To pop or not

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330GT
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To pop or not

Post by 330GT »

I recently took my 330 down to the Forest Grove Concours. It's about a 200 mile drive each way, and the Pacific NW was having an unusual heat wave, i.e. days of 90+.

I knew that the 330 had some vapor lock issues from getting stalled last summer going up to Whistler, BC. I managed to procrastinate all winter and some of the summer. Prior to leaving, I did take off the mechanical fuel pump and do some measuring. The net result is that I didn't shave the phenolic block, but did remove a gasket that was .017" thick. From my measurements it looked like the pump rod was providing a full stroke to the pump lever.

This didn't solve the vapor lock as I ended stopping 8 times, anywhere from 5-20 minutes to let the under hood temperature drop enough for the electric fuel pump re-liquefy the gasoline. Then I could drive anywhere from 5-50 miles, depending on how hot it was outside and the traffic. The closer I got, the hotter it was. Eventually I did make it, but only after having to be pushed out of traffic just 1.3 miles from my motel.

Note, the car was not overheating, usually running from 70-95°C.

Now to the why of the post?
First, today, a Citroen buddy of mine suggested popping the hood (hinged at the front) to allow a gap at the rear for air to flow out from under the hood better.
Any comments if this might have helped? This seems to be common knowledge in France for 2CV owners.

Second, what about engine speed vs. engine heat? In general, my thought pattern was to keep the revs low, thus minimizing fuel need and keep engine heat lower. But in hind sight, perhaps keeping the revs higher so the mechanical pump would be working faster with more fuel flowing through to the carbs (thus less time for it to vaporize) at the expense of more engine heat. The radiator was keeping the engine temperature under control. Comments?

Of course, I need to attack the mechanical fuel pump issue, or perhaps like TomY, add a second electric pump.

PS, I stayed an extra night and drove home leaving at 5 when it was still cool. Only took 4 hours vs. the 7 hours going down.
At least the car got a First in Class award.
Regards, Kerry
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tim
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Re: To pop or not

Post by tim »

Greetings… Shouldn't the electric pump suffice? At first sign of distress I would switch on the electric.

Also, what was the pump stroke. I'll have mine off next week and that is one of the things I need to address.


Tim
1964 330GT 5769 -the big yellow taxi 61&66 Morgan +4's Daimler SP250 Turner 950S and some other dull stuff plus a brand Mercedes C300 4matic
DWR46
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Re: To pop or not

Post by DWR46 »

If you wait until the mechanical pump begins to fail in hot weather, the electric will probably never be able to pick up the pressure, as the fuel setting in the pump above the exhaust will have already boiled. Best to get the electric turned on early if driving in hot weather. You can tell if you have the electric working correctly when it initially runs fast, then slows to a steady click. if it never slows down, it is also cavitating.
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tyang
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Re: To pop or not

Post by tyang »

I suspect Dyke is right and it's not the underhood temps, but the fuel rail by the headers that's boiling. It also doesn't help to have the electric pump mounted directly over the mufflers!

The stroke of the mechanical fuel pump is very short. It's about 3mm in total!

I'm going to see how well this new set up works on my car, but was thinking about making another shield to insulate the facet pump from the heat.

Tom
'63 330 America #5053
Steve Meltzer
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Re: To pop or not

Post by Steve Meltzer »

Everyone in this discussion knows way more than I, but my GTC will vapor lock unmercifully if I don't run my e-fuel pump all the time in Houston's summer traffic. I really run it all the time, as it's a cheap item and pretty easy to replace. Also, I'm using some pretty good insulation on the fuel log that feeds the carbs on my Daytona. Easy to cut to fit around the lines and wire tied to stay put. Under the air cleaner, you can't see it and i think it helps keep the line a bit cooler. Used the same stuff, glued on, under the heat shields of the GTC. Here's the link to their stuff.

http://www.designengineering.com

s
steve meltzer,
"I've spent all of my money on wine, a beautiful woman, and stunning cars. Then, squandered the rest."
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330GT
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Re: To pop or not

Post by 330GT »

Just a note, I had the electric (original FISPA) pump on the whole time. When the car would stall, the electric would click very hard (more like a bang). Eventually (perhaps a few minutes), it would start sounding normal as when filling the fuel bowls before starting the car. Then after a few more minutes, it would slow down and almost stop like the fuel bowls were full. At this point I would be able to start the car and drive for a while.
Regards, Kerry
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DWR46
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Re: To pop or not

Post by DWR46 »

Today's gasoline is responsible for much of this problem. I am not sure you can buy ANY new car today with a carburetor. All the cars use fuel injection and the fuel pumps drive at 40 psi or more. Therefore the oil companies have no reason to blend fuels that resist boiling at 3-7 psi as in a carbureted car. As long as the fuel does not boil at 40 psi, there are no complaints from the manufacturers, so the oil companies can get away with the cheaper blends.
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tyang
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Re: To pop or not

Post by tyang »

After a drive in a warm day, I can hear the fuel boiling away in the carburetor bowls when the Ferrari is parked!

Tom
'63 330 America #5053
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michaelbalk330
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Re: To pop or not

Post by michaelbalk330 »

i re-did all my fuel hoses and covered the ones by my facet pump ( which I run all the time) with Earl's Flame Guard. see attached pics.. silica covered fuel resistant heat protection sheathing.
Also made a new heat shield and covered it with a reflective material from a speed shop.

Actually works well- I have no vapor lock, in atlanta in 95 degree heat.
If I still had problems I was planning on covering the fuel rail with a radiant material but so far, not needed.
My pump is an older Facet pump.
Car looks stock in the engine bay. I think the key is minimize the heat the best you can, and have good fuel flow, clean filters, etc.
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Michael
1967 330GT #9693
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330GT
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Re: To pop or not

Post by 330GT »

I haven't fixed anything yet, but as a point of reference, I measured the pressure from the FISPA electric pump and it pumps 4 psi on each stroke and re-strokes at 3 psi. This is with the engine not running and the float bowls full.

The pressure at the outlet of the pressure regulator is 5.5 psi with the engine running (on the electric pump) at an idle. Revving the engine didn't change the pressure. I didn't measure the outlet of the mechanical pump.

So I guess I'll get some sheathing as mentioned or else put a silent electric pump in parallel with the FISPA one. That way it can be run all the time.
Regards, Kerry
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250GT
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Re: To pop or not

Post by 250GT »

Concerning the 2CV owner i can say he know his car not at all
the bonnet of his car opens in front so his solution is BS
Second its a air-cooled engine like a 911 but a bit less HP

I am also very familiar with the boiling fuel problem.
I used to drive the real classic rallies through whole Europe.
and I dont mean those runs from bar to the next restaurants.

I did let run the fuel line with an U shape brass tube in front of the radiator.
i can operate the electric fan from in side before it get hot.

this works PERFECT as long you are not in the mountains ( not too much airflow)
will also bypass this winter the V12 with supplement electric new pump.
Here some pics of the Mont Ventoux run stage (France) a year ago I think.
waiting to cool down
My copilot got a little collapse in side the car 68 degrees celcius ,
out side 44 degrees in the shadow
after the first snow water came down we could stabilizes his condition.
best
C.
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250GT
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Re: To pop or not

Post by 250GT »

Here it seams to work
Sumbeam Tiger ?


C.
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