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Discussion Starter #1 (Edited)
Hello guys.
I have been chasing a knocking/tapping sound in my Juniors motor for a while now. Sounds like it is in the head and when I listen with a screw driver it taps loudest on the exhaust side rear cover nut. This is a picture of my #4 exhaust cam lobe. I can feel a little ridge with my nail and the arrows point to a 'flat area' on the cam lobe.

Two questions please:
1) Is this lobe warn and will it cause a tapping noise ?

2) I have two spare cams from another Nord - can I simply replace this cam with another without destroying the motor. Do I need to do line boring in other words or could I simply fit another cam?

Thanks in advance
 

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Hello guys.
I have been chasing a knocking/tapping sound in my Juniors motor for a while now. Sounds like it is in the head and when I listen with a screw driver it taps loudest on the exhaust side rear cover nut. This is a picture of my #4 exhaust cam lobe. I can feel a little ridge with my nail and the arrows point to a 'flat area' on the cam lobe.

Two questions please:
1) Is this lobe warn and will it cause a tapping noise ?

2) I have two spare cams from another Nord - can I simply replace this cam with another without destroying the motor. Do I need to do line boring in other words or could I simply fit another cam?

Thanks in advance
No, i messed with different journal caps (even though right position ones) from a different head. This is a big Nord mistake - if one is not going to align-bore the head journal seat and cap. If ever you buy a 2nd hand head be as sure as you can that the caps are the original head caps - there are a few checks to getting this right (but not fool proof). Need to know who you are buying from. Then I thought engineers blue and water paper was a solution to align-boring when you have a cam that is harder to turn than normal - it is not!

Some hints - I am no expert - just sharing experience from the expensive and unforgiving school of hard knocks

1. From the cam lobe in the photo - the cam is past its serviceable life (but keep it as you can rebuild and reprofile them). It is way too sharp and the tapping you are hearing is probably slap of cam against cam follower because the ramp on the lobe is no longer there. See I am staying away from why this may be so, servicing and oils etc because I may inadvertently trigger an honour challenge requiring me to get up at sparrow fart for a battle with oil squirters. LoL

You may find that the inlet cam is similarly worn so if the cams were originally a pair. So you may have to replace both. You may well recover some performance because both duration and overlap with that kind of cam wear will not be optimal

2. Different capacity Nord engines and different year models do have different cam profiles (and lift) - they are designated by different manufacturer numbers so try to get a matched pair using the correct cam on the inlet side and the correct one on the exhaust side. If you are not sure take them to Kevin at AK and he'll figure out what you have and tell you what to use. He may even have a good set of highish lift (standard) ones that you can use. Or you may be sitting on some yourself.

3. Only do this yourself if you have timed a Nord motor, know how to get the motor to be 'on rock' on 1 or 4, and know how to deal with the tensioner etc. There are engine crank markings and cam markings on the front most journals caps and cams. If you are fitting different cams you'll need to undo the locknut on the cam pulleys and reposition them to get the cam timing and crank timing on their marks (making sure that you distributor is also pointing to 1 or 4 as the case may be). So it's a bit tricky.

4. Also, if you are fitting another cam (even if only on the exhaust) you'll need to reset the cam to follower gap because the cam base circles can be different from cam to cam. This too is a tricky job made worse if you have not (like a good Nord owner) collected every (good) shim that you could lay you hands on over the years. So if you do not have shims do not start a job like this). However if you are committed to doing this yourself. You can save a lot of time by recording the clearances for each inlet lobe and exhaust lobe and the doing the math backwards by removing the cam follower and shim for each valve and measuring and marking them ( or put in a plastic packet marked inlet follower no 1 inlet shim no 1). With these measurements for each inlet and exhaust valve you can with a high degree of accuracy work out what shims your new cams will need at each valve because you have taken all the measurements that are a constant base circle, follower thickness (but each follower must go to its original position - there are in any case other good reasons to follow this procedure of same follower going back into same place), shim thickness and known required gap needed. Doing this will save you time and you will know exactly what shim thicknesses you need for your new cams (and may even be able to utilize the shims you took out because they are your target thickness). In order to do these measurements you'll need a proper dial gauge.

Lastly, since you are not removing the head you'll need to be careful when putting the new cams in loading up the followers with the cams more or less on their marks. This is obvious but I mention it anyway. If you do not do this you can bend valves against Pistons very quickly because valve lobe is in extended position and its piston is at tdc.

It's a fun job to do, but takes patience, common sense, having some around who has done it before and a few beers. Good luck!
 

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Exhaust leak caused a tapping noise in my engine too.
 

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Discussion Starter #9
Exhaust leak caused a tapping noise in my engine too.
Hi El - I have done this check already with soap water and listening for air blowing with a hosepipe - my exhaust headers are sealing properly. I am actually 100% sure my issue is this worn cam.
 

