Race Engine Forum UK

Healthy machine or nice looking figures on the dashboard instruments?

A rhetorical question Tom I assume. Just one answer to that as we all know.

The Alfa manual doesn't actually specify in which location the oil pressure should be taken from but I imagine at the filter where the low pressure sensor is positioned.

I need to modify an adapter I have to position it here after the rebuild. Previously it was placed on the main channel outlet which is just after the filter.

As you saw from my previous posts the pressure is good above 1000 rpm.

Considering that Alfa probably did their homework

It's funny you should say this as Alfa didn't do all of their homework. Quality did suffer a little when they moved their original factory and lost some of their experienced staff.

Among the Alfa community we have made some improvements/modifications to our later models that Alfa apparently overlooked. Mainly electrical and cooling.
Some design issues/flaws are evident with the gearbox(1st and 2nd gear) and also lubrication to pistons 1 and 3. They improved this in 1989/1990 by adding oil spray jets on that side.

Also the alternator exciter. When they changed from Marelli to Bosch they didn't take into consideration the different resistance needed to initiate the charging of the alternator.
The dash light has a 1.2 watt bulb which worked fine with the Marelli but with the Bosch you had to rev the engine for the warning light to turn off to start charging.
Simple solution was to add another 1.2 watt bulb in parallel with the original one behind the dash.
Now on cold start ups you don't need to rev. The alternator starts charging immediately.


wink

New CV outer boot required!

Found a rip in the rubber CV outer boot with some grease leaking around the edge. Not good.
Just purchased a new one.

Dispatched after 6 minutes of ordering. Very swift service.

Hi Chris, There was one mention of new oil pump gears in your early posts. Did you measure the clearance between the gears and pump housing? Desired oil pump running clearance is usually .002-.0025 in. It is not unusual to see .004-.006 in. in factory pumps. Proper fit may address your low idle pressure.

It has been my experience that immediately after a race the engine oil pressure at idle will be 5-10 psi whether I run 30wt or 50wt. After a short period of cool down the pressure goes back to 30psi. I run 30wt for the common list of reasons. Under race conditions max oil pressure is set to 65psi. It takes about 2 hours to modify the oil pump to achieve these results.

Tim

Hi Tim,

Yes the new pump gears were at their min clearance. Very tight.
I'm not worried about the new pump unless during break in something nasty happened and a pitting occurred. I will see hopefully this weekend if the engine drops as planned.

I did read that helical gears tend to pump less at idle and straight gears a bit more. Is this true?
Do the race engines tend to have straight gears?

One thing that was not changed at that time was the oil pressure relief valve (it works fine opening at 87 psi). But could it be leaking slightly when hot - seeping through?.

I do have a new one to fit and I will check the fitting carefully.

Hi Chris, Straight cut or generated rotor type are the only pumps I have experience with. Don't know if helical gears have any low pressure problems. Hard to believe a manufacture would select a pump that would not produce sufficient oil pressure at idle. The OEM's number one goal is to get the vehicle past the warranty period.

It is possible that the pressure relief valve could leak, but not likely.The common problem would be the valve sticking open. With high demand oil systems the pressure relief spring is a high spring rate type that would tend to slam the valve back against it's seat. That being said it does not mean you should not investigate further. Hope our tear down leads to an easy fix.

Tim

hi Chris,

Of course it was a bit of a rhetorical question, my point being that it's no use upping your readings by choosing another location for your sensor. That won't change the actual pressures in your engine of course.

I found some Alfa documentation online, all 33 and/or boxer related, and it states that oil pressure must be checked by unscrewing the electric sender (pressure contact as they call it) from the block, then screw a hose for a manometer in there and fire up the engine. This hole would be located in the main oil gallery, so well after the filter.

Not saying that Alfa always got everything right (oh no!), or did not need to improve their products over time (oh yes!). All products evolve over time. You may look at your car as "Alfa 33 v2.1.6" as you would expect software to be labelled according to version and patch level.
Still I do think that when those guys documented their stuff, they were not quite amateurs. Pressure is bound to the location you measure it. The main oil gallery would be a logical choice, but not always the one that is used (packaging and production reasons for instance). As long as it's representative of what's going on in there it's OK.

Don't know what manuals you have available, but I'll be happy to help with what I have if you pm me.


regards
Tom

Of course it was a bit of a rhetorical question, my point being that it's no use upping your readings by choosing another location for your sensor. That won't change the actual pressures in your engine of course.

