1974 TCS = Idle Issues

[CCM911]

Hello:

Currently refreshing 3797R.  The carbs have been rebuilt and car will start fine.  Yet when I let my foot off the accelerator pedal it dies.  I have the idle screws turned almost all the way in, yet to no avail.

Would an empty dashpot affect idle?  Is there anyplace else I should be looking?

Thanks so much.

[jbcollier]

Can you tell us some history of the problem?

Why did you rebuild the carbs?

The carbs are attached correctly with the proper flex mounting and new o-rings?

Was the engine idling before you rebuilt the carbs?

What did you change when you rebuilt the carbs?  Throttle shafts?  Throttle butterflies?  Diaphragms?  Needles? Needle jets?  Decell valve diaphragms?  Idle compensation valve seals?  How were the iC valves tapered needles and seats?

Have you done any tune-up related items?  Points and condenser?  Timing?  Valve adjust?  Compression test?

How old is the fuel?

[4129R]

When you say the engine dies if you take your foot off the throttle, is the engine up to temperature when this happens?

Engines with carbs (unlike injection) will not respond properly unless they are up to operating temperature.

[CCM911]

Hi:

I bought the car from a friend of a friend.  It was verified that the carbs had been rebuilt.  Not sure of the details.  Everything appears to be correct in terms of mounting, and I replaced all fuel lines and added a facet fuel pump.  I bought the car non running, as it had sat for about twenty years or so in a garage.  The car has a verified 10,922 miles on the clock, so I would assume the engine is OK.

Once I completed all the fuel items, the car fired right up.  The engine sounds great, and it revs just fine.  The issue is that it will not idle.  I'll run it longer today to see if the temp issue is what is going on.


Thanks so much for the feedback.

[jbcollier]

Make sure you have a roll-over switch on the power to the fuel pump.  Also that all tees and fittings are metal, no plastic.  Lots and lots of Europas have engine fires and burn to the ground.  Fibreglass contains all the required elements for a fire including oxygen.  They are very difficult to extinguish once they start burning.

What is the pressure rating of the fuel pump?  Stromberg carbs require low inlet pressure, 2 to 3 psi is ideal.

[CCM911]

I am back on the Lotus Twin Cam project once again. 

I just went through the factory manual, and there really isn't much about the throttle linkage.  Is there a decent reference out there to which I could refer?  I still can't get the car to idle.

All fuel lines freshly plumbed with metal tee junctions.

I just don't know how to get the initial settings done.  Not even close to tuning at this point.  I just want it to idle.

[Grumblebuns]

So I'm assuming that you are using the choke to start the car. Once the engine fires up will the choke keep the engine running or do you have to depress the throttle to keep it running? What's the lowest RPM that the engine will run at before dying? Is the linkage connecting the ZSs snug so that both carbs are operating together?

[EuropaTC]

In addition to Grumblebuns' comments, can I ask if you got the car with the carbs in place or did you mount them yourself ?  I'm just wondering if the linkage is sync'd properly or if one carb is slightly open and the other being forced shut by the linkages. 

Generally speaking if there's no internal faults with the carbs then if you wind the idle adjustment screw to a ridiculous amount you should be able to keep it ticking over even if it's wildly out of balance. As you reduce the idle speed any imbalance will be clearly seen. 

There's a reasonable section on fault finding with Strombergs in the manual and as you've inherited these carbs as "rebuilt" then I'd treat everything with suspicion and strip them down to check everything is in order.  But before that I'd check the ignition system, that it's advancing properly and not sticking given that the car has been standing for so long.

Brian

[brucelotus26r]

I would look for air leaks, try plugging vacuum lines, brake servos & distributor vacuum retard .