My Alfa Romeo 33 rebuild - FIRST TIMER

[Urbancamo]

Seems that all older italian engines do have pretty low oil pressure on lower rpms. But that doesn't mean lubrication isn't adequate. No need for high oil pressure when idling.

I have 0.5 bar oil pressure when engine is hot on my rebuilded engine. All clearances in spec. Of course it rises to 4.5 bar when flooring it, and oil pressure relief valve opens at 5 bar.

[Brit01]

Very true.

Not so critical when idling. AR recommend min 15 psi when idling so just a little more would make me feel comfortable.

The used cam box I received from UK is in very good condition. These good unworn tappet bores can raise the pressure a little. It did with the right cam box when I changed it some months ago.

[Brit01]

I had a tough weekend confronted by some complications trying to prepare the car to drop the engine.

First issue was the exhaust manifold and trailing pipes.
The rubber supports were extremely tricky to remove and the middle joint where the manifold joins the mid section would not pull apart.
The whole system would not pull out from the back or front due to the angles at the back.
So it will be tight squeeze but sliding the exhaust to the far left side will enable me to drop the engine.

Second issue was that one of the allen bolts that connects the drive shaft to the gear box was totally rounded inside. Obviously done by the previous owner/mechanic and just left in the bad state.

After some thinking and discussions I decided to cut the head of the bolt.
Once the head was off the remaining part of the bolt came out very easily by hand luckily.
I just need to source a new allen bolt with the same characteristics now.

Chris

[WhizzMan]

This sounds like a horror story to me. I can just walk to my cupboard and pull out a plastic jar of those allen bolts (used, but I keep the good ones). They're 10.9 steel, fine metric thread and have nylocs on the other side, so be careful what you get as a replacement.

If your oil pressure is low at idle, it's most often the big end bearings or the cam support on these boxers. I personally don't feel happy when a boxer that's on a normal temperature drops below 15 psi. I'd rather see double that, which is not uncommon at all for a healthy Alfa boxer engine. You may not directly damage bearings, but it's not good for them at all.

[Brit01]

The bolts are M8 x 1.25. There is a specialist here that can supply one of these bolts with the same specs or better. Not sure if they are 10.9 steel whizzman. Are you sure?
The hack saw cut through it rather easily to be 10.9 to be honest.

New main bearings lined up.
Another new cam box ready for the other side (almost unused - sourced from the UK).

There are no nylocs on the Alfa romeo 33 drive shafts.

Yes you are right about the low idling pressure. I'm not happy about it either.
But at least the pressure rises very quickly with a blip on the throttle.
If after the rebuild and the pressure is better(within specs) but not very good I may switch to 20W/60 oil.

I also have a new pressure release valve for the pump. I will be double checking the oil pump clearances.

No horror story here please. Lets call it a challenge and a learning experience for me.

[Brit01]

Possible source found for original driveshaft bolts. Better of course.

He's also going to send the second cam box as I was inspecting the one he has already sent me and it's almost new. You could eat your breakfast of it and the internal surfaces are in pristine condition, just one single tiny scratch or sign of wear on them.
Gold mine as he put it. He found 5 boxers in superb condition like this.

[Guy Croft]

All black (socket head) capscrews (allen bolts as you call them) are 12.9 grade and in that applicatio should be too. Very ahrd indeed to cut!

That is a bolt industry protocol.

Plated ones will be 8 grade max because it is risky to plate at higher grades due to hydrogen embrittlement.

G

[Brit01]

Thanks Guy.

Then original ones it will be then. Worth the wait to be shipped from the UK along with the second cam box.
Certainly don't want a drive shaft splitting with my son in the car.

It did take maybe 30 minutes or so to cut through the head with a very sharp hack saw (with rests in between as I was working upside down in a tight space!).


Regards

Chris

[Urbancamo]

This might seem very odd question, maybe semi-stupid, but without knowing your country, there isn't even bolt shops in the next corner? Of course fine-threaded 12.9 bolts are little bit harder to find.

