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 10-05-2020, 07:27 PM   #1
Dave K.
Registered User
 
Dave K.'s Avatar
 
Join Date: Jul 2009
Location: Milwaukee, WI
Posts: 575
Rochester 2GC Woes

I have a 68 K10 with the original 307. Original 2 barrel carb, Pertronix ignition, new fuel pump. I've rebuilt the carb and gone through it a couple of times due to leaks at the throttle shaft. Not a lot of play evident in the shaft mind you but just can't get it to run right and the leak makes me want to upgrade to a more modern, new carb. Any recommendations?

Thanks, Dave.
Dave K. is offline   Reply With Quote
Old 10-05-2020, 07:45 PM   #2
geezer#99
Registered User
 
geezer#99's Avatar
 
Join Date: Aug 2009
Location: Bowser
Posts: 13,512
Re: Rochester 2GC Woes

Those leaks are caused by flooding.
Could be a fuel pump putting out too much pressure or a float level that needs lowering.
Lower the float first.
Go 1/8 inch lower than the normal setting.

Sometimes you can hear the flooding in the carb Venturi. Listen for a crackling sound.

My ‘motors manual’ shows a float setting of 9/16 inch.
geezer#99 is offline   Reply With Quote
Old 10-05-2020, 07:50 PM   #3
Mike C
Registered User
 
Mike C's Avatar
 
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,709
Re: Rochester 2GC Woes

The '70 and newer carbs you can get a new one, but not the 69 and older. You could convert but need to make choke work somehow. Change intake? You can get a throttle shaft bushing kit on Amazon for $40.
__________________
44 Willys MB
52 M38A1
64 Corvette Coupe
68 Camaro 'vert LT1 & TH700
69 Z/28 355 12.6's @110
69 Chevy Short Step 4 1/2"/7" drop
72 Jimmy 4WD 4spd 4" & 35's
02 GMC 2500HD 4x4 Duramax
Mike C is offline   Reply With Quote
Old 10-05-2020, 07:59 PM   #4
notsolo
Registered User
 
notsolo's Avatar
 
Join Date: Apr 2008
Location: Md
Posts: 2,451
Re: Rochester 2GC Woes

Wish I had asked Geezer#99 about this a month ago, too much fuel pressure. 5-6 psi for a Rochester 2 jet.
notsolo is offline   Reply With Quote
Old 10-05-2020, 08:36 PM   #5
dmjlambert
Senior Member
 
dmjlambert's Avatar
 
Join Date: Apr 2016
Location: Cypress, TX
Posts: 3,563
Re: Rochester 2GC Woes

I suggest call National Carburetor and see what they can do for you. They can probably outfit you with a new one exactly like yours, or put together a more modern one with throttle linkage suitable for 1968. They built a Quadrajet with electric choke but push rod style throttle linkage to replace my original Quadrajet for my 1969 pickup. It was inexpensive, it just works, and has a lifetime warranty. For my truck there was no difference in cost between 1969 carburetor or the more modern 1981-86 carburetor.
dmjlambert is offline   Reply With Quote
Old 10-05-2020, 09:01 PM   #6
Dave K.
Registered User
 
Dave K.'s Avatar
 
Join Date: Jul 2009
Location: Milwaukee, WI
Posts: 575
Re: Rochester 2GC Woes

Thanks all for the inputs here. I'll re-check the float level and give it a try but I kinda suspected that perhaps the fuel pressure might be an issue as well and will get a regulator or pull the one off my Scrambler and see if that helps (assuming float level doesn't help things). I had read somewhere that sometimes the new fuel pumps really challenge an old style carb. Since it's 100% original I'd like to keep it that way if at possible. Will update as soon as I get a chance to putz with it this week. Once again, thanks for the quick inputs here. Cheers, Dave.
Dave K. is offline   Reply With Quote
Old 10-05-2020, 09:32 PM   #7
geezer#99
Registered User
 
geezer#99's Avatar
 
Join Date: Aug 2009
Location: Bowser
Posts: 13,512
Re: Rochester 2GC Woes

If you have any rubber fuel line between the pump and carb you could give it a light squeeze and see if that helps.
geezer#99 is offline   Reply With Quote
Old 10-06-2020, 06:11 AM   #8
notsolo
Registered User
 
notsolo's Avatar
 
Join Date: Apr 2008
Location: Md
Posts: 2,451
Re: Rochester 2GC Woes

I replaced the 1st new fuel pump, with a Carter m6624...from Rockauto....Looks exactly the same outside, specs says minimum 2 psi....I think it's going to be ok.....I started to do the fuel regulator also...Not impressed with what's available..... Will follow up in about a week.
notsolo is offline   Reply With Quote
Old 10-07-2020, 11:14 AM   #9
54blackhornet
Registered User
 
54blackhornet's Avatar
 
Join Date: Jul 2008
Location: Eastern Oregon
Posts: 2,257
Re: Rochester 2GC Woes

I had the 2Jet on my 71 C/20 rebuilt by carberatorusa.com , ask for Joe, did a great job for $200.00
__________________
71 C-20
07 Magnum RT AWD
54blackhornet 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 12:42 PM.


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