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daves6guitars

BMC 1.5 Cylinder Head rebuild

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I'm just off to rebuild my BMC 1.5 cylinder head, however, when dismantling it I found it had been running ( perfectly well I might add) without 7 of the 8 bottom valve cups. Its a small dished washer that sits under the valve spring, presumably to prevent wear to the head. I have had no luck from the usual suppliers locating more than 1 of these things. Does anyone know how crucial these things are. It ran fine without them, but will it run better with them? Will a flat washer of the same dimensions do the same job. Do I leave them out alltogether? Any opinion will be appreciated though I wont be able to reply till I get back......cheers

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I'm just off to rebuild my BMC 1.5 cylinder head, however, when dismantling it I found it had been running ( perfectly well I might add) without 7 of the 8 bottom valve cups. Its a small dished washer that sits under the valve spring, presumably to prevent wear to the head. I have had no luck from the usual suppliers locating more than 1 of these things. Does anyone know how crucial these things are. It ran fine without them, but will it run better with them? Will a flat washer of the same dimensions do the same job. Do I leave them out alltogether? Any opinion will be appreciated though I wont be able to reply till I get back......cheers

 

 

I know just what you are on about and I think your aside in brackets has given you the answer. They are thin tin type thing so a washer might be a bit thick and "over-tension" or cause the spring to become coil bound. However I am sure you would check that before trying to start the n engien and I am also all but sure both are theoretical rather than actual possibilities. If it was mine it would go back without them. I am not even sure all the 1.5/1.8s had them fitted.

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I'm just off to rebuild my BMC 1.5 cylinder head, however, when dismantling it I found it had been running ( perfectly well I might add) without 7 of the 8 bottom valve cups. Its a small dished washer that sits under the valve spring, presumably to prevent wear to the head. I have had no luck from the usual suppliers locating more than 1 of these things. Does anyone know how crucial these things are. It ran fine without them, but will it run better with them? Will a flat washer of the same dimensions do the same job. Do I leave them out alltogether? Any opinion will be appreciated though I wont be able to reply till I get back......cheers

 

Initially the valves on a 1.5 I ran had these fitted, but after I re-built it the engine smoked badly. I contacted AMC and they suggested leaving these caps off - they cut the oil seals on the valve stems as the springs were compressed to allow for refitting the retaining cotters.

 

I did this and to my knowledge the engine still runs satisfactorily to this day.

 

Hope this helps, I would leave them all off.

 

Leo

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I'm just off to rebuild my BMC 1.5 cylinder head, however, when dismantling it I found it had been running ( perfectly well I might add) without 7 of the 8 bottom valve cups. Its a small dished washer that sits under the valve spring, presumably to prevent wear to the head. I have had no luck from the usual suppliers locating more than 1 of these things. Does anyone know how crucial these things are. It ran fine without them, but will it run better with them? Will a flat washer of the same dimensions do the same job. Do I leave them out alltogether?

You are referring to the valve spring bottom collars which were fitted to some engines using the old valve stem oil seals, they served a number of purposes and if you are still using the old type seals they may have to be retained. Without them there will also be a different spring pressure applied, unless the springs have already been changed (why there are some missing).

I would check all the valve guides, springs and seals to determine which are original and which need collars.

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Initially the valves on a 1.5 I ran had these fitted, but after I re-built it the engine smoked badly. I contacted AMC and they suggested leaving these caps off - they cut the oil seals on the valve stems as the springs were compressed to allow for refitting the retaining cotters.

 

I did this and to my knowledge the engine still runs satisfactorily to this day.

 

Hope this helps, I would leave them all off.

 

Leo

 

Hi all and Leo.

 

Yep I have that boat with that engine that Leo is referring to. It starts first time, well after holding the heaters on for 30 seconds anyway, even in all that cold weather we have just had it fired upp on the first turn of the key. I do get white smoke from it if I rev it up in neutral but when it is running it is fine. It does leak a bit of oil but for a 30 odd year old engine it runs just fine.

 

If I can pick up a running BMC 1.5 I will recon that as a spare but to be honest my present engine is about as good as it can be for it's age. I certainly haven't had any problems with it over the last year.

 

Cheers

 

Pete

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As previous posters have said some 1.5's had them and some didn't. I wonder why you have one fitted only?, Repair at some point maybe?. Just to be sure I would check lengths of the valve springs on removal, and make sure they go back on the same valve. Out of curiosity, can you determine if the lengths of the valve guides are the same across the piece?

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Many thanks to you all for your replies, I've had new guides fitted to the head and set at the correct height, new valve seats cut and the old valves brought up to scratch, the valve springs were measured and are within limits so I decided to reassemble minus the bottom collars anyway, which seems to fit in with TB's reply...thanks Tony.

 

Cheers

 

Dave

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