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Camshaft refitting


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So crankshaft back from the machine shop, no big dramas just a light polish to take of the spare big end bearing aluminium that had transferred to the crank, looked terrible to me but the engineer said not  a big problem and no need to grind any more material away.

It seemed like a good idea to get them to renew the little end bearings which the did in no time and no doubt a far better job than I could ever have done.

So time to start putting it all back together, seems straightforward enough but I have a question of course.

Having slid the camshaft carefully back in to place and bolted on the front end bearing thing it looks to me like the cam lobes don't line up exactly with the holes the cam followers drop in to, I know I probably should have looked more closely at what was what When I pulled it out.............

 

Thanks David

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Cam lobes and follower holes don’t line up. That’s perfectly normal. I questioned this as well. The lobes are off-centre to the cam followers to ensure follower rotation. Do make sure the followers are new and are free to rotate.......don’t ask how I know!

Iain

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They don't, the asymmetric action (off centre) helps the camfollowers to rotate as they travel up and down, that's normal.

On the other hand take the opportunity to check the crankshaft for straightness as you fit it. Place the crank onto the oiled bearing mains of the block, WITHOUT CAPS and measure the run out with a DTI on each main journal as you spin it. With luck each journal will run true, then bolt the centre main bearing cap on by hand just nipping it,  and measure the run out again on the front and rear mains journal. As each journal continues to run true nip up the mains caps on each (don't mix the caps up !), then if all is well torque up the caps SINGLY to the full torque amount, and spin the crank with your fingers, it should spin easily on the oiled bearings. I measure the turning torque by using a small torque wrench that measures torque in inches per foot or if you don't have one use fishermens scales and a socket "T" bar with the bar pulled across to one side. I think all sets are made with the square drive to bar inset ball bearing  at 12" spacing, set your scales at the end next to the ball bearing and vvwwwalluh you have a lbs or oz or grams whichever you prefer per foot scale. The turning amount  for each journal isn't initially important, you are looking for an incremental increase in torque (which is drag) for the crankshaft as you torque each main journal cap which is in line with the first journal ie 31 grams -64 grams - 96 grams which shows the drag is incrementally increasing as you turn the crank...ie the crank is straight. Bottom line is the when torqued up as per Workshop manual the crank should spin with purely your finger action on the nose... BSF...(British Standard Fingers) equates to about 1/3rd of 1 lb ft (well mine do anyway).

Mick Richards

Ooops...Ian beat me to the post because of my loose lips.

Edited by Motorsport Mickey
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Thankyou both, that sets my mind at rest and even with my limited mechanical skills I can see how off center would induce a turning "moment"?

Mick I seriously doubt my skills and tool kit would be up to the job of making the sort of measurements you quite rightly recommend, you mentioned this on my last post and I had taken note and will do what I can using the BASF method (British Arthritic S**ding Fingers). I would like to think the engineer that polished the crank would have told me if it was obviously out of true.

Thanks again for all your help and advise....................I don't doubt I shall be back with more dumb questions.   David

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No dumb questions David, ask away as they come to mind...Oh trust no one, measure everything yourself, then you know.

Mick Richards

Edited by Motorsport Mickey
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Hi David,

            follow Micks words. if it feels good then it is good.

Back in the 80's my father-in-laws Vauxhall viva came to a grinding halt.

When I stripped the engine down one of the con-rods had a different letter stamped on it. It wasn't a matching set.

The odd rod was super tight on the crank with the new shells in.  There was no way that the engine builder in the engine shop could have followed Micks comments.

Thankfully the local scrap yard had enough of everything to sort it out.

 

Roger

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Very little point in asking for advise if your not going to at least try and follow it, especially from someone like Mick who could probably put my engine back together before lunch and have it back in the car in time for tea.............running properly. unlike your father in laws Viva. Ah the days of scrapyards, many a happy saturday morning looking for "sporty bits" for my MK 2 Consul.

 

David

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