GTV - mystery problem

[poohbah]

I changed the plugs earlier today, straight after I changed the HT leads. Made no difference. It was when I changed them that I noticed No4 plug was black. I should add that the plugs were actually only changed a month before today as well - I changed em today on the off chance one of the new ones put in then was a dud. I also checked the gaps and made sure they were all 0.025 inch as per the manual.

And I just did the "darkness" check - no signs of sparking.

It's so bloody frustrating - I'm sure it is something relatively simple, if only I can find what the damn thing is!

[Beatle]

OK so it seems you have it narrowed to one cylinder.
Go back to basics.
Fuel:  As the Fetta has one throat per cyl it could be carby
Air:  Is that cylinder sucking air downstream of the carbs?
Spark:  You seem to have eliminated that (but could be a sucker punch...)
Compression:  Test

Check valve clearances to at least eliminate that.

[Neil Choi]

Another aimless guess, coil?

[poohbah]

Cheers guys. I put in a new coil first thing today. I am suspicious that it might be the carbies. The previous owner fitted Weber 45s (himself) and to be honest, all the evidence to date suggests the quality of his mechanical work hasn't been great.

[Alfapride]

Sounds like a tuning issue if you have eliminated electrical issues get the carbs balanced and tuned by a pro. FYI the 2 litre nord engine originally is fitted with 40mm dellorto not 45mm

[poohbah]

Yep, I am actually thinking about swapping back to 40s. The 45s are too big with standard cams.

Its a bit of pain though - I only had them tuned and balanced last month by an Alfa specialist. Then this darn problem emerged two weeks later.

[Alfapride]

Go back to 40mm if Alfa thought the engine needed 45 they would put me on..other place to check is your distributor maybe something else in it is faulty

[Mick A]

It sounds to me by what you've described that the problem may be a sticking needle & seat valve in the carby. If they stick open the carburettor floods. So the engine runs OK for a few minutes but because the valve doesn't seal properly the float level slowly climbs till flooding occurs as you've described it may only be one carburettor so it is only affecting 2x cylinders.

Cheers Mick. 

[Mick A]

Or I could be wrong, it's just a guess as it doesn't seem to have been covered yet.

Also - I agree with what others and yourself have said, 45mm is too big for standard cams, much better off with 40mm.

[GTVeloce]

I have a set of 40mm dell ortos in Perth if you are interested. Actually two pairs and both came from Alfettas. They have sat for a while now so will need a refresh before you could stick them in.

[carlo rossi]

the question really is
Is it a standard engine? what cams does it have ?and has it had head work?
you might sitting on  a little goldmine I think once again Choderboy is on the money
I would start with a kit through the carbs  needle and seats to start with if it sat around it could be sticking

can you post a photo of the carb tops with the numbers or just the codes as in DHLA?? and xxxxx.xx on both
and if you dont want to service them or cant find a local  ill look at them for you
its one of 2 things I do alright so the wife tells me

[poohbah]

Cheers all, for the input and advice.

I am also still not 100% convinced the current problem is not electrical - the fact it only happens once the car is warmed up to operating temperature makes me suspect a dodgy connection somewhere. My missus had a Fiat 85S Regata (electronic ignition) in the 90s that did something similar, and after spending plenty of moolah on random things that ultimately proved not to be the cause, it was finally tracked down to a corroded electrode in the ignition module - once it heated up it would expand and separate. Cost about $3 to replace...

So I am resigned to trucking the car back to the workshop to have it sorted out by the experts - whether it be electrical or carby-related. GTVeloce, I may be in touch about those Dellortos! (Or feel free to PM me with what you reckon you would take for them)

What I have quietly been toying with is asking the guys at the workshop (if they have a set of Dellortos or Weber 40s on hand) whether they would be interested in doing a straight swap - my 45s for their 40s - and only hitting me for the labour and any ancillary parts that might be needed.

Carlo, in answer to your question it is a stock 2.0L, with the standard cams, which is why the oversized 45s are problematic.

[Alfapride]

Check all vacuum hoses for good measure maybe they split with heat and check the earth points on the car any fuses blown in the fuse box ? Worth checking and making sure all contacts are clean

[carlo rossi]

could you send the numbers anyway i like 45s
but pull the covers off and clean them out and see if the needle is sticking
and tell me if its 1.75 or a 2.0 needle and seat
dont know why they would put 45s on because the ports are only 40mm
its a real bad miss match square peg in a round hole
thats why i was wondering about the port has it been enlarged to match
if so re consider 40's
also if it works well in cold and then fumbles when it heats up  check that your chokes are not leaking  its too rich send me the jettings
main, emulsion and idle  numbers

[Beatle]

You'll be ripping yourself off doing a straight swap of 45s for 40s!    45s are of interest to a wider audience than Alfa crowd only.