Valve guide / valve spring seat question.

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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Pharisee
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Valve guide / valve spring seat question.

Post by Pharisee »

Having pretty much sorted out the bottom end and cylinder of my basket case '54 G3LS, the time has come to start looking at the cylinder head.
Apart from being grubby, it looks like it's survived it's garage incarceration well. The valve seats are rusty but having cleaned them up with a wire brush in a Dremel, they don't look too bad at all..

The valve guides are another matter. These are steel (cast iron?) and are rusty in the bore so I'll replace them and re-cut the valve seats at the same time. Is there any mileage in going for 'Colsibro' valve guides or would I be better sticking to the original material?

I've got new valves supplied with the engine bits and have all the valve springs, spring seats, collars and collets.... And a question.
The exhaust guide has a wire circlip fitted... The inlet doesn't (nor is there a groove for one). Neither of the two valve spring seats that I have are relieved for the circlip so the seat sits against the circlip, not the cylinder head. That doesn't look right to me so I'm assuming that the 'mix and match' bits that I've got, don't actually match.

Should the valve spring seat be relieved on the underside to clear the circlip or is there a different spring seat for use with circlip valve guides?
I'm from the Fens.... Gimme six.
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1608
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Re: Valve guide / valve spring seat question.

Post by 1608 »

The seat on my AJ 18s is relieved for the circlip.
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Re: Valve guide / valve spring seat question.

Post by 56G80S »

Same here, the seat is relieved for the circlip. I think there's another thread about it on the site as well.

I may be teaching an expert and if so, sorry. Don't forget that on the ally heads the guides come out the opposite way to usual practice. Get the outer (spring) end clean as poss. Move out just enough to remove circlip. Clean again. Heat the head and take the guides down into the combustion chamber. Personally I put the new guides in freezer and try and get them straight in after the old ones come out. And there's the oilways to line up. I had some replacement guides once where the hole didn't match the head.

Don't whatever you do just flog them out cold the wrong way like a so called motor vehicle engineer did to mine. That's why I never made it to the last IJR in Germany.


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Duncan
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Re: Valve guide / valve spring seat question.

Post by Duncan »

There are two types of hairspring setups, the earlier type that the spring "slid" into may not be relived as the circlips were not used, they also have a locating spike that may not fit a later head if my memory serves correct.
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Re: Valve guide / valve spring seat question.

Post by 56G80S »

Duncan is right, there is what I'd call a "pip" in the underside of the seating plates.

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Re: Valve guide / valve spring seat question.

Post by Pharisee »

OK... thanks for the insight.
The two valve spring seats I have are not relieved for circlips so I'm assuming that these are early items, used before the valve guides were fitted with circlips. It seems likely that the exhaust valve guide has been replaced at some point and the later circlip guide fitted but not the appropriate spring seat... ho hum. The 'un-relieved' spring seat do have the locating 'pip' and the head is drill to suit so that's not a problem.
I've ordered two new valve guides, both with the circlip. As later, relieved spring seats don't seem to be available from AMOC Spares I've found a set on eBay that look serviceable so I'll bid for them.
I'm from the Fens.... Gimme six.
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Re: Valve guide / valve spring seat question.

Post by Duncan »

John

You may need to use what you have and just relieve the bottom of the spring seats, the early type has holes in it that the springs slide into, the springs sit on the later ones, I am not sure if the springs are interchangeable between the two sets.
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Re: Valve guide / valve spring seat question.

Post by Pharisee »

Duncan wrote:John

You may need to use what you have and just relieve the bottom of the spring seats, the early type has holes in it that the springs slide into, the springs sit on the later ones, I am not sure if the springs are interchangeable between the two sets.
This is the valve gear that I got with all the other bits. The spring seats have no relief on the underside, nor do they have holes for the springs to slide into.

Image

I'm looking at this set on eBay. They definitely have the circlip relief on the underside but they also have an 'extra' bit on the top side.

http://www.ebay.co.uk/itm/262907092105? ... EBIDX%3AIT
I'm from the Fens.... Gimme six.
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