Weber 40 V 45s On A 1.9

[Masekwm 2]

I'm baffled by a sea of posts, I've searched, I've read, I've gone back to other posts but I'm left confused.

 

By the posts fitting the 40s to the 1.9 = Good torque but lower top end power

 

By fitting the 45s = Good top end, but less torque?

 

So I look in the For Sale Section and everyone is selling 40s, is that because a good set of 45s is kept hold of?

 

Would I be wasting my time fitting 40s so I should wait for 45s to come up for sale?

 

Thanks

Keith

[Baz 421]

Not alot of difference at all, as it's more governed by what chokes are in the carb, as 40's and 45's will have the same either way!

 

IMO on something like a 1.9 8v you'll never need anything more than a pair of 40's anyway, so in essence 45's are a bit OTT if you can get hold of a good pair of 40's.

[mfield 20]

Not alot of difference at all, as it's more governed by what chokes are in the carb, as 40's and 45's will have the same either way!

 

IMO on something like a 1.9 8v you'll never need anything more than a pair of 40's anyway, so in essence 45's are a bit OTT if you can get hold of a good pair of 40's.

 

Really ?

 

I thought 40's biggest chokes are 34mm and 45's smallest are 36mm ?

 

So on the 40's the choke area is only 15% and on the 45's the area is 20%, with that the airflow in the 45's will be comparable lower down and be less of a restriction higher up ?

 

In the past I've used a 30mm choke in 40's and the low down torque was better than the 45's using the 36mm choke, but the top speed was wank. The choke area with the 30mm was 25%, I always wanted to try getting a set of 34mm chokes for 45's, I just thought that it would suit the 1.9 8v engine a treat.

From what I understand the trouble with high air speed in carbs to early in the revs is that the main jets have to be smaller otherwise it will suck to much fuel in, this is obviously a compromise when trying to get good torque and top speed.

[Baz 421]

Well yes, but my point was would you really need/want 36mm chokes on a 1.9 8v as an ideal? -Unless it's quite massively non-standard of course. (Massive cam, headwork etc etc)

 

 

I should've added above though, that there's always exceptions of course!

 

 

For example, my Longman 8v runs 36mm chokes, but it has a full race head and 308deg cam with massive lift, it's very peaky and anything below about 3500-4000rpm and it's dead. For driveability i think i'd consider slightly smaller, as you say, 34 might be better.

 

 

For added reference, Screwloose's Mi16 also runs 36mm chokes in it's 45's.

Edited May 25, 2010 by Baz