Fuel vapourisation Holley carb.

[mjheathcote]

This is causing me some issues, again.
Went to a local late afternoon early evening car show today, and suffered bad fuel vapourisation issues.
It was lovely and warm but lots of traffic, water temperature okay but as soon as stood in traffic for any length of time can't maintain tick over, stalls, but starts again. Holley carb.
After the show, light traffic, no issues.
It must be change in fuel formulation never used to have this problem, ethanol?
Only read resently that this is becoming more of a problem with carburettor equipped cars.
Really don't know the answer, other than getting my efi project finished!

[marshman]

Yes annecdotal evidence suggests it is becoming more of a problem. Do you use regular unleaded or super unleaded? Some brands of super unleaded have no ethanol at the moment, though it us getting harder to identify which?

next try to identify where the vapourisation is occuring. In the fuel line or in the carb float chamber?

is it possible to mitigate against it by sheilding? Wrap or reroute fuel line, heat shield under carb?

[flying farmer]

I used to have this problem with the TR when it was fitted with the Holley.

It wasn't fuel vaporisation in my case, simply that the underbonnet air temperature was so high it dropped the air density to the point where the idle became unsteady due to the mixture being excessively rich.

I also found the required main jet sizes varied by 3 according to air temp and most of the problems were solved by fitting a shield around the air filter with a duct fed from in front of the radiator.

Why not just get your efi project finished. I will probably have built another one before you do

Neil

[mjheathcote]

Neil, what you say makes sense, however I've had the Holley fitted in its current configuration for 24 years and only had this problem in the last year.
I've run in warm conditions in traffic before this many many times over the decades with no issue.
I only use BP fuel, not super though.
As soon as I get moving at any sort of speed, with air flow under the bonnet, she is fine.
Generally my motoring is away from any sort of stop start traffic, and this issue has reoccurred going to the same car show as last year, same time, same traffic, and almost same air temperature!
Yes getting the EFI project finished would solve the problem. Cheaky

[mjheathcote]

Yes annecdotal evidence suggests it is becoming more of a problem. Do you use regular unleaded or super unleaded? Some brands of super unleaded have no ethanol at the moment, though it us getting harder to identify which?

next try to identify where the vapourisation is occuring. In the fuel line or in the carb float chamber?

is it possible to mitigate against it by sheilding? Wrap or reroute fuel line, heat shield under carb?

Having a Google super unleaded without ethanol sounds the solution, however trying to determine which does not have ethanol, is not easy to determine. With the Holley sat right in the middle of a V8 engine is the worst position for maximum heat.

This video nicely shows the problem, and a solution being basically a EFI petrol ring main. When ethanol jumps up to 10% in the future, such kits will possibly become common place for our classic cars.

https://youtu.be/cadNfSNi_Oc

[marshman]

Agreed on the google thing. There was a thread a while back which some companies said that it depended on the are of the country as to whether the super unleaded they supplied had ethanol or not. As you say if and when we get to 10% ethanol i am sure there will be kits available for the more popular classics.

[marshman]

Found the thread here:

https://socforum.com/forum/forum/sta...ne-cutting-out Post #10 onwards - fairly inconclusive!

[wilf]

Do you have the original engine driven fan still?

[trunt]

A bit of perspective

We have been running exclusively E10 over here for years, (8-10?) yet I have never been aware of such problems on my classic cars or my friends cars. The only thing that comes up is storing the car with E10 in it, it’s hydroscopic so water can corrode things.. some fuel stabiliser usually helps with that.

I remember the same thing happened when you went lead free years after we did. In the end a lot of fuss about nothing.

Terry

[mjheathcote]

Do you have the original engine driven fan still?

Yes I do, no electric fan fitted.

[richardthestag]

is the chassis fuel line copper replacement or "plastic" original?

[mjheathcote]

is the chassis fuel line copper replacement or "plastic" original?

Neither, one continuous length of stainless steel braided PTFE hose.

[Stagdad]

Having a Google super unleaded without ethanol sounds the solution, however trying to determine which does not have ethanol, is not easy to determine. With the Holley sat right in the middle of a V8 engine is the worst position for maximum heat.

This video nicely shows the problem, and a solution being basically a EFI petrol ring main. When ethanol jumps up to 10% in the future, such kits will possibly become common place for our classic cars.

https://youtu.be/cadNfSNi_Oc

Mike, thats the exact System that Chris with the supercharged stag has fitted after bad running using an external swirl pot and after talking about my in tank pump last year, he says it has transformed the car. Mind you at £600 i'll stick with my £30 Range rover classic in tank pump.
incidentally i have switched over to 98ron as 95ron was giving me some miss firing at max torque. Much improved now.

[mjheathcote]

Mike, thats the exact System that Chris with the supercharged stag has fitted after bad running using an external swirl pot and after talking about my in tank pump last year, he says it has transformed the car. Mind you at £600 i'll stick with my £30 Range rover classic in tank pump.
incidentally i have switched over to 98ron as 95ron was giving me some miss firing at max torque. Much improved now.

Don't say things like that, I've already got a neat custom swirl pot mounted ready inside the rear wing for the EFI project!

[Stagdad]

Don't say things like that, I've already got a neat custom swirl pot mounted ready inside the rear wing for the EFI project!

Not sure what was the reason but he said it kept getting fuel starvation, was terrible going up presscott hill climb apparently. Im sure yours will be fine. He also noted how quite it was now, he showed me how noisy the old external HP pump was last year and it was bad, so something to consider getting a quiet pump nicely insulated from the body work.