My Alfa Romeo 33 rebuild - FIRST TIMER

[Brit01]

It is a good idea to to preload the plug gasket to compress it and then release and then final tighten.

This is a practice I do. Thanks.

I will start using anti-seize on the plugs as you suggest. Maybe I can get hold of Loctite here but finding it specifically for high temps and aluminium may be tricky. May have to be an overseas purchase.

Also just found in the AR maintenance manual that is does recommend anti-seize grease!
Thumbs up to you Guy.

Regards

Chris

[Brit01]

Disaster struck.

When I took the car out of the garage it felt like it was missing sparks and kept stalling when lisfting off the clutch at the corners.

Then wouldn't start at all. (luckily only 2 blocks from the garage).

So I took off the new cap and rotor and put on the old original one and started up straight away.

Looking at the new rotor, it looks a bit burnt and the rev limiter arm is stuck like the plastic around it melted. Looks like they gave me the wrong rotor (even with the old to cross reference it with Facet - I trusted the guys at the shop!!- my mistake).

I bought a facet 3.7527RS.
Wasn't cheap (35 USD) but half the cost of the Bosch (Brazilian) which was out of stock anyway.

I guess it's the wrong one.

In contact with Peter Webb who has original Bosch rotors.

[Brit01]

Now I have the brakes working (yes silly me putting the vacuum valve the wrong way round yesterday!) and a rotor arm that works properly, a Sunday storm has hit us early.

I got up early especially to get out on the quiet roads, while drinking a cup of tea I heard rumbles of thunder and then the rain came down!!

What bad luck!


Anyway here's a shot of Fridays night's job - installing the headlights and bumper.

[Brit01]

well I'm never buying Facet rotor arms or Brazilian made Bosch again (the cap was broken also - the small contact point in the middle that connects to the coil was burnt and jammed in). No refunds either!! Can you believe that? I wonder why???

Same as the car batteries here. They are all made in Brazil and only last 18 months. Guarantee is normally 6-12 months max.

Really they are the chinese of South America.

In 8 days I'll have a new original german Bosch cap and rotor arm in the post from UK.
For now I have the old german ones that still work well but are worn.

[Brit01]

First test around the area was not good.

Lots of hesitation/stuttering as if it was very lean. AFR was jumping to lean when accelerating but idling at 13.1 which is good for the Alfa boxer. Pump jets are working well.
Maybe they need increasing in size if I can't find any other faults.

Placed bigger idle jets in and still the same.

advanced the timing 1 degree - maybe a touch better but still bad.

This weekend I will check all jets in case 1 is blocked.

I'll also check the timing belts, maybe slipped a tooth. Always a possibility.

Before I had 52/53 idle jets in and it was always on the rich side and had a smooth transition to mains.

Not sure what is happening yet. Bit fustrating but it is my first rebuild.

Maybe a compression test also - chance a new ring has broken or a valve is not seating properly?

[Guy Croft]

A comp test is a 'must' and there is a thread on this at:

http://guy-croft.com/viewtopic.php?f=4&t=583

Are you sure you've got the engine firing order right?

G

[Brit01]

Thanks Guy. Firing order is correct yes. Also it idles very nicely.

I will also check the float level.

Now the floats were changed and set to fact. height standard but I read that old floats can become less floaty over time (23 years in my case).

If the new ones are more floaty then the level of fuel in the carb chamber will be lower affecting the air corrector jets on the idles making the mixture leaner. Just another possibility if everything else looks fine.

[Guy Croft]

Floats do not exhibit that particular phenomenon!

They are either intact and float or leak and sink. Easily checked and very unlikely to be probable cause.

Don't go guessing - check the cam timing & belt setup & do the comp test and report.

G

[Brit01]

Don't go guessing - check the cam timing & belt setup & do the comp test and report

Will do thanks.

But I wouldn't call it guessing per se.

Process of elimination in my opinion. :)

From past experience varying the level of the floats in my boxer has altered the AFR ratio. I was under the impression that the higher the float the richer the mixture but if you say this has no influence then I'll take your word for it.
Maybe there was another factor in that particular case.

[Guy Croft]

I'm not saying the float height has no influence on mixture but if it's set according to carb mfr data you can assume it's right.

I always advise a fault-finding sequence based on my own wide experience. Proceed as directed and forget mixture for the moment. Just trust me OK?!

G

[Brit01]

Thanks Guy.

Yes first I will remove the plugs - check the timing belts at TDC.
I know the left one was 1/4 tooth out but I don't imagine this would make such a difference.
But this is something to check carefully of course. Could have slipped a tooth or stretched of course everything being new and tight.

Then if that all looks good, I will replace the plugs, but not to full torque, warm up the engine and then remove the plugs to do the compression test.

If this is all ok then I'll move on to the carbs, checking for blocked jets, checking float height etc.

Fuel pressure also maybe? But I believe these carb set ups don't need much fuel pressure to fill the float chambers sufficiently. (because what concerned me was the AFR - idles nicely at 13.1. But then shoots up to 17/18 while stumbling, normally it goes down a little to 12 or so as the pump jets action).

Best regards.

[Brit01]

One thing I left out.

About 4 months ago I put new floats in. Old one had a crack appearing, caught it before it leaked.

The old ones were set at about 5.5-6 mm.

I set the new ones at the same height. The car stumbled and was leaner.
New floats were much more buoyant although identical and original. Old ones were 23 years old!

I set them to 4mm and ran much better.

But when I did the rebuild I put them back to the factory recommendation of 5/6mm.

A little trick to accurately measure and set them I saw is to use an allen key of the specific size. Easy and quick.
Place the allen key across the gasket under the float and adjust.

[WhizzMan]

Follow Guys advice on fault finding.

AFR measurements with engines skipping is useless. You'll measure misfires as way too much oxygen in the exhaust gasses and could make the mistake to set mixture way too rich to compensate. If you want to use gas measurements to determine the cause of a misfire, you'll need to measure more than just Lambda/O2. Both CO, HC are just as important in that case.

Metal floats kept in humid conditions, tend to get metal oxide on them, weighing them down. If you keep your car dry and in use, it's not an issue, but "barn finds" can suffer from this. That's probably where the warning originates.

[Brit01]

Thanks whizzman.

Yes for sure I will be checking the timing, belts, ignition and compression tonight or tomorrow first.

If all looks ok then move on to the carbs/jets.

My Dellorto floats are plastic but they can accumulate gunge and become heavier over time or also crack and leak of course.

[Brit01]

Results of compression Test. (heated engine of course - just a dry test also)

First checked the timing belts, all ok. Left as stated initially is just a fraction out, less than 1/4 tooth. Not much I can do about that without vernier pulleys.

180 psi on every cylinder.

This is with JUST 9 kms on the clock, not even broken in yet. Haven't had the chance the take it out and push it a little yet on the open road.


There was a little, just occasional back fire/spitting through the carbs while warming up but disappeared once it got up to temp. And the odd misfire when I let off the accelerator quickly.
Do I need to be concerned about this backfire/spitting? Just to add the fuel has been sitting in the tank for 2 months. Maybe a little old and could be a cause of the spitting or too lean a mixture. Idle jets 53. I held it at 2000 rpm to warm up when it was spitting occasionally.
This was also without the filter box on so a higher air flow was obvious.

I think with 180 psi the valves and rings are seating ok no?

I wait for your thoughts Guy.

Regards.