SU Carby Help Needed

[terryo]

if you send me the SU number, I'll tell you what they came off. the number is on a small alloy tag screwed to either the dashpot or float bowl. I have a big selection of springs, needles & jets for most SU's. I have been fixing them for over 30 years .
floats are rarely 'shagged". if plastic, they may get a few drops of fuel in them. usually its a faulty needle valve that gives gross richness. if you have SU's designed for angled mounting and mount them horizontally, or vice-versa, you'll always have grief. Bowls must be level.

[sleepin22]

You are right. The "floats" aren't "shagged". I was just describing the general area of the problem. I am grossly amatuerish at these things It was actually the needle and seat as well as the pin that holds the float in place. There is no tag on them but there is a somewhat serial number stamped on the flange closest to the manifold. It reads: 4FG7 and the last number/letter is not readable. Other markings on them are AUD where the fuel goes into the float bowl and S.U. CARBURETTORS, BURMINGHAM, ENGLAND on top of the float bowls. They are the slant type and the float bowls are level.

Now that I have had the car running again for a few days I have come across 2 more issues. The first is, I cant get it to idle low enough without stalling. I have followed some of the tuning manuals from various websites and they all use prety much the same method to tune idle and mixture but I still cant get it to idle low enough without it cutting out at some stage.

The second issue which has earthed today is the backfiring of the carbs. I initially put this down to timing and check and adjusted that but it still happens. Then I remember when I topped the dashpots up with oil, it did the same thing, and I thought I had filled them up too much. Revved it for a bit, backfired for a few minutes then came good. So I'm guessing(as I usually do) that perhaps I have the wrong type of oil in there? Possibly too thick? as the pistons are fairly solid to push up with my finger. Could this be the backfiring
and idle issue??

[sleepin22]

I'm also thinking again that the jets are the wrong size for this engine. ie: letting too much fuel in. Its not running ridiculously rich like before but its still a bit rich.

[ian]

hi sleepin 22
i useed sewing machine oil in the dash pots
if the oil is to thick the piston raises to slow
to thin then it raises to fast
check to see that the ckoke arm is not stuck as that will make it run to rich
also what fuel pump are you using ? if the pressure is to high that can cause flooding or to run rich also what size SU is it ?
was the carb manifold from an engine of similar capacity as yours
ian

[sleepin22]

Hi Ian,

Fuel pump is stock. The SU's are HS4's and they were on a standard 4K corolla with extractors. I dont have have extractors yet but I dont think that would be the issue. Choke arm seems fine.

So if the oil is too thick and the piston is raising too slow, that would make it run rich because its not sucking in enough air for the amount of fuel??

George.

[sleepin22]

I have done/adjusted/replaced/measured everything except replacing the needles and jets. Yes the problem may lie there but I have had too much frustration over the past month to care anymore. I am going back to the standard carby and manifold so these SU's will be for sale.

Items include:

1 X Lynx SU manifold to suit K series motor.
2 X HS4 SU Carby's
New needle and seats(installed) $40
New gaskets(installed)
1 X Dual choke cable, brand new(never installed) $35

They are clean, painted and chrome polished.
They run but obviously dont suit my application as I cant seem to get them to run consistantly. Either that or I'm stupid. Probably both. Will let them go for $220. I will also include all the fuel lines and T pieces required for fitment.

Unless someone is in the Oakleigh area with knowledge and can come over and get me out of trouble(paid of course), I will be getting rid of them.

Thanks to the guys who have tried to help out so far. Its unfortunate that it hasn't worked out but i'm over it

[sleepin22]

i'll even throw in the exhaust manifold plug that my friend Tim made, so you can run these even if you dont have extractors. You can view pics of them here on my members ride thread, I think they are on the last or second last page:

http://www.toymods.net/forums/showthread.php?t=18560

[Crazyracer]

Don't give up too easily.

Idling problems usually come down to worn throttle shafts, or actually the body which is also the bearing for the shaft wearing. A good carby shop should be able to re-bush these for you.

If you need new needles give this place a try. They're in Sydney, but they know their stuff when it comes to SUs

http://www.sumidel.com/Products.htm

Jets can also be worn if the previous needles have been bent, but can be replaced. You can usually tell if the jet is worn as the hole in it is oval shaped.

To set the fuel level, it usually wants to be about 3mm below the top of the jet when its in the full up position.

Midel should also be able to give you some hints on tuning the SUs.

[Rolla_kid]

Hey mate. I ran set of HS4's on my 5k ke20 and had a lot of grief because of an inlet manifold air leak. Check it isn't leaking around the shared inlet/exhaust bolts. I found the exhaust manifold was actually thicker in places than the inlet manifold so the bolts weren't holding it on. Good luck.
Nice car BTW.

[Crazyracer]

And you have connected the vacuum advance hose from one of the carbies to the distributor, haven't you!

[sleepin22]

Don't give up too easily.

Idling problems usually come down to worn throttle shafts, or actually the body which is also the bearing for the shaft wearing. A good carby shop should be able to re-bush these for you.

If you need new needles give this place a try. They're in Sydney, but they know their stuff when it comes to SUs

http://www.sumidel.com/Products.htm

Jets can also be worn if the previous needles have been bent, but can be replaced. You can usually tell if the jet is worn as the hole in it is oval shaped.

To set the fuel level, it usually wants to be about 3mm below the top of the jet when its in the full up position.

Midel should also be able to give you some hints on tuning the SUs.

I haven't given up easily. Its been long and frustrating.
Its not even just idling problems. I'll get it to idle consistantly, take it for a drive and it will stall on me and wont start again for hours. But there is no pattern to it. Its different symptoms everytime but it usually ends up with the car not being able to start up again for a long time. I have found a great place that specialises in SU's in victoria. They are called Wilson Carburettors. But they are about an hours drive from me. I was hoping I could get the car driveable so I could drive it to them and let them sort it out but it has not been the case. I'm not willing to pay for a tow just for this so yeah I'm over it. If they dont sell and I feel like having another crack in the future I'll take the carbies down to them so they can rebuild them. I just want to drive my car, I haven't for months. I have been cracking the shits every night for about 4 weeks now. I'm sure you can understand that.

[Turdinator]

Doh too slow!!!

Don't give in George!!! I'll sus out some places that can re-jet/tune SUs and let you know. It'll be worth it. They probably just need a rebuild and a different jet, needle combination setup on a dyno. SUs are on datsuns jags and minis so there will still be people around who can get it running sweet for you i'm sure, but a toyota forum is probably not the best place to start looking.

[sleepin22]

And you have connected the vacuum advance hose from one of the carbies to the distributor, haven't you!

yup. I did it from both of them.

[sleepin22]

Hey mate. I ran set of HS4's on my 5k ke20 and had a lot of grief because of an inlet manifold air leak. Check it isn't leaking around the shared inlet/exhaust bolts. I found the exhaust manifold was actually thicker in places than the inlet manifold so the bolts weren't holding it on. Good luck.
Nice car BTW.

Yeah I checked for leaks and everything seemed fine.

[sleepin22]

Doh too slow!!!

Don't give in George!!! I'll sus out some places that can re-jet/tune SUs and let you know. It'll be worth it. They probably just need a rebuild and a different jet, needle combination setup on a dyno. SUs are on datsuns jags and minis so there will still be people around who can get it running sweet for you i'm sure, but a toyota forum is probably not the best place to start looking.

Yeah i know this aint the best place Marcus. Wilson carbs are great, but they are in airport west and they dont freight. So for every little thing I have to physically go there and pay them. its a pain in the ass. I have pulled them off now and stuck the standard setup back on. Just waiting for my battery to charge and see if this thing goes again.