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Discussion Starter #81
Yes to all the above except the RTV on the outer circumference of the seals. Never have done that before on any of the other engines I have done, so we will see. Thanks for the input.

Marc
 

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Do not put rtv on the seals. The seal material is the sealing agent and shouldn't need more. My experience has been that the seal becomes compromised and actually has a greater chance of coming out. Good luck
 

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My only leak so far appears to be coolant, seeping from the 'T' hose connector by the firewall for the heater. The CA silicone hoses seem a little too large both in I.D. and O.D. I'll probably drain the coolant and replace them with stock rubber hoses.

To prevent oil leaks, I think it is most important to seal the threads on the crankshaft for the pulley nut and replace the cigarette seals with RTV. I am cleaning up a spare 1600 '502' engine. The main pulley/timing cover was caked with dirt and oil and the rear main seal is a hazmat area. RTV on the outer circumference of the seals seemed like overkill but who am I to argue with a very experienced engine builder; a Ga Tech graduate that owned a race shop for 30 years and built many engines for AutoDelta. I'm just sharing what he taught me...

Mark

Yes to all the above except the RTV on the outer circumference of the seals. Never have done that before on any of the other engines I have done, so we will see. Thanks for the input.

Marc
 

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Discussion Starter #84
My only leak so far appears to be coolant, seeping from the 'T' hose connector by the firewall for the heater. The CA silicone hoses seem a little too large both in I.D. and O.D. I'll probably drain the coolant and replace them with stock rubber hoses.

To prevent oil leaks, I think it is most important to seal the threads on the crankshaft for the pulley nut and replace the cigarette seals with RTV. I am cleaning up a spare 1600 '502' engine. The main pulley/timing cover was caked with dirt and oil and the rear main seal is a hazmat area. RTV on the outer circumference of the seals seemed like overkill but who am I to argue with a very experienced engine builder; a Ga Tech graduate that owned a race shop for 30 years and built many engines for AutoDelta. I'm just sharing what he taught me...

Mark
Do not put rtv on the seals. The seal material is the sealing agent and shouldn't need more. My experience has been that the seal becomes compromised and actually has a greater chance of coming out. Good luck
 

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Discussion Starter #85
Made more progress lately with time on my hands like everyone else. Finished assembling the engine, cleaned and rebuilt the carbs, distributor, etc. Also built a test stand and ran the engine on Tuesday. Ran fine with only one small oil leak which I how have fixed.

This does leave me with one question about the fuel pump which I would like to pose to the forum. The car came with an electric fuel pump. I have converted it back to a mechanical fuel pump. Now I question the ability for it to draw fuel from the fuel tank. It took me a long time just to get the carb bowls filled with a very short supply line to the engine stand. Should I just convert it back to an electric pump. Any comments.

Marc
 

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There is no absolute "yes - no" answer to that question. Obviously mechanical pumps work OK - Alfas used them for years. And if you plan to compete in concours, you'll want to keep your Duetto as original as possible, including the type of fuel pump.

However, electric pumps do offer a couple of advantages:

- If you don't use your car regularly, it does take a lot of cranking before the mechanical pump delivers fuel to the carbs. With an electric pump, you just turn on the key, wait 10 seconds or so, and start.

- There is certainly less chance for vapor lock with a rear-mounted electric pump.
 

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I really haven't had much trouble with mechanical fuel pumps but in general I convert to electric primarily for the reasons Jay noted. The important thing is to get the right size pump (2-4 psi). You shouldn't need a regulator but if you have the glass bowl regulator I would still use it. My personal favorite is the Carter P74021 - the quietest pump I've ever had.
 

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Discussion Starter #88
Gentlemen,

As usual, thanks for the comments. I have several other Italian and German cars, but this is my first Alfa and the assistance I have received from this forum is simply great. I have a Ferrari and older Lambo both with Webers and Bendix pumps that dead head at the carbs(no return). I installed pressure regulators and set it to 3 PSI. Works great and that is what got me thinking I should do the same on the Duetto as I already have the bowl/filter regulator installed and happen to have a brand new Bendix pump.

However, I have been trying to keep the car all original just because (I don't plan on showing it at judged concours events). This is the first car with a mechanical fuel pump I have had since the late 70,s. If I leave the car set for a few weeks, what length of cranking time should I expect to fill the carb bowls.

Thanks in advance.

Marc
 

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Hi Marc,
I've found in my Duetto that if I let it sit longer than 3-4 weeks between running that I need to add about 70cc's of fuel to each bowl. I made a small dipstick out of thin cardboard and use it to determine the fuel level in the bowls. I just remove the two thumbscrew caps from the tops of the 40DCOE's and add 70cc's via a plastic syringe. Starts normally and is easy on the starter.
 

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Discussion Starter #90
Now that, once again, is great information and advice.

Can you describe the syringe and where you purchased it?

