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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: zieg85 on January 03, 2012, 02:29:39 PM

Title: Rochester Quadrajet differences
Post by: zieg85 on January 03, 2012, 02:29:39 PM

Can anyone tell me if there is a difference between a Rochester Quadrajet  made for a TH350 and a 700R4 in the detent(kickdown) versus the TV cable?

Title: Re: Rochester Quadrajet differences
Post by: Lt.Del on January 03, 2012, 03:56:59 PM

don't know fer sure, but, as for the mounting, here are pics of my '79 before i took my old 350 out years ago....
(http://www.delbridge.net/detent.jpg)


(http://www.delbridge.net/detent2.jpg)

Title: Re: Rochester Quadrajet differences
Post by: HAULIN IT on January 03, 2012, 08:54:07 PM

Zieg, I found no difference between the Two when I was setting up my 700. I had the carb from my '74 Olds engine & one from a 700 equipped mid 80's Implala. My original plan was to change baseplates or at least the arm on the shaft, but found the length, placement, ect. to be identical. I did find one that wasn't the same...it was an old carb (early '70's) & had a pin with a hole for a cotter pin & the placement was not the same. Lorne

Title: Re: Rochester Quadrajet differences
Post by: BADAZ chevy guy on June 25, 2014, 01:58:09 PM

I don't know if you're still wondering about Q-Jet differences or not (Thread is 2 years old) but after asking the same question, and doing a LOT of research, I finely found out. The top pic is the throttle plate 'Bell crank' for a TH350 with kick down cable. The bottom pic is the later Q-Jet for a vehicle equipped with 200-4R or 700-R4 transmissions. Note the differences in the right/rear arm. For the 700R4, the arm has more of a 'Hook' and the location of the cable attaching pin is moved closer to the front of the carb. This is the RIGHT geometry for a 200-4R or 700-R4 transmission.

Title: Re: Rochester Quadrajet differences
Post by: zieg85 on June 25, 2014, 05:54:41 PM

The question back then was for a 1985 C10 5.0L with a TH350C, going to a 700R4.  I was wondering if the carb was different between the 2 transmission offerings.  I did the swap and the trans seemed to adjust fine going to the TV cable.  The guy I sold the truck to had transmission problems but I put a used one in.  He didn't blame me cause he actually had a choice of the Th350C that was in it with no 2nd gear or the unknown used one I put in it.  He had the one rebuilt and it has been fine so far.  I've been thinking about a 700R4 in my C30 in place of the Th400.  I haven't looked at the carb to see if even has provisions for a TV cable since the kickdown is an electric switch on the pedal.

Title: Re: Rochester Quadrajet differences
Post by: Irish_Alley on June 25, 2014, 11:11:32 PM

how much you plan on using the c30? do you have a 700 already? if not it might be a little more expensive but i would recommend the 4l80e