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crankshaft/cam timing

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bob hughes

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Ok guys

Dire straits here, can not get my newly built engine started. We think that there could be a timing issue, but have checked through the dizzy and it's drive down to the can shaft and can not find any problems there. I am sure that I timed the crank/cam relationship properly when I installed the timing chain and sprockets as I painted the marks on the chain to coincide with the marks on the crank shaft and cam shaft sprockets, but stupidly did not take a photo of it. Without raising the engine and removing the damper and timing chain cover, how can I be 100% sure that the relationship is correct. As far as we can tell from observing the tappets, we have number 1 cylinder with both valves shut at TDC whilst number 6 is - exhaust starting to close and inlet is about to open all as per book.

Ideas welcome please.

:cheers:

Bob
 
Bob Hughes said:
Ok guys

Dire straits here, can not get my newly built engine started. We think that there could be a timing issue, but have checked through the dizzy and it's drive down to the can shaft and can not find any problems there. I am sure that I timed the crank/cam relationship properly when I installed the timing chain and sprockets as I painted the marks on the chain to coincide with the marks on the crank shaft and cam shaft sprockets, but stupidly did not take a photo of it. Without raising the engine and removing the damper and timing chain cover, how can I be 100% sure that the relationship is correct. As far as we can tell from observing the tappets, we have number 1 cylinder with both valves shut at TDC whilst number 6 is - exhaust starting to close and inlet is about to open all as per book.

Ideas welcome please.

:cheers:

Bob
Click to expand...
If both valves are completely shut with the #1 piston all the way to the top of the bore then I'd go to the dizzy to see which way the rotor is pointing. Make sure it is pointing to the #1 plug wire connection on the cap, which is about the 1 or 2 o'clock position. If it isn't then you need to turn pull out the dizzy and rotate it until it is.
 
The shaft that sits on the camshaft and spins the dizzy can be inserted in the block in any number of orientations. Check to see if the rotor is pointing at #1 when you're at TDC and both #1 valves are closed. If not, then you will need to change the orientation of the shaft so that it does. You will need to remove the dizzy, stick your finger down into the hole and remove the shaft (or at least lift it enough to change the orientation). As I recall there's a hole in the middle of the shaft, and I was able to jam my finger in the hole and lift the shaft. You will have to approximate the right position of the shaft to make the rotor point at #1 and then fine tune the timing by the normal method of rotating the dizzy. I had to do this for my newly rebuilt engine.
 
the center hole is tapped for a 5/16 NF bolt; find a nice long one (MGB air filter bolts suit the bill) and use that as a handle.
 
Randy Forbes said:
the center hole is tapped for a 5/16 NF bolt; find a nice long one (MGB air filter bolts suit the bill) and use that as a handle.
Click to expand...

well that explains why I had to jam my finger in the hole; all my fingers are coarse thread. :playful:
 
Thanks guys, all good stuff.

Finally sorted my problem out, timing chain and sprockets all correct, silly me, I was pointing the rotor at the wrong part of the dizzy, doh!!!

:cheers:

Bob
 
Rich
Perhaps I did not explain myself properly, I set the crankshaft up to give me 10 degrees before TDC then applied myself to the dizzy, I rotated the dizzy body to get the rotor pointing to the number 1 position on the dizzy cap - it was not the number 1 position by a long way - and that I do not understand because the terminal lead was marked number 1. I rotated the dizzy body a 1/4 inch each side of the mark but it still did not fire up, I eventually moved it over an inch and then things started to happen, and then I got to a position when it fired up and ran like a dream.

:cheers:

Bob
 
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