My Alfa Romeo 33 rebuild - FIRST TIMER

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Urbancamo
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Urbancamo »

You might have said it before, but Chris, what is your average winter temp?
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Brit01
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Brit01 »

You might have said it before, but Chris, what is your average winter temp?
Probably about 8-9 degrees, sometimes falling below freezing in the evenings.
TomLouwrier
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by TomLouwrier »

Chris, Tim,

Where I speak of thick and thin oil, I mean it in a fairly broad sense. Of course the oil will be pressed into those small holes eventually and even more so when hot.
But when the engine (rather: oil) is still fairly cold and thick, it can reach those places with not enough volume (feed rate), leading to starvation under load. Well, you shouldn't hammer a cold engine anyway.

Chris, It's not the pump pressure that forces the oil into the wedge, it supplies the bearing exactly on the opposite side where pressure is low. The real load bearing pressure is built up by the internal friction of the oil and the two moving parts on either side of the oil film. This pressure is much higher and will force a relatively thick oil through that small 0,05mm slot (the bearing play). I will look up some nice pages with pictures about this subject and either post here or mail them to you. No time to draw them myself now and no need because there are some very good sites on the subject already.

Keep in mind there is a big difference between 'running clearance' and 'production tolerance'. The first is designed into the bearings and has an important minimum value, the second one is the amount of inaccuracy that the part may have and still function. I will look up better words to describe this.
This also implies that you can not just say 'BMW's likely have narrow tolerances, so their oil must be good for my engine'. For all we know Alfa set up your boxer with wide clearances deliberately, taking oil viscosity, pump capacity (both pressure and volume), engine speed and bearing size all into account. BMW may have come up with another solution altogether.
Again: oil pressure alone is not very interesting. It is just a 'second hand indicator' of how well your pump can keep up with the demand in volume. Not a goal to achieve in itself.

But I think we're once more taking things a bit too far. As long as the oil you choose conforms to factory specs and you did not change bearing sizes and tolerances (we discussed those a while ago), then the engine will perform as designed. I'm sure Alfa specified oil for northern climates and more tropical regions so that's your reference.
And as Tim very pragmatically says: if it works for you, then fine. I agree.

regards
Tom
Last edited by TomLouwrier on June 14th, 2012, 7:36 am, edited 1 time in total.
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andy wright
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by andy wright »

Evening,
Carbs were Dell'orto's DHLA's 36's with 32 mm chokes. 55 idle jets worked a treat once the carbs were set up carefully. By that I mean that I used 4 vacuum gauges to balace each barrel with the bleed screw and then across the two to balance the 'draw on each pair. With some effort and time, the engine would tick over very smoothly at 900rpm and pick up cleanly on a very light throttle under load. Oh, almost forgot, I did experiment quite a lot with various springs in the distributor. As I recall, static timing was at 10 degrees with 38 degrees of total advance at 4000 rpm. That did need some modification to the distributor.
Andy
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WhizzMan
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by WhizzMan »

Chris, what temperatures do your winters get to as a maximum. Around 15 Celsius, maybe 10? So you're basically in between lightly freezing and a bit over 10 in cold season? Summers are 10-30 C or so? I think both will be good for 10W40 or 15W50 or anything in between those. If you get more extreme temperatures, I'd really go for 15W50 or something like 15 or 20W base in summer and 10W for winter. In general, how higher the second number, the more quality the base stock has and the more "extreme" additives that are in there to get the oil perform that extreme. It may be that the additives are not effective in your engine and maybe the ones that are effective for your engine are not in the more modern extreme oils, so study carefully what additives your engine is designed for and if the modern oils cater for that, or have a proper alternative for the ones that have been taken out.

For cold starts, look at the base stock number, the first number. That is what determines how fluid your oil will be in cold winter mornings when the battery has little capacity and has to move an engine with thick, cold oil in it. If you have a proper battery in and your engine still has trouble turning in extreme cold, you may want to consider a slightly thinner base oil, but be careful and check with te recommendations in the user manual of your car.

For winters, you may want to choose something slightly thinner than for summers in your climate, but you don't even really need to if your climate is what I was guessing in the top of the post. We get -5 or sometimes -10 in winter and sometimes 30C in the summer and driving with 10W40 all ear works out fine for me.

