Home Forums General Counties Cars Discussion Camshaft end float

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  • #5159
    ToadofToadHall
    Participant

    Hi,

    As indicated in my previous post I am reassembling a 2.2 engine.

    Whenever dismantling an engine or anything with a large number of parts, said parts are all bagged and tagged. Perhaps something got away in the process. One thing is for certain the old memory isn’t what it once was.

    Does anyone know how the end float is taken up in the camshaft please?

    Although the front plate and camshaft locating plate are not yet fitted it is easy to position the cam correctly in the block. This appears to leave room at the rear, maybe for some kind of thrust to be applied. In my bagged and tagged box of bits there doesn’t seem to be anything that fits the bill. I have a manual and two binders of exploded diagrams but sadly no mention.

    #5163
    Davewhy
    Participant

    I’m pretty sure that the camshaft end float is set by the sprocket timing gears. There is a triangular plate holding the camshaft in and this should be checked for obvious wear. Replace it here if worn.  https://www.ahspares.co.uk/austin-healey/big-healey/engine-4-cylinder/retaining-plate-camshaft.aspx

    The endfloat is then set by the timing chain on the sprockets and the adjustment is made with shims behind the crankshaft timing gear. https://www.ahspares.co.uk/austin-healey/big-healey/engine-4-cylinder/shim-006-crankshaft.aspx

    While you are on replace the timing gears and tensioner and convert the front timing cover oil seal from a cotton one to a lip seal. or exchange covers here.

    https://www.ahspares.co.uk/austin-healey/performance-parts/1004-engine-bottom-end/timing-cover-lip-seal-conversion-exchange.aspx

    #5165
    ToadofToadHall
    Participant

    Thanks for your reply Dave.

    So the front camshaft retaining plate and the timing sprocket are the only thing taking up the end float, yes?

    I will get a crankshaft shim ordered thanks. The lip seal is definitely something that is going to be changed as I dislike felt seals a lot. Though I was going to attempt to fit one to the original timing cover as I didn’t know the exchange unit was available.

    #5177
    Davewhy
    Participant

    Hi,

    That is my understanding – The camshaft floats whereas the crank is held in place by the central main thrust washers. The timing chain then holds the camshaft sprocket parallel to the crank sprocket which is shimmed. Obviously you need to replace both sprockets., chain and tensioner whilst you are rebuilding. On Austin engines of this era timing chains last about 25,000miles or so before you hear the rattle which tells you they need changing. The retaining plate for the camshaft stops any excessive movement and should be replaced if worn at all.

    #5205
    ToadofToadHall
    Participant

    Thanks Dave,

    Got the sprockets and the shim from Ah Spares along with a number of other bits.

    #5207
    Davewhy
    Participant

    Great – let us know how you get on.

    #5227
    number5
    Participant

    Hi-just a note on the cam sprocket, in that I recently read that these are being sold by some suppliers without the front cover.  Did you supplier mention about removing the one from the original and attaching it to the new one.

    Regards-Peter.

    #5263
    Davewhy
    Participant

    Do we know what the purpose of that pressed steel cover was? I don’t think they were fitted on the later engines. I certainly didn’t fit one on my engine rebuild. I would be interested to discover their function. They don’t hold oil nor do they have anything to do with the timing chain tensioner.

    #5273
    number5
    Participant

    Hi there Dave,

    Some time ago,  a Healey owner mentioned that the reason for the plate attached to the upper  cam gear is to ensure that there is an adequate supply of oil is fed onto the chain.  Over the past 55 years, having worked on numerous engines, including three Atlantic and two A70 rebuilds in the past 1o years, I have never come across an engine where there was no plate attached to the upper timing cog.

    Whether or not this is the reason the original designers put it there in the first place, I can’t say, but there must have been a reason, and I would not fit the cog without it attached.  My current coupe has travelled 300.000 miles,  with only the chain and tensioner changed during rebuilding it last year.  On my previous convertible, undertaking me 475,000 miles over 20 years of everyday driving, not quite sure of the mileage, but perhaps just over half of them, a new chain, tensioner, bearing shells and a set of new pistons,  fitted whilst the engine was still in the car.  On both that car, and my coupe, both still have the original crank and cam cogs.  Now,  20 years on since parting with the convertible, although now used as a club car, the engine still runs extremely well.

    Has the supplier of the chaps replacement parts given any reason as to why the plate has been deleted. It would be interesting to hear such.

    Regards-Peter.

     

    #5279
    Davewhy
    Participant

    I think that is what is may have been originally designed for. No such plate exists on either the A40 1200 engine nor the A or B or C series as far as I know. I am not sure where the oil would run as the holes drilled in the camshaft gear are blocked by the tensioner ring. I can’t see the plate shown on the original Austin 16 Sectioned engine artwork I have. I am not sure it serves any useful purpose but am willing to be proved wrong.

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