Hi all

Is there a topic on this anyone can point me to - I'm looking for for's and against's

Three options to get a 652 2cv.

1. Bore out the 2cv barrels. This leaves them very thin and prone to piston slap. To keep it all cool, the engine I used to have had been jetted very, very rich - so thirsty.

2. Fit Visa barrels. Much machining required, because the Visa barrels have the pushrod tubes built in, whilst the 2cv ones don't.

3. Fit a Visa engine. If you stick with the Visa ignition, you need to cut some holes in the bellhousing for the sensors (which hang off a mounting bar from the engine bolts). You also need to fanny slightly with the starter/ring-gear.

3 is the simplest and most reliable. If you can find a half-way decent Visa engine.

Hi
If you go with the Visa engine take a look at the 1-2-Spark topic as this will probably be cheaper than trying to source all the ignition parts required to get Visa engine running
Cheers
Boggy

I asked Burton about the overheating issue with their barrels/pistons and they said it wasn't an issue on their own brand ones... maybe they're magic?

Either way, they got through the 24 hour at Spa without an issue or an engine change afaik.

Adrian,
piston slap would be the result of making the clearance between piston and barrel greater than the ideal ( 3 thou?), not because the barrel wall thickness had been reduced.
The real problem with taking so much out of the barrel walls is their increased tendency to distort, with partial or complete seizure then a probability.

Of course, boring the barrels to make the pistons a slack fit may minimise the chances of seizure, but blowby, piston slap and high oil consumption are the penalty for that approach...

ken

Wouldn't that presuppose they distort inwards, whereas they could distort outwards...?

Who knows?
A thin-walled tube under compression can buckle in either direction, as you'll find by standing on an empty drinks can.

I do recall Two Horse Stables having lots of problems with their 'bored out to 652' engines, though.
Have a look at the early 375/425 barrels to see what 'bullet proof' means....


ken

There are much problems with big bore 2cv barrels/pistons, be it from Burton or otherwise.
Heat is building up in the thin(ner) walls deforming them and then the pistons get stuck in the barrel; the engine is going to lockup, cooling down will help, but when it returns a few times you can write off the pistons and barrels.... Theres also a long period of driving very carefully about 5000km from new not going faster then 90 km/h, but mostly this won't help....

I personally believe that the better way is to take a complet Visa engine, but never let a Visa engine run faster then 5750 rpm they aren't designed for it......... the pistons are to heavy and at higher rpm they are working against the engine (dead weight) insted of working with it.......

If you can open up the Visa engine first and look if the oilplate inside is in a good shape or make a new one (Harleys topic)....

Thanks guys

I thought there may be some issues with the thin barrel.

The reason I ask is because I have been given some and thought I may be pre warned before I fit them. I would appear the worst I can do is seize it and have to refit my old ones.

Any more thoughts ....