The stock 33 8V engine has no oil cooler and no fins on the oil pan. That can be an issue in summer and traffic jams. It won't kill your engine, but you may want to give the oil to cool down a bit before you do any hard acceleration, extended high rpm and or load after some traffic jam time. Also, your oil may "wear" quicker chemically, so don't keep it in the engine for over 10000 km or an entire year, but switch to "winter oil" once it's really cooling down and you don't really risk getting the oil that hot for a longer period.
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Urbancamo
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Urbancamo »

I have pretty much nothing to add here. No matter what the country or the forum is, oil conversations always have a bit of mystique on them and most of the things are real hard to understand if you are not oil expert.

In my country where winter could easily be -30 deg C and summers 20-30 deg C, very common viscosity is 5W-40 full synthetic. Works nine times out of ten and base oil doesn't need huge amount of additives. Same oil all year round.
Of course there are lots of newer cars with all kinds of regulations, and they need 5W-30 etc.

Do you folks know a car which had it's engine worn out if serviced reqularly? I haven't seen one yet. And 95% or more of cars do not have any kind of external oil coolers at all. So oil temp cannot be an issue in normal conditions where car manufacturer has designed these cars.

If you want too see places where oil quality really matters, check out heavy duty trucks wich haul a 40 ton cargo 24/7 with 100 000 - 150 000 km oil change interwalls or heavy duty industrial compressors which are size of an small apartment house or even more and produce pressures of 2000 bars 24/7. There are millions of applications like this. Compared to these, average car engine is pretty modest case what it comes to oil.
Of course all applications are different. but this is to give some pespective.
Last edited by Urbancamo on June 13th, 2012, 9:37 pm, edited 4 times in total.
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Brit01
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Brit01 »

Summers are 10-30 C or so?
Before I read and respond to the other kindly posted comments I'll tell you here that are summers are very hot at times.

33-40 in the shade and way more out in the sun on the tarmac. I measured 55 out in front of the car last summer. Getting stuck in the traffic with this heat begin sucked in is not pleasant.
Jan-Mar usually.

When that occurred I used 60 oil just to keep the idle pressure up a few psi. (and of course the cruising)
Carbs were Dell'orto's DHLA's 36's with 32 mm chokes. 55 idle jets worked a treat once the carbs were set up carefully. By that I mean that I used 4 vacuum gauges to balace each barrel with the bleed screw and then across the two to balance the 'draw on each pair. With some effort and time, the engine would tick over very smoothly at 900rpm and pick up cleanly on a very light throttle under load. Oh, almost forgot, I did experiment quite a lot with various springs in the distributor. As I recall, static timing was at 10 degrees with 38 degrees of total advance at 4000 rpm. That did need some modification to the distributor.
Andy
Thanks Andy, another confirmation that 55 idles work better with 32mm chokes on the Dellortos. Great
TomLouwrier
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by TomLouwrier »

Found the right words.
Running clearance is what the bearing should have by design
Tolerance is the deviation from ideal that is still permissible
Edited my previous posts accordingly.

Since we're now gradually shifting more towards ambient temperature: Chris, when the weather is that extreme, you're probably facing more than 'just' oil pressure loss due to running hot. You may consider a modification like louvres in your bonnet to get hot air out from the engine bay.
Also, since this a road going car and not a full racing engine, I myself would consider adding an oil-water heat exchanger. They do not add to the total cooling capacity of the engine as a system like a regular oil cooler does, but will help transferring heat from the oil to the water and from there to the radiator. You must have a good radiator up front with an electric fan for when you are stuck in traffic. You can plumb it in parallel to the interior heater (in the bypass circuit). Another effect of these is that they help the oil heat up sooner when you're running in the warm up phase.

regards
Tom
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timinator
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by timinator »

Hi Chris, Sorry guess I forgot to answer these questions.

What kind of oil pressures are you getting with a 30 viscosity oil when hot?

The target is 55-60 psi @ 220-230 F. I spend a lot of time getting the oil pump set up to do this. Also the entire oil circuit needs to be massaged to remove as many of the pressure losses caused by factory drilling of the passages. The oil return drains need to be reworked to get the oil back to the pan as quickly as possible.

