Helix and the cold
 

Hey guys, still proudly running out Helix over here in update NY. Just got some snow yesterday, and having some good fun out there. It runs great for the most part, but I'm still trying to tweak the idle, and it's having a strange issue running cold.

When it's cold, it doesn't seem to like to run in the lower RPM range, but kicks in once it gets up to, say, 20-25mph. Riding it slow makes it miss a lot. Once it's running for a few minutes, though, it doesn't miss a beat. There's some backfiring, but probably due to the crappy muffler decaying on the inside.

As for the idle, it seems to be all over the place. I'm wondering if having the idle screw mixture on the side of the carb too rich would do this? I had it tweaked in the summer so that where it is now gives the highest RPM (then, of course, adjusting the idle speed screw/throttle stop). Now, it seems that it struggles to idle cold, then picks up, sometimes as high as needing to shut it off to switch gears. Sometimes it's quite high when coming to a stop, other times it isn't so bad (sometimes blipping the throttle calms it down a bit).

Might it be a bad choke by chance?

Hope everyone's had a great Thanksgiving holiday, and you're all having fun riding out there! :biggthumpup:

It will naturally run leaner in the cold. I would try adjusting the air/fuel screw first.

Yep,

Cold air is denser then warmer air so there is more oxygen molecules for the same volume. You may have adjusted the carb right to the edge when the weather was warm, so now that it is cold you are probably running lean. Also, backfiring is one of the symptoms of a lean running engine.

Thanks for the replies guys, will have to look into it then. So is that one screw on the left-hand side of the carb, towards the front, the only mixture screw on this model? I haven't found another one, just making sure I'm not missing something!

That is it. I would suggest turning it in (clockwise) until it seats, and count the turns. This way, if you feel you have made it worse by adjusting it, you can always set it back to where it is now.

Hey 351,

does that mean Windsor or Cleveland?

It's a windsor. Lightening short block, gt40 heads, b303 cam, high ratio rockers, performer rpm intake, holley 650 dbl pumper, headers and 2.5' exhaust, flowmaster 3 chambers, aluminum drive shaft, 3.55 gear, 5 speed, blah blah blah. In a bone stock looking '83 gt (aside from the dual exhaust). I drive it to the track (best runs are 12.90's at 108+mph on street tires in the 1/4) and drive it home. About a 50 mile round trip. The car still has factory air condition and cruise.