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paulhide
P4
Joined: 20 Dec 2003
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Location: Oh Beautiful Billingham
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 Posted: Fri Jun 25, 2010 6:28 am Post subject: |
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Tuning carbs is hard work. Slow returning idle can also be caused by the throttle bar sticking on the oil breather pipe/sticking butterflies or by air getting in underneath the carb.
Also make sure that pipework to brake servo and the one between the distributor and carb are in good nick.
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Brit01
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Joined: 24 May 2010
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| Posted: Fri Jun 25, 2010 8:58 am Post subject: |
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I haven't cleaned the idle mixture screws yet.
Are these easy to remove?
Can I just unscrew them?
There should be a spring, washer and gasket right?
Any tips?
I guess another source of a vacuum leak could be the small vacuum ports, I unscrew 2 of them to test a new gauage I have. Maybe old gaskets that didn;t seal properly when screwed back in. |
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paulhide
P4
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Location: Oh Beautiful Billingham
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| Posted: Fri Jun 25, 2010 9:57 am Post subject: |
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Yes idle mixture screws just unscrew out. Be careful with them. Yes there will be a spring, a tiny washer and a tiny gasket. The latter two may stay in place, but should come out with some light tapping.
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Brit01
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| Posted: Fri Jun 25, 2010 10:00 am Post subject: |
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Thxs Paul.
Just arrived at work.
Strange it seems to have symptoms of a rich and lean mixture. Signs are confusing sometimes.
Bit of a sick sweet smell. But it doesn't pull well, heats up quickly on idle and idles high when warm.
Definitely have to check the balancing. 
Maybe one side is rich and other lean?
Update: Just noticed the throttle stop screws are raising the idle speed: aren't they supposed to have a 1 mm gap when idling so the throttles are completely closed when idling?? |
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Brit01
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| Posted: Fri Jun 25, 2010 2:38 pm Post subject: |
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Just been out playing with the mixtures again. Idling nicely at 850 when hot.
When I blip the throttle while in neutral, revs increase quickly then drop to about 750 for a second and rise again to 850.
Is this a little rich when drops below idle rpm after blipping? I can't really smell any petrol from the exhaust. |
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paulhide
P4
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Location: Oh Beautiful Billingham
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| Posted: Fri Jun 25, 2010 2:56 pm Post subject: |
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Probably okay? Idling is always going to be a tiny bit rich for a second after revving before it settles out, especially if as you've drilled your pump jets out to 0.45 instead of 0.35 ?
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Brit01
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| Posted: Fri Jun 25, 2010 3:49 pm Post subject: |
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| Quote: |
| Probably okay? Idling is always going to be a tiny bit rich for a second after revving before it settles out, especially if as you've drilled your pump jets out to 0.45 instead of 0.35 ? |
Got new 33 pump jets now  Went for the smaller ones instead of 35. Easier to go up in size.
So far so good.
I have a 30km run home tonight so I'll see how the carbs settle after this.
Prefer to be a tad rich than lean.
Need to get myself a wideband lambda to make these judgements easier.
Just got the complication of not having a fitting hole in my exhaust |
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BigAl
P4
Joined: 06 May 2003
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Location: U.K Surrey
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| Posted: Fri Jun 25, 2010 7:12 pm Post subject: |
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Rather than a WB Lambda sensor, the hastle of getting manifold drilled and welded you could use , now bear with me, something called colourtune.
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Brit01
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| Posted: Fri Jun 25, 2010 8:22 pm Post subject: |
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| ok ok BigAl. good for idling without load but when you want to monitor your main jets while driving? |
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BigAl
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Brit01
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| Posted: Wed Jun 30, 2010 9:49 am Post subject: Balancing the carbs |
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I will attempt to balance my carbs for the first time soon.
Read plenty of articles but would just like your opinion guys.
Just like to clarify a few steps.
1) First I need to disconnect both throttle linkages so they sit fully closed.
