Buick newbie with '69 430 running problems!

Great to be on the forum.
New to Buicks but 2 months now with my '69 Wildcat 430 4 barrel (Rochester).
Car is very stock. 115k miles. Bought from original owners.

Original problem: a month ago it started "fast idling" when starting cold. It doesn't sound like a normal cold idle, I mean it's screaming away (3000 rpm? no tach but you'd know "this ain't normal"). Luckily, if I took it for a decent high speed drive, it would idle normally again, likely when the engine got warm enough. Lately I'm having to wait longer and longer for it to get back to normal. When I turn the engine off with it fast idling, it keeps spitting and sputtering, trying to keep running ("dieseling" might be the term).

New problem: On my last drive, the idle wouldn't go back to normal and now I'm experiencing hesitation during acceleration. Open throttle and the thing is stuttering and hardly moving. Now it's parked.

Me: moderately mechanical, new to carbs, armed with a service manual.

Question: Do I just drag this to a shop (fingers crossed I pick a good one), or are there some "simple" things I can check off? Where would you start?

Thoughts rolling around my head:
- Could it be fuel pump? Those look cheap
- Do I replace the carb and cross my fingers? Rebuilds from quadrajetpower.com site shows 20 week lead time! Switch to a Holley? Crack the Rochester open and start making a mess?
- Is it fuel related? I ran 87 octane the first couple tanks, then 89 octane. Tank is full.

 

Fast idle cam is part of the linkage and may be hanging.
It is supposed to "pull off" from temp change as engine warms to operating temp and idle drop.

Supposed to set to start with single, full pedal to the floor and release then crank, should fast idle depending on ambient and underhood temp and where the cam selects.

Sometimes the fast idle can be reduced after a few minutes by "stabbing the pedal" quickly (think "blipping" the throttle).

Someone with a 69 big car should have the correct manual and be able to help more.

I have a 68 manual but not 100% certain the same carb was used for both years.

But the choke is on the passenger side, and you want to be able to verify all the rods, cams and adjustments are correct before you start making changes, because you might be able to "fix" it and introduce other problems getting other settings out of bounds.

The linkages are designed to work over the whole range of throttle settings

It is not complicated, just complex and it's all tied together. So, don't fear tackling it.

Can you get clear pics of the carb and linkage on both sides?

 

Where are you located? Welcome aboard!

 

First I’d like to say welcome from south Florida. This is the best Buick forum in town! There’s a bunch of smart people on here. Definitely smarter than me. So I’ll be very general in my answers. Stick with the Rochester. It is a great carburetor! I personally think you can rebuild it easy. You can at least take it apart and clean it and put it back together correctly. Sounds to me like you have something stuck on your choke. Maybe not the choke itself but the part that controls fast idle. I don’t know about that stuff because every carburetor I own has the choke plate literally removed and all the choke objects too. They’re kind of useless in South Florida. I don’t think you can run 87 octane gas in your car at all. It’s meant to run on premium. But that’s not your problem right now. There are a couple guys on here that turn Rochesters into brand new carburetors. Somebody smarter than me will check in soon and lead you in the right direction.

 

I coulda/shoulda did the welcome thing, but I thought I had to bring cookies...

 

Cookies sound like they would be really good right now.

 

Oh yeah, back to the subject. You got a nice looking car there sir! I can’t believe somebody smarter than me hasn’t already helped you. They must be sleeping tonight

 

Thanks all! I found some cookies and ate too many to celebrate the occasion

@Waterboy I was told this car made a number of trips from Canada to Florida with a 20 foot camping trailer behind so it's been in your neck of the woods before

@TrunkMonkey Here's the pics. I remember seeing something in the manual about stabbing the pedal, can't find it now, but I think it's probably applies to this carb. The manual is like a foreign language. I probably need to read it 100 times. They went short on the artwork and figured everything could be done with words. I did get the idea that the problem might be on the choke rod settings, so when it was idling high, I stuck my fingers on the rods and wiggled things a little but nothing happened - was hoping for a lucky win but it might take a bit more.

DRIVER'S SIDE


PASSENGER SIDE

 

This is the choke valve (the plate that is closed/near closed when choke is on) and open, much like it shows in the image when the engine is warm.

