Twincam With Poor Performance To 3500rpm

[LaikaTheDog]

Dear people;

Had my plus2 for 6 years now, but broke the chassis two years ago. While I was replacing the chassis I decided to fit Lumenition and recon Dellottos, new leads, plugs and coil.

Set up the timing using a lamp at 12 degrees. (1500rpm)
starts fine
runs a bit lumpy and 'gobbles' when you accelerate, otherwise sounds pretty good.

However I can barely drive it !

I have to blip the throttle to get it above 3000rpm, a steady pedal depression will stall it, once over 3000 rpm the car drives ok, but I dread slowing down !

As I have rebuilt evberything except the engine (was reliable and good before the chassis problems) I guess it should be the dellortos or my timing.

I intend to get it driveable and then drive over to the local rolling road dellorto specialist (10 miles through suburbia)

your advice would be greatly appreciated.

[tdafforn]

Hi,
Sounds like it could be the dell ortos, what does the car sound like when it is dieing?
It Sounds like the car is having trouble on progression from idle to main jets. Does it "pop"? what size idle get have you got?
Cheers
Tim

[type36lotus]

It sounds about what my Elan did with it's new dellortos. Below 3000 RPM (IIRC) is the idle circuit. the correct set of Emulsion tubes, idle jets and accelerator pump jets will set things right. The DBE Elan parts catalog shows the different setups based on the performance level of your engine. It took me about 6 months, lots of different combinations of the aformentioned being mailed from the UK before I finally got mine right. Mine is a very non-stock configuraton so it took a lot of trial and error.

Mike G

[twincamman]

if it ran well before you diddled with it it may be an air leak around the carbs turn on your propane torch [ DONT LIGHT IT] and point the the gas around the carb base a change in idle will confirm a leak ed law

[worzel]

Hmmm- sounds like fuel starvation- is it like hitting a brick wall at those revs- before you start playing with jets (assuming it doesn't have any wildly sized ones) try the cheap options-

sticking floats/float levels
dizzy weights stuck
air leaks
assuming the carbs are reasonably balanced if the dellortos are the later versions set each slow running volume screw to about 5 full turns out- or - when the problem next happens pull out the choke- if the problem disappears/reduces your'e too weak

Regards

John