Xflow bore options

[Westfield]

I am planning to build a Xflow engine over the next 2 months. I had what I thought was a serviceable 1700 block which only has a very very slight wear lip at the top of the cylinders. However, when I used a three stone hone on it today and inspected the bores afterwards, I was dismayed to see that number three cylinder has some very deep score marks in it. What are my options now? The plan was to use 83.5 Accrilite pistons but I don’t want to put £450 worth of pistons in anything but good bores

 

Question is will it go to 84mm and if it does how will I know how close I am to breaking through? It’s a 711 block, not sure how old.

 

Anyone like to comment on the percentage chance of it working at 84mm?

 

[Taran Las]

Tony,

 

Not a reply I'm afraid. Just a method of moving it to the top again. I'm interested in the answer too.

 

Philip. D. Owen

Membership No. 3976

[Roger King]

If you have a 711M block it may well go to 84mm, but you would need to check it first and then pressure test afterwards.

 

If you have an AX block (fitted by Caterham since around 1989), you would be very unlucky if it wouldn't go to 84mm.

 

Please be aware that any overbore above 1600ccm must be regarded as a slight risk.

[Phil P]

 

Not sure if this is of any use but John Wilcox can supply recon 711m linered blocks (as I'm sure can may other suppliers) - not sure if they go up to 83.5mm though.

 

I am no mechanical expert but would be interested to see if there is a remedy to you problem that doesn't involve using liners

 

All the best

 

Phil

[rgrigsby]

Tony as Roger says it's a gamble but if it's any help my '92 711M block has been bored out to 84mm and survived OK!! (as it happens this was done by Roger 😬)

 

Cheers

 

Rob G

www.SpeedySeven.com

[alicat]

Tony

 

So you couldn't keep the spanners away from it then and had to take it apart.

 

Let me know when it's running again - it will no doubt be the dogs b******s *thumbup*

 

Alicat

 

 

[Westfield]

Alicat

 

This is my spare engine! My intention is to get as much done to this engine as I can and then do an engine swap. This way I can minimise the time off the road. You can bet that when I take the engine out we have 2 weeks of sunshine!

 

So for the time being I am still available for a blat if we have a nice day over the holiday.

 

Regards

 

Tony

 

[Westfield]

Thanks for the replies.

 

So far one successful bore of a 711 to 84mm, has anyone else been successful?

 

Or more to the point has anyone had it done and failed?

 

Roger, you will probably be getting the job anyway, as a matter of interest do you see many fail and also what pressure are the bores tested to after boring?

 

 

Tony

 

[alicat]

Tony

 

Watching the weather - forecast not promising - but who knows?

 

Have a ggod Christmas.

 

Alicat

 

 

[J.R.]

I have in the past bored a 681F block (pre 711m) to 85.6mm and an AX block to 86.25 without problems.

 

The pre 711m block was also sverely rusted in the waterways as it had been left standing outside with plain water in the jacket for several years.

 

Give it a go, if it fails a pressure test after then get it linered.

 

I have a set of as new 85.6mm forged (cosworth) X/flow pistons if you want to make an offer.