Timing chain touching front of inside of case
Posted: Sat Feb 23, 2019 3:12 pm
Hey, folks. I've been lurking for quite some time, as as this forum has more twin-cam info than the Europa forum.
I bought a '74 Europa TCS 5 1/2 years ago with a seized engine, and have been slowly rebuilding it. After an 18 month wait, I got my hands on a Dave Bean cartridge water pump with its inner and outer timing covers. I've spent the past two months carefully test-fitting the covers doing a little fettling. There appeared to be a problem with clearance of the timing chain as it comes down off both of the cam gears; it was touching or almost touching the front of the inner surface where the cork gasket sits. In test-fitting, I found that if I shoved the head all the way forward on the bolts, it increased the clearance just enough that I felt comfortable assembling it.
So, yesterday, I finally assembled and sealed the front covers, dropped the head on, shoving forward as I did during test-fitting, bolted down the head, and put on the chain, gears, and tensioner. Unfortunately, now that I've spun it a few times by hand, I can see that the chain is still very very close to the inside timing chest surface of the front part of the head where the cork gasket is. This photo shows the chain coming down off the exhaust cam gear. It looks the same where the chain comes down off the intake cam gear.
If it's not actually hitting, it's certainly close enough to be catching the tiny (and I mean TINY) amounts of RTV that have squeezed out of where the cork gasket is at the back of the chest:
It looks like the cam gears themselves are about in the middle of the chest. I've measured the thickness of the Bean inner cover (the backplate), and it's about ten thousandths thicker than the original, but since the chain is so close to the inside portion of the head itself, I'm not sure that the extra thickness of the backplate thickness is the root cause of the problem. It almost seems like the crank sprocket itself isn't far enough forward. I didn't take it off the crank when I rebuilt the engine, so it hasn't moved from where it was.
The crank has a set of stock symmetrically-sized thrust washers on it. It does look like there's ample room to move the crank slightly forward with asymmetrically-sized thrust washers. Is that what I should do?
Any other suggestions?
Thanks.
--Rob Siegel
I bought a '74 Europa TCS 5 1/2 years ago with a seized engine, and have been slowly rebuilding it. After an 18 month wait, I got my hands on a Dave Bean cartridge water pump with its inner and outer timing covers. I've spent the past two months carefully test-fitting the covers doing a little fettling. There appeared to be a problem with clearance of the timing chain as it comes down off both of the cam gears; it was touching or almost touching the front of the inner surface where the cork gasket sits. In test-fitting, I found that if I shoved the head all the way forward on the bolts, it increased the clearance just enough that I felt comfortable assembling it.
So, yesterday, I finally assembled and sealed the front covers, dropped the head on, shoving forward as I did during test-fitting, bolted down the head, and put on the chain, gears, and tensioner. Unfortunately, now that I've spun it a few times by hand, I can see that the chain is still very very close to the inside timing chest surface of the front part of the head where the cork gasket is. This photo shows the chain coming down off the exhaust cam gear. It looks the same where the chain comes down off the intake cam gear.
If it's not actually hitting, it's certainly close enough to be catching the tiny (and I mean TINY) amounts of RTV that have squeezed out of where the cork gasket is at the back of the chest:
It looks like the cam gears themselves are about in the middle of the chest. I've measured the thickness of the Bean inner cover (the backplate), and it's about ten thousandths thicker than the original, but since the chain is so close to the inside portion of the head itself, I'm not sure that the extra thickness of the backplate thickness is the root cause of the problem. It almost seems like the crank sprocket itself isn't far enough forward. I didn't take it off the crank when I rebuilt the engine, so it hasn't moved from where it was.
The crank has a set of stock symmetrically-sized thrust washers on it. It does look like there's ample room to move the crank slightly forward with asymmetrically-sized thrust washers. Is that what I should do?
Any other suggestions?
Thanks.
--Rob Siegel