(miserable) MOT failure

So. Despite a fair amount of work, the alfa failed its MOT today. The NSF caliper was binding, so i removed and rebuilt it yesterday. It now does not bind. However, my attempts to bleed the brakes were obviously not 100% successful, so there's a brake imbalance: hence the failure for this and a RHD headlight on one side which I've now rotated to make it legal (I hope.)

Advisory was issued for tyres being near the limit and for it running rich. I've colourtuned it now so it should be better.

Annoyingly, I don't think the various carb stripdowns/cleans have worked - the idle mixture adjuster on cylinder 4 is still a fair way further out than the others in order to get the cylinder firing at idle at the correct mixture on every stroke (seen using a colourtune.) My distributor is still not advancing properly too - suspect the springs. It wasn't advancing enough so I tried reducing the inertia weight spring preload, but now it's still not advancing enough and is all over the shop at idle. Stripdown time, and new springs.

I've tried spraying a fair amount of WD40 around the manifold to try to determine if there is an air leak, and listened using a stethescope, but I really don't think I can hear one. Carb cleaner in through the intake whilst it's idling? Switching the idle mixture adjuster screws to see if they're damaged? I'm out of ideas.

will

Originally Posted by ill_will

Annoyingly, I don't think the various carb stripdowns/cleans have worked - the idle mixture adjuster on cylinder 4 is still a fair way further out than the others in order to get the cylinder firing at idle at the correct mixture on every stroke (seen using a colourtune.)

It is often the rubber carb mounts, check by flexing the carbs up and down a little to open any potential cracks. A common air leak for no. 4 is the vacuum pipe for the brakes. Check it all the way back to the check valve on booster.

Colortunes are great things but I found that a set of vacuum gauges really helps to balance a pair of carbs and pinpoint air leaks.

My distributor is still not advancing properly too - suspect the springs. It wasn't advancing enough so I tried reducing the inertia weight spring preload, but now it's still not advancing enough and is all over the shop at idle. Stripdown time, and new springs.

If you feel like you deserve a present then the latest thing is an all electronic distributor with 16 different advance curves. Saves all that messing around with springs.

Distributor is fixed! advancing perfectly from idle to 5000 rpm. One problem down, two to go... For the record, I straightened out the bracket that the springs attach to using an engineering vice, so that the mounting points were diametrically opposite the centre hole. Then the spring preload was set so that it was the lightest preload where there was no play in the advance rotor (which the cap goes onto - NB not to be confused with no play in the centrifugal weights, as with this (working) set-up there is still some of that.)

1) BRAKES: they are the two-pot front calipers with a single bleed valve on the brake pipe side. MOT man said they were unbalanced, which was probably caused by having to strip down the NSF caliper to repair a binding problem. Despite numerous goes at bleeding, that caliper still isn't pulling its weight, i.e. OSF and NSR lock first. Could there be air trapped in the outer pot? The 4-pots i've got on my other car have two bleed nipples, one for each side... Even with the brakes slightly unbalanced, they stop incredibly well (better than my integrale! probably due to the lightweight car.)

2) I gave the car an Italian tune up today and at full throttle it pulls beautifully, no hesitation, lovely noise, no smoke - perfect. However, I'm still getting misses at constant rpm cruise at lower rpm, i.e. 1500-3500. As you can imagine, this is very annoying in town/traffic. I'll try the suggestions above some time over the weekend and keep posting on progress...

will

Originally Posted by ill_will

Distributor is fixed! advancing perfectly from idle to 5000 rpm. One problem down, two to go... For the record, I straightened out the bracket that the springs attach to using an engineering vice, so that the mounting points were diametrically opposite the centre hole. Then the spring preload was set so that it was the lightest preload where there was no play in the advance rotor (which the cap goes onto - NB not to be confused with no play in the centrifugal weights, as with this (working) set-up there is still some of that.)

1) BRAKES: they are the two-pot front calipers with a single bleed valve on the brake pipe side. MOT man said they were unbalanced, which was probably caused by having to strip down the NSF caliper to repair a binding problem. Despite numerous goes at bleeding, that caliper still isn't pulling its weight, i.e. OSF and NSR lock first. Could there be air trapped in the outer pot? The 4-pots i've got on my other car have two bleed nipples, one for each side... Even with the brakes slightly unbalanced, they stop incredibly well (better than my integrale! probably due to the lightweight car.)

