Packard Forum Index » Pre-War (1899-1942)

Since I'm having a little problem with my 37 120, I was just wondering how common vapor lock was back in the 30's, 40's and 50's. Has it always been a problem? Was this just part of everyday motoring. Is there a sure fire way to correct this problem or is it one of those problems that just come with the pleasure of owning an older car???

In recent decades, the underlying problem has been more a matter of alcohol as a component of fuel blends - some brands were worse than others. It was especially troublesome for carbureted vehicles of the early 1980s. I was working as a service rep for Chrysler back then, and there was a mad scramble to develop, certify, and deploy "fix kits" to upgrade the affected models to a pressurized fuel system. IIRC, GM and Ford faced similar challenge, but I believe GM had a lot more vehicles equipped with EFI by then.

In the time frame you cited (and under normal vehicle operating conditions), I'm not sure what the underlying causes might have been back then - other than high altitude and ambient air temperatures.

I'm not so much into pre-war cars, but have read shop manuals for other cars of the post-war era and found references to the topic. In fact, the 1950 Pontiac shop manual goes out of its way to explain (then) new technology employed in the carburetor to address vapor lock and percolation issues.

I don't recollect any mention of that kind of stuff, however, in the 1955-56 Packard Service Manual or any supplemental service info for those cars.

The main problem is the difference in fuel formulation. Today's gas is designed to evaporate, FAST. Yesterday's gas could last for a long, long time. Many collectors who own many cars, go out and buy 55-gallon drums of hi-octane avgas or racing fuel (106 octane or so). This lasts a long time, and will not gum up in your fuel tank, lines or carburetor when sitting a long time.
Sta-Bil stabilizer is good, but it, too, will not last a long time either. Good for a season of sitting, but better to drain or fill the tank with the avgas if it's going to sit longer than one season.

I recall that any old car my dad from the 1930's and 40's especially Ford V-8's all vapor locked at some point in very hot temperature so I think it was a common problem. I remember wrapping tin foil around the gas lines as a remedy but it wasn't very effective but seemed to help. My 47 Packard has not had a problem with it. I have an inline pulse type electric pump but have never had to use it for vapour lock yet.

I believe that vapor lock was a pretty common problem. It is only made worse today by the current gasoline formulas as pointed about by West Peterson above.

Just an electric pusher pump solved this problem 100% on my 55 Pat and I have driven it in 110F during the Summer.

A fuel return system is a good idea, but the problem comes in the complexity of the plumbing. No Packards have a return fuel line, so that would have to be laid front to back and somehow connected to the fuel tank, not a convenient thing. If I were going to plumb this I would probably use a fuel bypass regulator at the inlet of the carb. Typical electric fuel pumps will output 6-7psi and the older carbs can get by with 4psi, so one might need a regulator anyway, although my 55 Pat with 4GC did not.

Craig

I just put one on my 1940 180, and it came from Car Quest. I installed it quickly (well... I had a lot of help), inline. When it starts to vapor lock, I flip the switch until it's back to normal, then right off. I also use it to prime, when it hasn't been run for more than a week or so.

Quote:
<p>
It must be a pulse type fuel pump. Those can be drawn thru by the up front mechanical pump whereas the rotary vane (Carter, Holley) cannot.</p>
<p>I leave mine on all the time since one can never tell when the dreaded vapor lock might occur at an inopportune moment.</p>
<p>Craig</p>

I'd like to know why my 88 ranger with mechanical pump on engine NO RETURN line to tank and a common 2bbl carb does not vapour lock????? It is in everyday service in weather temps of 96 degrees daily and 107 degrees 2 years ago.

Ditto for my 73 Impala sold only 2 yearsa go.
No vapour lock on my 56 Exec.

How come i don't have vapour lock?????

I don't recall much vapor lock from the 60's or 70's when alot of 50's cars were still on the road. UNLESS it was due to something like a stuck heat riser or something like that.

Not sure why some cars are more subject to vapor lock than others. It was surprsing on the '55 Clipper Super. My '53 Hudson has the problem even with the lines insulated; but the electric pump way back at the tank clears it up. My '54 Kaiser had it big time EVEN with the electric pump working full time until I rerouted the fuel line well away from the exhaust manifold. I drove another '54 Kaiser home today from an engine shop about 40 miles and it was ok until a mile from home. But fortunately it recovered. I have no electric pump on that car yet. But vapor lock is a fairly common thing. I never heard of it until 1994.