Of course i order some special hardware in UK too, lastly 50 mm long 3/8 UNC studs wich definately are not available in my country. Of course i would be able to do them in lathe from long 3/8 UNC bolts which i can buy my local bolt shop, but i'm lazy whenever finished product are available.

[Brit01]

This might seem very odd question, maybe semi-stupid, but without knowing your country, there isn't even bolt shops in the next corner? Of course fine-threaded 12.9 bolts are little bit harder to find.

Yes, and not a stupid question, but you never know the quality here, they say one thing and the quality is inferior. Always a risk. They make them locally.

Peter my supplier owes me money anyway so better to come from him with the originals.



Regards

Chris

[timinator]

[quote="Brit01"]

But still on the low side when idling just 10 psi at 850 rpm.

I hope the new cam box and new main bearings will fix this.
Should be about 15 psi when idling.


Hi Chris, Any chance your tach is not accurate and the engine is not at 850rpm. If all you want is 15psi why not just speed up the idle until you get 15psi? If nothing else the car will leave off the line with less effort.

Tim

[Brit01]

Very true Tim. I'd like to see 20 psi at 850.

Let's see the results with the new cam boxes and new main bearings first with the same oil pressure gauge (new from OrlanRober) and at 850 rpm. Tachometro is original Alfa! Could be off but just a little.
If not then raising it to 950 rpm won't do much harm when idling to bump it up a touch.

Or a thicker oil - 60 viscosity maybe.

But wait until the main bearings have been inspected and changed along with cam boxes.

Thanks

Chris

[WhizzMan]

I'll have a look at what it says on the bolts I have then. 12.9 is also possible I guess. On the 33 there is no nylock? Do they screw into the flange directly then? That could very well be, I don't do 33s that much, mostly the more modern stuff.

The minimal pressure that Alfa themselves want isn't what you'd expect from a "fresh" engine. It should be much more than 15 psi when idling, 15 is the absolute lower limit before the factory workshop manual recommends you need to stop driving it and take it apart to fix it.

[Brit01]

I'll have a look at what it says on the bolts I have then. 12.9 is also possible I guess. On the 33 there is no nylock? Do they screw into the flange directly then? That could very well be, I don't do 33s that much, mostly the more modern stuff.

The minimal pressure that Alfa themselves want isn't what you'd expect from a "fresh" engine. It should be much more than 15 psi when idling, 15 is the absolute lower limit before the factory workshop manual recommends you need to stop driving it and take it apart to fix it.

Yes the bolts screw directly into the inner flange thread. Would have been a better idea to add bolts with nyloc nuts on the end for sure. Peace of mind. But that's an old Alfa for you.

The car is on it's stands ready for the engine to be dropped. Off the road.
One thing to note is that the idling pressure level is normally taken from the outlet next to the oil filter but I have the tube taken from the main oil channel that feeds the crank and splits to the cam supports also.

I've been told the idle pressure will be higher if taken from the oil filter location where the low warning sensor is also located.
I have an adapter I need to modify and will be taking the reading from there after the rebuild.

[TomLouwrier]

I've been told the idle pressure will be higher if taken from the oil filter location where the low warning sensor is also located.

Excuse me?
Of course you'll get different readings from different locations. The filter alone accounts for a drop in pressure, especially noticeable at idle.
However that doesn't change a single thing on the actual situation within your engine.

Oil pressure in itself is not much of a goal, it's an indication of how well the oil pump can feed the bearings. (Otherwise just put in the thickest you can get, you'll have high pressure but way too little flow into the smaller gaps...)
Considering that Alfa probably did their homework when developing this engine, the oil pressure *given in the manual, taken at the indicated location* will be representative of the lubrication system's functioning. The absolute value might be 15, 45, whatever. Different location, different value. Can't be compared just like that.

What's the goal here? Healthy machine or nice looking figures on the dashboard instruments?

regards
Tom