2) I gave the car an Italian tune up today and at full throttle it pulls beautifully, no hesitation, lovely noise, no smoke - perfect. However, I'm still getting misses at constant rpm cruise at lower rpm, i.e. 1500-3500. As you can imagine, this is very annoying in town/traffic. I'll try the suggestions above some time over the weekend and keep posting on progress...

will

Ya can't beat a good 'ol Italian tune-up
With regards to the brake problem, don't overlook the flexy hoses, if they are old they can swell/implode internally without showing any signs of a problem externally, for what they cost, if the age/history is unknown its money well spent replacing them. also, did you just do a quick strip n clean on the l/f caliper or a full down to the bare castings n pistons rebuild?
Highwood (who you already mentioned you use for spares) do a rebuild kit for about £12 which does a pair/axle-set of calipers, again money and time well spent on getting the best from your brakes.
Are you in Cambridge propper or elsewhere within Cambridgeshire? I'm over in Peterborough next weekend if you need a little moral support and some additional Italian tuning-up doing
Keep us posted,
Ian.

it was a full piston-out job. i've got the re-test today so fingers crossed! I ended up taking the caliper off again (still connected to the brake line) and leaving it propped on it's side to try to get any air left in the outer piston through to the bleed valve. I also noticed I hadn't got the cut-outs on the pistons quite perfectly aligned so those were sorted too. they felt much better when i tested them.

i'm in cambridge proper unfortunately. nice berlina, by the way. there's a fulvia berlina for sale in cambridge at the moment, i'm tempted to go and have a look.

will

sick - the car now has an MOT. i am looking forwards to driving it properly so much. thanks so much to all those who advised/encouraged - much appreciated. The brakes, whilst feeling slightly spongey (Ian - i reckon that is probably the flexihoses, as you suggest) are very good, in that I can easily lock the wheels at 50 if i press hard, but they have very good feel, and awesome stopping.

i took some photos (unfortunately on film) which i'll post as soon as they're developed.

Re: the carb problem, i ran the checks that COSMO suggested. With the vacuum gauges attached, cylinder 4 was recording a slightly greater vacuum than the other cylinders at idle. (This wasn't just the gauge, i tried switching them round.) If i rev the car slightly, the gauges equal out, then on the overrun when the strongest vacuum develops, they are approximately all equal. I adjusted the air bypass screw (under the white plastic cover, NB these are 40DCOE44/45s) and equalled the vacuum on all cylinders. flexing the carb mounts didn't appear to make any difference to the vacuum on any of the cylinders. I adjusted the number 4 mixture using the colourtune.
Problem hasn't gone away, but is possibly marginally better. Seems to get worse as the engine gets hotter, not that i use the choke at all. I'm going to try switching the idle mixture screws around, checking the progress with the colourtune.

will

Will, good job on getting back on the road - hope we have a few good days coming for you to enjoy the fruits of your labours.

For the carb adjustment, are you sure that you have backed off the throttle stop adjustment so that you are truly running the carbs at idle through the idle circuit rather than the setting of the throttle butterflys? If you block off the brake booster connection does that change the vacuum reading of #4 at all?

I may be completely out of my depth here but i thought I'd chip in anyway .

I had the exact same symptoms on my car last year (its got 2 dellortos) . It would run fine for 15 minutes and then deteriorate very quickly to the point where it wouldn't idle. turns out that the springs for the choke on one side was weak and it was opening itself when it got warm. Replaced the spring and it been fine since.

It's probably completely irrelevant but it might be worth checking though...

Webers don't have a conventional choke, they have a cold running circuit that enriches the mixture instead of closing off the venturi. There is also no spring but it could be partially ON if the actuating lever and cable isn't adjusted correctly.

cosmo - i did try blocking the booster circuit - no change to vacuum levels.

My choke cable is disconnected and when i rebuilt the carbs i seated the pistons and checked the springs so I think it's unlikely to be this.

as I understand it, there is some air going through the butterflies at idle, and some through the idle circuit. i set up the carbs as described in the workshop manual, and looking at the progression holes they are covered at idle, - is this what you meant?

Originally Posted by ill_will

cosmo - i did try blocking the booster circuit - no change to vacuum levels.

That's the only external influence other than the carb|manifold|engine interface. If it is not that then whatever is causing your #4 imballance seems to be internal to the carb.

My choke cable is disconnected and when i rebuilt the carbs i seated the pistons and checked the springs so I think it's unlikely to be this.

as I understand it, there is some air going through the butterflies at idle, and some through the idle circuit. i set up the carbs as described in the workshop manual, and looking at the progression holes they are covered at idle, - is this what you meant?

At idle, only the idle circuit should be in operation - (Grabs Pat Braden's "Weber Carburetors" for confirmation... yup) the butterflys would be closed and the progression holes should not be in operation.

Is it just the imbalance between the mixture screws that is bothering you or is there some other manifestation of poor engine performance that we should be looking at?

