Camshafts and camcarriers

To be honest, I think I have been putting off the tackling of the cam houses/cam carriers... I had expected these to be complex but eventually there was no room for further excuses and I had to tackle them. In the event the work wasn't too difficult although as always, trying to judge what's too badly worn and what isn't is very difficult with  my lack of prior experience.
In my case the cam carriers were already off as the motor was stripped, so I wont be describing their removal. I tackled the exhaust cam carrier first. Both camshafts turned... but I wouldn't describe it as "free". They were definitely a bit stiff. However they were obviously both pretty dry and dirty so best not to rotate them in this condition!

Ex cam housing, cover removed

left hand end

Right hand

The camshaft didn't look too pretty. These covers had been removed from the car and stored. During this time they had deteriorated although they had been covered in grease...  and the grease had acted as a magnet for grit and dirt! There will certainly be a major clean up required. I used a paraffin bath and scrubbed to remove most of the dirt and then rinsed with carb cleaner as best I could. However a full clean up really requires that the cam houses be stripped. I started by removing the 2x 10mm bolts holding the end cap on

End cap- easily removed.

The end cap was quite tight on the camshaft but the shaft itself could slip to the left (rearwards) as its this cap which controls end float, remove the bolts and there is quite a lot of that! and this pushed the end cap off. Once the end cap was off the thrust washer and its mounting bolt and 2 washers were exposed.

Thrust washer, bolt and washer. Note the locating dowel/pin which anchors the thrust washer to the camshaft

End cap with O ring seal, camshaft protruding towards rear

In order to remove the bolts on the camshaft its necessary to hold the sprocket. The recommended method was to hold the sprocket  in a soft-jawed vice. I used the fibre jaws.


However don't let the camshaft hang from the sprocket! Support the housing to avoid straining the bearings etc.

Hold cam sprocket firmly in soft-jawed vice. Support the housing so its weight isn't carried by the sprocket

Supporting the cam housing- undo the rear retaining nut 17mm

... and remove the bolt, spring and normal washer

The thrust washer can be lifted off its locating pin.Whilst the cam housing is held in the vice you can undo the sprocket retaining nut. I found it tended to slip in the jaws so I loosened it with a sharp tap with a dead hammer.

Using a ring spanner to remove sprocket nut

Sprocket bolt washer and spring washer

However, having removed the bolts at both ends I was still unable to pull off the sprocket or remove the camshaft by hand. The suggested method is to use a puller to press the camshaft out towards the sprocket end. I used a pinion puller intended for Triumph motorcycle gears. I simply substituted two 10mm  bolts for the  imperials to fix the puller to the end of the cam housing via the end cap screw holes. Screwing the bolt in then pushed the camshaft forwards pushing the journals out of their locations and pushing the oil seal out of the front  with the sprocket at the same time.

Re-tasked Triumph pinion puller

Puller (pusher?) in position.

Oil seal pushed out as camshaft emerges.

Camshaft removed with sprocket still attached.

I then removed the sprocket using a two legged puller

Puller hooked through central holes in sprocket

 I wouldn't usually use a puller here as the sprockets are fairly soft and I don't want to bend or crack it... but this was a fairly loose fit and it didn't require much force. I suspect it would have come off by hand if I had found a way of anchoring it while I pulled.

Sprocket removed.Oil seals simply pull off. Note, Woodruffe key and rear washer still on shaft, fixing bolt and washers at top. The rear washer behind the sprocket isn't shown on any of the parts diagrams I can find so I will compare with other shafts to make sure that its meant to be there. This washer has a profile to fit around the key so its not there by accident!

After this step it was necessary to clean everything up and examine the shafts and bearings. To my surprise the shafts are the same for both exhaust and inlet housings. As this is a low compression motor the shafts are the "107" type and should be marked "777" ahead of the front journal. However these cams had no markings. They had oil holes in all journals and also on each cam which is a higher spec than original Lotus which have oilways only in the journal. There were some minor scratches on the journals which will need a light hone to clean up. This car was fitted with standard cams and as far as I am aware it still had those. However the fact that these weren't marked might indicate that they are replacements. Standard cams are cheaper than the racing ones but having checked the price of new  camshafts I really don't want to replace them and will try to polish these as best I can first. The following pictures show the journals and cams on the shafts.

Forward cams and front journal

Central cams and journals

Rear journal and cams

I found that there was a blob of silicone inside the end of the camshaft (ie behind the sprocket). I fished this out, but on reviewing the parts list I found that there should be a blanking screw in this point, presumably to stop oil spraying out the front of the camshaft. I assume that the blob of silicone implies that these have either failed or been lost. I ordered two new ones just in case.

Grub screw blanking oil way inside camshaft

Removed with 5mm Allen key, will refit as a new screw with threadseal.

The blanking screw was indeed present and tight! However it came outwith a 5mm Allen key and I will fit a new one with some thread lock.

The case has no separate renewable bearings for the shaft, it rotates in the alloy case itself. This is also scratched and the following pictures show the various bearing regions. Again I would prefer to recondition rather than replace but luckily in my case I do have another  set of cam housings from motor no 2 so I will compare and choose the best.

Forward bearing area of alloy housing. I had expected this housing to contain a bush but it seems to mount straight into the alloy- this has become scratched

Second bearing region- again some marking evident

3rd bearing

4th bearing

Rear bearing surface

At some time this cam housing was painted yellow. I don't think this has any particular significance (other than an indication of the bad taste of a PO) so if I can remove it I will. I managed to clean most of the solidified jointing compound and gasket traces off with a combination of gasket scraper and a Ro-loc bristle brush... cant say I was very impressed with the quality of the casting.

sealing surfaces cleaned up

Sealing surfaces cleaned with bristle brush, note poor moulding here.