2) I need to use the idle speed screw to adjust idling while adjusting the idle mixture screw of each cylinder.
Using the vacuum meter also to make sure front and back carbs are taking in the same amount of air.
Once all 4 are balanced and idling at 900 rpm reconnect the throttle linkage bars making sure both are the same length and the rpm does not change on either side when reconnected.
In a nutshell is this the correct procedure for Dellorto's DRLA? |
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Brit01
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| Posted: Wed Jun 30, 2010 11:33 pm Post subject: |
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| Ha ha you big chickens, i got that tipform an alfa mechanic, easy peezy |
you know what?
On the flywheel there are a couple of what looks like balancing holes and also a kind of stud sticking out.
Good job i didn't stick a screwdriver in there. 
Maybe it was out of balance and they corrected it like they do with the wheels.
When I paint the marks white I see nothing!!! They seem to be invisible with the flashing xenon light!!!!
Maybe I should clean marked the area with some sandpaper/file for it to shine instead.
Also I'm a bit confused with the idle speed screws and idle screw on the linkage arm.
Which one do I use to adjust idling speed? |
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BigAl
P4
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| Posted: Thu Jul 01, 2010 8:33 am Post subject: |
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If those lugs were on the same plane as the timing marks and you tried the screw driver method, all that would have happened is that the screw driver would have risen up over them.
The other alternative is to rotate the engine until you see the timing marks and scrape with a flat edge.
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Brit01
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| Posted: Thu Jul 01, 2010 12:51 pm Post subject: |
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Thxs BigAl. I'll try cleaning the marks.
Going back to the idling setting. Still trying to figure this out.
If I have the 2 throttle lever idle speed screws turned out too much to set idle at 900 rpm then I understand the throttle plate could be open too far and reducing the effect of the idle mixture screws.
At this point the transition port is coming into effect rather than the idle mixture port due to reduced vacuum.
If this is the case I need to unscrew the 2 throttle lever idle screws and increase the idling using the 4 idle speed screws next to the mixture screws.
Am I on the right track? |
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RFlower
Alfa 33
Joined: 17 Feb 2004
Posts: 432
Location: S of France
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| Posted: Thu Jul 01, 2010 2:02 pm Post subject: |
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| Brit01 wrote: |
When I paint the marks white I see nothing!!! They seem to be invisible with the flashing xenon light!!!!
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If you see nothing,
1) You have painted the wrong mark(s),
2) Your timing light is not flashing,
or, 3) Your timing is too far out for the mark to be visible in the window. - Did you set the distributor points to just be opening with the static timing mark aligned before you tried the timing light?
Try lining up the flywheel TDC mark with the pointer.
The mark should be a semicircular cutaway on the front face of the flywheel, followed in a clockwise direction (looking from the front) by 3 marks on the periphery for Static, 2000rpm and 4500rpm timing.
With the engine in this position, mark the crankshaft pulley with chalk, next to some easily visible reference point.
Run engine and point your strobe light at the crankshaft pulley.
You will see if the light works and if your timing is way out.
Incidentally, if you add your car details to your signature everyone will know what car we're talking about. 
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BigAl
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Brit01
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Joined: 24 May 2010
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| Posted: Thu Jul 01, 2010 2:39 pm Post subject: |
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| Did you set the distributor points to just be opening with the static timing mark aligned before you tried the timing light? |
Nope . I have never done this before. I will read into this.
Once I confirm which is the TDC mark I need to set the dizzy to light when the pointer matches the TDC mark no? (engine off but electrics on).
| Quote: |
| The mark should be a semicircular cutaway on the front face of the flywheel, followed in a clockwise direction (looking from the front) by 3 marks on the periphery for Static, 2000rpm and 4500rpm timing. |
I have 4 marks on the flywheel.
First is an arrow mark (TDC?), next the 3 marks with a line I assume are the static ,2000 and 4500 marks.
