My Alfa Romeo 33 rebuild - FIRST TIMER

[Urbancamo]

Like you had opened a new engine.

How much mileage this engine had? Might be mentioned earlier this topic, but i couldn't find.

[Brit01]

Crank journals look good then?

Engine has done almost 140,000 kms.

Hopefully get the plastigauge test done in the next few days.

[TomLouwrier]

hi Chris,

Seems to be looking good here.
I hadn't seen those grooves before in the small end bushes (at least not like that) but I do know similar ones. If they're Glyco bushes they should be fine. New pins go in OK, without play, wobble or rocking?

Crank looks unmarked too, just give the journals a good clean and rub with Scotch Brite.
And another clean ;-)

regards
Tom

[Brit01]

New pins go in just great. Little bit of wd40, no play at all. Nice and smooth.

Main bearings measured with Plastigauge today.

Not great but just within factory specs.
I can't afford to buy a new crankshaft this year so some new bearings and the old crank will have to last for a few more years.

Main 1: ~0.060 mm
Main 2: ~0.058 mm
Main 3: ~0.062 mm

0.028mm - 0.063mm main bearing clearance stated in manual.

Chris

[TomLouwrier]

Within specs is within specs, be it only just. No need to change your crank yet and no need to feel bad about that either.

If you still have the choice, get the fattest set of shells from the ones you mentioned earlier. That will help closing up the gap. On a total clearance of 0.028mm - 0.063mm a difference of 0.01mm does count.

regards
Tom

[Brit01]

Thanks Tom.

But 010 oversize is 0.254 mm so that would never fit without a regrind and this is a nitrite treated crank. Please correct me if I am wrong.

So I believe I have to stick with the standard size mains for now.

Regards

Chris

[TomLouwrier]

hi Chris

No, not oversized of course.
We discussed some bearing shells with the same nominal size but about 0.01mm difference in journal size and different part numbers some days ago (dec 13 to dec 16).
I suggested that might be to allow for journal and housing bore class, Guy thinks it's not that.

Like here:

Part Number: 66625RA
Component Number: 66625RA
For bearing clearance from: 0,02 mm
For housing diameter from: 53,7 mm
For shaft diamater from: 49,99 mm
Thickness: 1,84 mm
To bearing clearance: 0,07 mm

Part Number: 66325RA
Component Number: 66325RA
For bearing clearance from: 0,02 mm
For housing diameter from: 53,7 mm
For shaft diamater from: 49,98 mm
Thickness: 1,84 mm
To bearing clearance: 0,08 mm

I'll be honest and say that right now I can't really see the 'why and how' of the differences between these two parts.
Thickness and housing diameter are both given as identical. Thickness has a 2 digit precision: 1,84mm, but housing diameter is in 1 digit only: 53,7mm. Confusing.
But if I'm reading this right, the 66325RA is meant for the situation with the larger bearing clearance / smaller journal diameter. That would be fitting for your somewhat roomy measurements.

Guy, your opinion please?

regards
Tom

[TomLouwrier]

Hang on, found another listing for these part numbers:

Part Number: 66625RA
Chemical Properties: Unleaded
For bearing clearance from: 0,024 mm
For housing diameter from: 53,696 mm
For shaft diamater from: 49,992 mm
Quantity Unit: Pair
Supplementary Article/Supplementary Info 2: Aluminium alloy on steel base
Thickness: 1,836 mm
To bearing clearance: 0,069 mm
To housing diameter: 53,708 mm
To shaft diameter: 50,000 mm
Width: 17,800 mm

Part Number: 66325RA
Chemical Properties: Unleaded
For bearing clearance from: 0,024 mm
For housing diameter from: 53,696 mm
For shaft diamater from: 49,984 mm
Quantity Unit: Pair
Supplementary Article/Supplementary Info 2: Aluminium alloy on steel base
Thickness: 1,836 mm
To bearing clearance: 0,077 mm
To housing diameter: 53,708 mm
To shaft diameter: 50,000 mm
Width: 17,800 mm

Still not clear on the difference between the parts, as the only thing between the two listings is the shaft diameter and resulting bearing clearance.
This may have to do with the factory changing its mind on bearing clearance over the years, specifying another part from engine number 12345-etc.
I just can't tell (and that's Frustrating!).

