cfm carb for Buick 350...places sell 600 and 650...is that enough?

You said earlier you saw fuel squirting in. The accelerator pump does this.

See that lever attached to the throttle that pushes down on a rod on the front drivers side of the carb? that controls the accelerator pump.

When it pushes down it squeezes a diaphram and pushes gas through nozzels, one into each venturi. This is to offset bog caused by sudden throttle opening, offsetting the introduction of air with extra fuel until the engine can compensate by being able to draw fuel out of the jets.

You will be able to see the fuel squirting in without even looking down the venturi, as it will be misting up out of the carb slightly. The streams are quite noticable and provide copious amounts of fuel per squirt. (get yer mind outa the gutter)

Open up the throttle and you should see (and hear, when the engine is off) the fuel squirting. If it just sputters or trickles in (saying 'yeah they work' because you saw some fuel) the accelerator pump is bad.

Can you see fuel around the accelerator pump rod? When I said 'diaphragm' I mean there's a little rubber 'washer' around the rod that when you push down on it will force fuel through journals that lead to the venturi.

This rubber 'washer' can wear out over time and if it is brittle or cracked or chunks missing (it may have looked 'good' when it was rebuilt and therefore wasn't replaced...if it dried out when being rebuilt and was re-introduced into fuel it could have affected its longevity), will let fuel blow by and not push fuel out properly, allowing some fuel to escape up the top and leak out the top of the carb around the rod.


Maybe some Qjet gurus here can clarify things better than I.

 

Did you say choke flap moves when warm. Choke flap should be tight and not move with engine warm the only way you should be able to move the flap is by moving the throttle a bit and then push down on the flap your over riding the fast idle, Again if you can move that flap by hand then either your fast idle is way off or your choke is not heating up. That will cause a bog when you accelerate if your choke is slamming shut

 

I tested vacuum here are some vids.

The manifold vacuum reads 17.
(when the hiss gets quiet my finger was accidentally over the mic. The hiss is the carb sucking air.

http://www.youtube.com/watch?v=N-o8KVCmqik




Ported vacuum to dist

http://www.youtube.com/edit?o=U&ns=1&video_id=Mfe5NevnQvk

---------- Post added at 08:12 PM ---------- Previous post was at 08:07 PM ----------

I took a look and the squirt is substantial, I figure no prob with the accel pump. No leaky either.

 

Could you make a video of you revving it up some just using the primaries? A few quick jabs to the throttle to show us what it does when it does the 'bog'?
Or maybe make one of you going down the road showing the bog?

 

It look like it says:

1111964 9F16

But the four 1s are so close together they don't really look like numbers just lines.

---------- Post added at 08:23 PM ---------- Previous post was at 08:22 PM ----------

The bog only seems to happen going down the road (with a load) and I don't know how to vid that. It would have helped me long ago if I could have too
Or do you mean just hold the camera while driving?

 

Just record yourself driving up a hill while you jab the accelerator to reproduce the 'bog'

Describe this 'bog' again?

Larry's trying to determine if it's your timing, which it could very well have something to do with it!

We'll get this ironed out. Just have to go through all the possibilities and pinpoint the cause.


Thanks to all involved here who have contributed.

Did you ever check around your intake for leaks? We had discussed this earlier in the thread but I don't remember seeing any response to it other than not to use a flammable gas.

 

If you have 17 in of vacuum at idle at manifold you have a vacuum leak or possible valve train problems. you should have at least 22 .you could add a little inital timing and see if it comes up. Did you mention how old the timing chain is?

 

Here is something to try engine running advance timing slowly and see if vacuum increases try to get it as close to 20 in as you can take it for a ride did it help again (Free and Easy)

---------- Post added at 08:48 PM ---------- Previous post was at 08:36 PM ----------

Ya know people used to use a vacuum gauge to time an engine me included (Now before every body jumps in to say why it's not the right way to do it) I'm not talking about a performance set up when you need to worry about total timing, rate of advance... I'm talking about a bone stock engine that was known be running well but say you had to pull the Dist. for a repair well with a vacuum gauge you could set the timing pretty close with some practice. I worked in shop that repaired Dodge vans thermo quad carbs and lean burn SMEC's they required a mag probe to set timing so all I ever used was a vacuum gauge

---------- Post added at 09:25 PM ---------- Previous post was at 08:48 PM ----------

I'm sorry Buicks/Jason I jumped in to quick on the choke answer with out really understanding what you said. I thought you meant the choke was FLAPING like loose I thing you were just referring to the choke flap by name. My bad.