I wasn't at all impressed with the quality of the casting, it seems unsurprising that these cam carriers suffer from leaks. This section shows some particularly nasty moulding. It doesn't seem to be damage, simply poor moulding.  was going to use the nitrile rubber re-usable gaskets to seal these housings on rebuilding, however these gaps may be too big and I may have to use  silicone RTV or similar to accommodate. I also need to see how best to polish the interior bearing surfaces of the cam housings and smooth the scratches as far as possible, a light hone should do it as its not necessary to remove or enlarge the bore, just remove any possible high spots. Any lower points will simply hold more oil and help lubrication. Of course I do have a second set of camshafts/cam housings. These come from the motor in which I found the rebuilt head- albeit it a rebuilt head catastrophically damaged by cam belt breakage- and which I have now repaired. This could imply that the cam housings from that motor may also have received previous attention and so could be in better condition than those that I have stripped here. It will be worth taking them apart as the housings may be in better condition.

exhaust cam carrier from second motor

Well surprise surprise!!! The other exhaust cam turned out to be in much better condition! I dismantled it in exactly the same way except that the cam carrier had the bracket for the belt cover attached. This had to be removed to allow the camshaft plus seal to press out forwards.

Belt guard bracket on the front of the exhaust cam carrier. As fitted it covers the oil seal and prevents camshaft extraction. Unlike the snubber (see on) this bracket can be fitted and removed with the sprocket in place. Access the bolts through the holes in the sprocket.

bracket removed

Both shaft and housing were in much better condition although in between the cams the shaft has gone a little rusty which will need cleaning off so that it doesn't detach in use. There is another benefit too in that I don't have to clean off that awful yellow paint! I will probably have to consider end float though because the second cam did not have the Woodruffe key washer present on the first which presumably has an influence so I will check that on reassembly.

bearings in carrier also better- here fwd 

... No 2

... No 3

...No 4

and rear- note still oil in position

 The shaft was also in better condition- and this time it was marked 777 forward of the front journal. However this shaft had oil way holes only in the journals, there were no separate feeds to the cams themselves. I cant help thinking this might be why they were in better condition, since the more exits for oil there are in the shaft, the less oil will flow through each one- so perhaps the bearings received more oil via this shaft than through the other described above.

777 marking around the cam shaft

I cleaned everything as thoroughly as I could and used an air line to blow out the oil ways and the blind screw holes. I then reassembled by feeding the camshaft through from the sprocket end.

I then added red assembly lube to all the journals before slipping the crankshaft into place.

New rear O ring naturally...

 However, I can't fit the rear cap until the thrust washer is tightened. I temporarily refitted the pulley to the front- it just slides on, so that I could grip it as before in order to tighten the rear nut. This was torqued to 25 lb ft and the end cap then fitted.

temporary refit of pulley

 Once the  rear plate was fixed it was time to fit the front oil seal... again Lotus recommend a special tool (2 in fact) for this.... neither of which I  have- and frankly I cant see what its for anyway. I therefore used a universal seal replacement tool kit

New seal pushed over shaft and up to its housing

 I deliberately selected a press size that covered the outside of the seal so that it would press it up to the surface of the cam carrier and no further. There is an oil drain hole just inside the seal and if the seal is drifted right up against the housing then this will be blocked. Keeping it flush with the housing prevents this.

Using an oil seal adaptor to fit the seal, this seal kit uses the original sprocket bolt to push the seal in

I could then refit the sprocket and hold it  in the vice while I torqued its bolt up to 25lb ft. Finally I replaced the covers to keep as much dirt out as possible and wrapped the cam housing until I can set about sorting the tappets and shims.

Finished Ex cam carrier.

I still have to refit the belt-guard bracket and also strip and renovate the inlet cam carrier. I will start with the second motor this time! However I don't anticipate any problems so unless there is anything materially different from the exhaust cam carrier I will not send an account to the blog.

The inlets were indeed very similar and I found again that the original motor in the car had the better cams. Again this was marked 777 around the forward journal. The only significant difference was that the inlet camcarrier was fitted with a snubber. Although the retaining nuts were accessible through the holes in the sprocket, the snubber itself cannot be removed unless the sprocket is removed first, and must be refitted before the sprocket.

Snubber on inlet cam sprocket

It was pretty clear which way round my sprockets went owing to the marks on their surface, but the manual does stress that the coloured dots next to the "IN" on the inlet sprocket and the "EX" on the exhaust, must face forward. The dot next to the "IN" marking is visible in this pic.

Sprocket removed... note nut on stud and spacer plus nut on lower stud

Fixings removed, note fork cutout in snubber mount into which the spacer's shoulder fits

Inlet cam house reassembled. Oil seal fitted and snubber going on before sprocket.

Finally I tested both cam carriers for fit with the tappet buckets. All seemed to be fine except that No 1 valve on the exhaust cam carrier would fit any of the 16 tappet buckets I have. This valve was bent during the presumed cam belt failure and its possible that some of the force was transmitted to the tappet? In any event I was able to ease it in with a gentle hone using a well-oiled small cylinder (brake cylinder) hone. It then slid in easily. I think if I was doing this again I would obviously check fit and get any such honing done before assembly. However I was able to achieve the honing very neatly after inserting a sheet of polythene to cover the camshaft so that none of the honing dust fell onto it.

This is the small cylinder hone I have ostensibly made by Draper I think its a forgery because Draper never made a 2-armed hone! However it works fine.

Hone in use- note polythene protection over camshaft

This worked really well and I soon obtained a silky sliding fit in the bore. Thinking about it this is probably an excellent way to remove any of the scraped high spots/ridges in the cam carrier bearings themselves... Using the hone in a steel cylinder I don't think it removes any material... here of course its aluminium so treat it very carefully, test often and use it only for the minimum amount needed to get the effect you want.