<edit>
The illustrations that go with these suggest (if correct) that the 66625RA (also known as AEB91817 STD) has an oil groove, while the 66325RA (AEB91422 STD) is plain.
Different lubrication, different clearance. That makes some sense.
You pulled the grooved ones from your engine, so that would be the replacement bearing of choice. They are the more expensive ones of course ;-)
</edit>

Tom

[timinator]

Hi Chris, Food for thought. Try swapping the lower bearing on main 2 with main 3 and remeasure. See if it makes a difference. I don't do well thinking in metric but mixing a std. bearing with .001in. is an acceptable way to change clearances. Do you have .001, .002, etc. bearings available? Hope this is clear to you.

Tim

[Brit01]

Hi gentlemen,

Sorry if I mislead you. The listings/codings posted previously were for the big end shells, not the main bearings.

The main bearings which I measured today only come in 3 sizes and no other variations.
Standard, 010 and 020.

The measurements I just gave were for all new main bearings, all standard of course.

Do you have .001, .002, etc. bearings available? Hope this is clear to you.

Tim: The Alfa main bearings only come in the 3 sizes unfortunately (standard then 0.010, 0.020). Nothing in such small increments as far as I know.

Regards,

Chris

[WhizzMan]

yes watch out you don't end up doing it for a living!

Maybe it's my destiny Guy! Instead of being stuck in an office cube for 9 hours a day in front of a monitor with square eyes evolving.

Tell me about it. The money is much better and I have a mortgage to pay, so I'll be getting square eyes for a few more years I guess.


Alfa big end bearings come in Red and Blue. I don't know main bearing colors off the top of my head, but they have 2 or 3 colors as well.

Did you measure roundness of your crank journals? I don't see any damages to them, if they are round, I don't see a reason for getting a new crank or regrinding. Differences in size are normal for these, that is why you have the color system and plastigage and all. As suggested, mix and match bearing shells with journals until you have the best match you can get.

These engines are known to run for long distances even with bearing size slightly out of spec, they weren't very precise in the factory either and usually, they engines ran fine, with just a little lower oil pressure as a result. Mind you, I'm not talking about heavily modified performance engines on race tracks, but daily driver cars, being used mostly for moderate load conditions. If you can get a perfect match, by all means, go for it, but don't worry your head off if you miss it on one or two bearings by a very small margin.

[TomLouwrier]

Hmmm... that's why I don't do Imperial. And no pre-ISO either, if I can help it (except for HP, can't get a good feeling for kW).

When I did my studies ISO had just come in officially and both old metric (continental) and Imperial were still common. Of course in exams you got a nice panache of incompatible units in every question. The golden rule is: "write down all facts you see, convert to ISO (do check the right power of 10), do the calcs, convert back to original unit if needed." Stay within one system of units at all times during calculations. Always mention the unit with the number.

"(standard then 0.010, 0.020)" Chris, is that inches or mm? As far as I can tell it could be both, although I feel you mean oversize in inches here: 0,25mm and 0,50mm.

At least we seem to have solved the big end shell part number mystery here.
I'm with Whizzman: put in std shells and run that engine. Class Red or Blue would be great to get the best match, but can you get those?
Oh, and what shells did you use with the Plastigage to get your readings? The old ones?
Did you measure the journals with a micrometer? Several points along their length (taper) and then two times, perpendicular to each other (out-of-round)?


