Never a dull moment

[Andy B]

and I don't even own a real Lotus.
So she's all back together and looking good but suddenly not running so well.
I think it's a fuel problem, today I was approaching a right handed sweeping bend. It's one of those you can see all the way around and as there were no other cars in sight I decided to "give er some wellie!".
Just as soon as I could feel centrical force doing it's thing my poor little twin cam started popping and misfiring. When the car was in a straight line it cleared and came back pulling strong. I took 3 more rights and returned to the bend and again as soon as the car was into the bend it started to misfire.
On the rest of the journey I tried to replicate the problem on left handers but the engine ran fine.

Any thoughts?

[WayneB]

How much fuel was in the tank?

If it was less than about 1/4 full the fuel could slosh away from the pick up and stave the pump on a hard / long corner.

I think the later Caterhams have an internal baffle in the tank to combat this.

[clockwork]

As above,if more fuel cures it you could try putting a swirl pot in the line,it should hold enough to drive you round the bend (in a nice way) Clockwork :)

[Al B]

Andy,

The race car does the same thing on hard rights. In it's case it's the float in the carb. As the G-forces come on the gas is sloshed/pulled to one side of the float chamber causing a disruption to the flow.
check your floats, a bit of an adjustment may be required. Unless it's F.I. then forget the above.

Al

[Andy B]

Thanks guys she was close to half a tank although I'm sure that condition has existed before without the same result. Tomorrow I will gas up and try again.
I am leaning to Al's explanation only because the misfire comes on so quickly.
Thanks again and I'll keep you posted.

[WayneB]

Andy, Are you running a sticky DOT treaded slick type street tyres (like the Toyo RA 1 or R888?)

If you are, besides the fuel issue (which Al was dead right in pointing out may be made more tollerable by raising the float heights a bit) you may also now have an oil pressure issue you havent yet noticed.

I would be watching the oil pressure gauge like a hawk to make sure you are not loosing any pressure due to surge when cornering hard also.

[Andy B]

Andy, Are you running a sticky DOT treaded slick type street tyres (like the Toyo RA 1 or R888?)

If you are, besides the fuel issue (which Al was dead right in pointing out may be made more tollerable by raising the float heights a bit) you may also now have an oil pressure issue you havent yet noticed.

I would be watching the oil pressure gauge like a hawk to make sure you are not loosing any pressure due to surge when cornering hard also.

Aaargh! Now you've got my attention.
Could oil starvation cause that kind of misfire so quickly?
First thing tomorrow I will gas up and try the same bend a few times in both directions and with one eye on the road and one on the OP gauge.

The tires are Dunlop Direzza and marked DOT V46K, Treadwear 300, Traction A, Temp A. What does all that mean?

[WayneB]

No oil starvation wont cause the missfire, but it will ruin the engine if you are not carefull.

Those tyres aren't all that sticky and in fact are quite hard for such a light car.

The DOT street/racing tyres have a treadwear factor of 150 to 50, the lower that number the softer and more grippy the tread compound is.

[lwasson]

My '72 Europa used to do the samething on right hand turns. Turned our the triode in the alternator would lose connection when turning right. Re-soldered the connection and that cured the problem.

Louis
'83 Turbo

[clockwork]

I sometimes find this useful Andy http://www.carbibles.com/tyre_bible.html although the knowledge that my tyres are liquorice and my wheels are coconut candy is a touch disconcerting. Clockwork :)

[Autocross7]

Still sounds like a sticky carb float to me. The number 1 carb on the 308 get like this and the car sputters in a tight or long left turn.


Cameron

[Andy B]

Nothing to report as it rained just about all day in fact it's rained most of the week which figures because I took this week off work:crying: Tomorrow promises to be sunny so we'll do our test then.

[Andy B]

One of the club members heard of my fuel problem and showed me on his Europa what he thinks my problem is.
He says it's sort of flooding not starvation.
He suggests that as I corner fast, right handers only the fuel in the Webers sloshes to the left and up on to that tiny shelf or stepped area. It is then sucked down into the little holes on the main jet that are supposed to inhale air only making the mixture not a mixture but fuel only.
He suggests as a test I remove the little inspection caps and place a piece of cut tubing or mylar between the side of the carb and jet and run that bend again to see if my problem is solved. I'll give it a shot at the weekend and let you know if it's plausible or busted.

IF my problem is solved I then have to decide how to solve it permanently. The member with the Europa has top hats fitted instead of the small caps, unfortunately there's no room between the carb and the bonnet on a Seven for that type of conversion.

[Kylie]

Hi Andy hope you can nail this issue, id be interested to know. Like many here I had this same problem in my carbied 89 Turbo Esprit. It was only at track days doing hard right hand turns (hair pin type corners) I would feel a loss of power. I could never work it out until I got the carbies stripped back to new again and all seemed to be ok after that. But I forgot to ask the carb specialist who did the work if he found anything sticking etc so I will never know what the culprit was.

[WayneB]

Too High a float level(s) leaking inlet needles (due to dirt or damage) or just too high a fuel pressure setting are the most plausable culprits (to me anyways).

Andy's friends idea seems to be a Heath Robinson solution to the above, I have run Weber side draft carbed F3 cars on very sticky slick tyres and never had to resort to that kind of modification measure

[Andy B]

Thanks Wayne, excellent point.
So you've answered my question of how to solve the problem but I think I will still use his idea to test the theory as it's so quick.

Thanks again.

[Andy B]

It's only taken 10 months to fix this problem and one I should have discovered way sooner.
Two brass screws in the forward Weber had come loose and backed out all the way to the point they now have polished heads from making contact with the top cover. Looking at a schematic they appear to be the "progression hole inspection covers" but I could be wrong. Either way I can now go through a right hander with my wellie planted firmly on the aluminium and she just keeps pulling.
I guess from now on my screw/nut tightening schedule should also include those hidden.
The really good news, I will attend the Ancaster British car show tomorrow despite the weather man calling for an AM temp of 4c or 39 f and a high of only 59 f :lol:

And yes the roof will remain down and I will don the sheepskin bomber and the wool lined leather Mig helmet.:D