Hot Starting

[IanBosher]

The age old problem of starting which I know has been asked before. Could anywhere has solved or improved this problem please let me know how.

I had a reconditioned full engine fitted last year. Had my old carbs put on and then tuned / balanced by my local old school garage who fitted tge engine. From cold even after weeks of non use starts up on half a crank and drives perfect. Stop. Try to restart, turns over fine but not even a glimmer of firing up. Leave it for an hour and after a few cranks it coughs, splutters, misfires for 3 or 4 seconds and there's runs fine!! Fuel starvation??it has new HT leads and plugs and has lamentation fitted (don't know when and I've had the car 6 years)

Thanks all

[Lingen]

Ian.
That sounds like flooding rather than starvation.Check that the ballast system to the coil is working. It was fitted to reduce hot starting problems

[sujitroy]

I have 2 stags 1 behaves well the other doesn't. I for now have a switch to switch off fuel to the pump. I let the car run on for some time and then shut down. I can then start the car. It is said it could be valves in the carbs. leaking and causing the car to flood. Maybe try this for some time and see.

[v8ken]

When I experienced the same issue, I overhauled the carbs, paying particular attention to setting up the temperature compensators.(I was convinced these were the main culprit)
Also worth checking is the thermic valve in the air intake, I did a piece on here on how I changed the diaphragm in there.as mine was stuck in'' the air coming from the exhaust manifold, position'', great for quick warm up, but shouldn't be in that position all the time.
Since then I spent the last 6 years in Malta, sometimes in 40c temperatures, often using it as a daily driver,,not had a hot starting or suspect fuel evaporation issue since.
E10 not been a problem.

[Paul Kelley]

Much has been written about the lower boiling point of modern ethanol-based fuels. Once you've been out for a run and stopped the engine, it will actually get hotter than when running with the fan, lasting half an hour or more (hence modern cars having electric fans that can continue running). So, the fuel in your carbs could be boiling over and flooding. The standard test for flooding is to crank it and floor the throttle to clear it out. If it fires up pretty soon then flooding is your issue. What to do if it is flooding? Try using super fuel with 5% not 10% ethanol for starters. I have the weber 38 fitted and have a bakelite plate between the carb and manifold (yes, bakelite is a great heat insulator). Someone will know if such a plate exists for the strommies. Before any of this though I suggest you check that all is well with your carbs, i.e. no floats sticking and flooding. In extremis, maybe an electric fan that runs on but I would follow cheaper paths first and others with experience may advise for/against this option. Good luck. Paul

[NeilR]

E10 boiling in the carbs & dumping contents into the inlet manifold gets my vote (an issue I had with stroms & e10 and to a lesser extent with 38dgms).

[DJT]

Vent valves.

I've not had any issues with E10 in the past two years.

[marshman]

How long after you stop will it not restart, pretty much straight away or after you have left it for 5 minutes? If straight away then it will be a weak spark, possibly due to the "ballast" system not working - i.e. no 12V feed from the starter solenoid to the coil as mentioned by Mike (Lingen) - there will not have been enough time for flooding to occur due to fuel boiling etc.

Also how do you restart it? Standard technique on any old car with carburettors that is hesitant to start when hot is to put press the accelerator to the floor and hold it there whilst you crank it over, when it fires and starts to rev you can then release the accelerator.- (mentioned by Paul above).

There should already be some thick heat insulating gasket/spacers between the pedestal on the stromberg carbs. Difficult to fit any more as this will alter the spacing and the elbows and the air filter would no longer fit.

[trunt]

Vent valves.

I've not had any issues with E10 in the past two years.

I can only get E10 and it gets a lot hotter over here than UK so would say that if all else is fine then E10 shouldn’t cause a problem.

However initially I did have occasional hot start flooding, a pair of quality float valves - properly set up, and a malpassi fuel pressure regulator cured it.

[Ian F]

Years ago I had a similar problem;

Stop it, and restart it within 5-15 minutes and it’s fine
Stop it, leave it for 2-3 hours, it restarts and it’s fine
Stop it, leave it for 30-45 minutes and it would start fine and tick over fine, but as soon as I went to pull away it would die as if flooded and the only way I could keep it going was to rev the nuts off it, ‘til it cleared.

I suspected heat soak and boiling fuel, bypassing the needle valves and pooling in the inlet manifold, it would stay there on tick over, but as soon as you applied the throttle, the extra vacuum sucked the fuel in and “killed” the engine!

I re-set the float height and replaced the fuel pipes under the bonnet with heat resisting stainless wrapped fuel pipes from the fuel filter to the carbs……It worked and that was pre E10 so a while ago. I rarely use E10, trying always to use Super/E5, but when I have had to use it, the problem didn’t/hasn’t recurred - give it a try!

Ian F

[jbuckl]

A restricted bleed pipe back to tank can help.
A fan wired to stay on after key off can help.
A pvc & fibreglass lagged fuel line from pump to filter is good…. RH exhaust is very close to fuel pipe… not good.

modern fuel is such a low boiling point! = root cause

check fuel pressure…. 2.2 psi max.

set needle valves to lowest level cut off that works…. About 18mm iirc.

[marshman]

A restricted bleed pipe back to tank can help.
A fan wired to stay on after key off can help.
A pvc & fibreglass lagged fuel line from pump to filter is good…. RH exhaust is very close to fuel pipe… not good.

modern fuel is such a low boiling point! = root cause

check fuel pressure…. 2.2 psi max.

set needle valves to lowest level cut off that works…. About 18mm iirc.

But why are some cars OK and have none of the above and no hot start issues, and others seem to suffer?

I run several classics, all unmodified, and none have hot start issues. Of those, 3 are supposed to be "marginal" on cooling, my Stag being one of them,. Ok, I do run them on E5, but all have original cooling systems, and no extra mods or the "precautions" listed above, none have an "extra" electric fan and none overheat sitting in traffic on a very hot summers day.

I think it is a cop out to blame the ethanol content of the fuel. Our friends in the US have "put up" with E10 for a long time and they don't seem to have these issues.

I often wonder if it is down to particular engines running hotter due to one or more of the following:

Inefficient cooling system due to partially blocked rads, or electric fans restricting airflow.

Too much antifreeze, 50% for example, which reduces the heat capacity of the coolant and makes it slightly more viscous so it doesn't circulate so readily.

Incorrect carb mixture, i.e. too lean which will make it run hotter.

Sub optimal ignition timing which again will affect engine running temperature.

Or is it just incorrect starting technique when starting a hot engine??? I have watched some "new" / inexperienced classic car owners pull the choke full out to start a car that is still "warm", then wonder why it stinks of fuel and won't start.

Worth checking before spending hours modifying something which really ought to be ok.