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Discussion Starter #1
I'm the owner, but not a mechanic. Car is with a local specialty mechanic that I have been happy with, up until now. Car is a 1969 Giulia Super, with its original 1600 engine in stock build. Total mileage is unknown, but the current reading is +/- 8,000km as of August 2019. Prior to importing, the car spent its entire life in Florence, Italy.

The shop recently replaced the mechanical fuel pump with an electric unit, following the failure of the mecanical unit after only a few thousand kms (from a known supplier in Atlanta). When it failed, the car bucked and came to stop a short distance from home. After a few minutes, I was able to nurse the car home, limed to second gear and low speed. After replacement of the fuel pump, performance fell off with poor acceleration and surging in all driving conditions. I returned the car to the same shop and had the owner drive the car. Thereafter I was advised that compression across all four cylinders had fallen to 75 psi. Timing is reported to be spot-on. Could it be that the mech. fuel pump was not the only problem?

For comparison, three years ago in August 2016 tests indicated the following, with the odometer displaying 5,586kms.
Compression dry:
1 155
2 140
3 165
4 165

Compression wet:
1 180
2 160
3 180
4 189

Leakdown:
1 0%
2 10%
3 5%
4 0%

Given that the head is coming off and I'm expecting I will be told it needs a rebuild, what should my next step be? Purchase a new valve train and rebuild, or purchase a completely new (to me), specialist-built head?

Lastly, how could the failed mech. fuel pump lead to loss of engine compression, as the two are unrelated?
 

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If she ran lean she might have burnt a few valves?

In the end, do you trust your mechanic is what matters. I assume he/she has shown you the compression readings, and now I'd want to see what the combustion chamber area looks like with the head off, so I'd ask him/her to remove the head, and that before any further work you would come and discuss the next steps.

If your engine has burnt valves, you will be able to see that or if something else has happened like a piston land has burnt, etc. you should also be able to see the damage. If you cannot see anything wrong, then you are in the right place for a chat, and if a good honest mechanic he/she will be confused too.
Pete
 

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Richard Jemison
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7,081 Posts
Engine issue

I don`t see a reason to jump into a rebuild just yet, till you check other things.

If the fuel pump failed and the engine stopped I doubt you had long enough run period to burn valves or damage pistons. The only way to tell is a leakdown test.

I strongly suggest that the issue is the new electric fuel pump creating too much pressure, causing fuel to be dumped into the engine. At pressures over 3 psi at the carbs, the needle & seat cannot shut off the flow. That overfills the carbs and raw gas drains into the engine and airbox if it`s a Veloce (2 Weber induction)

Measure the fuel pressure!
 

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Richard Jemison
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7,081 Posts
Gas / oil

Yes it would.

As well, remove the cover on the air box, turn on fuel pump. Do you sense a strong smell of gas, or see it leaking in the carb intakes?

If you smell any gas in the oil or see a higher level of oil, or thinning. the pump is the culprit...
 

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Discussion Starter #6
Reviving this topic, Richard got it right. The electric pump's pressure overwhelmed the carbs. Back to a new block-mounted mechanical pump. The 2017 installation failed rather quickly: <2,000 kms.

If the car was driven in this condition and the oil contaminated with fuel, what damage could have resulted. The shop's owner stated that a borescope inspection showed no damage to the liners. Would a compression test confirm this?

That 2 liter long block for sale was starting to interest me...
 

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If the car was driven in this condition and the oil contaminated with fuel, what damage could have resulted. The shop's owner stated that a borescope inspection showed no damage to the liners. Would a compression test confirm this
My guess is that you didn't put enough miles on the car to damage anything while the fuel pressure was excessive. So your mechanic is probably correct that the borescope inspection shows no damage to the liners (and let's hope the bearings).

Still, the mechanic did make a "rookie error" by installing an electric fuel pump with too high a pressure rating; it isn't as if low-pressure electric fuel pumps aren't available.

I returned the car to the same shop and had the owner drive the car. Thereafter I was advised that compression across all four cylinders had fallen to 75 psi.
I'd like to think that your mechanic is competent and honest (though perhaps a bit clueless about electric fuel pumps). But this part of the story just doesn't hang together. I'm not getting how the compression could have fallen to 75 psi when the fuel pressure was too high, and then healed itself once a mechanical pump was re-installed.
 
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