So I have a little issue with my 425. Since installing my intake and Quad I have an idling problem under load.

When in Park or Nuetral it idles pretty good. When I put it into Reverse or Drive it really starts to chug.

Today I installed new Cap, Rotor, Wires and Plugs cause they were very old and under accell I could feel a definate ignition miss. I still haven't checked my timing to see if its good but I figured I would ask.


QuadrajetPorts.jpg

Above you can see a picture of my carb before it was completely together. I currently have the distributor and transmission connected to #1, PCV #2, #3 & #4 blocked off. Can you please tell me what the names of these ports are and if I have them connected properly.

I tried adjusting the idle screws after installing all the new ignition parts based on all the quadrajet adjustment stuff I could find and it definately got better when accelerating at cruising speeds but still really chugs at idle in gear and has some hesitation off the line.

Any help is much appreciated.

 

There is a procedure in the shop manual for adjusting the accelerator linkage to be sure the switch pitch is not engaging during idle. It will make the engine "chug" during idle in gear and the shifts will be a little weird. The idle mixture screws should only affect idle and not acceleration. You should be able to stall the engine by leaning them out. A good way to test to see if they are responding.

 

The procedure I used to adjust them was:
1) Screw them both in all the way.
2) Back both out 2 turns
3) Back off idle stop screw until the engine barely ran.
4) Adjust idle mixture screws 1/8-1/4 turn each until I reach maximum idle RPM.
5) Adjust idle stop screw to correct engine idle.

Yes if I screw them in while the engine is running the engine will die. I was wondering if the switch pitch switch (WOW THATS A MOUTHFULL) might be the culprit. Thanks I will check that.

 

Nope readjusted the switch and still have the same problem. Downshifts better though!!! LOL

I will have to go back and check all the basics on the old girl. Starting with compression, leak down, timing etc etc.

 

you have a vacuum leak. Get a can of carb cleaner and go around the intake manifold and spray the cleaner. You will know where the leak is by the increase in engine RPM when the carb cleaner is pulled in. Be sure and check any threaded bolt holes in the manifold some go through into the air flow. Check around the manifold and head joints. Then check the carb gaskets both top and bottom. You have a vacuum leak.

 

Trans goes to #3
Dist goes to #4
PCV is correct.
I say block #1
Make sure timing is 12/15* @ 900rpm
set idle stop back to 700 rpm
adjust idle/air screws until runs the best
reset idle stop to what you feel is good for you
hook up vacuum advance again, should not change idle
run rpm up to 2000 and see where timing is at
with rpm at 2500/2800 you should have 36* degrees total
if not adjust dist up to 36*, lock it down
bring back to idle and check timing at idle, if idle high adjust idle stop to what you like.
Gene

 

Thanks for the tips.

My tranny and distributor went to the same vacuum port on the 2 barrel. Would it be alright to put them both to #4 or are they different?

 

#3 is supposed to be connected to the vapor canister.
#4 could be connected to the distributor, but my 425 likes manifold vacuum at an idle.
the trans. should be connected to full manifold vacuum.

my guess is that the carb. you have there is not calibrated properly, seeing how it's a 1705 series, likely for a '75 and newer vehicle. i'll bet it's calibrated too lean overall.

need more info on how/what it was calibrated for.


bill

 

The carb was built to order for me . I told them it was going on a 66 425. Hopefully its setup correctly. I haven't had any lean misfire or pinging problems under load or WOT.

 

Distributor should NOT have full manifold vacuum. It should only have ported vacuum. Which is #4

Gene