Carb Talk/Advice

[58Panel-Youny]

We have a set of 34ICT's on the 1955cc motor in the van. Some love these carbs, some hate them.. I've found them great so far, with no issues in over 17k kms on this engine.

Saying that, the itch to go faster is always there I'm hoping to be able to upgrade them before Drag Day 3.

If I can make the investment, what would be the best to go for? I first thought 40's, but then was wondering would I be left wanting to upgrade them again soon after?

Would 44 IDF's be a better option?

Would 48's be too big for a 1955cc? - And if not, which would people recommend, IDF's or IDA's, and why?

All opinions, advice and discussion on carbs welcome

 

[JustinOval]

I've had 40s that worked really well on a 1600 (Dells) and an 1835 (Webers). I experimented briefly with a larger exhaust and different chokes (CB 'update' kit) on the 1835, but felt it was just losing torque. I'd imagine that 44s would be better suited to over 2000cc or heads with larger valves? Unless you put smaller venturis in them, defeating the purpose of going larger in the first place...

 

[Lazy Dog]

Bigger engine dude..........

 

[58Panel-Youny]

I've had 40s that worked really well on a 1600 (Dells) and an 1835 (Webers). I experimented briefly with a larger exhaust and different chokes (CB 'update' kit) on the 1835, but felt it was just losing torque. I'd imagine that 44s would be better suited to over 2000cc or heads with larger valves? Unless you put smaller venturis in them, defeating the purpose of going larger in the first place...

Thanks justin. My thinking on 44s or 48s was I'd be using smaller vent's, but leaving the option for future upgrades without needing to buy carbs again.... The next upgrade after carbs would be to change the heads for ported big valve heads... (Fook knows when I'll have money for that though..)

i know damn all about carbs though, hence the thread hoping those in the know can tell me if that's a good idea, bad idea, or just won't feckin work at all...

 

[58Panel-Youny]

Bigger engine dude..........

Haha.. I wish dude..., someday.. But I can't wait that long to go sub-18! Gotta work with what I have

 

[Roadcow]

Talk to Ben,
he really knows his stuff. Having said that you need to match all of the parts of your engine for optimal performance. Heads are where most of the horsepower is made, but you need the correct comp. ratio and cam choice with proper springs to make it all work together. Always do what your engine builder says, they knoe their stuff. I keep thinking while Dave has my drag engine apart that I should upgrade. I suggest a different cam or bigger carbs, my builder calmly tells me why that will not work. Dave also knows his stuff and is very happy to help.

 

[56oval]

i don't know much, but with your engine in a bus, leave it, until you decide to up the ante in the engine department an upgrade to 40's or 44's isn't really worth spending if you only do one drag event a year, you could get your times down with more seat time which would cost significantly less than an upgrade. The ict's seem to be working well so no point in changing, if the engine doesn't need any more air than the ict's give then all you will be doing is amplifying off cam flat areas which in a bus isn't your friend.

fyi. a stock 40hp solex carb will flow 40cfm @ 10"

Ict's 82cfm @ 10"

40's 202 cfm @ 10" with a 28mm vent

44's 278 cfm @ 10" with a 36 mm vent

my ida's with with a 42mm vent flow near 350 cfm.

It all amounts to how much air your engine needs, not how much you can throw at it.

 

[58Panel-Youny]

Thanks ben
is the restriction on my motor more the stock valve size/heads than the carbs?..
would it make more sense to wait as upgrade carbs and heads at the same time?..

in the short term maybe I should look to the cheapest option of finding another 1300 gearbox.. Lol... The change of box saw me lose a second from 2013 to 2014..

 

[56oval]

stock heads without much work at all will flow enough to make 120bhp, just look at liam neales engine for an example, stock valve sizes on a 2276 and its making 170ft lb of torque, which is mental, not a huge power band but with a 1200 box its a right handful, 13.9 is his best on stock heads, which is immense. What cam are you running?

 

[58Panel-Youny]

The heads are stock valves, with some chamber work done.. Pat kindly sold them to me 2nd hand

It's a scat C25 cam, which I believe is comparable to the engle W100?... I know it's a pretty mild cam, but having the power low down is perfect for the van.

 

[58Panel-Youny]

... And 8.6:1 c/r..

 

[56oval]

I wouldnt change a thing until ( if ) you decide to upgrade the engine.

 

[58Panel-Youny]

I wouldnt change a thing until ( if ) you decide to upgrade the engine.

Well thanks for pissing on my parade.... Lol..

by 'upgrade', are you talking upping displacement, or just cam/heads?..

 

[rascal1]

I have a set of IDF36 complete with manifolds and CB centre pull linkage.
You are welcome to borrow if you wish to play with them. They are as follows.
I think I have a spare set of mains as well. Let me know if you want to try them.
Might allow you to experiment without having to buy.

Vents .....27
Air..........215
Main........110
Idle...........50
Pump.........40
Tubes........F11

 

[58Panel-Youny]

I have a set of IDF36 complete with manifolds and CB centre pull linkage.
You are welcome to borrow if you wish to play with them. They are as follows.
I think I have a spare set of mains as well. Let me know if you want to try them.
Might allow you to experiment without having to buy.

Vents .....27
Air..........215
Main........110
Idle...........50
Pump.........40
Tubes........F11

thanks Liam, that's a really generous offer. I might just take you up on that in the new year and see what difference they might make.
what size motor were they on with that jetting?

 

[rascal1]

I was planning to use them on a 1745 for the bus.I ran them for a while and they seemed to work well.
But I went back to a more simple approach for the trip to Spain..