Second opinions sought on bedford engine.

[No Signals]

Second opinions invited. Bedford MW. Blue smoking a bit at the end of last season so took head off to inspect. Replaced all valves, guides and had seats re-cut. Dodgy exhaust seats look to have been the main culprit. While head was off decided to drop sump and check for big end play –everything seems ok. Paraffin tested rings overnight- all of them seeped, 1,5 &6 worse than others. There is a lip on all cylinders.

Options are 1) Put it all back together as it is without touching cylinders etc. 2) Try and source some new std size rings and just replace them (after deglazing bores). Anyone know a part number? Or know any modern equivalents. Cant find anything in any of the limited manuals I’ve got.

Reboring isn’t an option at the moment, as I don’t have the lifting facilities to take out the engine where it is. I have heard of re-bore equipment which can be put on a motor in situ, but not having seen any I am still pretty sure it would not be able to do at least No 6 and maybe No.5 due to the shape of the bulkhead.

Useful input invited regarding which way to go

[Brooky]

Could try Bygone Bedford or John Morter (01935 602581)for rings, cant lay my hands on Bygone Bedfords number at the moment. If they havent got any i am sure they will point you in right direction

[Grumpy]

Try a set of Cords piston rings http://www.cordsduaflex.com/ have used them with great success in the past, take a bit of time to bed in, but their oil control and increase in compression is amazing on a warn engine. Even used them on race prep A series when I was broke and got to the nationals on them.

[Richard Farrant]

Paraffin tested rings overnight- all of them seeped, 1,5 &6 worse than others. There is a lip on all cylinders.

 

Options are 1) Put it all back together as it is without touching cylinders etc. 2) Try and source some new std size rings and just replace them (after deglazing bores).

 

"Paraffin test" is not very accurate, because there is always gaps in the rings and holes in the piston grooves for oil scraper rings, and paraffin has a searching effect, so will swiftly leak through. I don't suppose you did a compression check before stripping? If the compressions were within limits, you only need renew the oil scraper rings and use Cords Duaflex as Grumpy said. If you put in new compression rings, the top one may chatter on the bore lip, and may have to have its upper edge radiused. Even after a light hone / glazebust, this will still be a problem. It all depends on how oversize the ring gaps are on the comp. rings, if very large, then you will have to renew them, but pay attention to the top ring.

 

Don't worry about part numbers, just go to a engine parts specialist telling them bore size, and they will sort you out. Try Cox and Turner Engineering, John Cox is very knowledgable, 01425 652627

[snowtracdave]

If the info is of any help - We had the 220 successfully rebored in situ on our old TK570 a few years back - not much room to play with in there either .

[No Signals]

"Paraffin test" is not very accurate, because there is always gaps in the rings and holes in the piston grooves for oil scraper rings, and paraffin has a searching effect, so will swiftly leak through. I don't suppose you did a compression check before stripping? If the compressions were within limits, you only need renew the oil scraper rings and use Cords Duaflex as Grumpy said. If you put in new compression rings, the top one may chatter on the bore lip, and may have to have its upper edge radiused. Even after a light hone / glazebust, this will still be a problem. It all depends on how oversize the ring gaps are on the comp. rings, if very large, then you will have to renew them, but pay attention to the top ring.

 

Don't worry about part numbers, just go to a engine parts specialist telling them bore size, and they will sort you out. Try Cox and Turner Engineering, John Cox is very knowledgable, 01425 652627

 

Yes Richard, I did do a compression test and there was quite a bit of difference between the cylinders and against the spec. 6,5 and 1 were the worst in that order. I hadnt thought of the 'contact' you mention, but as ever you are right. I ran out of time this afternoon to measure anything up but hopefully will get this done, if not tomorrow, then Wednesday.

[LeeEnfield]

Hi No Signals,..............part no's as follows, std rings......

 

Ring, piston, No 1 groove, std........................7052068

Ring, piston, No 2 groove, std........................7052069

Ring, piston, scraper, std..............................7052070

 

 

if required, I also have O/s part no's........

 

 

(these no taken from feb '45 edition schedule of spare parts bedford mw models)

 

 

hope its of some help.

 

Andy

[Chrisg]

Could probably get hold of a complete set of rings if you need. Still got the my old Hepolite catalogues

[No Signals]

Cheers fellas, much appreciated.

[Swill1952xs]

Could probably get hold of a complete set of rings if you need. Still got the my old Hepolite catalogues

 

I don't know if you can still get them, but many moons ago; Hepolite used to do sets of rings for engines with slight bore wear. I think they were called 'Cords" rings. The new ones replaced the old cast oil ring with a three part ring...... two spring steel very thin rings with an expander ring behind it. That was supposed to give more pressure on the cylinder wall and the slim section allowed it to follow the wear on the bore easier than the cast ones.

The top ring was known as a "Ridge dodger" because the outer upper edge of the ring had a step machined in it to avoid contact with the wear ridge.

