1100 Unitrak head and cams issue
Posted: Sat Jan 17, 2009 5:27 pm
I am having the top end of my J1 Debbened at the moment.
I found an 1100 Uni-trak head in the garage and have decided to use it and its cams.
On very close inspection i noticed that both; number three bearing journals have been running against the sides of the bearing shells at their extreme right hand end. (cam shafts appears to have moved to the left hand side of engine) but this is only evident from number three journal and number three and four lobes.
Looking at the cam lobes; number three cam lobe (inlet and exhaust) is mis-aligned with the bucket well, and therefore the valves by half a mm or so.
Number four lobes (inlet and exhaust) are mis-aligned to the left of the engine by approximately 1mm to 1.5 mm each, give or take.
Number one and number two journals and lobes are as near as dammit to dead centre but it looks as if the cam shafts are slightly too short by a mill or so and i am at a loss to explain why this might be.
As yet no-one has come up with a plausible explanation and i thought one of you guys might have the story.
Cams have no rings machined round the identifier boss which puts them as uni-trak rather than early twin shock.
I know that the uni-trak exhaust valves are 'more stood up' than early models to accommodate larger valves which is the case with this head.
This head also has the bi-spherical inclusions in the combustion chamber and came with an american spec cam cover with emission controls boxes cast into it.
It is not possible to show this mis-alignment detail with a photo but have included a photo of the cams and one of the head just for good measure.
Head
Cams
Raised lip at extreme right hand edge of number three bearing journal
Same again
It looks from the last two photos that the journal must be very badly worn in order to leave this lip edge raised above the surface like this but that is not the case. I seems more as if the raised lip is a burr, albeit a very regular one and it goes all round both number three journals
As far as i know the cam caps are the correct ones for this head and have not been buggered about with save some snapped off cam cap bolts.
The machined retainers on the inside of the cam caps look to be in 'as-new' condition and this head looks to be very low mileage and near perfect condition. Cam end float is virtually un-detectable.
Reason it found it's way into a breakers yard ten plus years ago was one broken valve spring. Number one exhaust before you ask!!!
Anyone??
AL
I found an 1100 Uni-trak head in the garage and have decided to use it and its cams.
On very close inspection i noticed that both; number three bearing journals have been running against the sides of the bearing shells at their extreme right hand end. (cam shafts appears to have moved to the left hand side of engine) but this is only evident from number three journal and number three and four lobes.
Looking at the cam lobes; number three cam lobe (inlet and exhaust) is mis-aligned with the bucket well, and therefore the valves by half a mm or so.
Number four lobes (inlet and exhaust) are mis-aligned to the left of the engine by approximately 1mm to 1.5 mm each, give or take.
Number one and number two journals and lobes are as near as dammit to dead centre but it looks as if the cam shafts are slightly too short by a mill or so and i am at a loss to explain why this might be.
As yet no-one has come up with a plausible explanation and i thought one of you guys might have the story.
Cams have no rings machined round the identifier boss which puts them as uni-trak rather than early twin shock.
I know that the uni-trak exhaust valves are 'more stood up' than early models to accommodate larger valves which is the case with this head.
This head also has the bi-spherical inclusions in the combustion chamber and came with an american spec cam cover with emission controls boxes cast into it.
It is not possible to show this mis-alignment detail with a photo but have included a photo of the cams and one of the head just for good measure.
Head
Cams
Raised lip at extreme right hand edge of number three bearing journal
Same again
It looks from the last two photos that the journal must be very badly worn in order to leave this lip edge raised above the surface like this but that is not the case. I seems more as if the raised lip is a burr, albeit a very regular one and it goes all round both number three journals
As far as i know the cam caps are the correct ones for this head and have not been buggered about with save some snapped off cam cap bolts.
The machined retainers on the inside of the cam caps look to be in 'as-new' condition and this head looks to be very low mileage and near perfect condition. Cam end float is virtually un-detectable.
Reason it found it's way into a breakers yard ten plus years ago was one broken valve spring. Number one exhaust before you ask!!!
Anyone??
AL