General Category > Quadrajet Carb Talk and Tips

Rochester 2 barrell to 4 barrell swap, and Cam q.

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geberhard:
First of all I would like to thank Cliff and the gang here for a the wealth of Rochester Quadrajet info!  I ordered the book and it simply rocks!   And thinking I almost fell into temptation and went with another carb.

My car is a 67 Firebird 400 with TH400 auto.  It actually came with the original 2 barrell Rochester, what I link to breathing through a straw for a 400 engine 


I swapped in a Pontiac intake and a Rochester I got off ebay that seems in good shape and supposedly was in a running Pontiac (7029268)

I swapped the intake, installed the carb, and was very excited that the car started right away, and idles smoothly.  I took the car for a drive eager to put the new carb to the test.  In low RPM (primary), the car accelerates fine, but as soon as I go in WOT the car seems to surge\choke, and loose power.  It does not choke and die, just seems to be fuel starved.  I got a tip to check the cam for the secondary and sure enough, the plastic cam was missing, so the fuel metering rod would not lift.  I ordered the cam kit here yesterday so hoping this is the issue 

When the car is in park and I go WOT (not under load) the car seems to accelerate fine without any issues. (I was able to see the secondary flap opening slow with the “good to hear Vuuushhh” sound :0 

Any other areas I should check for?   

Also when I get the cam kit form Cliff, how do I install the plastic cam, do I need to remove the secondary shaft and flap, coil, etc?

Before:



After :D








The carb looks like it had a recent rebuild, so I am planning to run this one as is.  I am picking up this weekend another Rochester I want to rebuild using the parts and tips form Cliff’s book for more HP 

Thanks!

Gui

Cliff Ruggles:
The shaft must be removed to install the cam.  The cam comes with 4 screws for the shaft, and a new spring. 

Make sure to grind off the staked portion of the screws, and they will come right out.....Cliff

geberhard:
So am very STOKED to say the least that the carb and the can live again J

Cliff thanks again and thank you for putting this small kit together!!!  I was wondering about the 4 screws in the package when I opened the envelope, but waas definitely a perfect touch!

I got the part from Cliff (a small envelope with a plastic cam, spring and the flapper 4 bolts), and went to town on it, and was a one hour project (including removing the carb and lines and re-install), so not too bad.  I disconnected all lines, removed the carb, removed the old 4 flap bolts  - of course one bolt took about half an hour : ) , and the whole procedure was very straight forward aside from figuring out the return spring position.

 
Here is the pic of the old cam (or what was left of it).



 
I took the car for a spin and what a difference a little piece of plastic makes!  Of course I had to try the car out, so will not post details here but lets say that my next project will definitely be getting better brakes as the 4 wheel drums will not cut anymore ;)

The carb still has some minor hesitation once in a while when pressing full WOT on the get go, but I will probably do a rebuild in the near future or build a nasty carb on the side with the help of Cliff's book, parts and will probably be bugging yuo again soon with more questions :D

I will do a small write up and post around so hopefully may help others doing a  2 to 4 barrel swap on 67 Firebirds which seems to be the ofdd year (pun intended) for the swap.

Here are a couple recent pics of the Bird :D











http://img.photobucket.com/albums/v256/geberhard/United%20Family%20day%202010/IMG_2910.jpg

 
Cheers and thank you again for the help!


Gui

geberhard:

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