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Thread: Cosworth BDG Tappet Adjust

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    Cosworth BDG Tappet Adjust

    Help wanted - checked the cam clearance on my Cosworth BDG today and the tappets need adjusting.

    Was wondering if anyone has a workshop manual with info on how to get to the small tappets?

    I was wondering if I can slide out the cams to get to the tappets or do I need to loosen the cam carrier?

    I was hoping someone might have the MK1 RS 1600 workshop manual with the BDA engine?

    Any help appreciated!

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    Re: Cosworth BDG Tappet Adjust

    You need to loosen the camcarrier. Changing the shims on a BDA/BDG is one of the worst jobs there is especially with the engine in the car!

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    Re: Cosworth BDG Tappet Adjust

    Thanks - was thinking it needed loosening!

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    Re: Cosworth BDG Tappet Adjust

    Believe it or not Haynes did a workshop manual for a Mk1 Escort Mexico and RS1600 back in the 70's and I had one somewhere. I remember reading about how to adjust the tappets on a BDA and it showed slackening the cam carrier off and using magnets to remove the shims.

    If I were you I'd probably entrust the job to a BDA specialist that's familar with the job, they should have full range of shims of various sizes to ease the job. They'll probably moan at you for taking them the job as the job is very time consuming.

    As mater of interest are the tappets tight or loose, either way the reason that they have gone out of adjustment needs to be investegated. You can't take chances with such a fine and valuble engine.

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    Re: Cosworth BDG Tappet Adjust

    the magnets were to hold the cam followers in the carrier so you could lift the carrier off with the cams in it and expose the shims on top of the valves

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    Re: Cosworth BDG Tappet Adjust

    Quote Originally Posted by Graham View Post
    the magnets were to hold the cam followers in the carrier so you could lift the carrier off with the cams in it and expose the shims on top of the valves
    You are absolutely correct Graham that was it, not a job for the faint hearted.

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    Re: Cosworth BDG Tappet Adjust

    Hi,
    I tackled the job yesterday and as mentioned above its a tricky job!

    My engine is relatively newly built (1000 miles) and I guess the valves are now settled home - some were tight, others a little loose. I needed to re-torque the head anyway which involves removing the cam carrier to get at the end bolts.
    For reference this is what has to be done:
    - measure with a feeler gauge all 16 valves
    - using permanent marker, number top of each cam followers (in case they fall out later)
    - remove cambelt
    - slacken off camshaft carrier bolts and remove bolts - I did this carefully so as not to stress the bolts but one still managed to break - feeling it may have been over-torqued at some stage, who knows!
    - quickly remove cam carrier and turn upside down, if you do not do this quickly the cam followers and small tappets will fall out. It may help here if you turn the engine sideways a little - my engine was out of the car. I had 2 fall out on me - will know better the next time!
    - the cam followers and the small tappets slide out now - easy pull out with a magnet. Tappets sit on a stem in the bucket of the follower and can be removed.
    - Now I measured the cam follower and tappet shims/caps with a micrometer
    - Now You need to figure out what gives the best clearance with what you have - i.e. fit bigger tappets in valves that are loose and smaller in tight ones. Slow work!!
    - I ended up having to grind 6 tappets, removing 2 to 4 thou on each
    - Assemble back into head with some grease on the followers and tappets to stop them falling out when you invert to assemble
    - clean up mating surfaces and add gasket sealer
    - I had to remove one broken stud from the engine block - luckily this was easy enough, I slotted the top of the stem with a dremel and unscrewed it.
    - assemble - grease buys you time when you invert cam carrier and stops cam followers and shims falling out
    - torque down carrier slowly to avoid stressing bolts. I did not like the look of some of mine so I replaced the ones that I thought looked stressed with new bolts. In hindsight I should have replaced them all but I had only 6 new ones to hand, imperial bolts are a bit scarce in my shed! Spec is 8 to 10 lbs.
    - Put on cambelt
    - check spacing, happy enough with outcome, I was aiming for 10 thou inlet and 11 thou exhaust, 2 inlets were a little under at 8 and 9 and 2 exhausts were over at 12 and 13. Will run for a while and check again.

    Took me all day! Would guess if I were to do this again it would take less time, maybe 6 hours.

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    Re: Cosworth BDG Tappet Adjust

    I am glad you are sorted and she now runs well Seven, thanks for sharing your info with us.

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    Re: Cosworth BDG Tappet Adjust

    No problem.

    I like the magnet idea mentioned above!

    By sticking 16 small magnets to the top of the cam follower you could prevent the followers/tappets falling of during removal and refitting.

    I would use this if I had to do this inn the future!

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    Re: Cosworth BDG Tappet Adjust

    Are shim sets not available or different thickness ones? Many bikes use shim adjusted valves and sets / shims are available usually in 0.05mm steps so clearances should be able to be set nearly spot on - hand grinding valve shims sounds a bit 'cheap' (LOL) on a 10-15K engine.

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    Re: Cosworth BDG Tappet Adjust

    Hi Katana,
    No shims in this engine I’m afraid, they use tappets or “top hats!” to set clearance. The tappets come as full size blanks with a height of 200 thou and diameter 9/32” and you have to grind to the required height yourself.

    I think you would struggle to hand grind them as the steel is very hard - I have a mill/lathe and made a simple jig to mount them in and ground them with a very fine grit wheel slowly so as not to overheat the steel.

    I did take 2 brave pills before I started......... working on this engine makes me nervous!

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    Re: Cosworth BDG Tappet Adjust

    Excellent report, much appreciate your info.

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    Re: Cosworth BDG Tappet Adjust

    For future reference there is an online copy of the RS1600 manual here.. http://barnblinker.com/index.php/tag/rs-1600/

    Brian.

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    Re: Cosworth BDG Tappet Adjust

    Thanks Briang, useful link!

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