Loss of power

[pete.reeve]

For all crossflows make sure that the inlet gasket has got some sealer on it at high rev’s this happens water damage

[Dollyman1850]

I told you those lightweight plastic pistons wouldn't work.. Thats a very strange melt pattern.??

[griff 200]

Is it a water cooled inlet manifold then ? Air leak makes it run weak so hot but that pic is something I would not expect to see coming out of a failed engine. No piston rings ???? Very strange ! But not it to racing engines. Richard

[madsvlund]

Look's like a self ignition promplem in the squize band area, typically if the piston to head clearnce is too small. Lean burn problems do normally occur under the spark plug. But ban be a combination of things. How did the other pistons look ?

[Dollyman1850]

griff 200 said:

Is it a water cooled inlet manifold then ? Air leak makes it run weak so hot but that pic is something I would not expect to see coming out of a failed engine. No piston rings ???? Very strange ! But not it to racing engines. Richard

You have a couple of water passages on the inlet on a crossy so I would guess that that is no 2 or 3 Piston that has failed…I would suspect hot melt due to lean then failure of the gasket and water ingress after the damage done.
OOPS !! Hope the block is saveable.

N.

[pete.reeve]

The block is fine and is being bored. It was a combination of the luminition playing up and water ingress so will be fitting a MBE ignition system.

[Dollyman1850]

pete.reeve said:

The block is fine and is being bored. It was a combination of the luminition playing up and water ingress so will be fitting a MBE ignition system.

I am running an MSD 6AL which I have been finding good.

You did say you wanted to go up to 1700
N.

[pete.reeve]

I think it's 1760

[Dollyman1850]

pete.reeve said:

I think it's 1760

Is that stroking to get displacement at 90 thou? or offset boring?

[pete.reeve]

Dollyman1850 said:

Is that stroking to get displacement at 90 thou? or offset boring?

Not sure tommy fields ( http://www.fieldmotorsport.com/index.html ) is doing the work.

[timelord]

85mm pistons give 1760, I recently had a problem with my 1600M running lean on 2 and 3 cylinders also down to inlet manifold gasket leaking round the waterway but not with such disasterous results. Geoff

[Moto]

The usual route to 1760 is 85mm. This is on the limit with a 711M block but the AX block had thicker walls and can be taken out to 2000 I believe.

[Dollyman1850]

I was always told that the max was 90 thou on a 1600 711M block and thought that was approx 83.5mm.. AX blocks and South African blocks could go bigger but not recommended.. Its a long long time since I messed with crossflows though.
N.

Edited by Dollyman1850 on Sunday 7th December 18:49