Technical Crank too tight??

[jolly500]

Hi all,

I'm busy putting together a 650cc engine for the first time. I had the crank 'main' journals measured as standard. I've installed the crank with new standard main bearings at both ends and it turns perfectly.

I've installed the camshaft and the timing gear (including the 2 'spacers') and the crank still turns smoothly.

I've now put on the timing gear cover, the crank pulley and the oil thrower device and when I tighted the big hollow bolt on to the end (to 150nm) the crank is extremely stiff to turn.

Where am I going wrong?

Thanks
Steve

 

[Toshi 975]

Hi Steve
Did you make sure that the dog drive to the oil pump was lined up properly ? One other thing I stripped an engine recently that had been rebuilt by a well known specialist garage here. They must have had a bad day as someone fitted the timing chain the wrong way round and the self tensioner parts of the chain links had been forced by 108 foot/pounds of torque on the big nut up against the front main bearing. I am amazed that the engine would run but it did and the owner was not too happy with it. The chain ground out a crazy pattern on the front main bearing housing

 

[jjacob]

I would agree with Toshi. Either the oil pump is not engaged correctly or the timing gears are installed backwards or chain (if you have the self adjusting type) is installed in the wrong direction.
My bet is the timing gears are facing the wrong way.
John

 

[jjacob]

Also make sure the components in the picture are also assembled the correct way.
John

 

[jolly500]

Thanks for the replies.

I've checked what I've got against the diagrams above and all appears correct.
When I loosened the big hollow bolt everything turned smoothly again? Are there different thickness spacers available perhaps?
Failing that, its off to the local engineering shop to have a selection made up to experiment with.

Steve

 

[jjacob]

Maybe I do not understand. I thought the crankshaft turned fine without the timing cover installed. If this is true then there is something not installed correctly on the timing cover or something is binding on the cover when installed. Could be camshaft engagement with oil pump. Try removing the oil pump from the cover and see if things are still binding.

In your last post it seems that you are saying if you loosen the crank that the problem goes away? Check the crankshaft end play. It should be 0.30 -0.40mm (0.0118 - 0.0173in).

John

 

[jjacob]

If you have installed a new oil pump in a 110F block timing cover, then you may have a problem. As I understand new pumps are possibly 126A1 block versions and there is some machine work on the timing cover on the 110F that needs to be done?
John

 

[Toshi 975]

It's a bit of a pain but you could try assembling the crank shaft components without the cover & timing chain . So you should have the hardened inner large washer that should have the internal chamfer facing inwards so it locates on the crank face. Then the piston ring type seal, timing chain sprocket, pulley, oil flinger, locking washer then nut. If the crank still tightens then you know that you are pinching the front main bearing for some reason. If it still runs well then you will have to look at timing chain & oil pump/cam drive. I did have a problem on one engine fitting a new Abarth 595 camshaft as the drive shaft dogs were an interferance fit on the cam, width wise, so I had to shave them down a little .