you for posting photos
Jonesey

Nice looking engine you have got there. Great find.

keep us posted on the renovation.

regards

martin.

Thanks for sharing the pics with us, sorry I can't answer any of your questions as I know nothing about these engines.

Stu.

Me neither But I'm sure if you keep fiddling with the carb and the guvnor you'll get somewhere near.

ukluke wrote:I'v cleaned out all the bearings and oiler points and found the main bearing broken, since the engine runns and it's getting oil i'm leaving this alone, the cost of repair set against the amount of use it will get don't add up.

I don't think you should be trying to run an engine with a bearing like that in it ..............

TBH Hob, me neither, but needs out weigh cost. Regarding this bearing, there is a grease cup on it, that i put on, but after spending a while looking at it and scratching myself, i think it's probably supposed to have an oil cup ? Anyone confirm please ? Still on the oiling side, i have both the original drip feeders, but need 2 new glasses, is there a new part on the scene yet for these ? When i collected the engine from it's previous owner i tipped it up and broke both of them, much to his disgust and my shame. One was beyond repair, the other was super glued back together. I had to make this (pic) to fit another oiler i had , for the big end oiler.



For a while i'v been looking for a nut for the spark plug, after searching Rufforth and Newark Autojumbles, i gave in, only to find one tonight on the end of a new spark plug i'd been hording for 20 years. See pic. Also i'v noticed that the high / low cam is only touching the exhaust rocker on one side (see pic), this wasn't bent by my poor lifting skills 17 years ago, as the shaft is well worn from years of use. I may need to look into having a new shaft turned and fitted to the exhaust arm, and look into how to fit it straight, i don't fancy trying to adjust / bend the arm it's self.



On a happier note, when i refitted the fly wheel, i cleaned up the key and found it had the engine number stamped into it. I did put the flywheel on the wrong way at first, but the key didn't fit so it was obvious straight away. I'm not sure why the flywheel's are not both fitted "hub" inwards, like the pully side ??



Finally, i think i may have to adjust the depth of the carb needle, to lower the fuel intake, i think it's using too much. I hope this goes some way to slowing it down. I'll take a pic of that when i do it. I'll be marking the needle so i can adjust it in increments. More to come.
Luke

Luke if you want a new bearing made there is a company called JEL bearings you could send the old one and he would make you a new one

here the contact details

http://www.jelbearings.co.uk/

matt

Thanks, i'll look into that.

oilers are still available and come up quite often on ebay..........they are not that cheap at the moment but there are some in this search

http://www.ebay.co.uk/sch/i.html?_from=R40&_npmv=3&_trksid=m570.l2736&_nkw=drip+oilers

If you tell me the size of the glass oilers I keep a lot in stock and the cork washers
Jonesey

Drip oiler glass, it's 65mm tall, 50mm outside accross the top opening, 27mm outside the bottom hole, 17mm inside the bottom hole. If you had two the same Jonesey i'd be a happy chap !



As for the needle, i recon i'v missed the point. The needle and float set up is only for the intake of petrol into the carb, not for induction to the engine. When i got the engine the needle was non existant, so we made a new one, but didn't know where to solder on the weight. So, tonight i'v been trying to set up nothing, with very poor results.



So i still need to find out why it's sucking up so much petrol and why it's going so fast.

Luke

Sorry Luke , I have only got strait glass oes yours are wine glass ones
Jonesey

No problem jonesey, i'v still got two working oilers on it, just wanted to use the other original one.

Hiya;
As far as I know the Rustons have oil not grease cups, from photos I have and what I have seen.
Nice looking
With regard to the slow running are you saying it runs away from the governer or that there is a problem with the richness of the fuel setting?
Are you running on parrafin or petrol?
Shame about the main bearing half, looks nasty. Are they in shell halves? I know what you mean about the costs balance of use versus repair cost - but I'm sure it will be worth doing in the end. Especially if you suffer more damage.
I've got a source who may have the instruction book for the AP, I shall ask about the carb setting. You are right that the float and needle is just a float bowl set up, for the induction of fuel to the carb, not like more modern engines with a sliding needle for slow running and throttle.

regards
Matt

Slow running....
https://www.youtube.com/watch?v=b8X__BnxzBA

Oooof , if i could just get my engine running like that !!
I got the oil cup sussed on the big end, had a look in Nigel McBurney's ace book (i have two copies, if anyone wants one ?) Open Crank Restoration. I'v cleaned out the grease but will use the cup to squirt oil in to.
Mat it's running fuel rich, on petrol only at the mo, like it's drawing all the fuel out of the bowl as fast as it can. There dosen't seem to be any control on the carb for fuel / air, or mixture ? Only the air intake adjuster (hot /cold), but this is not fine enough for setting the running ? I think there may be a part missing ?
Does any one have a picture of the early type of carb they could post up, from a rally maybe ??

