My Alfa Romeo 33 rebuild - FIRST TIMER

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Brit01
Posts: 825
Joined: June 28th, 2011, 4:54 pm
Location: Uruguay

Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Brit01 » August 21st, 2013, 7:52 pm

Well I am glad I changed the oil pump last weekend as I found the old one had a couple of mm's vertical movement on the shaft (the first gear is pressed onto this).
The new one has no play whatsoever and is in.

15w50 gone in and pressure very good. Still got the low OP at hot idle though.
I was informed that in the alfasud manual it states that the OP can be as low as 5 psi at hot idle without issues!
As you have mentioned it is not under load at idle.
The pressure shoots up rapidly once revs increase.

Hot oil after 30 mins of hard motorway driving:

40 psi @ 2200 rpm
50 psi @ 3200 rpm
60 psi @ 4000+

Regards

CD

timinator
Posts: 116
Joined: March 9th, 2011, 5:20 pm

Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by timinator » August 22nd, 2013, 4:43 pm

Brit01 wrote:Wideband up and running.
Mains circuit on the lean side dipping to 15.2 on occasion such as climbing up hills on the motorway at high speeds.
Idle circuit good on the rich side just a little.
Hi Chris, Keep in mind the best way to judge how your engine is running is by looking at the spark plugs. Wide band o2 sensors are not all created equal. Lab grade o2 sensors are about $500 US as opposed to the $100- 120 sensors found in alot of the kits offered. Big range in accuracy goes along with the price. With one sensor you are only taking an average of what the individual cylinders are doing. So it is best a little richer rather than leaner. If you want to explore tuning to the extreme invest in data logging equipment so you have a record of what is going on instead of trying to look at gauges and meters while you are driving. I will not discuss the how to's, that is to long a discussion. Just be safe.

Tim

Brit01
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Joined: June 28th, 2011, 4:54 pm
Location: Uruguay

Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Brit01 » August 22nd, 2013, 5:32 pm

timinator wrote:
Brit01 wrote:Wideband up and running.
Mains circuit on the lean side dipping to 15.2 on occasion such as climbing up hills on the motorway at high speeds.
Idle circuit good on the rich side just a little.
Hi Chris, Keep in mind the best way to judge how your engine is running is by looking at the spark plugs. Wide band o2 sensors are not all created equal. Lab grade o2 sensors are about $500 US as opposed to the $100- 120 sensors found in alot of the kits offered. Big range in accuracy goes along with the price. With one sensor you are only taking an average of what the individual cylinders are doing. So it is best a little richer rather than leaner. If you want to explore tuning to the extreme invest in data logging equipment so you have a record of what is going on instead of trying to look at gauges and meters while you are driving. I will not discuss the how to's, that is to long a discussion. Just be safe.

Tim
Thanks Tim.
I understand. This is just a Bosch LSU4.9 sensor. Just looking for approx values more of a hobby than anything professionally accurate.
I did feel a tad less power on the stock mains (142) when it was showing 14.5 -15.2.
I had larger mains in previous to the installation of the new sensor. I want to give them a try again and see the readings. It had more oomph in 4th and 5th on the motorway.

Brit01
Posts: 825
Joined: June 28th, 2011, 4:54 pm
Location: Uruguay

Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Brit01 » August 23rd, 2013, 8:57 pm

Larger mains went im today and it felt better.
Bit smoother and a tad more power when accelerating in 4th and 5th.

Do need to tune down the pump jets a little though. Maybe a turn or two out.

Regards
Chris

Brit01
Posts: 825
Joined: June 28th, 2011, 4:54 pm
Location: Uruguay

Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Brit01 » August 24th, 2013, 12:58 pm

Another drive last night and much better drive ability with 150 mains.
Smooth progression and a nice power curve.
Maybe related with the ethanol fuel here also.

Great!

Urbancamo
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Location: Finland
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Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Urbancamo » August 24th, 2013, 5:13 pm

Getting close there Chris!

I really appreciate when blokes are tuning their carburettor engines "in depth" in 2013 when everybody are planning to use somekind of FI system because they believe it's the "easy way".
I always admire how fantastically engineered and simple some well known carburettors are even their design is half a century old. Especially Weber/Dellorto sidedrafts. You wouldn't believe how good drivability such a simple mechanical thing can produce. It isn't an easy task to get this level with fuel injection. I have seen it many times.

It doesn't take long when almost all carburettor specialists are gone forever. They are almost gone even today in my country. Some are allready passed away, some are retired. Younger generations are not interested at all when it comes to old school technology. Sad but true.

T
GC_25

Brit01
Posts: 825
Joined: June 28th, 2011, 4:54 pm
Location: Uruguay

Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Brit01 » August 26th, 2013, 8:14 pm

Urbancamo wrote:Getting close there Chris!

I really appreciate when blokes are tuning their carburettor engines "in depth" in 2013 when everybody are planning to use somekind of FI system because they believe it's the "easy way".
I always admire how fantastically engineered and simple some well known carburettors are even their design is half a century old. Especially Weber/Dellorto sidedrafts. You wouldn't believe how good drivability such a simple mechanical thing can produce. It isn't an easy task to get this level with fuel injection. I have seen it many times.

It doesn't take long when almost all carburettor specialists are gone forever. They are almost gone even today in my country. Some are allready passed away, some are retired. Younger generations are not interested at all when it comes to old school technology. Sad but true.

T
Thank you for your kudos. You are right that this is a dying art. it is a shame. The boxer is rather a tricky one to work on also due to its susceptibility to become unevenly balanced.

This goes for the distributor remapping also as you may know I've just had a unit worked on by H&H. Not in my hands yet but looking forward to using it. My maximum total advance has been crudely reduced by squeezing some hard tubing over the stops for the centrifugal weights and putting in a stiffer spring. This has stopped the detonation but most likely is far from ideal and I have lost power. But at least I have put an end to the issue I was having with detonation at 3500 rpm. I can rev happily now all I want.


Isn't it fun to work with carbs and collect sets of different jets etc?
I don't have access to rolling roads here so all is done by feel, trial and error.(and a lot of patience and time)
All the manuals say 142 mains, even Dellorto UK didn't recommend mains bigger than 142.
Dellorto UK suggested larger idle jets as big as 60.
I tried 55's and 60's - too big, very rich! The 55's were too big. Black soot coming out of the tailpipe!!
Settled on 53's.

I enlarged the mains from 142 - 145 - then have settled on 150's. I guess every engine and scenario is unique.
Even with the mains being this big the AFR still peaked at ~15.0 but picked up much better and felt overall smoother.

Regards

C

Brit01
Posts: 825
Joined: June 28th, 2011, 4:54 pm
Location: Uruguay

Re: My Alfa Romeo 33 rebuild - FIRST TIMER

Post by Brit01 » September 18th, 2013, 5:50 pm

Strange event happened this week.

What i thought was a blocked jet turned out to be loss of compression on cylinder #2.
Limped it along to my local mechanic. He was almost ready to remove the head as we suspected a burnt exhaust valve.

Then all of a sudden the compression returned and it was firing perfectly with good compression!
Bit of carbon stuck on the valve seat??

There were no other noises such as a valve ticking.

Anyway while it is in the garage the water pump and tensioners/belts are being changed. Old water pump had a plastic impeller and I have no history of when it was changed. Looked pretty old!
One of the tensioners began to make a grinding sound so new ones are being installed.
New gaitor on drive shaft also as one split!

Brake service next week as he has a rally on Friday so he closes up shop. He was prepping his car while I was inspecting their progress on my old thing.

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