---------- Post added at 10:23 PM ---------- Previous post was at 09:25 PM ----------

Advance your base timing at least 10 deg. then drive it like you stole it. if it pings back it down till it does not ping. Your running a stock set up with headers. Think of it this way say you rolled in to a Buick dealership in 197!!! with a bog or is it a bog is it a flat spot , or a vacuum leak we have to eliminate all the basic stuff. I can tell you that most all of the time it's an ignition problem

---------- Post added at 10:47 PM ---------- Previous post was at 10:23 PM ----------

I think everybody need's to shut off there SBB performance tips and redirect there attention to stock info for this Buick friend. He can address total timing and other tricks when he can come off idle with out bogging (I'm not even sure he's bogging 1 man's bogging is another mans out of time, bad vacuum leak, erratic valve action, internment miss. The oversight of basics will come back to bite you in the ass every time

 

Ok so this weekend I can try a spray bottle of soapy waterto check for leaks. Wont the fan blow the soapy water away? Where are the places a vacuum leak can be, could it even be in the cabin from HVAC controls? Brake booster? (my pedal does have alot of travel)

The intake gasket used was the tin factory style one with a light skin of high temp silicone around the ports. Yes sequentially tightened. The ends are rubber with silicone on the corners. I've never had a noticable symptom of vacuum leak such as high or wandering idle, and the compression test showed the vacuum remaining steady, but apparently low if I am supposed to have 20. (I had 17) Does it matter that the idle seems low rpm? I dont have a tach to know what rpm it is at I just left it low because I figured low was good. Could it be 17 vacuum at 700 and 20 at 900?
This also could pose a problem setting timing if I dont know rpm right?

Thanks again guys for sticking with me.

---------- Post added at 08:04 AM ---------- Previous post was at 08:01 AM ----------

Thanks could you clarify what I need to do timing wise? Are you saying do not go over 0 initial timing (set it to zero now), and leave my light springs for now? It sounds like ideal is about 30 at 2500?
Also is too much advance then possibly my problem causing the "hesitastion/bog" not sure what to call it...?

 

If you had a vacuum leak that gauge needle would be moving not steady. If you had a vacuum leak big enough to cause a bog/stumble/hesitation your idle would be erratic. Forget power timing (For the love of God and both creatures large and small advance your timing see what happens) why does every body want to over look the obvious. I said to check your timing 2 pages ago. Or maybe you should tear down your carb, pull the front of the engine apart to check the slack in your timing chain, pull the gas tank to check for obstructions, check for week spark (Still can't believe that was suggested) or Power tune a stock engine with headers.

 

So then i wouldnt need a tach or even need to know what rpm it is at that way?

 

The chain could be original I have no idea.

At least 22? Sounded to me like 20 was good. What do you think about the idle rpm question, could 200 rpm equal 2-3 vacuum?

 

Good Luck. Hope you find the problem

 

Timing will be checked this weekend when I have time, possibly tonight. I agree about the needle being steady and no erratic idle i always thought these were tell tale signs of vacuum leaks.

With so many ideas I am choosing to explore ones that dont require tons of work or expense first.

 

Dont close up shop yet larry. Like I said I havent checked timing yet this round myself.
I'll have plenty of opinons I'm sure, but when they stop coming is a different story.
A shop put the crane parts in and set the current timing.
I only get a few hours a week free time sometimes.

 

PLEASE no disrespect to any one on this site regardless of experience or back ground. As far as your post on power timing I could not agree more that is a must read for everyone. My only reason for harping on advancing his timing a little is because it will take all of about 2 minuets (Not that setting up his Dist the right way and using a light would take a lot of time) I'm still not convinced it is the timing but we can all agree its possible. Just as a control advance the timing a little of all the things he has tried bumping up the timing is just so dam easy. I also just want to say I was just trying to help I have been an auto tech for over 20 years mostly involved with drivability problems now having said that no one knows it all I certainly don't but one thing I do know for sure that it's so easy to over look the obvious I do all the time and I know better. But I am truly sorry if I have offended anyone it was not my intention I would like to apologize