webber 40s/pierberg

[marc69]

Will i see a big difference in performance in my track car changing from 2 barreled pierberg to twin 40s?

I am running my 1.4NV on a 2e2, I changed the vacuum for the 2nd barrel to the distributor advance, this opens the 2nd barrel far earlier, basically on the track I am never below 3500rpm, so the second barrel is operating all the time.

The difference in having the 2nd barrel on 0-60 (on the speedo whatever speed this really is)
is 1.5 seconds faster than with it disconnected so it really makes a big difference. Will I see that much more a difference with the 40s, bearing in mind the expense of jetting (jetted for a 1.8 engine just now) them etc?

I have a manifold and the carbs but jetted wrong.

Would be great to hear from anyone who has done this.

[garyc]

I'd look at the hp for a 1.3sr and a sport with 40's for the hp gain assuming you can get someone who knows how to set carbs up to do the job.

[marc69]

The problem with the bhp for the sr is that vauxhall never changed it from the single peirberg to the double barreled pierberg, they said 70 bhp from the outset for the SR up till they changed it. The sport had many other contributing factors to gain it's increase so again, I don't really know how much difference the carb change would make.

[Royston]

Std SR 70HP
Sport with forties and a back box 82HP, not all had cams, it was an option
Sport with Cam, forties 92and a back box 92HP

Sport "base engine" was a 1.3SB, SR engine, the changes are above

[marc69]

Yes, I see what you mean, however the SR standard with 70 bhp is with the single 1b1 carb. With the second barrel opening on the 2e2 there is a huge difference at higher revs with the foot flat (to remove the lock for the 2nd barrel) and there are no figures for this.

I just wondered if someone had used one of these which was working (rare) and then converted to the 40s to see how much of a difference there was?

[Royston]

I am pretty sure twin forties will be better that a 2e3, modified or not, if you have other engine mods, forties will work/improve performance.

I would also say that a 32/34 Weber DMTL will work better than the 2e3 carb (converte my SR from 1b1 carb to weber 32/34 DMTL, worked well) When I restored the SR I ran Sport Forties, but she is now on Irmscher Injection.

To me there isn't a decision to make, forties all the way (assuming they are in good condition and have correct venuris and jetting to suit your engine)

[C612DNM]

Oh yes, you'll notice a difference!!
It will be numbers of seconds per lap better!

[marc69]

I would need to buy all the jets etc and decide whether to stick with the 1.4 head or go for the 1.2 carb head and get the manifold machined to suit. I suppose it depends on cost for which way I am deciding to go but the 2e2 compared to the single carb knocks 1.5 seconds of 0-60 therefore on a 1.3 mile lap round knockhill, this already takes a lot of seconds of a lap. If the forties are going to do a lot beter than the 2e2 them perhaps it's the way to go?

I'll just have to price the change of jets and start saving!