Yes there is also a circular cut out but on the periphery (not semi circular).
I haven't look on the front of the wheel yet for a semi circular cut out.
Is this arrow mark the TDC notch??
Yes I'm using spark 1.
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paulhide
P4
Joined: 20 Dec 2003
Posts: 1607
Location: Oh Beautiful Billingham
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| Posted: Thu Jul 01, 2010 2:43 pm Post subject: |
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Should the timing gun light up the TDC marker on the flywheel or the next mark (about 2cm further round) at idle (900rpm)?
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Brit01
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| Posted: Thu Jul 01, 2010 2:55 pm Post subject: |
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| Quote: |
| Should the timing gun light up the TDC marker on the flywheel or the next mark (about 2cm further round) at idle (900rpm)? |
I understand the gun should light up on the first of the 3 timing marks at 900 rpm.
btw. How do I update my profile with my car model? |
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paulhide
P4
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| Posted: Thu Jul 01, 2010 3:11 pm Post subject: |
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So that's the mark just after the TDC mark I take it (anyone else confirm?)
To update your profile go to forums menu at the top and choose 'profile'
Regards.
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RFlower
Alfa 33
Joined: 17 Feb 2004
Posts: 432
Location: S of France
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| Posted: Thu Jul 01, 2010 3:53 pm Post subject: |
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| Brit01 wrote: |
| Quote: |
| Should the timing gun light up the TDC marker on the flywheel or the next mark (about 2cm further round) at idle (900rpm)? |
I understand the gun should light up on the first of the 3 timing marks at 900 rpm.
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The static mark is what it says, the mark to line up, with the engine static (stopped), to get a starting point for adjusting the timing with the engine running.
It may or may not line up at idle speed when using the timing light. There may already be some centrifugal advance from the distributor, or it may be worn.
The important settings are those at 2000 and 4500 rpm, the first being after any wear in the advance mechanism has been taken up, and the second to prove the advance is working properly.
The vacuum advance pipe must be removed from the distributor when checking the timing. If you didn't do this it might be the reason you don't see the marks on the flywheel.
You might find the Haynes Manual for Alfasud and Sprint useful. They didn't produce one for the 33, but there is a section on later Sprints, which used many 33 parts, and is relevant to early 33's.
I have seen them on eBay from time to time.[/u]
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Brit01
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| Posted: Thu Jul 01, 2010 5:16 pm Post subject: |
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Thanks guys.
| Quote: |
| Also when at TDC is the rotor arm pointing towards "plug 1" or where you are attaching your timing gun? |
Just to confirm which is cylinder 1 if I'm sitting in the car.
I understood it was the closest cylinder on the left if I'm sitting in the drivers seat.
Bonnet
3-2
1-4
Seat
I just read on another thread it was opposite: cylinder 1 was first on left if looking from the front of the car.
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BigAl
P4
Joined: 06 May 2003
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Location: U.K Surrey
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| Posted: Thu Jul 01, 2010 5:32 pm Post subject: |
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hey brit
when sitting in the car front right is no 1, but its all relevent.
When at TDC where your totor arm is point is no1, my no1 is actually no3.
To change it means removing the oil pump and rotating it.
As you look at the engine from front of car to back it is,
front left =1
rear left =3
on the dizzy the firing order goes clockwise, to match the cylinders but the other side as in 2 and 4 get swapped over.
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Brit01
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| Posted: Thu Jul 01, 2010 5:37 pm Post subject: |
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Now I'm confusing myself.
Ok so which cable does the ignition timing light attach to?
Maybe I've been attaching it to 4 so no visible marks on the flywheel!!!
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BigAl
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| Posted: Thu Jul 01, 2010 5:44 pm Post subject: |
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Its all relevant to TDC, get the engine to TDC, then connect the timing gun to whatever ht lead the rotor arm is pointing to.
It doesn't really matter what cylinder is "1" as they will all be firing in the correct order.
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