SU Carby conversion

[Whitty]

Brayden,

I have e-mailed you some piccies of my SU conversion. Could you post them up here for everyone to have a squiz?? It runs about 735% better now than with the old solex, the change is unbelievable. Still rooting around with getting the right jetting, it hasnt got the top end the old carby had, although it hasnt got the bore wash happening from all the dumped fuel either!! I had the old carb set up with the mechanical linkage to open the secondary, was good but not in the same ballpark for driveability. Thanks

Whitty

[Almost a Mini]

I hope you're reading this Fritz!

[Brayden]

I'll post the pics up tonight.

[Almost a Mini]

Probably should wait until I see the pics but:
What type of SU are you using? And what needle, spring and oil does it have in it?
Aaaand, how did you deal with the coolant passage that normally runs through the inlet manifold?
If you hadn't worked it out - I like SU's - I reckon they are THE most versatile carbs bar none. . .

[fritz]

Yep, I'm closely monitoring this thread.

[Whitty]

Probably should wait until I see the pics but:
What type of SU are you using? And what needle, spring and oil does it have in it?
Aaaand, how did you deal with the coolant passage that normally runs through the inlet manifold?

Inch and a quarter SU, GG needle with a blue spring, 25/50 oil in the bell.
Used the original inlet manifold with a piece custom made to mount the SU - piccies will tell a thousand words. Its on an F5A - would be a lot easier to tune on a F8 due to capacity being roughly the same as half a mini motor - which run with dual carbs - but the little motor is a bit of a challenge.

[Brayden]

Job is done, Whitty. I have set up a gallery for you that you can either add to yourself, or just email to me and I can do the leg work if you prefer.

http://www.tamon.org/gallery/v/members/Whitty/

VERY nice job on the SU as well mate.

[Whitty]

Thanks Brayden, as you can see some of the linkages and other stuff are a bit dodgy at the moment and we had to flog bejeesus out of an old carby linkage plate to set up the choke and accelerator cables, but the main aim was to get the car running so I could drive it to work. When time permits, I will get the fitter at work to machine up some nicer looking bits and pieces to clean it all up. I also happen to have a new ring thingy (??) that holds in the ignition barrel, another friend machined it from solid brass and it works a treat, and looks good into the bargain. What would be a reasonable price to ask for one of these, as I may be able to get a few more done, but only if it is economically viable (I have to pay him in beer and he is a thirsty type of lad) Just curious.

[Brayden]

Brass you say? If they were machined out of alloy I reckon $5-10 each wouldn't be out of the question considering how easily the plastic retaining rings break and how difficult they are to find.

The reason I suggested alloy is because I don't like the colour of brass.

[Almost a Mini]

Inch and a quarter SU, GG needle with a blue spring, 25/50 oil in the bell.
Used the original inlet manifold with a piece custom made to mount the SU - piccies will tell a thousand words. Its on an F5A - would be a lot easier to tune on a F8 due to capacity being roughly the same as half a mini motor - which run with dual carbs - but the little motor is a bit of a challenge.

You said earlier in the thread that the car feels like it's running out of legs at high revs. . .do you think that is likely to be fuel related? I would have thought a single HS2 would have flowed plenty of air for a F5, so it's probably down to fueling at the higher revs. Maybe take it for a drive, and when it feels like it's starting to lag, pull the choke out - if it picks up a bit, then it's probably short on fuel. . .
Looking at the profile of a GG needle, it is pretty thick at the top end, so possibly something like a M or a BS might be a bit better. Looking at the profiles, you can see how they compare:

Station - GG - M - BS
1 - 890 - 890 - 880
2 - 870 - 855 - 856
3 - 845 - 832 - 836
4 - 825 - 808 - 817
5 - 808 - 785 - 798
6 - 790 - 763 - 778
7 - 780 - 745 - 760
8 - 770 - 726 - 740
9 - 758 - 707 - 720
10 - 745 - 688 - 701
11 - 732 - 669 - 683
12 - 720 - 650 - 664

The GG does stay pretty thick right to the end, so quite possibly it does need a bit more fuel. Of course, if you're brave, you could also sand the GG down a bit at the end and see how it goes. . .but remember, there's no going back with that method!
It may also be that the blue spring is a bit weak. . .from memory, they are the weakest spring you can get - possibly a shift to a red might improve things.
If it was me, I'd probably try an M needle, red spring and shift to ATF in the damper. . .after I'd worked out if I was running out of fuel or not. . .

[Whitty]

You said earlier in the thread that the car feels like it's running out of legs at high revs. . .do you think that is likely to be fuel related? I would have thought a single HS2 would have flowed plenty of air for a F5, so it's probably down to fueling at the higher revs. Maybe take it for a drive, and when it feels like it's starting to lag, pull the choke out - if it picks up a bit, then it's probably short on fuel. . .

Did this with no joy. Theres plenty of fuel there, I used a full tank to do 200 k's this week. And yet it run real hot like it was lean. It is funny, it will accelerate to any speed in any gear, but you have to really work the throtle to get it to sit on a speed. I can do 110 kph all the way to work no drama but have to work the throttle all the time to get it to sit - it either accelerates or dies, no in between. Same around town, always up or down but never sitting on a constant speed. Finished work this morning so will have another look tomorrow, might be air cleaner as well - only have a small motorbike type pod on there so that might be choking it a bit. As for the oil, it was from an old bottle of Shell Helix that I had in the car from a previous oil change.

[Trevor]

Oil too thick try auto tran fluid or singer machine oil

[Almost a Mini]

Yeah, thinner oil will improve your throttle response a bit, and will lean things out slightly (piston can rise faster, so there is less accelerator pump effect).
Does the filter your using leave the air passages for the low pressure side of the dashpot open? To the left hand side (fuel bowl side) of the carb mouth there is a little hole (5mm or so). This need to be open to filtered air (not blocked off by the filter baseplate) so that the carb piston can rise. . .

[nrgtic]

bump baby bump

[me217]

so howed you go with the conversion in the end and what performance did u manage. i am thinking bout this conversion and i wanna no if it is worth it. i will be putting it on a f8b.

me217