Pre 84 Trucks 1st gen pickups

20R Weber Troubles..HOT Exhaust

Thread Tools
 
Search this Thread
 
Old Mar 8, 2013 | 11:10 PM
  #1  
Vang530's Avatar
Thread Starter
Registered User
 
Joined: Feb 2012
Posts: 237
Likes: 0
From: NorCal
20R Weber Troubles..HOT Exhaust

cold start fast idle revs up to 2k rpms or so...this is when the cat turns red and its runs rich and you can hear a very mellow backfire in the exhaust. my best guess is that its dumping too much fuel and runs rich on cold fast idle. spark plugs were a slightly bit more black then I'd like. I have to let it warm up until the fast idle turns off, then turn engine off and on again, after that it runs good and nothing wrong.
when engine finally warms up if I don't turn off and on engine again after fast idle turns off, it runs way rough and I have to adjust mixture screw to get it smooth (running too lean after the rich fast idle)..causing my manifold to get hot. Again, if i turn the engine off and on after the cold fast idle it doesn't happen and runs ok.

short version:
runs rich on cold fast idle and cat gets red hot
after cold fast idle goes away runs lean and rough and manifold get hots
no problem if i turn engine off and on after cold fast idle goes away

running a weber 32/36 with smog legal water choke
new points, new spark plugs, all new vacuum hoses
timed to spec
haven't touched jets, tried to tune mixture screw following redline instructions (2 screws out and adjust from there) etc..
everything else stock...passed smog few weeks ago with very clean numbers.

TIA
Reply
Old Mar 9, 2013 | 11:45 AM
  #2  
gillesdetrail's Avatar
Registered User
iTrader: (1)
 
Joined: Jan 2013
Posts: 803
Likes: 1
From: Montreal, qc
You might have a clogged catalyser, I don't think running rich would make the exhaust hotter, I think it would be the oposite.
Reply
Old Mar 9, 2013 | 11:49 AM
  #3  
INFINITY's Avatar
Registered User
 
Joined: Apr 2006
Posts: 1,043
Likes: 1
From: Show Low, AZ
also a for to drop the pressure from the pump will help the carb. also what is your timing set to
Reply
Old Mar 9, 2013 | 04:46 PM
  #4  
Vang530's Avatar
Thread Starter
Registered User
 
Joined: Feb 2012
Posts: 237
Likes: 0
From: NorCal
it looks like my octane adjuster plastic knob thing doesn't go up and down so i'm guessing vacuum advance shot?.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Zach_trun
Product Reviews
3
Jan 22, 2020 04:42 PM
user 82300
Items Wanted
3
Jan 19, 2016 02:01 PM
urabus
Pre 84 Trucks
11
Nov 10, 2015 07:38 PM
LucasF249
Pre 84 Trucks
1
Sep 8, 2015 01:17 PM




All times are GMT -8. The time now is 12:46 PM.