@Whizz, Chris:
In the same boat as you guys. Mech engineer making his living in IT services. Sure I'm enjoying that too, but my first love is still machines, engines.
Funnily one of the guys who lectured programming and CAD/CAM turned out to be a former instrument maker, just like me. He spoke the words 'Van ijzer word je niet wijzer", meaning "You won't get any the wiser from Iron". A bit sad, but true for most of us.
One of my fondest memories is waking up in a sleeping bag, in a pit box in Ledenon, France, from the sound of the neighbouring team warming up their engines. Comfortable? Nope. Exciting? You bet.

regards
Tom

(Oops, I'm starting to sound really old now.)

[Brit01]

put in std shells and run that engine. Class Red or Blue would be great to get the best match, but can you get those?
Oh, and what shells did you use with the Plastigage to get your readings? The old ones?

I can only get hold of Glyco shells here and they don't come in different colours. What are the thickness differences between the 2?

Comparing Glyco with another brand, the 2 listed below, they are both the same thickness but stated slightly different bearing clearances. Glyco seem to state larger bearing clearances.

I do not have a micrometer available unfortunately. Just the plastigauge and a digital caliper type instrument.
Haven't checked for ovality. The shells looked worn uniformly.
Measurements were taken with the new shells and not the old.
The only option at present is to put the new standard main shells in.

"(standard then 0.010, 0.020)" Chris, is that inches or mm? As far as I can tell it could be both, although I feel you mean oversize in inches here: 0,25mm and 0,50mm

Yes inches, so in metric, 0.25, 0.5, 0.75 etc


Part Number: 66326RA
Chemical Properties: Unleaded
For bearing clearance from: 0,024 mm
For housing diameter from: 63,663 mm
For shaft diamater from: 59,944 mm
Quantity Unit: Pair
Supplementary Article/Supplementary Info 2: Aluminium alloy on steel base
Thickness: 1,841 mm
To bearing clearance: 0,072 mm
To housing diameter: 63,673 mm
To shaft diameter: 59,957 mm
Width: 23,400 mm


Part Number: 4076CP
For bearing clearance from: 0,020 mm
For housing diameter from: 63,663 mm
For shaft diamater from: 59,944 mm
Quantity Unit: Pair
Supplementary Article/Supplementary Info 2: Steel back with sinter-fused bronze
Thickness: 1,842 mm
To bearing clearance: 0,070 mm
To housing diameter: 63,673 mm
To shaft diameter: 59,964 mm
Width: 23,400 mm

[TomLouwrier]

hi Chris,

Big ends: difference between shells is groove or plain. Sizes are identical, bearing play is determined by shaft/journal diameter.
Main bearings: difference in shell thickness is 0,001mm -nothing really-. Difference in bearing play is again determined by shaft/journal diameter and is well less than 0,01mm. I strongly suggest you check features like grooved or plain, but as far as sizes are considered, I find no functional difference here. Get the ones that are like what came out (groove, plain, lipped, left/right handed, etc).

Red and Green OEM would be to allow for bearing and big end bore classes, as Whizz said. I described the idea for you on dec.16th; this world is imperfect and all parts have their tolerances. Factories mix and match to get to their goal as best as possible.

Measurements were taken with the new shells and not the old.

Given that you measured against new shells, obviously you already have those on your bench.

I can only get hold of Glyco shells here and they don't come in different colours.

And you can not get shells in Red or Green classes.

The only option at present is to put the new standard main shells in.

So you fit what you have and be happy with them. Now what was the question again? ;-p

grinning at ya,
Tom

[Brit01]

Red and Green OEM would be to allow for bearing and big end bore classes, as Whizz said. I described the idea for you on dec.16th; this world is imperfect and all parts have their tolerances. Factories mix and match to get to their goal as best as possible.

Yes but unfortunately I was unable to get hold of any original standard size bearings (only original oversized available from my known contacts). All out.
The aftermarket Glyco here do not come in the different classes like the originals, only the one standard size.

Not happy no but they are still within factory specs.