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More Triple SU dramas

Started by _mello92_ , Nov 24 2009 10:59 AM

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#1 _mello92_

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Posted 24 November 2009 - 10:59 AM

Hey guys,

Finally got around to putting the 1 3/4 HIF SU's on my 202, and Ive got an issue.

The regulator was initially set at 2.5psi (fuel guage said 2psi), that started and ran fine. I adjusted the idle's to 1000rpm and they are all pulling the same airflow - used a gauge to check.

Then No. 3 carby, near the firewall, started pissing fuel out of its overflow, its just a constant dribble of fuel. The other two carbs are fine.

Turn fuel pressure back to 1.5psi - no change... turn back to 1psi (guage isnt reading anything but the car still idles and revs), and the carb is still pissing fuel out. I should note that it is running slightly rich. They are running brand new OA6 needles, I have pulled them apart and put kits through them, using ATF fluid in the dampers.

So why is that carb pissing out fuel?

Posted Image

Im gonna set it to .5psi and see if that helps.

Cheers.

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#2 orangeLJ

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Posted 24 November 2009 - 11:21 AM

completely disregarding the problem-

Are you running an overflow line?

As for the problem,

How much fuel is actually coming out?

you said pissing out, then said it was a dribble?

I honestly havent played with the internal bowled type before, so im not too sure on the exact way they work, but external bowls have a "float" that sits in the top of the fuel bowl, there is a little valve and spring that sits under it. When you rebuilt the carbies, (assuming these are the same) you might have left the little spring out or put something back in wrong.

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#3 _oldjohnno_

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Posted 24 November 2009 - 11:29 AM

Most likely a bit of shit in the float needle/seat

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#4 _mello92_

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Posted 24 November 2009 - 11:54 AM

Chris - no Im not using an overflow line, I didnt think it was necessary. As for the amount of fuel, the rocking and movement of the engine throws it out at idle, then when revved up to ~3000rpm, it dribbles out. Sorry, should have worded it better.

Everything that came out of the carbies, went back in with new gaskets.

Johnno - Im gonna go check that out now.

Cheers.

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#5 orangeLJ

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Posted 24 November 2009 - 12:10 PM

I ran an overflow tube, partly because I had it, but mainly because I didnt like the idea of fuel overflowing directly onto the exhaust.

Johnnos probably right, are you running a filter?

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#6 _mello92_

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Posted 24 November 2009 - 12:25 PM

Yeah, Im not a fan of fuel on a hot exhaust either, it gets a bit exciting.

Course Im using a fuel filter...who's dumb enough not to?

Just taken the bowl lid off, had a fair amount of crap in it. Cleaned out the bowl, put the lid back on.

Lunch was ready, so I didnt have a chance to start it.

Will report back in 10 minutes.

As a side note..the bowl lines up with the chassis rail in a LX. Its a PITA to take the lid off.

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#7 greens nice

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Posted 24 November 2009 - 12:36 PM

sorry for offtopic, but how much were your ram tubes and where'd you get them, they look sweeet!

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#8 _mello92_

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Posted 24 November 2009 - 01:31 PM

Kevin - $40.20 each from SU Midel in Lakemba, NSW.

OK - the fuel overflowing problem is fixed. But now the thing doesnt want to idle or rev below ~2000. It backfires and dies.

Ive tried different fuel pressure settings, with no differences or change.

The only way to get the thing started is by using the choke. And its thoroughly warmed up to normal temp.

Ive adjusted the idle so it's higher, and leaned out the mixture 1.5 turns because it was running really rich this morning.

Ideas please????

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#9 _brendan_h_

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Posted 24 November 2009 - 03:38 PM

sorry to hijack, but my Sus dont have an over flow line that i can put a hose onto. how can i get an overflow line so i can direct the overflowed fuel away from the exhaust

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#10 _oldjohnno_

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Posted 24 November 2009 - 06:28 PM

But now the thing doesnt want to idle or rev below ~2000. It backfires and dies.

The only way to get the thing started is by using the choke. And its thoroughly warmed up to normal temp.

Ive adjusted the idle so it's higher, and leaned out the mixture 1.5 turns because it was running really rich this morning.

Ideas please????

Sounds very lean to me.

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#11 _mello92_

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Posted 24 November 2009 - 07:58 PM

Yeah, you were dead right Johnno.

All good now, she hammers.

Time to update my project thread...

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#12 _mello92_

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Posted 25 November 2009 - 09:12 AM

Turns out it all isnt so great.

I must have been asleep yesterday, but this morning I found that No. 3 carb (near the firewall) is pulling a heap more air ( 8 kg/hr) at idle than the other two ( they are only pulling 5.5 kg/hr).

Its the same carb that had crap in the bowl, which I cleaned out and flushed.