I found some Alfa documentation online, all 33 and/or boxer related, and it states that oil pressure must be checked by unscrewing the electric sender

The electric sensor is located at the oil filter (on the outlet) on the boxer (factory location) so I guess it's at this location and not on the main channel plug in the middle of the block.



Thanks for the offer of manuals Tom.

I have most I think. Haynes and all Alfa models from the 33 forum links.

Almost ready to drop the engine. All disconnected, just remaining the front cross member.

Later today once the sun drops a little. Bit hot at the moment.

Guess we're both right: the text says 'crankcase main channel', the picture on the next page indicates the sensor right next to the filter and the dip stick.

Some photos of todays work. Also got the heads off.

Hi Chris,

While you are taking pictures can you get a well lighted picture of the ground wire on your spark plugs and down on the porcelain. Also into the exhaust manifolds from the flange side. Well lighted as in bright. Thanks.

Tim

While you are taking pictures can you get a well lighted picture of the ground wire on your spark plugs and down on the porcelain. Also into the exhaust manifolds from the flange side.

Sure Tim. What's the purpose of your photo request?

But the ground wire inside the rubber cap you mean? That will be tricky as the rubber tubing is very narrow which slides over the plugs.

Hi Chris,

A better description would be ground electrode or side electrode. Just lazy of me to call it a ground wire. Just looking for indicators of your engine tune. Coloring of the ground electrode indicates timing needs and proper heat range of plug. Porcelain coloring can show weak ignition, oil migration, improper plug seal, over heating and the other more destructive events. Exhaust tubes can indicate rich or lean. Always worth a look.

Tim

Sorry Tim, plugs been cleaned already but I can tell you that the porcelain part on all plugs is perfect. All white and no discolouration. I'm back in the city working now so can't take any photos until next weekend at the earliest.

3 plugs were a good colour, 4th a little rich.

Rods are now in the workshop to have the new small ends pressed and honed to fit the new gudgeon pins.

Old small ends had obviously been changed before and with non-original ones with no cross pattern oil channel (OE and Glyco have this cross oil channel) which didn't impress me.

Regards

Chris

Tom: photo of 2 locations of oil outlets.

hi Chris,

Good progress, and nice to finally see the bloke as well as the block...

I'd already been wondering about that brass thingy on top of the crankcase. I'm sure you'll find that both points you marked are actually the ends of one and the same oil channel, so hook up your manometer to whatever suits you best. Mystery solved.

How did those small ends turn out? Did you measure them before replacing, just out of interest? Any play you could feel apart from the sliding motion of the pin?
How are your pins?

regards
Tom

Yes the man himself appears with his Italian boxer in the photo.

Thanks Tom.

2 of the small ends has a very small amount of play I believe. Not too easy to detect when they want to slide from side to side. But I guess any amount of play you can feel is too much.
But they all had signs of wear on the surface in the middle of the pins even after cleaning well with kerosene and wiping dry.
I haven't measured them as I believe the cheapish digital caliper measuring device I have is not accurate enough and does not have enough decimal places.
Some things I need to add to my Christmas gift lists!

Some of the ends of the pins had some light scouring, maybe due to the old circlips badly placed or slightly bent.
I have a pack of new 8 circlips.

Anyway all are being replaced.

Also evident were some yellow/yellow-orange deposits on a couple of the pistons.
Haven't seen this before on previous head removals.

Possible causes?
- too low an octane fuel used or fuel with too much alcohol used
- jetting too lean or failure of the fuel system, i.e., clogged fuel line or filter, fuel tank not venting, problem with fuel pump, carburettor air leak into crankcase
- spark plug heat range too hot
- ignition timing too far advanced
- restricted exhaust system: back pressure too high
- overheated, loosely-installed spark plug

I am suspecting lack of fuel causing lean mixture/clogged filter as I found a hidden fuel filter in an unlikely location I never knew of. A cheap plastic type filter at the back of the tank where the flexible hose joins the underside solid piping. Nicely hidden!
The last few weeks I had issues starting and had to prime the carbs 4 times.
The fine filter on this car is meant to be between the carb and output of the pump, which is where I have mine and change it frequently.
the previous owner must have put this other filter there 3 years ago!! So 3 years unchanged and probably very clogged.