My Alfa Romeo 33 rebuild - FIRST TIMER

[Brit01]

Comparing the new and old floats I see a difference in how the holder/clamp was adjusted.

The new ones close much sooner than reaching the top 6mm height due to the small metal clamp. (I blew through it comparing the 2).

I believe the new floats are filling the carb chamber up much less than the previous floats.

Well I adjusted them so they matched the old floats as they were running fine.

[Guy Croft]

You don't have a compression problem!

What you need now is attention to ignition (maybe) and fuelling.

G

[Brit01]

Great that's what I thought with 180 psi on new rings that haven't been broken in fully yet.

Thanks Guy.

I have the floats and jets removed and inspecting all lines/filters/passages etc.


I also have a new cap/rotor being shipped from UK on Monday. That will take some weeks to arrive but at least it will be original German Bosch and not the Brazilian poor they sell here.

The contacts on my old cap are somewhat worn, this can cause misfires.

I was told that backfire is normal as boxer engine has long overlap duration ( both valves simultaneously open) which creates fuel ignition on the exhaust. Depending on carb settings the backfire can be small or big....

[Brit01]

Well all running smoothly now.

Will take it out for a good run this week.

The fault was such a silly assembly mistake of one of the carbs that I'm too ashamed to say what it was!

[Brit01]

30 km drive to work and all fine.

Drove in light and slightly heavier bursts of acceleration in 2/3rd gear watching the temp. and listening for noises.

It was unavoidable to use 4th gear sometimes due to the traffic.

Arrived at work in one piece. Will give the engine a good check over at lunchtime.

Just to check is it normal for the oil to have a slightly grey colour maybe due to all the molykote paste I used on the bearings and cams?

(just keeping an eye on the level of coolant to make sure non is leaking through the head gasket) this would be a mayonnaise colour no?
Went down slightly initially but due to bubbles and filling up the heating system. The 33 has a self release valve for the bubbles to escape.

[Guy Croft]

the cam paste will DEFINITELY discolor the oil, don't panic!

G

[Brit01]

the cam paste will DEFINITELY discolor the oil, don't panic!

Thanks Guy. That's what I was assuming (hoping!).

I'll do an oil/filter change next weekend after 120kms, 2 round runs to work. Approx 2 hours of driving.

Probably take the oil sump off and just double check triple check the torque of the conrod bolts (bit paranoid about those), also a good opportunity to clean out the sump really well and check for any bits that shouldn't be there.

A real pain to get the sump back on though due to 5 bolts that require mini fingers to access.

[Guy Croft]

I wouldn't worry about the rods, you would have 'thrown' one by now if they weren't torqued-up right.

G

[Brit01]

ok thanks Guy.

Had nightmares about them after hearing horrific stories of rods flying through the steel blocks getting wedged in roofs and walls due to lose bolts!!


Lol

[Guy Croft]

yes I know what you mean.

You (and all readers) should get into the habit of photographing things as_you_go. Tighten and then check-tighten and paint mark one out of the set. Then when you wake up at night you can look at your pics and rest easy.

Oooh - maybe you set the torque wrench wrong or on Nm instead of lbf ft... yes these things haunt most engine builders(those with imagination anyway)

But seriously it is vital NEVER to work instinctively on engines. One must always concentrate 100%. Keep you wits about you.

And if you do you can reassure yourself, 'I know they are right because I always double-check..'.

G

[Brit01]

Oooh - maybe you set the torque wrench wrong or on Nm instead of lbf ft..

ah yes I had that same thought and almost did it once especially when working at night under limited light and when you are tired after a days work!

Also the conrod bolts on the boxer are a little more difficult to access as they are always at an angle due to the flat four configuration.
Alfa manual also says to oil/lubricate ONLY the head bolts when torquing and not the conrod bolts. I followed this recommendation.

The bolts on your picture are perfectly vertical and easier to work with IMHO.


Many thanks for all your assistance.

I will take some final photos and videos soon.

[Brit01]

Beautiful spring day today and went out to the parking lot to finely tune the carbs with my vacuum gauges in the sunshine before I return home later.

Just a touch out and now nicely balanced (will continue to revise them during the week as I accumulate more kms), revs very quick up to 5000 rpm with a blip on the throttle and produces the distinctive Alfa raspy tone.
Set at 1050 or so idle rpm for now, will reduce that a little once it has some more kms on it.

Then pops/crackles when you release quickly.
This is a characteristic of the Alfa flat four boxer.

[Brit01]

Think I will do the first oil change tomorrow at lunchtime as there is a garage across the road who can do it free with the oil purchased there. Instead of getting my hands dirty in a dark dirty garage at home.

The car will have 100 kms on it by tomorrow lunchtime.

Sounds ok?

[Brit01]

some snap shots

[Guy Croft]

Looking good, well done for being careful with everything.

"Then pops/crackles when you release quickly. This is a characteristic of the Alfa flat four boxer"

On the over-run, yes. It may well be characteristic - but it is also symptomatic of the idle mixture jets being set on the lean side. You need to set them borderline rich. A Colortune from Gunson is the best way to set by far (see links and also my YouTube channel gc1438)

G