I cant back the idle on No. 3 carb off anymore, thats as low as it will go.

The only thing different with that carb is where Im sourcing the vacuum for the carbon canister and distributor. On that carb Im getting vacuum from the 1/8" BSP fitting on the RHS, but on the other two Im getting vacuum from the little fitting on top near the manifold.

Ideas?

Also, there are small amounts of blue smoke coming from the exhaust, all through the rev range. Oil?

This engine was 'supposed' to be reco'ed 3 yrs before I bought it. Ive got the invoice with a list of stuff done. Is it a problem that they only drove the car 5 times in 3yrs, not starting it in between?

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#13 _threeblindmice_

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Posted 25 November 2009 - 03:48 PM

Keep at it ,in the end , you will know all about them , then they become fun .

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#14 orangeLJ

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Posted 25 November 2009 - 03:51 PM

disconnect the vacuum lines and see if that drops the volumes.

I ALWAYS had a problem with my SUs where one carb wouldnt sync up perfectly with the others, it always ran a little richer, I put it down to the fact it was the odd carby out (other two were from a twin carb setup and it was the ring in I assume)

Blue smoke out the exhaust could just be running a wee bit rich and you think its blue smoke?

Does it use any oil? has it blown smoke before and you just havent noticed?

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#15 _mello92_

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Posted 25 November 2009 - 05:59 PM

Playing with the vacuum lines results in a small drop in airflow, probably about .5 kg/hr.

Yeah I know its blue smoke because you can see it when it blows over a white car.

It used to blow tiny amounts of black smoke with the 320 Holley, and I thought that was because it was running rich.

Yeah it uses some oil, though it does have a persistant rear main leak. About 10-15 drops overnight.

Not even as half as much as the gearbox leaks.................

Cheers for the help Chris.

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#16 _oldjohnno_

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Posted 25 November 2009 - 07:12 PM

The vacuum lines shouldn't have any effect on the measured flow at the mouth of the carb. Even if there was a massive amount of air going thru the line the gauge only shows what is going across the butterfly, not whats flowing in downstream of the butterfly so you have to find out why it isn't sealing. Two likely causes: it's being held slightly open by the linkage (disconnect that link to check), or the throttle disc isn't centred. Pull no 3 carb off and check that the disc seats right round with the idle screw backed off. If it's had a particularly rough rebuild you might have to loosen the 2 screws that secure it to the throttle spindle and re-centre it. SU's are pretty prone to wear in the throttle spindle so check that too.
Blue smoke is oil, stick some high detergent oil in it and drive it for a couple of weeks to see if it settles down - might just be sticky rings.
Edit: I just remembered the late style SU's also have a spring loaded valve in the throttle plate (for emissions on the overrun) so check that it's not stuck open too.

Edited by oldjohnno, 25 November 2009 - 07:13 PM.

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#17 _mello92_

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Posted 26 November 2009 - 02:53 PM

Johnno, on this carb, Im getting vacuum from a 1/8" BSP port of the side, which goes straight through the wall of the carb. The hole is almost inline with the needle. Having said that, blocking this off does bugger all.

I'll have to check that the linkage isnt holding it open, but Im sure it isnt.

As for the throttle disc; I pulled that all out and checked everything when I put kits through them. I remember they were all sealing good, there was no wear on the shafts or bushes and I replaced the rubber seal on the shafts. These throttle discs dont have those spring loaded valves.

As for the smoke; I think it might be valve seals. There was a small amount of black oil in the inlet ports when I took the 320 off. Sorry, should have mentioned that before.

I took it for a decent run today, and bloody hell it goes good. Sometimes it will backfire through the carbs under very slight throttle openings. For instance, doing 30km/hr around a roundabout in 3rd, and just picking up the throttle on the way out, doing ~1800rpm. But it really hammers above 4000rpm now, the Holley was doughy.

Cheers for the help, appreciate it.

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#18 _brendan_h_

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Posted 26 November 2009 - 04:35 PM

Johnno, on this carb, Im getting vacuum from a 1/8" BSP port of the side, which goes straight through the wall of the carb. The hole is almost inline with the needle. Having said that, blocking this off does bugger all.

I'll have to check that the linkage isnt holding it open, but Im sure it isnt.

As for the throttle disc; I pulled that all out and checked everything when I put kits through them. I remember they were all sealing good, there was no wear on the shafts or bushes and I replaced the rubber seal on the shafts. These throttle discs dont have those spring loaded valves.

As for the smoke; I think it might be valve seals. There was a small amount of black oil in the inlet ports when I took the 320 off. Sorry, should have mentioned that before.

