27 replies to this topic

[booton]

read in here some where that some one managed to find a template for a 998 pocket

going to be pocketing a block again soon and last one i had done were 3cc.

if some one could send me a link of a copy of the template. that would be great as long as it is for the larger valve 940 heads.


many thanks if anyone has a link or copy.

my email is [email protected]

[charie t]

Take the block being pocketed and the head the machinist. They will be able to sort it from that

[Spitz]

I had thought it was only #1 and #4 that needed pocketing......if at all. ( by if at all, I mean if no high lift cam or 1.5 rockers are used )

[bmcecosse]

It's MUCH easier and a lot less destructive to simply sink the 4 exhaust valves into the head by 40 thou. That's IF it needs it - measure up first...... With a standard lift cam/standard rockers you need 320 thou clearance. Some 940 heads already have that clearance due to valve seat recession.......

[Spitz]

I had thought it was only #1 and #4 that needed pocketing......if at all. ( by if at all, I mean if no high lift cam or 1.5 rockers are used )

Hate to tell you this spitz, but all four cylinders have exhaust valves
Just having a look at the 998 head gasket, will show you

WHAT?!

[Spitz]

I should have put a smiley face on that I suppose.....
(My "what" was meant in jest)

[bmcecosse]

I don't believe the standard ex valve hits the block on a 998.........

[Ivor Badger]

I don't believe the standard ex valve hits the block on a 998.........

Would there be any logical reason for that?

[Rusty1182]

It's MUCH easier and a lot less destructive to simply sink the 4 exhaust valves into the head by 40 thou. That's IF it needs it - measure up first...... With a standard lift cam/standard rockers you need 320 thou clearance. Some 940 heads already have that clearance due to valve seat recession.......

how do you sink the exhaust valves

[booton]

with my high lift cam it need to be sank 3mm

[booton]

thanks for the template much appreciated.

[bmcecosse]

The valves are easily sunk into the head - 5 minute job with a 45 degree countersink in a pillar drill - it doesn't ruin the block, or expose the top ring to hot gases..... Using a 940 head on a 998 is best done with a standard lift camshaft - MG Metro is thus ideal for the job. The relatively huge valves means you don't need to lift them high! I don't believe you need 3mm deep pockets - where does that come from ?? You will be right down at the top ring - don't do it! A standard 998 Mini head - the exhaust valves go down the bores - they can't hit the block......

[Rusty1182]

So 40 thou would be plenty
But just for reference if I didn't sink the valves how deep would u make the pocket

[bmcecosse]

First it was 3mm - now it's 40 thou (= 1mm) - where are you getting the figures from?? You need to measure first - not just guess....... What cam are you using?? Do you know the cam lift??
Also -do you know the distance from the head of the exhaust valves to the face of the cylinder head? You need to measure this.......accurately.

Edited by bmcecosse, 06 February 2012 - 10:09 PM.

[Rusty1182]

Mg metro cam