The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 07-08-2005, 12:39 AM   #1
walker
Registered User
 
walker's Avatar
 
Join Date: Jul 2003
Location: north of Phx AZ about 30 miles
Posts: 698
Need some Emissions help

Well it is time for emission test again on my '67 C-10. Last year when I went through I was right on the allowable for hydrocarbons and just under for CO. It was a little too close for comfort for me to go back again this year without trying to improve it a bit. So If you all can help me out with some suggestions I would appreciate it.
I have a '67 C-10 with a 350/400 combo. It has HEI, Performer intake with a 1406 edelbrock, no EGR, running at about 10* initial with 32* total timing. Idle is at about 700 in gear. The engine was a GM crate motor with about 6,000 miles on it, about 3,500 since last years emissions test. I just changed the oil, am running mobil one, and have a new air filter in it.
Thanks again, Andy
__________________
Andy,Phx AZ
'67 C-10 (Ahhh, done at last. Well there is that disk front end I want to put in and...)
"23 C-Cab-sold
'48 Ford 8N tractor(still working)
'67 Scout(Now on the road)
'70 MG B.-sold
walker is offline   Reply With Quote
Old 07-08-2005, 12:54 AM   #2
kwmech
Senior Member
 
Join Date: Mar 2003
Location: Colfax-California
Posts: 8,499
Bringing the base timing down will help with the HCs. Say set it a 4-6, adjust idle to about 700 and adjust the carb to match.
kwmech is offline   Reply With Quote
Old 07-08-2005, 07:39 AM   #3
68C15
blood type; Retumbo
 
68C15's Avatar
 
Join Date: Jan 2004
Location: next to my reloading bench
Posts: 10,269
do they run it on the rollers or test at idle?
__________________
Man rule #77...if you own a 67 stepside with a caddy 472 you will never be in danger of loosing you man card
68C15 is offline   Reply With Quote
Old 07-08-2005, 01:43 PM   #4
tomatocity
Registered User
 
tomatocity's Avatar
 
Join Date: Jun 2005
Location: Sacramento CA
Posts: 1,255
Quote:
Originally Posted by kwmech
Bringing the base timing down will help with the HCs. Say set it a 4-6, adjust idle to about 700 and adjust the carb to match.
agree with kwmech. you can also change to the leaner metering rods that came with the 1406. CRC sells a products to run in your gasoline. I forget the name but it is some like " pass smog now". It seems to work for me and was suggested by a technician that repairs failed smoggers. The biggest difference you can make is change the oil and oil filter just before you go to have the test performed.
* change oil and filter
* reset timing
* 1406 metering rods
* CRC engine cleaner
* make sure your plugs are clean and set
* new or clean air cleaner
__________________
Got bored, sold everthing. Got bored, looking for a 1960-66 C-10. Want to build my last truck.
tomatocity is offline   Reply With Quote
Old 07-08-2005, 04:58 PM   #5
Mixup
Registered User
 
Join Date: Jan 2002
Location: Henderson, NV
Posts: 358
I have just about the same setup as you and I had to retard the timing way back so it just about ran and turn the idle mixture screws way in. It passed everytime. Now I have classic plates on it so I don't have to get it smogged anymore.
__________________
1980 Chevy Shortbed Pickup

1969 Z28 engine

Turbo 350
Mixup is offline   Reply With Quote
Old 07-08-2005, 08:12 PM   #6
ratfreak888
Registered User
 
Join Date: Jun 2003
Posts: 104
if your taking an idle test, adjust your idle rpm to the highest allowable during the test
ratfreak888 is offline   Reply With Quote
Old 07-08-2005, 09:08 PM   #7
walker
Registered User
 
walker's Avatar
 
Join Date: Jul 2003
Location: north of Phx AZ about 30 miles
Posts: 698
Unfortunately they run it on rollers with a variable speed, so they have opportunity to stomp on the peddle, and they do. In fact, if they drive on the road like they drive on the rollers they would be terrors of road.
I also read last night that disconnecting the PCV valve from the air cleaner might improve emissions as well.
When adjusting the timing to 4-6 and setting the idle at 700, what is the best procedure of setting the carb? Do I just run the mixtures screws in till it stumbles and back it out just a hair?
Thanks again, Andy.
__________________
Andy,Phx AZ
'67 C-10 (Ahhh, done at last. Well there is that disk front end I want to put in and...)
"23 C-Cab-sold
'48 Ford 8N tractor(still working)
'67 Scout(Now on the road)
'70 MG B.-sold
walker is offline   Reply With Quote
Old 07-09-2005, 12:00 AM   #8
rage'nrat638
Account Suspended
 
rage'nrat638's Avatar
 
Join Date: Mar 2003
Location: ** THE FALL GUY **CHICAGO IL
Posts: 5,883
go to auto zone buy a 4 barrel adaptor 16.00
to a two barrel carb....
slap a two barrel on.....you will pass with flying colors.....
reinstall your four barrel......


trust me .....i did it cut every thing into half.......i am leving the two barrel on.......4 more miles per gal........
rage'nrat638 is offline   Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 08:04 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com