Cam belt tensioner issues
Posted: June 21st, 2008, 10:12 pm
Guy
Finally putting my engine back together and I have come up against one final challenge. The engine uses Fiat FIRE 1368 pistons in a 1242 block and needed to have a reasonable amount removed from both the head and the block to get the right CR. The net result is that the timing belt adjustment now goes beyond the range of the standard cam belt tensioner. As I see it there are a few options to get the right tension on the belt but I'm not sure which is best/possible
1) source a new belt with the same pitch as standard but with one or two less teeth – not sure where to start looking, have looked at the Dayco and Gates catalogues but they do not list the pitch.
2) source a bigger diameter bearing – again I'm not sure where to start looking, I have searched several on-line bearing suppliers to no avail
3) source a bigger diameter bearing from another car that can be modified to fit – again I'm not sure where to start looking, possibly at a scrap yard where I can see lots of engines and measure up the options.
4) have a sleeve made up to fit onto the standard bearing to increase the diameter – I'm confident that I can get it made to the correct tolerances and by freezing the bearing and warming up the sleeve a little, get a good tight fit but do you think this will be safe/viable?
The last option is probably the easiest for me to sort but easy is not often the best! any help or advice you can offer would be much appreciated.
Below is the pulley with tape wrapped around it to work out roughly how much bigger it needs to be to get the right tension. It needs to go up in diameter from 57mm to 67mm.
Finally putting my engine back together and I have come up against one final challenge. The engine uses Fiat FIRE 1368 pistons in a 1242 block and needed to have a reasonable amount removed from both the head and the block to get the right CR. The net result is that the timing belt adjustment now goes beyond the range of the standard cam belt tensioner. As I see it there are a few options to get the right tension on the belt but I'm not sure which is best/possible
1) source a new belt with the same pitch as standard but with one or two less teeth – not sure where to start looking, have looked at the Dayco and Gates catalogues but they do not list the pitch.
2) source a bigger diameter bearing – again I'm not sure where to start looking, I have searched several on-line bearing suppliers to no avail
3) source a bigger diameter bearing from another car that can be modified to fit – again I'm not sure where to start looking, possibly at a scrap yard where I can see lots of engines and measure up the options.
4) have a sleeve made up to fit onto the standard bearing to increase the diameter – I'm confident that I can get it made to the correct tolerances and by freezing the bearing and warming up the sleeve a little, get a good tight fit but do you think this will be safe/viable?
The last option is probably the easiest for me to sort but easy is not often the best! any help or advice you can offer would be much appreciated.
Below is the pulley with tape wrapped around it to work out roughly how much bigger it needs to be to get the right tension. It needs to go up in diameter from 57mm to 67mm.