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Have you disconnected/reconnected the spark plug wires? Maybe you messed up the firing order when you put them back. Check firing order. 1-3-4-2
 

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How did you check the spark? Are you sure that the plugs aren't fouled? If something got screwed up in the carb adjustment when they were reattached to the head, the plugs could foul that quickly. If that's not it, and it's not the firing order (as Roadtrip suggested) you may need a compression test to see what's going on.
 

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Discussion Starter · #4 ·
Plugs it is - i removed plugs 3 & 4 and they were black and oily. Once changed the car now runs fine but it's not a good sign for a plug to fail after a mere 250 odd km of driving. The head was replaced after I allowed a screw to fall into the combustion camber and %^$#@ everything up.

I am wondering if oil fouling on my plugs indicates that the cylinder liner and rings were damaged in the process or if this could be due to other problems.
 

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I am wondering if oil fouling on my plugs indicates that the cylinder liner and rings were damaged in the process or if this could be due to other problems.
Yes. It could be 10 other things as well. It's pretty hard to diagnose over the Internet!

The fact that two cylinders are fouling probably argues against damage to the rings/liner - unless you dropped screws down both cylinders #3 and 4. The fact that you have problems in the rear two cylinders suggests that it could be the rear Weber set too rich. Determining whether the plugs are fouling due to oil, or an over-rich mixture would be helpful.

Did that reputable shop do the whole job? That is remove the head, repair the damage, and re-install the head? If so, they should make it right.
 

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71 Berlina 74 GTV 17 Giulia Q4
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try a compression check and better yet a leakdown, the guy that did the work should be happy to do this.
Any blue smoke on acceleration?
 
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Discussion Starter · #7 ·
I think Alfajay may be right about the over rich mixture on the rear Webber being too rich. The mechanic indicated that the Webbers needed to be overhauled although he didn't elaborated on what he meant by this.

In response to your question, there is no blue smoke on acceleration buts what's a 'leakdown'?
 

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71 Berlina 74 GTV 17 Giulia Q4
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it measures how long the pressure stays in the combustion chamber on compression, usually to check rings against valves. If it's not burning oil, no smoke, and just fouling those plugs then time to check the carb. good luck! I'd do a compression check just for the hell of it and have a baseline for down the road.
 

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I personally wouldn't stress too much, were the plugs that were in there new to begin with? When I first built my engine it used to foul plugs every couple of days (keep in mind that my engine had new pistons, liners, everything!), if your jetting is not correct this can happen pretty easily.

A leakdown test is a very good idea, you'll get a good feel for what the condition of the engine is, but in the meantime if it keeps fouling plugs you can even look at going a little higher in plug heat while you get it tuned properly.
 

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71 Berlina 74 GTV 17 Giulia Q4
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you can (sometimes) unfoul a plug by taking the lead off the plug and holding it (not with your hand:) ) about a half an inch from the tip of the plug and jump the spark to the plug. You'll know when the plug starts firing the mixture by the way the motor smooths out.
 

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Carbs?

Check to see if the choke on the back carb isn't stuck partially open. We've had this happen. 3 months sitting shouldn't foul the carbs enough to need a rebuild.
KG
 

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3 months sitting shouldn't foul the carbs enough to need a rebuild.
That was my thinking too. Especially if the gas was fully drained out.

The problem I have had when carbs sit long enough for the gas to evaporate is non operative accelerating pumps, due to the check valves sticking. But that doesn't cause fouled plugs.
 

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Discussion Starter · #14 · (Edited)
Well it's been a while sice my original post now and I've put almost exactly 1000 km on the car. Over this distance I had to change the number 4 plug three times over this distance with number 3 plug changed once. The machanic fiddeled with the mixture and re-torqued the head, and replaced number 4 plug again. I then drove home it home (only 5km) and it drove great but after sitting for 3 hours it would not run on all four cylinders again and when I changed number 4 plug yet again all was fine. A fouled plug after only 5km! I looked closely at his invoice and it notes that the value guides weren't replaced. How normal and significant could this be to my problem?
 

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71 Berlina 74 GTV 17 Giulia Q4
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I doubt it. Check your float level, if it's to high you'll foul a plug no matter what condition the motor is in. As for it only fouling #4 that does present a problem in that the float level affects both rear cylinders. How about taking a good close up of each plug and posting after they are fouled. Is it black wet and oily looking? Heck it could be something as simple as the plug wire breaking down or the cap. It's usually the simple "I coulda had a V-8" stuff. for our friends in the south that's the juice not the motor:) or maybe you guys have V-8 juice down under....
 

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As I mentioned on a previous thread That if you you choke on a Weber the choke pistons can stick.remove the choke cover and look at the pistons.
More likely IMO the float needle valve has stuck open flooding that carb. Something is sticking and it will be simple to fix.
 

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As I mentioned on a previous thread That if you you choke on a Weber the choke pistons can stick.remove the choke cover and look at the pistons.
More likely IMO the float needle valve has stuck open flooding that carb. Something is sticking and it will be simple to fix.
You are responding to a question from 2011. Though helpful, I doubt it’s still an issue.
 

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:D

Pete
 
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