Thanks Phil,

Marc
 

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It's just a standard plastic 10cc syringe you can get them on Amazon, Mcmaster-Carr, or probably your local Walgreens or CVS. I happened to have some plastic BD syringes (from work). I've noticed that the rubber piston seal can swell a bit from the fuel but it's not really a problem.
Also, if you happen to have access to aviation 100LL fuel, I'd recommend using that as it doesn't varnish up like regular car gas. Don't tell the gestapo!
Cheers,
Phil
 

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I just re-purposed a household squeeze bottle for squirting gas into dry carbs. I think mine formerly held dishwasher "Jet Dry".

You can be fairly imprecise about the amount of fuel added for his purpose.
 

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Gentlemen,

As usual, thanks for the comments. I have several other Italian and German cars, but this is my first Alfa and the assistance I have received from this forum is simply great. I have a Ferrari and older Lambo both with Webers and Bendix pumps that dead head at the carbs(no return). I installed pressure regulators and set it to 3 PSI. Works great and that is what got me thinking I should do the same on the Duetto as I already have the bowl/filter regulator installed and happen to have a brand new Bendix pump.

However, I have been trying to keep the car all original just because (I don't plan on showing it at judged concours events). This is the first car with a mechanical fuel pump I have had since the late 70,s. If I leave the car set for a few weeks, what length of cranking time should I expect to fill the carb bowls.

Thanks in advance.

Marc
Hi Marc,
Someone on the BB should know for sure, but I have heard of running the mechanical fuel pump up front and the electric pump in the back. That way you would have the look of the stock setup with the benefit of the electric pump also. And don't tell anyone haha, they will never know unless they hear the pump working.
DJ
 

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Hi Marc,
Someone on the BB should know for sure, but I have heard of running the mechanical fuel pump up front and the electric pump in the back. That way you would have the look of the stock setup with the benefit of the electric pump also. And don't tell anyone haha, they will never know unless they hear the pump working.
DJ


I like it. But don't forget to add a small Racor filter inline in front of the fuel pump to catch the tank crud. My rear mounted Racor has a drain bowl so it's an easier job to inspect and clean. The rear Racor keeps the electric pump clean and helps prevent tank crud from reaching the front mechanical fuel pump. The FISPA front filter/regulator is mounted on the engine wall bay after the mechanical fuel pump, so I was always wondering how crud from the tank might damage the mechanical pump. I found rust particles in the Racor bowl and cleaned them out fairly easily. You can mount the electric fuel pump and filter on a backing plate and then only need a couple studs bolted to the frame in the rear. Our cars are old so you have to expect some crud buildup in the tank. I never liked the idea of the tank liner product they try to tell you to line your tank with. I measured my low pressure electric pump and mechanical pump combination total fuel pressure at the Webers and it stayed at 3psi. I agree with Marc on a stock looking Duetto. I just have the changes fairly hidden.

I had a local terrific brake/filter/fittings company make me a new fuel line from the tank to the engine. I paid a price leaving the old metal line in, as I could not properly clean it out. Maybe you had a new one made, but that old line was a source of crud and wasted time with front filters clogging for me,:cry: I will sheepishly admit to. Don't make that mistake.
 

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Someone on the BB should know for sure, but I have heard of running the mechanical fuel pump up front and the electric pump in the back. That way you would have the look of the stock setup with the benefit of the electric pump also.
I've never tried that, but sure, I can't see why it wouldn't work. In fact, you could "hollow out" the mechanical pump, just leaving it there for show while the electric pump did the actual work. Simply removing the rod that drives the mechanical pump would render it passive.
 

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When I got my Duetto in 1984, it was a started restoration 'kit' car that I got to assemble. Upon examination, the original mechanical fuel pump had evidence of serious valve seat wear so a replacement pump was sourced and installed.

Unbeknownst to me, someone had previously added an electrical fuel pump between the spare tire well and the fuel tank. The electric fuel pump most likely caused the valve seat wear noticed in the original fuel pump. When rebuilding the engine last year I refreshed the seals in the electric pump and removed the replacement mechanical pump -installing a blank off plate instead.

Since then I have learned from my good buddy W.L. that if you install an electric fuel pump on a car with a mechanical fuel pump, you should install a hidden switch under the dash. The switch allows you to pump fuel up to fill the float bowls and filter for quicker starting with less grinding on the starter motor. Once the engine starts, you should switch off the electric fuel pump to preserve the mechanical pump. I am considering adding just such a switch and going back to the mechanical pump.

Mark
 

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A friend of mine did the same thing with his Triumph TR3, he has a button on the dash which runs the electric pump only as long as you’re holding the button. Just to fill the bowls of the carbs.
 

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The Alfabb is such a source of information. But as a scientist, I have to ask:
"The electric fuel pump most likely caused the valve seat wear noticed in the original fuel pump "
(Respectfully) How would you know that versus just an old worn out fuel pump? One could also say the electric pump, as a helper, puts less stress on the mechanical pump.:unsure: I am always trying to learn too, and grateful for the help.
 
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