Cam position and TDC

[HB Chris]

When I removed the head in December to do the valve guides I made sure I was at TDC on the flywheel and damper and the distributor rotor was pointing at cylinder #1, I also took a pic of the cam flange for insurance and have not rotated the crank. Now that I am ready to install the head the cam flange is 180 degrees off when the #1 valves are closed. That is, if I place the cam in the same way it is in my pic, the valves would be open at TDC. The blue book shows that the locating pin on the chain sprocket should be at 8:00 when viewed from the front, mine was at 2:00. I can only assume that the head had the cam flange in the wrong 2:00 position before removal and the machine shop put it in the proper 8:00 position.

So, I think I need to carefully remove the chain sprocket from the chain and turn it to align it with the cam (I had zip tied the sprocket so I wouldn't drop the chain). Does this sound right? Just being especially cautious, thanks in advance.

 

[MMercury]

When I removed the head in December to do the valve guides I made sure I was at TDC on the flywheel and damper and the distributor rotor was pointing at cylinder #1, I also took a pic of the cam flange for insurance and have not rotated the crank. Now that I am ready to install the head the cam flange is 180 degrees off when the #1 valves are closed. That is, if I place the cam in the same way it is in my pic, the valves would be open at TDC. The blue book shows that the locating pin on the chain sprocket should be at 8:00 when viewed from the front, mine was at 2:00. I can only assume that the head had the cam flange in the wrong 2:00 position before removal and the machine shop put it in the proper 8:00 position.

So, I think I need to carefully remove the chain sprocket from the chain and turn it to align it with the cam (I had zip tied the sprocket so I wouldn't drop the chain). Does this sound right? Just being especially cautious, thanks in advance.

With a ride as nice as yours, aren't you always careful? :wink:

Something in your description doesn't seem to add up, or maybe you are misreading your own photographs or I may just be having a difficult time following your straight forward explanation.

I do not have any M30 camshafts nearby, nor have I examined one closely for quite a while. If memory serves me, the camshaft is keyed where the so-called flange is attached to it. Thus, it should only be able to attach one way - unless the woodruff key was inadvertently omitted or sheared so that it does not do its job. In turn, the alignment dowel mates only one way with the flange (unless someone sheered off or omitted the dowel (pn 11311250096). It is possible the machine shop mavens, as infallible as they might be, goofed. It is also possible, your initial postulation was correct or that you are misinterpreting your picture.

With all due respect to your photographic skills, if the camshaft drive gear's alignment dowel is at 8O'clock and if no. 1 cyl's valves are closed and no. 1 cylinder is at TDC, I see no impediment to installation as-is. Of course, if you think something has been installed incorrectly, or you have a non-stock cam, your intuition is likely much better than mine.

BTW, does your picture of the cam flange include the dowel hole or the complete assembly, including the drive gear? I mention this, since I recently was asked about markings on a different style camshaft and it turned out that what were thought to be manufacturer's reference marks, were really uniform gouge marks made by a huge pair of channel lock pliers. This discovery was made by noticing a picture with the culprit holding the cam with the channel locks.

hth somewhat.

 

[HB Chris]

Thanks MM, yes I am very careful! My only pic was from the back of the flange. I know there is a key, don't know if it only goes on one side of the flange or if it can flip 180 degrees. From the pic the locating hole was at 2:00, I was at TDC and valves closed with rotor on #1. The hole needs to be at 8:00. Regarding the block, since the distributor is out, it doesn't care if I was off one rotation, number 1 cylinder is at TDC as I stare at it. Head is from `85, stock cam and zenith carbs. I am going to ask Mr Cain to come over and take a look.

Chris

 

[MMercury]

Thanks MM, yes I am very careful! My only pic was from the back of the flange. I know there is a key, don't know if it only goes on one side of the flange or if it can flip 180 degrees. From the pic the locating hole was at 2:00, I was at TDC and valves closed with rotor on #1. The hole needs to be at 8:00. Regarding the block, since the distributor is out, it doesn't care if I was off one rotation, number 1 cylinder is at TDC as I stare at it. Head is from `85, stock cam and zenith carbs. I am going to ask Mr Cain to come over and take a look.

Chris

I can't understand why the flange would be grooved to accept a key in more than one way, as there would not be any need for it and it would lead to confusion. The diagram below indicates the same cam and flange work with the later single row chain assembly which you seem to be using, per your picture.

I wish I had some specific M30 cams to look at, but they are all at another location.

 

[HB Chris]

I agree, the key would likely be on one side only. Here are the current pics, ready for install with #1 at TDC on the cam. I will rotate the sprocket under the chain to the proper alignment with the cam.

 

[sfdon]

Leaving my shop in Palm Desert in the am- for the SFbayarea- let me know if you need a hand.

 

[HB Chris]

Thanks Don, I am at work this AM. Your photo is how I will reinstall the head, the bolt hole lines up with the flat spot and the locating dowel is at 8:00 when viewed from the front. My next opportunity will be this Friday if I get everything else done in the engine bay.