I too was wondering about this.

Ruston certainly seem to have got their carb design ideas sorted to be as simple as possible.

These were after all designed and built in an era when they would be supplied to people with perhaps very little theoretical and practical nouse about engines and the way they are designed and built - so they should be very simple. I wondered if you maybe had a part missing.

Have you got a photo close up of the carb and bits you have? On my little favourite the PB's the carb bowl design is very simple, the level of the float is the same as the height of the main jet, otherwise if higher then fuel will run through it. The main jet is fixed and the air mixture is simply varied with the single rotating flap that also closes to form the choke for rich start mix.

Anyway, I will try and look out the right booklet!

Sounds like your engine is drawing air in somewhere. What like is the gasket between carb and the machined casting it bolts to? Any worn bushings at throttle controls? Are the linkages free between governor and throttle rods?

According to the hints and tips booklet the fuel valve on the carb should only need to be about 3/4 of a turn open to start, is the threads on the valve worn allowing air in, or as above, is the flange distorted or the gasket leaking?

You mentioned something about the flywheel[s] being loose. They are numbered and the shaft ends on both sides are numbered. Is is important that flywheel 1 is fitted to side 1 and flywheel 2 fitted to side 2, also the marked side of the flywheel should be on the outside of the engine.

The air flap valve on the carb also only fits one way, it has three projections on one side, this should be fitted to prevent it quite completely closing onto its face. I also noted that fairly early AP's have an air sleeve that needs hand adjustment. I don't suppose yours is one of these?

The only pic i have of the carb till sat morning -



There is no fuel valve on this carb ? Only the hot / cold air valve. This is why i thought there would be a part missing, like a mix screw. I'll have a look at the gasket, maybe squirt some soapy water at it, see if it sucks and blows ?? I think some air might be able to get past the butterfly pivot as some times on start-up it's backfired and blown fumes out past it. I'v had a look through youtube but the only AP's i found had the newer carb.
I only removed one flywheel and it would only fit back on one way, so not too worried about that.

I took this pic at dinner today, just because i was driving past



Luke

Yorkshire was right, the fuel level at the jet is set by the needle and float to hold the fuel in the bowl at the same level. Otherwise fuel flows straight out of the jet into the air passage.


The jet removed -


The jet is very simple with slotted holes round the edge of a sort of plug. However, i was right to be trying to set the needle, just wrong about why. The needle must be set to hold the float at the required hight so when the fuel lifts the float the needle drops into the intake and stops the fuel. It's all very simple, but thats if you have a factory making them, not a hammer, a vice and fat thumbs. This will be the hard part, but i understand it now i'v had it apart.
Once i get the weight set on the needle it needs to be soldered on -


There is no adjustment on the carb other than the hot / cold air intake -


So i think i may have cracked it once the float is set to shut the fuel off at the right hight in the bowl. As for the vid at the top of this page, i'd love to set my engine up to run this slow. The set up for throttle control off the butterfly looks easy to reproduce, and is fully adjustable. I think it's a great idea for a rally as i'v never seen an engine that slow and quiet (even for a vid) . So, i'll have to keep trying.

Made a little change to the running order thisaft, it's much slower, but not totally regulated, still a little up and down. The spring does a good job of letting the butterfly regulate it's self.


I'v had the spark plug out a few times, it's still running rich, the end of the plug is sooty, dry and black. The needle still need's some fine tuning.
Luke

Ruston Hornsby 4 AP running vid

Sounds like your getting there, well done.

Stu.

Thanks Stu.
I'v been to see an old friend down the road who has a 6 AP, a bit newer than mine. He made me aware of this - i'v made a new needle, and the weight is not yet soldered on, it will weigh marginally different to the original. Only a little less at the mo, till i solder the weight on.
But, will it effect the float hight ?

The point at which the needle drops (weight) = The level the float release's it (wieght X buoyancy)

I'm not sure weather i fully understand it ? The float must weigh more than the needle to hold it up, before fuel raises the float (the float thus letting the needle drop). I'f you've never seen inside a RH AP carb you might not understand this either.
So i'm wondering if, in 1922, the design engineers knew how buoyant the float was, and how heavy the needle had to be. I'm not saying they didn't, just, did they ? How far did they look into the float / weight / needle issue ? I doubt it was a brand new design, probably a development of another system. But it seems more technical now than it was three weeks ago.

Luke