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Grahaml

Advise please - cam (re-)timing

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Well I put it off a long time (but not many miles).  Had a go at changing cambelts on my V8 - engine in-situ.  Definitely do-able but it sure is limited access at the front of the engine - made worse by all the coolant pipes and various tubes and wiring!!

I got timing pins made up to exact (lotus) sizes by an engineering firm which saved a few £.

It was slow going - lots of time spent getting from under the car -then climbing into the boot (trunk) and lying over the engine - took ages even getting it locked into place.  Got the old belts off and new (blue) belts refitted - with lots of scratched, cut and bruised arms and hands -  I had to move one or two of the cams a little to align the teeth on the belts - but I believe this is quite normal.

Went to turn the engine over by hand a couple of times to recheck the pins but the engine wont turn over more than probably 1/8 of a revolution (45 degrees) before stopping.  I checked - nothing external I can see stopping it so I reluctantly wound it back anticlockwise and locked the crank in position again and rechecked the (tolerance) pins would go in.

They screwed in but the more I checked (and maybe doubting myself) I am thinking that they didn't go in properly when I changed the belts.  I've poked various sized drill bits (4mm and 4.5mm) down and even a bit of thick wire and then tried moving the cams a little by the 18mm nuts on the end to see if I can feel the cams move through the locking holes but I can't. 

What I'm thinking is that I had the cranks 360 degrees out - on the wrong stroke - and that the pins didn't go into holes on the cams to lock them - but just pressed against the shaft - the did screw in a but but looking again (and again...) at it I'm thinking they should maybe gave gone in further.  I did check at the time and was convinced it was OK!!  This is despite rotating the crank - testing if the pins went in - didn't think they did so rotating another 360 degrees.

So... unless there's a really simple explanation staring me in the face that I'm just not seeing I thing I will need to re-time the cams.

So - for the experts here...

  1. can I do that without removing the engine.  I will if I need to but was hoping to avoid that. 
  2. Is there anywhere offering a simple guide?  I have the workshop manual so I can follow "by the book" if necessary

Any other thoughts...

Many thanks in avance.

Graham

 

 

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I wish I knew, but there is a guy on Lotus Chat in California, He goes by Gonzo, G. Mendoza is his name, who absolutely can tell you.  He has taken these motors apart and is very generous with his time.  He actually in the last year started a garage to do work on Esprit's.  He has many U TUBE videos of V8 Esprit's that have been modded and also a video showing the complete rebuild speeded up of the assembly of a V8 engine.

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Thanks - he gave me encouragement to do it with the engine in place - he also gave me the exact dimensions of the tolerance and setting pins as well as the crank locking key and the tension adjuster tool -so I could get them made up here. Very helpful guy - I might drop him a note anyway..

Thinking about it now - I'm not too concerned - I think I can do it with the engine in place:  Take the cam covers off, move (might need to remove and refit) the camshafts until they are in the correct position, lock them up, check the belt is fitted properly - then finish the job (put it all together again.

Sounds easy when I put it like that !!  We will see!!

As I said I have the manual so I will just take my time - with the cam covers off I will see what I did wrong and why it happened.

I think it will be next week until I get a chance to try it though - maybe a few hours on Saturday though.

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On 22/01/2020 at 21:12, Grahaml said:

Went to turn the engine over by hand a couple of times to recheck the pins but the engine wont turn over more than probably 1/8 of a revolution (45 degrees) before stopping.  I checked - nothing external I can see stopping it so I reluctantly wound it back anticlockwise and locked the crank in position again and rechecked the (tolerance) pins would go in.

If the engine stopped turning because a piston contacted valves then you may well have bent the stems so they'll no longer seal & you'll have no compression on that cylinder.

Have you watched this video on changing V8 belts, he mentions the engine being on the engine being on the exhaust rather than compression stroke when inserting the pins at 2 mins 30 seconds?

Good luck. :thumbup:

Edited by jonwat

Cheers,

John W

http://jonwatkins.co.uk

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Hopefully with just turning by hand it will have been insufficient force to damage the valves, rather different had it been on the starter or worse engine running.

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29 minutes ago, andydclements said:

Hopefully with just turning by hand it will have been insufficient force to damage the valves, 

I managed to bend valve stems when turning the engine by hand on my Europa. 😡


Cheers,

John W

http://jonwatkins.co.uk

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Ouch, that must have been unlucky along with frustrating. There is the extra bit of force when coming off another cam lobe,  or the size of the valve head meaning there's more bending action from just a light touch (if you mean Europa TC / Special then they're just 2 big valves per cylinder so could bend more easily than 4 per cylinder).

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Here is one question? Is the car in gear? Ask me how I know.

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Many thanks all.  After my initial shock I'd calmed down and I believe it's all recoverable.  

The car isn't in gear  - I checked that first with hope in my heart- but no..,,

Thanks for the suggestion Gonzalo.  I have disc printed already in preparation to check the timing belt tension so I'll follow your advice.  I'm still a bit mystified about how I could have got it 360 degrees out - I did try the pins 360 opposite from what I eventually used but exposing the cams will let me see for sure.  Maybe the cams were mis-time d enough to stòp the pins fully inserting - I'll see though.  

I had already taken the plugs out anyway.

I'm optimistic about it being a relatively straightforward fix now -turned over slowly by hand (there's not much access to do anything else) I wouldn't have expected to do any damage.  Could do with getting it done though ..

 

Might be a wee while until it's all done but I'll post when its finished

 

Thanks again all.

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