[Healeys] Tapitty tapping of Fuel Pump

[Perry]

Listers
OK. Since Gary wrote to the list several days ago and twenty plus emails since, we have concluded that clothes pins should only be used for the originally intended use, pinning clothes and that the possibilities of vapor lock was not taken into the design of SU fuel pumps used on a Austin Healey. The designers did use a heat shield between the carbs and exhaust manifold perhaps with the intent to protect the fuel bowls for excess heat but as the 100 owners know the heat shield was only adjacent to the rear carb float bowl since there is no shield on the front carb.  By the way the front float bowl and the exhaust manifold are only 1 inch apart.  Suspect that the proximity of the 100’s four blade fan (read hurricane force fan-😊) was enough to quench any heat problems on the front carb.

For the later cars the heat shield covered it all and supposedly prevented any expected problems in the fuel delivery department. 

So where does all this rambling bring us to? 
For me it still begs the question, Where does the vapor lock begin? 

Temps at the exhaust manifold can be in the 300+ degree range (unless you are screaming around a race track) but the tail pipe will probably be about a third of that when the car is in motion. So the proximity of the fuel line to the heat source varies front to rear. I mentioned the factory moving the fuel pump to the right side of the later cars.  I suspect that there was a reason for that change. I’m not sure if Gary’s car has the pump on the left or right side. 

Any one want to write email 24+ on this subject?

This is what happens when you wear a mask and rebreathe your own exhaust all day…I anxiously await your feedback. And perhaps a tank of oxygen!
Perry

Sent from Mail for Windows 10






On Mon, Jun 22, 2020 at 9:12 AM editorgary--- via Healeys <healeys at autox.team.net> wrote:
Yesterday I took my Healey BN& out for its first good run of the season -- 75 miles of southern Oregon backroads -- with our local Rogue Euro Car Group. Everything was terrific from start to finish. Car started on the first push of the button after sitting for six weeks, ran smoothly from start to finish, never faltered in restarts, everything nominal.

Except that, towards the end of the run on a pretty hot day (in mid 90s though the car never ran warm all day) as I was cruising along about 40 mph, the fuel pump started tapping at a high rate of speed and pretty continuously -- certain enough so I could hear it behind me. I have a standard original-spec points-style fuel pump, purchased new from Moss about 10 years ago and running without any issues every since. 

Any thoughts from anyone -- could it just have been the heat? As noted, the car never missed a beat, so fuel was getting through the carbs smoothly at all times. 

Anyone?

Gary Anderson



-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://autox.team.net/pipermail/healeys/attachments/20200624/b1531c2d/attachment.htm>