 

Er............. jus' tryin' to be helpful. :embarrassed:

[Chrisg]

Hepolite made the "apex ring" as you say a three part ring sold lots when I was doing engines 1965- 1990. I feel old now :-D

[Swill1952xs]

Hepolite made the "apex ring" as you say a three part ring sold lots when I was doing engines 1965- 1990. I feel old now :-D

 

Don't worry.........I'm the same age as you. Did my apprenticeship with Endeavour Motor Co on Hove seafront stating in the summer of 69. There ya go......feel any better now. We're all getting old together. With age comes wisdom Grasshopper. :-D

[Guest catweazle (Banned Member)]

I also have used these rings with success,i did buy a mobile boring bar by van norman and did a lot of l/rover blocks.i think if i had the head off etc and could afford it i would go for the rebore.

[Chrisg]

There would appear to be several variations on ring & pistons that could have been used over the years. You need to look to see if there are any numbers on the piston crowns, Hepolite used to cast a number inside.You mat have to remove a pistion to check whats bee fitted.

 

Long time (1965/6) ago I built an engine for a Bedford SB coach and seem to recall that there were two different block hights. May be Richard will comment on this

[Richard Farrant]

Long time (1965/6) ago I built an engine for a Bedford SB coach and seem to recall that there were two different block hights. May be Richard will comment on this

 

Hi Chris,

 

I think the SB coach had the 300 cu in engine, at least all the army ones did, and that engine went through a lot of design changes.

 

The engine in question, should be a 28 hp, if the engine number is stamped with a prefix such as "MW" or "OY", that will prove it, postwar, there were improvements in the engine, then a revamp in to the 214 cu in and I am sure that parts are not interchangeable between 28 hp and 214.

[Chrisg]

Its the same bore size. The latest catalogue listed the 28hp & 214 petrol as the same piston. Catalogues are not always right :cool2:

[Richard Farrant]

Its the same bore size. The latest catalogue listed the 28hp & 214 petrol as the same piston. Catalogues are not always right :cool2:

 

Chris,

 

In this case the cat might be wrong . I have JP Pistons catalogue here ( Aussie manufacturer) and they list 27 hp ( should read 28), from 1939-57, for K, M, O, W, TA, 214 with gudgeon pin to crown height of 1.625" and later 214 1957-76 with pin to crown height of 1.812". So looks like you have to watch out for the later 214, post 1957 as it will not fit a 28hp.

 

As for your recollections of the SB, with 300 engine, just noticed, there were two different pistons, with a variation of about 0.5" , early 1950-56 and later 1957-76

[Chrisg]

All my catalogues are at work I suspect that someone has assumed that because the bore size is the same that they are interchangable

Edited February 17, 2009 by Chrisg

[No Signals]

The engine is marked OY. I am currently awaiting a response from 3 different sources regarding supply of new rings. They do seem to be more difficult to track down than I had first assumed. It seems easier to get a full piston/ring set than just rings! I would go that way and a rebore but for the previously stated reasons. Number cast in to the piston looks to be 040363.

Edited February 18, 2009 by No Signals

[Richard Farrant]

The engine is marked OY. I am currently awaiting a response from 3 different sources regarding supply of new rings. They do seem to be more difficult to track down than I had first assumed. It seems easier to get a full piston/ring set than just rings! I would go that way and a rebore but for the previously stated reasons. Number cast in to the piston looks to be 040363.

 

 

What size bore is it?

[No Signals]

What size bore is it?

 

Nominal 3 & 3/8" according to the manual and the tape measure. Not had chance to stick a dial in the cylinder to see just how worn it is. I have your Mr Cox and another company checking their stocks. Going away tomorrow for a few days so hopefully when I return I might have some positive news of a supplier. Cords dont do anything that is a direct replacement fit, but the range of data hurled at me by their two very efficient staff had me completely phased! Certainly I would try them again another time for different stuff, very helpful.

[Richard Farrant]

Nominal 3 & 3/8" according to the manual and the tape measure. Not had chance to stick a dial in the cylinder to see just how worn it is. I have your Mr Cox and another company checking their stocks. Going away tomorrow for a few days so hopefully when I return I might have some positive news of a supplier. Cords dont do anything that is a direct replacement fit, but the range of data hurled at me by their two very efficient staff had me completely phased! Certainly I would try them again another time for different stuff, very helpful.

 

 

What I meant was, do you know the oversize? Standard bore size is as you say, or 3.375", then you have rebore sizes, which on a Bedford, are +.005", +.010", +015", +.020", +.030", +.040", +.050" and +.060". When you got to the limit, liners could be fitted and you start from Standard size all over again. If you carefully clean the top of a piston, one of these oversizes should come up, stamped on it, or STD, if standard. After all these years, it has probably been bored a few times. You will need to know this size before ordering rings.

[No Signals]

What I meant was, do you know the oversize? .

 

Ah, sorry for the misunderstanding, although that is in effect what I meant; as surprisingly after all these years it is still on standard bores. No mark at all - other than a cylinder number, Y tolerance grade and an X, which I have yet to find a refence to anywhere (They might be quite a bit worn - but still on standard in theory)

Edited February 18, 2009 by No Signals

[Chrisg]

According to my old hepolite catalogues there were 3 variations of pistons used

 

1. 3 ring piston with 2.. 1/8 wide compression rings & 1... 3/16 oil ring

this I belive is an early type

 

2. 3 ring piston with 2...3/32 wide compression ring & 1...3/16 oil ring

 

3. 4 ring piston as 2 but with an extra ring below the pin

 

I can get hold of a set of standard size cord rings for the 4 ring piston

[No Signals]

Thanks Chris, pm sent.