I took it for a decent run today, and bloody hell it goes good. Sometimes it will backfire through the carbs under very slight throttle openings. For instance, doing 30km/hr around a roundabout in 3rd, and just picking up the throttle on the way out, doing ~1800rpm. But it really hammers above 4000rpm now, the Holley was doughy.

Cheers for the help, appreciate it.

you realy feel the difference hay. cant wait for the new radiator to come so i can take it for a good run without it overheating

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#19 _oldjohnno_

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Posted 26 November 2009 - 07:24 PM

Johnno, on this carb, Im getting vacuum from a 1/8" BSP port of the side, which goes straight through the wall of the carb. The hole is almost inline with the needle. Having said that, blocking this off does bugger all.

I'll have to check that the linkage isnt holding it open, but Im sure it isnt.

As for the throttle disc; I pulled that all out and checked everything when I put kits through them. I remember they were all sealing good, there was no wear on the shafts or bushes and I replaced the rubber seal on the shafts. These throttle discs dont have those spring loaded valves.

As for the smoke; I think it might be valve seals. There was a small amount of black oil in the inlet ports when I took the 320 off. Sorry, should have mentioned that before.

I took it for a decent run today, and bloody hell it goes good. Sometimes it will backfire through the carbs under very slight throttle openings. For instance, doing 30km/hr around a roundabout in 3rd, and just picking up the throttle on the way out, doing ~1800rpm. But it really hammers above 4000rpm now, the Holley was doughy.

Cheers for the help, appreciate it.

You're welcome. I'd still check the butterfly if the linkage checks out ok, they only have to be off by a few thou to not seat properly. And the occasional backfire is indicating leaness - they tend to get a lean spot on opening the throttle if the dashpot oil is too thin. They aren't super sensitive but I always found something like a 15w-40 to be better than ATF. Well tuned SU's are in a league of their own I reckon, just as sharp as a good EFI setup and good mileage too.

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#20 _mello92_

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Posted 26 November 2009 - 08:31 PM

I had a look; the linkage is fine, but the throttle on that carb still doesnt fully close with the stop screw wound all the way out. It feels like it gets stuck closed when you try. I cant pull it off just yet to have a look, I need the car for a few days - picked up a couple days work. I will try the 15W-40, but again, in a few days time. You're right, throttle response is 600% better than with the Holley, but the tempation to stick the boot in is resulting in a fair chunk of fuel being used.

What do you think about the valve stem seals?

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#21 _oldjohnno_

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Posted 27 November 2009 - 08:57 PM

Sounds like the butterfly isn't quite centred or back to front (they're usually chamfered).
It's fairly normal to have a light oily film in the intake ports - the classical symptom of worn guides/seals is smoke on startup, especially if the engine is still warm.

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#22 _mello92_

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Posted 28 November 2009 - 06:59 PM

I'll have a look at the chamfer.

There was more than a light film mate, more like 5mL sitting at the opening of each inlet port, near the gasket.

I had another check, it blows blue smoke at any rev, hot or cold, at startup or when idling.

Cheers.

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#23 _oldjohnno_

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Posted 29 November 2009 - 07:35 AM

Check that the oil isn't being pulled through the pcv line, especially if you have an aftermarket rocker cover. Most of these have shitty baffling though it's a bit unlikely they'd let that much oil through.
If that checks out ok then it looks like it's time to give the engine a freshen up.

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#24 _mello92_

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Posted 13 December 2009 - 09:23 AM

Excuse the late reply, but people have other things to do to...

I connected some clear hose from the PCV to the manifold to see how much oil is coming through there, and there is a distinct flow there. Its not pouring through, but you can see it running through the hose very clearly. The lack of oil coming through here is making me think this engine needs a freshen up, if there is anything left in it. (It was freshened up 2 years ago, I re-read the invoice I was supplied with.)

Also, I couldnt see any chamfer, all the throttle plates are facing the same way.

And since my last post here, I've had some more troubles with this motor. During a drive after one tuning episode, it felt like it was starving for fuel above 4000rpm. A new filter didnt fix, but a new rotor did - the old one had partly cracked the plastic lug which positions the thing on the distibutor shaft, therfore allowing ~5deg of movement. Any ideas as to how this happens?

But lo and behold, we have more dramas. Since putting the new rotor in, I took it for a 2 min drive, then parked it. Work took over and I didnt get a chance to check the mixtures, until yesterday. Oldjohnno's tuning method (from brendan_h's thread) and the tuning method in my SU book, tell me its running lean (engine stumbles when the piston it lifted 1.5-2mm). The black smoke from the exhaust, and the smell of the exhuast tell me its running rich. And it backfires through the exhaust (followed by large puffs of black smoke) on overrun (in gear), or when you floor it then take your foot off (in neutral, when parked).

I know its Sunday, but I could do with some help please.

I feel like a complete idiot for asking; but how do I check what the initial timing is set at?