bosch pump rebuild

[zx_volcane]

Rebuilding a bosch that was known to be crap, and discovered there was a head bolt missing hock:

Prob explains why it didn't really run very well.

and where it mates to the pump housing it looks like this:



Was going to clean it up with 1600 grit and hope for the best, but thought I'd ask here just incase its too far gone to bother with.

There is some wear inside too from the roller bearings / dynamic advance.

[darrenjlobb]

Its fine, they all look like that tbh....

Doubt head bolt missing will have effected anything, not unless the others were loose, in which case the pump would have ruined itself / leaked anyway.... just rub it back shiny again / re seal and be fine

[zx_volcane]

Happy days then!

[zx_volcane]

Next question

The wear on the inside of the casing indicates that the dynamic advance has room to go a bit further.

Limited I assume by the force needed to overcome the pressure of the springs in the advance unit.

So either internal pump pressure is down for whatever reason, or there is some room for it to go a bit further, either by increasing internal case pressure or by taking a bit off those springs and shimming back to length with a washer?

I've no idea how much I would have to shim off to get the increased movement though, and would want the dynamic advance response to revs to stay the same. again I can try increasing the internal case pressure, but without a way of measuring it, its like midding in the dark.

Can someone lend me a test bench?

[Dave]

What revs are you taking your engine to? because obviously the higher, the more your advance system will load up. This is also limited by the actual physical piston in your pump, unless its been apart/modified before then its probably still all moving to stock. You could well be down on pump pressure for any reason though.

Why was the pump known to be crap?

[zx_volcane]

What revs are you taking your engine to? because obviously the higher, the more your advance system will load up. This is also limited by the actual physical piston in your pump, unless its been apart/modified before then its probably still all moving to stock. You could well be down on pump pressure for any reason though.

Why was the pump known to be crap?

Just thought that, yes it hasn't been gov modded or anything, so will only have been reved to stock.

Didn't know what was limiting the advance.

Had pump on a car, was leaking practically from every orifice and wouldn't start when warm - changed pump and it was fine, so chronic air ingress at any rate.

If trimming piston, surely will have to elongate the hole in the casing so it can move more? Depends what limiting movement, either pressure on piston, or physically reached its 12degree limit.

[Dave]

Get it gov modded so it revs out abit more

[zx_volcane]

Good thinking batman

There is fudge all room for manoeuvre with the roll cage and governor spindle, maybe room for elongating the hole by 1mm before its going to foul, and there isn't much room to trim the edge of the roll cage to compensate either, besides too far and the roller will fall out.

Thinking instead of trimming the piston, i can space out the blanking plate it sits against, I've got a spare domed one from the transit pump that'll give the extra space (essentially the same as on the other side). giving it a little more offset and can set the static advance to compensate for that giving more dynamic.

Its not much difference, maybe a mm or two, but will all help I'm sure.

And if I do get brave enough to elongate the hole a tad it'll add up to maybe 3mm more dynamic advance.

I can't see the shape of it affecting the pressure on the piston, so all gravy?

[CJ_Derv]

Good thinking batman

There is fudge all room for manoeuvre with the roll cage and governor spindle, maybe room for elongating the hole by 1mm before its going to foul, and there isn't much room to trim the edge of the roll cage to compensate either, besides too far and the roller will fall out.

Thinking instead of trimming the piston, i can space out the blanking plate it sits against, I've got a spare domed one from the transit pump that'll give the extra space (essentially the same as on the other side). giving it a little more offset and can set the static advance to compensate for that giving more dynamic.

Its not much difference, maybe a mm or two, but will all help I'm sure.

And if I do get brave enough to elongate the hole a tad it'll add up to maybe 3mm more dynamic advance.

I can't see the shape of it affecting the pressure on the piston, so all gravy?

did you ever try this if so what was the result

[Dave]

So your talking about backing the piston up more and compensating with static advance. This wouldn't work because you still have the same IPP against the advance spring.

[zx_volcane]

So your talking about backing the piston up more and compensating with static advance. This wouldn't work because you still have the same IPP against the advance spring.

fudgecakes

[londondan86]

So your talking about backing the piston up more and compensating with static advance. This wouldn't work because you still have the same IPP against the advance spring.

fudgecakes

Lol, so you did it then!

[zx_volcane]

So your talking about backing the piston up more and compensating with static advance. This wouldn't work because you still have the same IPP against the advance spring.

fudgecakes

Lol, so you did it then!

Pump is still on the bench at the moment, I've hardly been around this summer to play.

Need to install an IPP gauge for a start...

[CJ_Derv]

Thats next weeks plan for mine IPP guage any ideas where to get guage from? or what type of guage can be used? and pressure rating required lol

[zx_volcane]

I found a gauge kicking around, but prob any hydraulic gauge would do - they're not too expensive, ebay maybe?

Up to 150/200 psi should do the trick - can't see them kicking to much over 100ish realistically, but if someone wants to jump in.

Thats next weeks plan for mine IPP guage any ideas where to get guage from? or what type of guage can be used? and pressure rating required lol

[CJ_Derv]

I found a gauge kicking around, but prob any hydraulic gauge would do - they're not too expensive, ebay maybe?

Up to 150/200 psi should do the trick - can't see them kicking to much over 100ish realistically, but if someone wants to jump in.

Thats next weeks plan for mine IPP guage any ideas where to get guage from? or what type of guage can be used? and pressure rating required lol

Nice one pal will have a look at the fitting im getting and order one that will fit im plumbing it in the same way they plumb the tester using and extension to take 2 banjos should be fun to see what it reads and if my pump is down