My Alfa Romeo 33 rebuild - FIRST TIMER

[Brit01]

Compression Test just performed and not too happy with the results.

Piston 4:

dry= 180
wet= 200 (possible worn cylinder bore with 20 psi difference?)

Piston 2:

dry= 180
wet= 190

Piston 1:

dry= 190
wet= 200

Piston 3:

dry= 190
wet= 200


I'm planning to drop the engine and box in December (4 week holiday).
small ends and pins being changed
new original main bearings ready to change after using plastigauge on old and new.
Total thorough cleaning of crank case and oil channels.

My question is:

If I was to de-glaze the bores again with flex-hone do the pistons need new rings again or can I use the existing ones with 1000 kms on them?

I was expecting 200 psi after break in but 180 is kind of disappointing. either mineral oil should have been used instead of semi or the cylinders are just slightly worn.

I will measure the gap with the ring down the cylinder and also the gap between the piston and cylinder walls.

thanks Chris

[Urbancamo]

In my opinion those are great numbers! Numbers you'll see on just builded engines. Nothing to worry about. Of course numbers depend highly on camshaft duration = more duration, lower numbers.

I've never worried about absolute numbers. Only differences. 10-15% difference between cylinders is totally acceptable and normal. Of course if some cylinder is in 100-120 psi range and others much higher, something is wrong.

My old engine had approx. 150-160 psi (very low-duration cam) on 150 000 km mark, consumed only 1 litre of oil per 10 000 km and produced, as seen on my topic, more power than stock!

[Brit01]

Thanks urbancamo.
Good to know.

I guess I was hoping to get nearer GC compressions rates of 210 psi. Think I need a few more years of experience for that.

One think I noticed yesterday while listening carefully during warm up is that one valve on piston 3 was spitting back a little every 5-6 seconds or so as if the valve was not closing fully every now and then.
(just checked the plug and it's a little too black, the others are fine. I leaned the idle mixture out a little now)

I'm out in our country house so it's all nice and quiet to listen to the engine well (back in the city of Montevideo it's impossible to find anywhere that is dead quiet).
This is where I'll be dropping the engine and box in Dec. Lots of space, workbench etc.

Chris

[Brit01]

My poor Alfa.

stuck for 4 hours in a 65 km traffic jam last night! clutch/1st/clutch all the way!
many steaming cars on the grass banks.

It doesn't like that kind of driving at all.

[Brit01]

I'd like to do a check myself of the valve stems, and general cleaning of the ports etc.

Now I need to source a valve spring compressor.
not much choice here.

Found a couple online and not sure if either are suitable for my heads.

What are your thoughts? One is cheapish, the other not.

[Brit01]

Correction:

I believe I need this type for my heads but not sure if I can can one economically here:

[WhizzMan]

You just had your heads done, you have no oil consumption problems that you've mentioned of and now you want to take it apart? I'd leave it in place. Fix the small end bearings, measure bearing play on the other bearings, maybe swap out the cam support if it has worn tappet holes and bolt it back together again. Most likely, all that you'll be doing with taking the heads further apart is create extra work and risk for yourself, there is nothing to gain with taking them apart, is there?

Compression test figures of 210psi don't mean a thing if you don't know what the exact engine setup is. It could have high static compression, cams with little or no overlap, non aggressive timing, any combination of a lot of factors will give different figures. You should know what is the factory number for a new engine of your exact type and you shouldn't be more than 10% off between individual cylinders. Once you're over 25% off from factory new on all four cylinders, you should start asking yourself if you may have a problem with wear. This is a road car, built on a budget and it's compression figures are better than most new engines that leave car factories today. If you fix the small end bearings and the cam support, most likely, it will perform perfectly for many years without a problem.

[Brit01]

Most likely, all that you'll be doing with taking the heads further apart is create extra work and risk for yourself, there is nothing to gain with taking them apart, is there?

Well I was hoping to do this for practice, also to smooth out the ports a little as the Alfa moldings are terrible with lumps on them, and I enjoy it thoroughly. Therapy and relaxing for me.

wink.

Probably leave them as they are as the tools here are just too expensive.

Buy as you mentioned I'll be checking all the main bearings with plastigauge and replacing them.
Also changing the other cam support.

Just a point of interest:

The original main bearings from Alfa came with no middle oil groove whereas the aftermarket ones from FM or Glyco seem to have the oil groove.