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Discussion Starter #10
It's a fun job to do, but takes patience, common sense, having some around who has done it before and a few beers. Good luck!
Hey juniorgtar

Thanks for the detailed response

I am actually quite happy that I finally identified the cause of the noise. I was worried that I had to remove the head and replace valves etc - but the cam is a pretty easy problem to solve.

I have done the valve clearance adjustment a couple of times chasing this tapping noise using a Haynes manual for an Alfetta. I also have a couple of extra shims I collected from my old head and bought some from Kevin at AK. My clearances are 100% within spec - but I must be honest - it does not run as smooth as it should.

I'm pretty sure this noise is caused by the worn cam profiles. My car has exactly the same cams on intake and exhaust : 1054 803 20001

I inspected my other two spare cams closely last night and they are better - but not much better.

Will call Kevin now to see what he suggests - maybe I should just take my two cams in and let them be rebuild and profiled.

My cam cap is also scarred - so I reckon I will swop it out with a good one from my old head and re-measure and setup the clearance.

Cant wait to have this done - I think this is going to be a big improvement on my car and maybe even its fuel consumption.
 

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Discussion Starter #11
Kevin says he has some good cams for me : 1054 803 20001 for R600 per cam :thumbup:
 

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I once had a piston slap that sounded like tapping...

Just on a note of caution:
1. Check the cam follower where that worn lobe was running. It may be worn as well. Usually both surface wear if it was due to lack of adequate lubrication.
2. NEVER EVER reface a cam follower. Buy new. Always. Or else your new cam will look the same, but within 6 months.
3. Valve clearances are important and could lead to cam lobe wear if not set correctly.

Contrary to popular belief, these days one often sees valve clearances get smaller as the engine gains hours, since the introduction od unleaded petrol. Even though Nords are safe from the horrors of valve seat recession, it still does happen on a much smaller scale, which leads to reduced valve clearances.
 

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Those are the standard 2 litre cams which remained in SA engines until the 80s. They first appeared in the 1750, I think. Personally, I would get the cam profile changed :).

There was a set of Richard Jemison cams RJR472 and RJR785 cams for R7950 on Gumtree. These are probably of the best cams for the 2 litre in the world for fast road application.
 

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Kevin says he has some good cams for me : 1054 803 20001 for R600 per cam :thumbup:
Winning already!! Before you try the new journal cap when you put the new cams back use the old cap first to feel how the cam turns (back and forth and not, full turn of course) - there should only be some valve spring resistance. Then fit your replacement journal cap and do the same - not terribly scientific, but you should know immediately if there is unusual resistance.:thumbup:
 

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Discussion Starter #15
Winning already!! Before you try the new journal cap when you put the new cams back use the old cap first to feel how the cam turns (back and forth and not, full turn of course) - there should only be some valve spring resistance. Then fit your replacement journal cap and do the same - not terribly scientific, but you should know immediately if there is unusual resistance.:thumbup:
Sorry - I meant my Cam Follower was scratched up - my cam caps are all good.

So I reckon I can just fit the new cam with my current cam caps and rotate slowly to see if there is any binding. But it sounds like if you have the original cam caps for the head you should not have any problems.
 

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Ok, if your journal caps are fine you're all good. If the relevant follower is scratched badly enough, it will eventually compromise the cam lobe above it. You should look out for a good used one - not sure you will find a new one locally (chicken dentures?) but I have not tried to source an recently. These followers were actually of quite exceptional quality hard chroming (even with infrequent oil changes or crap oil) so finding serviceable used ones should be possible. Again, ask Kevin.
 

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Discussion Starter #18 (Edited)
Ok, if your journal caps are fine you're all good. If the relevant follower is scratched badly enough, it will eventually compromise the cam lobe above it. You should look out for a good used one - not sure you will find a new one locally (chicken dentures?) but I have not tried to source an recently. These followers were actually of quite exceptional quality hard chroming (even with infrequent oil changes or crap oil) so finding serviceable used ones should be possible. Again, ask Kevin.
Went to see Kevin yesterday. He had an apple box full of cams. Different model numbers, some profiled, some standard. I found a very decent matching set. Look at the nice profile :thumbup:
He also had about 30 odd cam followers - some scarred, some even had dents in them. I found 4 that where very good - only had the normal rotation marks on them. Alfaholics charges 22 pounds per follower :paranoid:

Cant wait to fit the cams and see if my noise is gone.
 

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What are the numbers on the cams you took, Sling?
 

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Discussion Starter #20 (Edited)
I took exactly the same I had : 1054 803 20001 - unclear from the photo - my old cams had the numbers very clear - these ones not that clear - maybe the casts where a bit worn out by this time
 
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