When the engien is coild, you should be able to press the accelerator pedal to the floor, then let it back up and that should set the choke to on and this plate should be nearly or fully closed, and the fast idle cam set to hold the throttle to the "fast idle" position.

That's the peice outlined in red, and it is the white plastic part behind the metal plate. (the part in the not enough drawings picture, and the image below it in red circle)





It is hard to describe how all of those parts, and the rods move.

I might be able to make a video of a carb I have tomorrow, if I can see if it has the same choke setup.
Let me dig it out and see, and I'll post back.

If I cannot make a decent video, I'll see if I can post images of it in the various set positions, so you can try manually releasing the fast idle cam while it's running and see if it tames the idle.


I think you are just having the issue with it releasing from the fast idle cam, but the point is "why?"

 

Sometimes all those little levers and widgets and whatzeebops on the passenger side of the carb get gummed up and that caused the whole thing to misbehave.

Take off the air cleaner and spray some carb cleaner on the side, then gently work all the levers and gadgets. Maybe something will free up and you will be back in business? The high idle symptom usually is related to this kind "gummed up" issue in my experience.

Welcome from Seattle!, WA

 

X2^^^ I think you and Mike did a good job explaining the passenger side of the carburetor choke mechanisms. I think it just needs a little cleaning also.
Wildcat, you are correct on the crazy writings in those big fat manuals. When I got my 68 GS way back in 1980 it came with the service manual. I must’ve read that thing front to back four or five times. I called it to Buick Bible. My wife told me to stop calling it that.

 

By the way,in a 69 I would use only 93 octane fuel,as cheap fuel is more costly then good fuel.It does not make sense? Killing the engine with the cheap fuel,I would say its a lot more then the money you save at every fill up.Just my experience and opinion.Bruno.

 

With the accelerator pedal to carb using throttle rod you need to make sure it is freely moving and not binding at the connection joints or hanging up/binding from being in contact with hoses, wiring or anything.

Check to see that this rod moves freely, it should have spring tension, but still have movement.
The bi-metal spring (down in the well in the intake manifold under that rusty plate) is what moves the rod that sets the fast idle cam and when it warms and moves back, the fast idle cam should pull off by itself, or release the load on the fast idle cam when you blip the throttle.

They often get rusty and fail over many years of neglect. Or in a car that has been around near 10 times what it was expected to be in use.

 

Welcome . Stick with the Quadrajet . Its the all around best carb . You just need to find someone that is knowledgeable in their Adjustments that can service and adjust it the correct way . From COLD start to hot idle . Check local car clubs for some recommendations on someone that can do it .

You'll need an " OLD TIMER " as the " TECHNICIANS " of today have probably never seen a actual Carburetor much less work on one . That goes for at least 99% of them .

 

I told you last night some smart people would lead you in the right direction. TrunkMonkey showed you some really cool pictures, and gave you some great insight. Bruno said, like I said, you got to run premium in it, and maybe rec gas, if you can get it, (no ethanol), would be better. Larry the wizard is going to bust your butt on ignition and tuneup. He is right. It’s all interconnected. Hope you have a great time spending some time with your car, because I love spending time with my cars!

 

Thanks all! I’m feeling inspired to call off the tow truck, hold on to the Rochester, and keep my money in my pocket.
That is really great tips and advice, thanks to you all, particularly @TrunkMonkey.
I was ignorant on the first tank fill, then I noticed in the manual that premium was recommended, but I was feeling cheap and still bought mid-grade. I should’ve known better.
Carbs really are fascinating, looking forward to working with them. When I mentioned the carb problems to my local shop they said “we aren’t the shop for that and our old guy got sick”. Good thing there’s experts on here. Will let you know how it goes over the next couple days.

 

Welcome from another Floridian!

You found the right place, the technical information and support here is top-notch!

 

Hi all, things are running better - @TrunkMonkey punching the throttle resets the fast idle cam and settled the idle down back to normal. Both my original problems have gone away once I did this. I sprayed carb cleaner inside the carb and at the linkages. Even though the linkages look old, they seem to be moving smoothly.
Does anything else, besides the bimetal spring, set the position of the fast idle cam? I guess I have some reading to do. For now it’s pleasantly drivable. I would still like to find out why the fast idle cam doesn’t reset automatically.