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500T tappet

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500T tappet

Posted by martin_main at August 10. 2017

Hello,

just dismantled my bottom end to find one of the tappets is jamming badly in the guide. trying various positions suggests the tappet is bent.

reading the forum hints to using a sprocket puller to remove guide under the guide rebate. What i don't understand is what does the puller push off?  One contribution I read, says it pushes off the top of the tappet. Wouldn't that damage or bend the tappet where its edge touches the camshaft bush? Either way, pushing off the rounded ball end?

any guidance  appreciated

thanks, Martin

Re: 500T tappet

Posted by jim_hill at August 10. 2017

Previously martin_main wrote:

Hello,

just dismantled my bottom end to find one of the tappets is jamming badly in the guide. trying various positions suggests the tappet is bent.

reading the forum hints to using a sprocket puller to remove guide under the guide rebate. What i don't understand is what does the puller push off?  One contribution I read, says it pushes off the top of the tappet. Wouldn't that damage or bend the tappet where its edge touches the camshaft bush? Either way, pushing off the rounded ball end?

any guidance  appreciated

thanks, Martin

Hello Martin, I have just removed the tappet guides from my 48 es2, I guess it is similar to the 500t, not an easy task,in view of my recent efforts I offer you this, instead of using the follower foot against the camshaft bush,make up a spacer that will fit between the tappet foot and the inside of the timing Chest casting, now ,I made a Pushrod up that is slightly smaller than the o/d of the tappet shaft (0.500"),recessed the end so that it fitted over the ball end of the tappet and contacted the smaller diameter below the ball of the tappet, this was then used to hold the centre of whatever extracting device you intend using,finally get the case as hot as you can manage, my crank cases where split so less heat loss that way, I used a propane torch so I was in no danger of melting anything, I emphasise the hotter the better, Obviously the above diatribe is based on my experience,and I do have access to a myford lathe, without which I would be snookered, if you need to tap the guide to get it started use an aluminium drift, seeing the physical build of the tapett I would doubt if you could bend it maybe an application of heat and application of diesel oil or something similar may just do the trick, saves all that p#####g about with spacers and the like, good luck in your endeavours, Jim Hill

Re: 500T tappet

Posted by martin_main at August 11. 2017

Hi Jim,

thanks for reply.

That all makes sense - transfer the pressure via a nicely fitting block, across to the bottom of the timing chest.

Will have a closer look at - "I made a Pushrod up that is slightly smaller than the o/d of the tappet shaft (0.500"), ,recessed the end so that it fitted over the ball end of the tappet and contacted the smaller diameter below the ball of the tappet, - after work.

All four cam bushes are worn, so they have to come out anyway. A bit of a shocker on the price at around £14 + each. At least they are available.

Am unsure what you mean with "I would doubt if you could bend it maybe an application of heat and application of diesel oil or something similar may just do the trick ". Ah just worked out what you mean - the tappet isnt seized in, it's actually free in the guide in all positions of rotation, but if pushed up to where the cam would push it, it jams, but to a lesser degree depending on where it's rotated. I think its only a thou or two out but wouldnt help its contact with the cam. maybe relieve the guide a touch at the bottom, reassemble and check cam to tappet contact with engine blue.

You've got me thinking now!

Thanks again Jim, I'll let you know how i go on

 

Martin

Re: 500T tappet

Posted by martin_main at August 12. 2017

Well Jim, it became obvious, when i applied  your advice to what I was looking at.

Made up a tube to go over the ball, ground the feet of my two legged puller, to fit, a touch of mapp, and they moved - brilliant. Success with zero damage.

Having got them both out, it became obvious, the ex' was original. Lots of muck in around the top, and still had a dowel lurking in there.

The inlet - the one tending to jam, was cleaner around the top and the dowel missing.

I am a bit puzzled, given that both tappets have a flat along the shaft, as to why there is only a corresponding flat along the internal bore of the (prob original) exhaust guide. The inlet is circular bored allowing the tappet to rotate. Is this a later mod' or should I rectify this with a guide with a flat?

Going to have a friend dial up the jamming tappt, but apart from that I'd say they were servicable.

once again, any input welcomed

Martin

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