I cant decide!
My twin SU's are in need of a major overhaule!
Do I rebuild, buy new twin SU's or get a weber?

I want as much acceleration as possible!

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1970 mini K
1966 850 van

Weber!

I currently own a 40mm solex but i want to upgrade it to a weber 45

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http://www.flickr.com/by_dan
Current: 1970 Mini K 2014 Focus ST
Past: 93 Rover, 64 850, 97 Rover, 66 Deluxe, 66 Moke
81 Austin Estate, 2006 R53MCS, 66 Deluxe, 1978 Clubbie
2014 Land Rover Defender 90

If you love it to sound like this,

http://www.youtube.com/watch?v=6E2rllosOJs

Then weber

I have a 40mm Delortto to go on my 1215 when finished!

_________________
1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

hehe!
yeh the kid in me wants a weber! hard!!
but the sensible in me knows its not a race car, & ive heard webers arent really the best for road use. is this correct? lower revs they are a bit crap?

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1970 mini K
1966 850 van

There are Webers ..and then there are Webers...

Cheers, Ian





Sorted..I hope

After getting my mini back today I'm pondering the same question! My SU's need reconditioning... But I would love a 45!!!

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Zulu...

1967 mini Cooper S

I tried both a single HS6 SU (GR 7" manifold), and a 45 Dellorto (with 38mm chokes) on a well ported Redline 3005 manifold when we engine dynoed the 1412 stroker.

It made 113.6HP @ 6500 with the SU, and 112 lb/ft torque.

It made 114.0HP @ 6500 with the 45 Dellorto, but only 108 lb/ft torque.
[edit] figures with a 45 Weber would be similar.

So there ya go. I like Webers & Dellortos, but for a road car, an SU or 2 is hard to beat. Much quieter, and better economy too.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Just out of interest Kev,

what was the torque spread like in each case?
what revs did each make peak torque (your peak power revs are quoted)?


Peak numbers are great for the pub boast, but you and I know that high torque across a broad rev range is what makes maximum acceleration per the original poster's requirement

My 45 weber 1411cc had 113 lb/ft peak at 5000rpm and 127hp at 6500 on the same dyno, but more importantly, it had >100 lb/ft from 3000 to 6500 rpm. From 3500 to 6000 rpm it had >108 lb/ft. I consider that a very flat torque curve and it just pulls like a train.

Would a SU have been better? I don't know, I did not try it. But at least it destroys the myth that a Weber (or Dellorto) is only tunable for a peak power at a particular rpm or very narrow rev band.

cheers
michael

_________________
the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

In either case (SU, Weber/Dellorto) you MUST get it tuned on your engine.

Mine is ostensibly a high performance engine that i use in sprints but tooling around the pits at low speed is no problem. Picking the wrong gear (i.e 3rd instead of 2nd) for low speed corners has never been a problem, it just pulls out of it like a train.

The key is to have it properly tuned on a dyno by someone who knows their stuff.

One of the ways that a Weber/Dellorto can "use more fuel" is because it has an accelerator pump that squirts extra fuel in when you stomp the right pedal. In the same situation, the SU will gradually raise the piston as the vacuum increases, controlled by the viscosity of the fluid in the dashpot. If you drive around all day stomping the throttle, then braking for the next lights, then surging forward again, then yes, potentially the Weber/Dellorto will use some more fuel.

At stable revs, in either case, they should use the same fuel if they are correctly tuned.

The Weber/Dellorto makes a lot more noise than the SU, so it sounds faster.

Alfa Romeo and Fiat released road cars for decades using Weber and Dellorto carbs. The Japanese copied their designs and released cars for decades with Solex carbs. The big manufacturers can make these suitable for daily driven cars, so why can't you?

cheers
michael

_________________
the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

Mickmini,
Note, this is a roady motor I built for my missus' van, not a HP hero like my 1360 is (which has a 282 cam like yours).

Torque figures for the 1412 stroker [RE13 cam, 1.46:1 Corolla rockers, Vizarded (by me) 12G1316 head with Mk2S valves]:

SU HS6-
4000 (106lb/ft), 4.5 (112), 5.0 (113), 5.5 (107), 6.0 (97)

Dellorto 45DHLA-
4000 (104 lb/ft), 4.5 (108), 5.0 (107), 5.5 (104), 6.0 (97)

So, although it went hard with the Dellorto, the torque curve was flatter with the SU:


Here's the Dellorto plot:


The Dellorto & manifold was pulled off my 1360 for this exercise, but jets were not changed as the A/F was pretty good.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

cheers for all the info gents!
now im more confused than before!
I just want a set up that will give me maximum performance like high revs on a weber, but the smooth running of SU's for lower revs

_________________
1970 mini K
1966 850 van

2 x 1 3/4 SU's then ?

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did I tell you that I won a trophy?

Either this, or just 1x 1-3/4 SU on a Russell Engineering RE7 manifold.
I have since changed it to a Minispares 1-3/4 manifold, (due to lack of room for a filter) and noooooo, it's not nearly as good above 5000 rpm.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

How would twin HS4s go on a 1275 (a modified 1275). Is it too much?

Will be fine- Police Pack MK2 Cooper S got twin HS4s, Ramflo filters and a 731 camshaft.


[edit] I had twin HS4s on Barney with a Wade 104 cam (1293cc, now owned by Cooper Matrikon), it made 59.4HP ATW.
[edit] It has Corolla 1.46:1 rockers in it to make up for the 104 cam's relatively poor valve lift.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.