Now my 2cv is almost finished I've had in mind a 'stage 2' which is to rebuild the spare engine lurking in the garage as a 9:1, increase the jetting slightly, fit leccy ignition, and mate it to a refurbished Dyane gearbox that I have. because I'm a fan of the old heavy flywheel (which will be used too) what sort of engine characteristics would this whole set up then give me? I ask because of a comment I've just read saying 9:1 won't make much difference over a good 8:5:1, which mine is.

Can I expect for example a higher cruising speed? lower or higher fuel consumption? Smoother or rougher mid range pick up, that sort of thing.

Hi Mr Nail .....I've got 9:1's and re-jetted carb in my '88 2CV ....[and Luminition EI] .....the 9:1's were added long after the EI,and they do seem to increase the torque and help acceleration,I cant say I've noticed any decrease in fuel consumption [although I do occassionally treat the engine to a tankful of "Super" ...which is of course slightly more expensive than orn'ery unleaded].
Top speed is reached a little quicker and perhaps it gives me a couple of mph "top end" ....but all the extra "top speed" is doing is making the [my] engine work harder.
Hills seem easier with my 9:1's .... I'm not changing down as early.
I guess a Dyane gearbox will give you a few extra mph from the same revs in top [6.5% .... if my calculations are correct thats about 4mph] .... but [fwiu] the Dyane box has an annoying gap between 1st & 2nd ....so for that reason I've opted to stick with the 2CV 'box [for now .....plus the fact that quite often these days I'm towing a hefty trailer tent to some 2CV meet or another]
The [your] best option is a Rick Pembro gearbox ...basically its a 2CV bottom end with Dyane top end....not cheap though.
more info here
http://www.gearbox-guru.co.uk/

edit .....btw,I thought I'd got a good 8.5:1 ....until it went "bang" one day .....and I had the engine rebuilt by Uncle Ken.

hth
T.

Sounds good to me, very close to my set up. Definatly gives More power and acceleration and doesn't loose speed when you get to the hills which is great

Thanks guys. The two main things I'm looking for are a stronger mid range, allied to a less frenetic 75mph or so. What size jet is best to put in? Also I've never driven a Dyane so I can't picture what that gap is all about, but the gearbox I have is a good 'un so shame to waste it?

It means you're changing gear sooner [1st to 2nd] when setting off at junctions,roundabouts etc.
Increases the chances of some numpty behind you banging your pride & joy up the *rse considerably [imho].
Unless of course,you fix a huge towplate & towball [like wot I saw the other day on a dirty looking 4x4 Landie] .....with a sign saying .....
"Your skid stops right just HERE"

T.

That makes sense actually, there has been a few Dyanes bumped up the backside as I recall. I wonder why they did that then? I dare say I can't afford one of those Pembro jobs so I'll have to make do with either the 2cv or Dyane boxes that I have.

Can't say I ever noticed any difference between 2CVs and Dyanes when accelerating away. They may well have different gear ratios but I wonder how much of the difference people claim to notice is down to having read that there is a difference?

Very well said. Most of it is in the mind, the rest in the tuning.

Acceleration was definitely improved by changing to 9:1, though top speed was reduced for a few weeks before then going back up to about 70.

I owned [a number of] Dyanes from 1974 to 2000.
I've also owned my 2CV from 1988 to date.
I cant say I ever noticed a vast difference.....[although I always suspected that my 2CV was "quicker off the mark" ]
My mate [Dave Blackett] has both a Dyane & a 2CV .....he claims he notices straight away.
Having towed [the same trailer tents] with my Dyanes & 2CV .....I can confirm that the 2CV is a better car for towing with.

T.