autocraft pump/cam bolt clearance

[Jonny Grigg]

Basic tech question  :

Autocraft stage-and-a-half, CB perf. alu case, webcam 251, Magnum timing gear, 1/2 bolts with machined heads, spring washers and 'adjustable' washers (the ones that advance/retard the timing gear).

Bolted the pump in one case half with the cam assembly. I have 0.4mm (0.015") clearance between the pump body and the bolt head. I didn't include the paper gasket, so this will give me a little more, but my question is what clearance should I be aiming for here? It is all pretty close in my book..... OK there should be minimal axial float of the camshaft (measured out at o endfloat with the dial gauge), but it will always move a bit I would have thought, and when everything is at running temperature I am concerned I don't have enough clearance to accomodate the thermal expansion.

Any thoughts?

Thanks,

J. 

[Peter]

i ground the bolt heads until i had a millimeter...
nothing broke yet

[JamieL]

i ground the bolt heads until i had a millimeter...
nothing broke yet

thats what i did too, mate...

also - your favourite subject - watch out for parallax or whatever its called when measuring although i'm sure you did...
are you measuring worst case scenario?
is the pump in fully square?
torqued down?
can you manually push the cam/gear as far as it can go towards the pump?
how much movement will you realistically get in terms of thecam/gear towards the back of pump with doublethrust bearings?

dare i say but i know others have let the two "self-clearance" - eek - just keep changing the oil...

we must catch up soon,
J.

[richie]

Basic tech question  :

Autocraft stage-and-a-half, CB perf. alu case, webcam 251, Magnum timing gear, 1/2 bolts with machined heads, spring washers and 'adjustable' washers (the ones that advance/retard the timing gear).

Bolted the pump in one case half with the cam assembly. I have 0.4mm (0.015") clearance between the pump body and the bolt head. I didn't include the paper gasket, so this will give me a little more, but my question is what clearance should I be aiming for here? It is all pretty close in my book..... OK there should be minimal axial float of the camshaft (measured out at o endfloat with the dial gauge), but it will always move a bit I would have thought, and when everything is at running temperature I am concerned I don't have enough clearance to accomodate the thermal expansion.

Any thoughts?

Thanks,

J. 

Jonny,you can get button head allen key bolts instead that give much more clearance,and you can always stack the gaskets for extra clearance


cheers richie,uk

[Jonny Grigg]

Basic tech question  :

Autocraft stage-and-a-half, CB perf. alu case, webcam 251, Magnum timing gear, 1/2 bolts with machined heads, spring washers and 'adjustable' washers (the ones that advance/retard the timing gear).

Bolted the pump in one case half with the cam assembly. I have 0.4mm (0.015") clearance between the pump body and the bolt head. I didn't include the paper gasket, so this will give me a little more, but my question is what clearance should I be aiming for here? It is all pretty close in my book..... OK there should be minimal axial float of the camshaft (measured out at o endfloat with the dial gauge), but it will always move a bit I would have thought, and when everything is at running temperature I am concerned I don't have enough clearance to accomodate the thermal expansion.

Any thoughts?

Thanks,

J. 

Jonny,you can get button head allen key bolts instead that give much more clearance,and you can always stack the gaskets for extra clearance


cheers richie,uk

Thanks Richie,

the obvious solutions are always the best. 

J.