If installing a new timing chain-must both sprockets also be replaced?

[jjs2800cs]

In process of restoration of 70 2800CS, when parked had 155,000 miles.

Engine apart, new timing chain, oil chain on order.

So the question is, must both the crank and head timing sprockets also be replaced? Understand the crank sprocket is very difficult to remove, that a very special puller is needed.

If indeed old ones can be used, what wear indicators to look for on the old sprockets to determine their re-using and how will they mate (wear in) with a new chain?

Does the same hold true for the oil pump sprockets when use a new chain?

If we don't replace the sprockets are we asking for trouble.

Thanks
jjs2800cs

 

[m5bb]

If you had a new and used in your hand. Look at the tips of the sprockets, the tops of the mountains so to speak.
If they are very sharp as in almost cut your hand then they need replacing. If they have a little flat spot on top then ok you don't need to replace.
They can still be used if sharp and not available but may cause increased wear on the chain. Be sure and inspect them carefully to make sure there isn't any damage to one of the teeth, or a crack.
Pulling the crank hub sprocket can be troublesome sometimes but usually a good 3 leg puller and some heat to the sprocket will get it off. Look at it carefully before you start and see if you can see in the slot where the key is and make sure the key is not buggered up. Just a few weeks ago I was removing one on an M88 motor and it started to come off and then wouldn't budge. Got nut and moved it back in and then pulled, and it came right off with no heat.
Oil pump sprockets wear very little. But please inspect the nut holding the gear on. They have been know to come loose.
HTH
Gary

 

[jjs2800cs]

If you had a new and used in your hand. Look at the tips of the sprockets, the tops of the mountains so to speak.
If they are very sharp as in almost cut your hand then they need replacing. If they have a little flat spot on top then ok you don't need to replace.
They can still be used if sharp and not available but may cause increased wear on the chain. Be sure and inspect them carefully to make sure there isn't any damage to one of the teeth, or a crack.
Pulling the crank hub sprocket can be troublesome sometimes but usually a good 3 leg puller and some heat to the sprocket will get it off. Look at it carefully before you start and see if you can see in the slot where the key is and make sure the key is not buggered up. Just a few weeks ago I was removing one on an M88 motor and it started to come off and then wouldn't budge. Got nut and moved it back in and then pulled, and it came right off with no heat.
Oil pump sprockets wear very little. But please inspect the nut holding the gear on. They have been know to come loose.
HTH
Gary

Here are a couple of photos taken today. There are still distinct, albeit small flat spots on the crank sprocket and the same on the cam sprocket. I'm inclinded to say they will be ok. Car will not be driven high more like it was before I got it.

Comments?

Thanks
jjs2800cs

 

[m5bb]

Here are a couple of photos taken today. There are still distinct, albeit small flat spots on the crank sprocket and the same on the cam sprocket. I'm inclinded to say they will be ok. Car will not be driven high more like it was before I got it.

Comments?

Thanks
jjs2800cs

I would use those without worrying about any problems.
Very little wear.
Thanks for the photos. Definitely takes the subjectivity out of it.
Gary

 

[jjs2800cs]

I would use those without worrying about any problems.
Very little wear.
Thanks for the photos. Definitely takes the subjectivity out of it.
Gary

THANKS for the direction. Yes they don't look bad.
Of note is with the mileage of the engine, the crank shows no wear, the cylinders just need a light hone, so I'm luckily able to use a new set of stock Mahle pistons I bought years ago.

Too bad my cylinder head did't fare as well.
jjs2800cs