Boring out a sidevalve

[tortron]

How far can i safely and reliably bore out a sidevalve engine?

Im looking at increasing the bore to gain a bit more power.

[mike.perry]

The normal max rebore in UK is 1.5mm, 0.063 thou. However in Australia John Dobson reckons that they can go out to 0.080 or 0.140 thou but the block needs to be sonic tested. Read through some of the postings on the Series MM Messageboard.
There are other ways of tuning such as polishing the chambers, skimming the head, porting, camshaft mods etc. plus getting a decent exhaust manifold.
The Morris engine is very similar in design to the 1172 Ford block so any info on tuning side valve Fords would be of interest

[tortron]

Iv made up some twin carb manifolds and am currently making a new exhaust.
I have been thinking about skimming the head, tho i am also considering supercharging

Cheers for the ford info, i knew it was a scaled down mirror of something

[mike.perry]

What carbs are you going to use?
I have a selection of carbs so that I could make up a pair of H1s, a single H2 or a pair of H2s. With a decent exhaust manifold the ideal would be to have a selection of inlet manifolds so that I could see which gives the best results

[tortron]

a pair of "long" H1's

[mike.perry]

How long is long?

[tortron]

the engine side of the carb body is about a half inch longer
I also have a water pump to fit and will be using a morey's power booster

[kotemaori]

Will post a photo of a 4mm overbore, or .160" engine when I get to it behind other engines. Will also photo the intake and extractors. This may surprise many, a full race engine that operates at 7000RPM 95% of the time using a pair of H1's.

Tortron has the right idea (even though hes a kiwi :<) that theres no modification as effective as cubic inchs. Couple that with supercharging and you have the most effective methods to make any engine perform.

Kia ora