[WhizzMan]

Well I was hoping to do this for practice, also to smooth out the ports a little as the Alfa moldings are terrible with lumps on them, and I enjoy it thoroughly. Therapy and relaxing for me.

You can never get enough practice, but I'd do that on something you don't have to drive home, or something that actually needs repair. Also, from what I understood earlier, the heads were already worked on? If that is the case, there wouldn't be much left to do yourself if your tuner did even a half decent job on them.

[Brit01]

Also, from what I understood earlier, the heads were already worked on? If that is the case, there wouldn't be much left to do yourself if your tuner did even a half decent job on them.

yes true. Shame spare heads are not so cheap here as in the UK. Would love some old engines to play with but that cannot be the case here. cry.


Now I have another problem!!

Received my gudgeon pins/circlips today just in time for Dec.

Unfortunately 3 of them measure 61mm in length and the 4th 63mm!!!
Can't believe it. The seller has made a booboo I think.

So maybe the 3 are for a 1.5 piston I'm suspecting. Trying to find out the specific lengths as I don't know. Of course I've contacted the seller and waiting for a reply.

In the worst case scenario and the 3 shorter pins are for a 1.5 piston, I will use the good one on the worst piston 3 and fit all the new small ends to the other older pins also.
The small ends always needs honing anyway to fit the pins so I should get a tight fit on the older pins with less wear.
In most cases the small ends wear before the pins I understand.

Very frustrating though as they travelled 7000 miles over 2 weeks!

[Brit01]

Alfa Romeo from Argentina kindly confirmed the correct pin length for the 1.7 pistons are 61mm.

So I have 3 correct pins and 1 of 63mm, this appears to have a thinner side wall also.

The seller will need to refund my money for the 4th pin. I don't think he has any more gudgeon pins.

So I have 2 choices.

To buy an expensive 4th new pin from Argentina or re-use one of the least worn pins from my engine.

I will be fitting new small ends all round and having them honed/reamed to fit the pins anyway so maybe i can get away with using one of the older pins that has least signs of wear.

We'll see.

[TomLouwrier]

hi Chris,

There is a very slight chance that one of your current pins is still fit for duty, but given the rattling small ends you have now don't hold your breath.
Of course any wear on the pin will not be evenly spread along its length, but it will be in the middle where the pin sits in the rod. So if you hone the small end large enough for the end of the pin to slide in, the middle will be happily rattling away just like it was before.

Since you are wisely choosing to replace your pins, why not try to get a mate from the UK or from here to send you the missing one?

regards
Tom

[Brit01]

Of course any wear on the pin will not be evenly spread along its length, but it will be in the middle where the pin sits in the rod. So if you hone the small end large enough for the end of the pin to slide in, the middle will be happily rattling away just like it was before.

Good point Tom. Thanks.


Just waiting to see if the seller has a 4th pin. I have a friend travelling down here on the 27th luckily. (mind you it looks like a gun barrel section! Hope no issues happen at check-in!!)

If not then Argentina have them in stock but at 40 USD plus shipping!!

Regards,

Chris

[Brit01]

Driving back 120 kms on the highway last night everything running smooth, cool etc.

Then we hit a huge thunder storm and the rain came down so fast, flooded the highway almost, car almost water planing.

I didn't have my cambelt covers on!!

Something happened after that. The car lost some power, and the engine was running hotter, not too hot but about 3-4 degree hotter and when stopping and starting in the city on my return it was definitely heating up faster.

I will check the belts tonight. I'm suspecting it could have slipped a tooth with the water coming in and the timing is off hence the heat and loss of power. It can slip one tooth without the valves hitting the pistons but no more.

Or maybe water got in to the air box and wet the air filter.

I will do several checks tonight.

[Brit01]

After some checks I have concluded the reduced performance and somewhat elevated temperature (and a smell of gases through the air vents) were due to a build up of crankcase gases caused by a slightly blocked filter.

I will be testing the car tomorrow and return the vacuum pipe to it's strongest pick up point - the air intakes to oil filler pipe. To make sure all gases are sucked out of the crankcase and burnt up in the cylinder.

A catch tank would be great but not sure if these incorporate a vacuum attachment to 'suck' the gases out with force.

p.s 4th correct new gudgeon pin is on its way from UK. Should have it in hand next week.