Anyone ever 40'd a 1.2

[matt_vaughan]

Basically my dad's trying bike carbs on his Seven (kit car type thing) and there's going to be a matched pair of 40s lying around for a while, as he doesn't want to sell them just incase.
So I thought I'd mayaswell try it, see what happens.

Anyone tried 40s on a 1.2?

I think I've seen a bay piccy of one with 40s on, didn't save it though :mad:

If anyone has, what kind of jets did you use?

And results?

[ben doodar]

overrrrrrrr kill! me thinks mate, but i could be wrong. and i cant imagine it being worth all that work.

[mowgli]

with a head & cam & a decent exhaust you would probably get about 90hp, & with the short stroke, i would rev like mad but the torque would not be so great

[chimp007_uk]

a friend used to have a 1.2 with a 1.3sr head and 40's

[mowgli]

i always thought the 1.2 & the 1.3 heads were identical

[chimp007_uk]

dunno... just what he'd fitted. Never looked at modding a 1.2

[Welsh Dan]

The 1.2 and 1.3 heads are identical, bar the compression chamber size.

[MC]

Is the valve larger on the 1.3?

Anyway, I started a project many moons ago that CP then Stuart took over and we were targeting 120bhp(ish) from the 1.2 on 40's. Unfortunately I think stuart run out of puff and scrapped it. Shame as I believe there was a lot of good potential. The bottom end had been worked on with raised compression and I believe the head had larger valves with a wild cam and twin 40's.

What was left to do Stuart?

[Stuart]

1.3's never had bigger valves (unless they were modded of course)

CP had the std 1.2 carb head machined to take 1.6 size valves that were still 1.2 length (allegedly the 1.6's are longer). I got it ported to match the machining. It had the life skimmed out of it (by eye next to a std 1.2 head it was 2mm thinner lol)

I had a "special" cam made by catcams that was 303degrees but with less lift at TDC and a max lift of about 11mm as the valve springs bound up at more than that etc, so it wound up as a flat nose solid profile cam that had pretty much square edges lol.

Oh there was tons to do........ honest guv.
Top tip. dont bulid a 1.2 nova track car and then buy something better at the jod of the track car than you are willing spend in time or money ;)