Engine dies on cornering? ('83)

[DrieStone]

Okay, probably a question for Jim more than anyone (the human Esprit encyclopedia.) This has happened three times now:

I'll take a long sweeping right corner and really pushing the car (so the car is pushing some "G"s for a couple seconds.) When I come out of the corner and push in the clutch (each time has been an exit ramp,) the engine dies and the battery light comes on. Twice I put the car in neutral and cranked it over until it starts, it puffs to life after a little cranking (it sounds "wet" and takes a couple seconds to "clear it's voice.) The last time it happened I kept the car in gear and continued rolling until it cleared itself.

I'm sure this is probably carb related (a rebuild is on my list of things to do before the end of the season,) but what I'm wondering about is the battery light.

I'm guessing that it's not a fuel problem (since I think actually has too much fuel, hence the problems starting and the "wet" sound when it actually does start.) I haven't really pushed it hard around any long left turns so I don't know if the same thing might happen.

Any hints or tips from others?

[wedg1e]

Er... the battery light WILL come on if the engine dies. They all do that, sir....

[lotusguy]

DrieStone said:

Okay, probably a question for Jim more than anyone (the human Esprit encyclopedia.)

Hi,

As already mentioned, the cause and effect of the battery light is the engine dying, not the other way around.

Your problem is pretty simple, fuel flooding. This is what causes the engine to die. What causes the fuel flooding is also pretty simple, bad float height!

The heavy 'G' forces you mention cause the fuel to move to the inside (left) of the float bowl and up the sides. This causes the floats to drop with the lower level of fuel left in the main part of the float bowl, (since so much is forced up the side of the float bowl). This opens the needle valve which dumps more fuel into the bowl bringing the level much higher than it is supposed to be. When the G's lessen and the fuel levels off, the carbs flood the cylinders causing hesitation, or in extreme cases killing the engine. If the engine stays running, the proper fuel level is pretty quickly restored and everything is fine from there on. If the engine floods to the point where it dies, it will be hard starting until the excess fuel is cleared through the system (you may even get a backfire or two).

If the float heights are properly set (14-14.5mm), this lessens, but doesn't entirely eliminate this effect, especially in a sustained lateral G manuever. In a sustained manuever with high righthand lateral G's, you will still get the slightest hesitation for just a second, but the engine won't kill and the effect will be barely noticeable. Some people don't have a vernier caliper for setting float heights and so aren't very accurate. Others deliberately set the floats a little low to increase fuel levels (proper method would be to re-jet) and then, the floats do go out of adjustment over time as well. Hope this helps. Happy Motoring! ...Jim'85TE



>> Edited by lotusguy on Tuesday 22 June 07:06

[wedg1e]

Didn't I read somewhere about a mod to the Dellortos that involves drilling a hole through an internal web to effect some change...?

Or was I dreaming it...

Ian

[lotusguy]

wedg1e said:

Didn't I read somewhere about a mod to the Dellortos that involves drilling a hole through an internal web to effect some change...? Or was I dreaming it... Ian

Ian,

I've never heard of such a mod. I don't know where you'd drill since the Dellortos have a single large float bowl (as opposed to separate float chambers on some carbs), or what mitigating effect it would have.

I do know of a mod to DCOE Webers which calls for drilling the progression holes larger to mitigate the classic 2k-2300 RPM stumble they are notorious for. Webers lack the same kind of idle circuit that Dellortos have and fuel is metered solely through these progression holes above idle until the Main circuit takes over. Many people custom graduate these holes with a fine drill. I helped a friend do this on the BMC/ 2 DCOE engine in his Caterham 7, Car ran better than it ever did according to my friend. But with Dellortos, the idle circuit never cuts out and so transition to the Mains is much smoother. Maybe this is what you were dreaming?? Happy Motoring! ...Jim'85TE



>> Edited by lotusguy on Tuesday 22 June 14:26

[wedg1e]

lotusguy said:

Ian, I've never heard of such a mod. I don't know where you'd drill since the Dellortos have a single large float bowl (as opposed to separate float chambers on some carbs), or what mitigating effect it would have. >> Edited by lotusguy on Tuesday 22 June 14:26

Ah... found it

http://home.att.net/~giacopassid/lotus_esprit_1.htm

Ian

[kylie]

driestone...hi, this problem happens to my car as well. Mine is a 89 carbed Turbo. Am glad Jim has told us what it could be as I asked my mechanic about it and he was a little unsure, so this is great news.
...Thanks

[autocross7]

I love this site... learn something everyday! I guess I really had not looked into it, but since I have not seen one- I did not know Esprits after 88 had carbs! I should like to hear the difference in the sound of the exauhst.

... to bad the issue can not be solved in the way we solved the problem on aircraft... simply mount the carb so that it can pivot with the G load...

Drive topless!!!
Cameron

[benfell100]

The WW2 Spitfire had a similar problem I think. Carbed Merlin engine wasn't happy about going inverted (-ve G) as it starved the carbs of fuel, the ME109 was fuel injected and didn't suffer this. Not that you're getting inverted in your Esprit, of course!!!!! Mainly bad.

[lotusguy]

benfell100 said:

The WW2 Spitfire had a similar problem I think. Carbed Merlin engine wasn't happy about going inverted (-ve G) as it starved the carbs of fuel, the ME109 was fuel injected and didn't suffer this. Not that you're getting inverted in your Esprit, of course!!!!! Mainly bad.

Hi,

The Meserschmitt ME 109 was indeed mechanically fuel injected and this did help with negative 'G' fuel starvation, to a degree. But, it didn't eliminate it entirely, so those clever German engineers took the whole engine and inverted it as well.

Look at pictures of this aircraft (not the Spanish licensed variant which used the Merlin powerplant) and you'll see that the exhaust nozzles are all in a line at the bottom of the engine cowling as opposed to most fighter aircraft of the period (with upright engines) which had their exhaust nozzles in a row along the upper portion of the cowling. Happy Motoring! ...Jim'85TE