need advice from Weber 38 carb gurus

[itzdave]

alright, so i put my weber 38/38 in my car a few months back, when i was in oklahoma in the summer time (appx 100 degrees, high altitude). well, now im kinda up by seattle (whidbey island) and the temp is averaging 30ish degrees and im at about 10 ft above sea level.
so lemme get to the point, when i installed the carb i tuned it a lil and it ran great. now that im in the total opposite of that, my car runs a lil on the poo side. so what do i need to do to fix it. do i just need to mess with the 'rich/lean' or should i change the jets too?
and for the record... i also got a delta 272, paceshitter header, 2.25 exhaust, flowmaster muffler, no cat, and 'slight' headwork/rebuilt head. in case ya need to know regarding jetting or whatever...
thanks in advance. :cheers:

[forrest89sei]

alright, so i put my weber 38/38 in my car a few months back, when i was in oklahoma in the summer time (appx 100 degrees, high altitude). well, now im kinda up by seattle (whidbey island) and the temp is averaging 30ish degrees and im at about 10 ft above sea level.
so lemme get to the point, when i installed the carb i tuned it a lil and it ran great. now that im in the total opposite of that, my car runs a lil on the poo side. so what do i need to do to fix it. do i just need to mess with the 'rich/lean' or should i change the jets too?


and for the record... i also got a delta 272, paceshitter header, 2.25 exhaust, flowmaster muffler, no cat, and 'slight' headwork/rebuilt head. in case ya need to know regarding jetting or whatever...
thanks in advance. :cheers:

Sounds like a carb, my Truck runs kinda poo during winter

i'd play with the mixture a little bit, might be running a little rich, having a pre heater hose like oem would help the car run better too

[2oodoor]

well, can you describe a typical first thirty minutes of running the car for the day?
All the webers I have need to have the air screw adjusted slightly when the temp changes outside.

Is the choke working?
are you using the vacuum advance?

If you can't get it resolved by adjusting ign timing, checking outside things, you will need to get the jet sizes. You can do a simple check on the idle jets, there are two, one on each side of the carb. Pull one out, they will be the same on the 38 so just one is good, read the number on it and post. If it is smaller than a 60, you may need a 60. How many turns out are your air mix screws anyway?

[itzdave]

i appreciate all the advice guys. but what i was really lookin for was a kinda quick answer as to how to change the carb setting due to temp and altitude changes.
i dont have a garage and theres a ton of snow and ice everywhere, the base has been shut down for 5 days now, so im tryin to do 'too' much to it.
i guess i really want to know if i need to lean it or rich it.
the choke works fine, everything works fine, its a new carb. it just needs a lil tuning...

[2oodoor]

no problem, and yes just a quick fraction of a turn on the idle mix screws on either end, normal.

[2ndGenGuy]

The air is colder, hence denser, so it's probably a bit lean I'd guess. I'm still running the same tune from when I was in Arizona a couple weeks ago. It's running pretty much the same. I don't think you need to re-jet for temp changes, just the mixture screw should do it.

[cygnus x-1]

High temperature and high altitude mean lower air density. Low temperature and low altitude mean higher air density. So it would be running leaner than before. I found that in the winter I would have to bump up one of the jets a level to keep the mixture the same. I forget whether it was the idles or the mains. I would probably try the idles first.

C|

[2oodoor]

High temperature and high altitude mean lower air density. Low temperature and low altitude mean higher air density. So it would be running leaner than before. I found that in the winter I would have to bump up one of the jets a level to keep the mixture the same. I forget whether it was the idles or the mains. I would probably try the idles first.

C|

I was wondering about that, mine idles fine now that it is cold and I reset the idle air but I have noticed it to be little pulsey or almost a faint miss when I give it a good foot full.