So why the concern about a 1mm hole on the oil passage of a tappet?

Don't know. The hole is to supply the lifter with oil. If the lifter doesn't fill fast enough it will collapse.
Guy Croft
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Guy Croft »

Yo Chris

when you have 'digested' the oil thing - y'all going to try the engine with the new coil?!

G
Brit01
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Brit01 »

Sorry guys haven't had much time this week. Lots of overtime at work. Waking up this Sat not feeling the greatest.
What kind of oil pressures are you getting with a 30 viscosity oil when hot?

The target is 55-60 psi @ 220-230 F.
This target pressure is at what rpm? I can get 60 psi at about 4300 rpm then as we know it's not really a linear increase. Shoots up to 50 psi pretty quickly then gradually reaches 60 when pushed over 4000 rpm.

30 oil - no way. The min recommended for this Alfa is 10w/50. Tried a 40 once when the tappets were ticking like c.r.a.z.y, thought it may help to clean them out if they were dirty. Wasn't the case. This was before the rebuild.
Pressure dropped and probably just did more damage to the tappets.

when you have 'digested' the oil thing - y'all going to try the engine with the new coil?!
sorry you may have missed my posts Guy. New coil is in (still failing between 2-3000 rpm). Starts easier. Secondary coil measured almost 9K. Old one 5.5K!!! I woudl say the secondary coil was almost fried.
I will put the new oil in today and try to eliminate the flat spot with 55 idle jets.

The 10w/60 TWS has a HTHS value of 5.3 (on the thinner side of 60 oils - PAO/esther mix with about 1000 ppm of zinc). The Motul 20w/60 7.6 or so (very heavy) (double esther 100% also).
The engine should start nicely in winter with a 10w and warm up quicker for the misses.
Same thing applies to Weber IDF's too with long emulsion tube holders. Looking at the DRLA pictures, those trumpets might pass them just barely
Tried the new trumpets. Lots of room above the long emulsion tubes. Bigger/taller than they appear in the photo.
Brit01
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Brit01 »

Going to advance the timing a little tomorrow because even though the progression is somewhat better with the 55 idle jets it feels retarded, a little sluggish. It's at 8 now. Will try 9.

New oil in. Poured in nice and thin for winter start ups. Lets see how it copes. It primed extremely quickly even with the large Mann filter. The warning light flashed for a milisecond on the first start up. Very fast flow.
HTHS is quite a bit lower than the motul. 5.33 compared with 7.5. The motul is very heavy for winter here, too much.
timinator
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by timinator »

Hi Chris, I don't build Alfa sud engines. The difficulty with discussing oil system modifications with you is I don't know what basic short comings the engine has. I don't mind telling you what I prefer in regard to oil system parameters in the engines I build, but I can't tell you how to achieve them without having the engine in front of me. Along the way I have had engines that didn't work the way I expected. Taking the engine out of the vehicle and dis-assembling it several times did not seem like a particular hardship to me to solve the problem. Interesting to me is that most of the fixes I have used were not that expensive to achieve... unless you count the cost of my time as an expense. If your problem is solved with an oil change then that is one cheap fix. Enjoy it. Next topic?
Brit01
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Brit01 »

Ok back to the progression issues.

I put the 55 idles in but out on the test drive within seconds the rain came down.
100% humidity, raining and cold. Wasn't the best.

Smoother between 2-3000 rpm but when I accelerated hard this time it was nosediving (rich, not enough air getting in).

I'll need to take another test drive in dry weather. I can't imagine going from such a lean condition to nosediving with a change from 52 to 55 idles jets.
Brit01
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Brit01 »

Ok back to the progression issues.

I put the 55 idles in but out on the test drive within seconds the rain came down.
100% humidity, raining and cold. Wasn't the best.

Smoother between 2-3000 rpm but when I accelerated hard this time it was nosediving (rich, not enough air getting in).

I'll need to take another test drive in dry weather. I can't imagine going from such a lean condition to nosediving with a change from 52 to 55 idles jets.

Maybe even increasing the airflow by using the trumpets might be the solution. Only using small .33 pump jets!
Or maybe too much oil in the K&N panel filter reducing it's intake under WOT.
So many factors to think about with these carbs.
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