Stock Sigma Turbo - split personality?

[Shifta]

A question for the few peeps left driving stock Turbos - how does you car drive when cold? This morning I flattened yet another battery and the battery pack because the thing just won't start/run when cold. After finally getting it to fire, over 10 minutes of backfiring and stalling while manually keeping the revs up. After about 10mins, I finally got it to idle and even then it will drove like a pig for several kilometres. Once warm - not a worry in the world - drove all the way to Hahndorf and back and didn't miss a beat all day. So why is it a different car when it's cold? The carby has been rekitted, the choke works, all the plugs are new as well as the dizzy cap and rotor button. I know the carby setup is a pain and that's why most people go injected but surely it should run better than this? Any ideas? There's no way I could use the thing as a daily driver at the moment as I just can't rely on the thing starting when I need it to.

[amgis_obrut]

mines stock, need to crank it for about 10 seconds if its been sitting for few days regardless of temp but its never been a pain to start

Its a bit of a pig to drive until its warm but it will still idle ok


I would still like to do a Patton Machine injection conversion as I still want it to look std

http://pattonmachine.com/

[Shifta]

Good point, might replace the thermostat and see what happens! I was also wondering whether the spark plug temp rating makes any difference? I know there are hot and cold plugs, but not sure if that makes a difference in this case.....

[Sigmaproject]

They are not a good cold starter. I have mine set so that at full choke it is idleing at 1500rpm. No trouble actually starting up though

I like to leave mine to idle in the driveway until it has warmed up a bit. Once warm, no problem

[Shifta]

I've got the Choke idle backed right off as my accelerator spring is too strong and pulling the choke cable isn't enough to get it to move. The Choke butterly moves freely though and lately I've been popping the bonnet and adjusting the idle right up before trying to start it.I might take the car down to the Carby place that re-kitted it and see what they reckon.....

[Sigmaproject]

You dont need a strong spring, because the carb already has a return spring on the linkage. The spring only has to be strong enough to pull the throttle shaft back onto the idle stop when you take your foot off the go pedal.
If you are not using your choke when the engine is cold, its little wonder it wont run right.

[Shifta]

Cool mate. I'm using the choke, just the screw that brings the idle up at the same time has been backed right off. I'll try a lighter spring tommorow and see if that helps although the idle isn't really the issue as I've set the non-choke idle as far as it goes.

[Shifta]

Had a play around with the car this morning. Removed the extra return spring, turned the main idle down, adjusted the choke idle up. Greased a few things and gave it a crack. Seems better but was still hard to start initially. I tried a lighter spring on the return but still no go so will play around with it a bit more. I think I may need another choke cable as it's a bit stiff. It's a fairly new, after-market one but doesn't seem to be doing the job.

[Sigmaproject]

For the car to start cold first thing in the morning, you have to be able to give it full choke. And at full choke it must idle at 1500-1800 rpm.
During the initial start up you do not have to touch the accelerator pedal. There is no accelerator pump to add fuel, so giving it throttle is counter productive. It just adds more air, when you really need more fuel.

Most important , no vacuum leaks. That includes the throttle shaft of the carby, around the insulator block between the carby and the turbo, the o ring where the carby adapter bolts on to the turbo, the o ring in the crossover, the joint between the turbo outlet and the crossover, joins in the signal pipe to the wastegate, The fittings on the wastegate, signal hose from the inlet manifold to the dizzy, the dizzy diaphram on a turbo model, and leaks around the inlet manifold.

The O ring that fits between the Carby adapter and the turbo was the last thing to give me grief. I had to turn it around. One side fits in a groove and basicly stays in shape. The other side just fits hard against a flat surface, and goes flat, and leaks. Before that it was the fitting on the wastegate that was loose , and sucking in air ,and screwing up the idle bigtime.

[Shifta]

That's interesting about the accelerator pump issue ( or lack of ). I've never really thought about it but it definitely makes sense. Looks like I have a few more things to keep an eye out for

[sigtool]

i found i had to have full choke any less and she was a bit a mongrel also i had an electric fuel pump not mech which i found made it easier to start
even middle of winter it was a flick of the key and she was off.


cheers

[Sigmaproject]

Mine only comes out of the shed every Sunday.
I have an electric pump ,so I give it around 5 seconds of pump time before I hit the start button, just to fill the float bowl.

[Shifta]

More good stuff! I'm still running the mechanical pump but I'm thinking at high revs it may be running out of fuel so I'm thinking of going electric. It might help both scenarios.....