Yeah, there is a problem - what i *think* is a misfire. I posted it on the other forum, but have copied it here for reference:

" The other issue is the mixture adjustment needles. I've ruled out vacuum leaks, balanced the carbs, adjusted the mixture using colourtune, done the timing, etc, but am still getting some hesitation at lowish rpm cruise, particularly when trying to gently reapply the throttle, say, when coming up behind slower moving traffic and matching speed with the car in front. The car bounces forward and back, like it's missing on a cylinder (or more.)

Could worn/damaged idle mixture adjustment needles cause this kind of behaviour? or are there any other likely culprits? I've tried switching the idle jets between different cylinders but can't tell if the problem has moved! I have cleanen and serviced the carbs twice, including blowing out the passages with compressed air, to no avail. "

It's kind of like a learner with bad clutch control, if you know what i mean! At wider throttle it runs excellently. Any ideas?

w

Yes, your description sounds like it could be a problem somewhere with the idle circuit. Above 3000 rpm the main circuit kicks in.

*But* don't be fooled. I had a similar type of problem - idle was OK but it wouldn't rev properly, lots of misfire and judder, until I got over 3000 rpm. I spent ages pulling the carbs apart, cleaning them, adjusting them to within a gnats of any spec I could find. A little difference each time but no real improvement. Then, out on yet another test run the engine cut out and I was stranded.

Problem was the condensor was loose on the distributor and it was intermittently shorting out. Why it was OK at high revs I don't know but that fixed everything. It was never the carbs! I suspect you have another problem that is not related to the mixture adjustment on #4.

I know you've worked on the distributor but it would be a good idea to go through the whole ignition system to eliminate it from your inquiries - new leads, plugs and a distributor cap wouldn't hurt if you aren't sure of their heritage.

Good news with regards to the MOT.

As with all classics they benefit from use and I suspect the more you use it the better it will become.

However from your description it sounds as if you have a flat spot rather than a miss-fire. If that is the case your best course of action will be to have your car tuned on a rolling road. I suspect the jets may need changing to get the best performance throughout the rev range.

I need to have my Spider tuned properly on a rolling road, it has high lift cams and 45's fitted, at around 2000 rpm there is a flat spot above that and it is fine but get it wrong at 2000 rpm and it will kangaroo slightly but it is improving with use.

My carbs have been rebuilt and the jets changed to what the garage thought they should be and I think now they are far too rich.

I will let you know the results after the rolling road tune.

In the meantime happy driving!

Originally Posted by ill_will

it was a full piston-out job. i've got the re-test today so fingers crossed! I ended up taking the caliper off again (still connected to the brake line) and leaving it propped on it's side to try to get any air left in the outer piston through to the bleed valve. I also noticed I hadn't got the cut-outs on the pistons quite perfectly aligned so those were sorted too. they felt much better when i tested them.

i'm in cambridge proper unfortunately. nice berlina, by the way. there's a fulvia berlina for sale in cambridge at the moment, i'm tempted to go and have a look.

will

Thanks for the compliment, and well done on the MOT. I think i've only ever seen 1 Fulvia Berlina in the metal so its possibly fair to say that its and even rarer car than the Alfa Berlina is (in the UK). I don't know much about them so can't help with any hints or tips on looking at the one you've seen for sale.

BTW, I just put a Giulia Super (a '73 on an L plate) thru a test last week for a friend of mine, the tester got really anal about it having black and silver pressed alloy plates on it and was about to write a fail out for the plates and a side repeater bulb, when he realised that the number plate part of the test is currently under review/suspended . So I got a bulb fitted quickly and came away with a shiny new MOT certificate .

I can try replacing the condenser again but all ignition service parts are new. Two other thoughts i've had are:

1) that the float levels are too high. I've heard that this can lead to dripping rather than spraying through the idle circuit. I did set the floats to 7/14 as per Jim K. on alfabb, but need to physically check the fuel level in the chamber.

2) throttle butterflies. I noticed that #4 is very slightly more open/closed (can't remember which) when looking through the progression holes. Will try carefully straightening them out.

regards

will

Originally Posted by ill_will

I can try replacing the condenser again but all ignition service parts are new.

The condenser was just my example - if you've already gone through the ignition system then that's great and it can be crossed off the list.

1) that the float levels are too high. I've heard that this can lead to dripping rather than spraying through the idle circuit. I did set the floats to 7/14 as per Jim K. on alfabb, but need to physically check the fuel level in the chamber.

That does sound too high. When I was trying to fix my stumble it was thought that my level was too low and leaning out the mixture. I went higher to 7/14 but it didn't make a lot of difference. The stock level for my 40DCOE/32 is 8.5/15.

2) throttle butterflies. I noticed that #4 is very slightly more open/closed (can't remember which) when looking through the progression holes. Will try carefully straightening them out.

Be *really* careful if you do this. Messing with the throttle butterflys is strongly discouraged.