Odd camshaft timing

[boris]

Can anyone help me understand what's happening here. The bike is a 47 16M and while the exhaust cam is timed to the mark the inlet cam confuses me. It's currently timed to the red blobs and the actual mark is miles away. I don't believe there is another mark under the red paint so I'm wondering if I actually have a matchless exhaust cam in place of the AJS inlet cam. The bike runs fine but it does seem a little down on power but it starts first kick every time.

So as well as wondering if I do have an incorrect cam fitted I'd also like to understand how I can check the red blobs are actually in the right pace. I can find instructions regarding when there are multiple marks how I can check which mark I should be using but if there is only one mark and it's clearly in the wrong place how can I calculate where it should be?

Thanks

20230425_115425.jpg

[SPRIDDLER]

I can find instructions regarding when there are multiple marks how I can check which mark I should be using but if there is only one mark

Have you found the dot on the driving pinion? It may be hidden under the washer.

Have you read the instructions in the article which shows how to align the cams correctly even if there are no marks at all................?

Article here:

http://archives.jampot.dk/technical/Gen ... e_Dots.pdf

[boris]

Have you found the dot on the driving pinion? It may be hidden under the washer.

I have indeed. I can time it fine using the red paint marks. I'm just not sure the red marks are in the correct place on the inlet cam.

Have you read the instructions in the article which shows how to align the cams correctly even if there are no marks at all................?

Article here:

http://archives.jampot.dk/technical/Gen ... e_Dots.pdf

I haven't seen that one thanks. I'll give it a read

[boris]

I've had a read at the article and I can't see anywhere where it mentions missing marks. More marks that you need yes, but not where there are none or the only mark is obviously incorrect as there is no way the engine would run if I timed it to the only mark I can see, Of course there may be other marks under the paint but I don't think there are as the paint is translucent enough I would see any were they present

I also don't believe the small red spot covers a punch mark but I'm loath to start removing the paint as its the only mark I have and were I to lose them it would be a pain to get them back and anyway I'm not convinced they are in the right place to start with.

So can anyone offer a way of calculating where the mark should be for a 350 cam? Number of teeth left or right of the peak of the lobe or any other repeatable and accurate method

Or at a push can anyone for sure say that a 1947 iron head 350 engine is not an interference engine and I could at least try it a tooth either side to see what difference each way makes without any risk of piston meeting valve.

Thanks again

20230422_085321.jpg

[56G80S]

The info is there, in the box in the article. The only reference dot referred to in the box is the dot on the small pinion. The reference to other dots is simply an extra. Small pinion dot should be perfectly in line with the keyway in the crankshaft axle, you should just be able to see this behind the usually left hand thread nut on the end of the axle and be straight up at TDC. If this isn't the case the axle has been fitted incorrectly.

I've used this method as I have fitted a slightly non standard camwheel. It works.

Ken de Groome knows his business.

Johnny B

[boris]

Ok Maybe some confusion here. I can see the dot on the crank pinion just fine and I used it to set the timing based on the red paint on the inlet and exhaust cams and the engine runs. The problem I have is while there is clearly a manufacturers mark on the exhaust cam at the location of the red paint there is none on the inlet cam anywhere near the red paint so how do I know the red paint is in the correct place?

Looking at the box in the middle of page one it talks about cams with one or two dots and tells you which dot to use when you have the lobe at approx two o'clock but my inlet cam had no dots so that's no help. It does have a manufacturers mark but that's about 120 degrees away form the current timing mark (red paint) and considering the engine runs timed to the red paint there is no way the engine would run if I timed it to that manufacturers mark.

So my question remains. How do I know the red paint on the inlet cam is in the correct place and not one tooth out? It can't be far away but suspect it could be a tooth out and I'd like to be sure.

[Ralph]

You could put a timing disc on the crank and set it up that way.

[boris]

You could put a timing disc on the crank and set it up that way.

It may well be the only way. I was really hoping some kind soul would show me where the timing marks should be either by some repeatable way of counting from a known starting point such as the lobe or even temporarily marking them on the lobe side of the cam and taking a really clear straight on photo that I could project on to mine and copy the marks off that

[g80csp11]

14 teeth between marks , your red dot is correct counting the marks on my camshaft

[boris]

14 teeth between marks , your red dot is correct counting the marks on my camshaft

Assuming my only mark is in the correct place and I'm not 100% convinced it it seeing the other is missing altogether so something has clearly gone wrong when it was marked (assuming it really is an inlet cam) . Counting 14 teeth from an incorrect starting point will still give an incorrect answer. Any chance you could take a really straight on photo as described above with marks copied to the lobe side so I can reference off the lobe. That way I can be 100% sure .

Ta