Thread: SB 350 - Need some advice

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Again, thanks for all your post guys ! So glad for your help

I will try those thing out in the weekend and let you know how i works out

Hi again guys !

First of all, i finally got the shop manual techinspector1's talked about, and it's amazing, lots of pictures and diagrams, over 1000 pages, and a weight about 8 lbs

But, back on track to my morning start problem ! I was starting to disassembly the carburator, and found out the choke coil, didn't was attach correctly to the vertical bar from the carb !

I attach that again, and now the engine fires right up on a cold morning with 2 pump on the gas !

BUT it will still stall when i put it in gear
I tried to reset the cold idle screw - not better.
Screw it a half turn (to higher idle) - A little better maybe - but still need to hold a foot on the gas when put it in gear.

Do i just continue to screw on that screw - a half turn at a time to it won't stall on me? Or are there other thing to look out for ?

Thanks for your time

You can add a half turn, shouldn't cause any issue.. but what does your new manual say??? LOL..

And don't forget, these cars when brand new needed a few minutes to "warm up" before they would operate "correctly"... it was very common to start the car and wait 3 or 4 minutes before dropping it in gear. Or it would stall.

What does the manual say for a cold - high (fast) idle? Some of them were as high as 1400 or 1500 rpm. Also read up on the choke break ( choke pull off) make sure it isn't pulling to far and undoing the choke completely! It needs to pull a set distance to get the engine enough air and keep the idle cam on the top step.

Again, it should be in that manual.

Originally Posted by 34_40

Again, it should be in that manual.

Yea verily, read and heed.

.

Sounds like your turning up speed instead of adjusting mixture screws




AND HAVE YOU CHECKED THE exhaust crossover valve?

Hi again!

I have add a half turn to the idle, and it helped a lot, but it still need to stand in idle for a half minute before dropped in gear
Does your cars also need that? I mean, do i just need to get used to drive an old car with carburator ?

The manual says raise idle, or adjusting mixture. But when the engine is hot, is drive amazing, so i dont want to touch the mixture screw to much The manuel has some guidelines for perfect mixture, but that include a measurement with some water, and i think this is out of my league

Jerry Clayton:
No i haven't, but just looked it up. I'm not sure i have that mounted on the carb? http://s11.postimg.org/and2rphfn/201...8_17_13_02.jpg

And yes, next project, is to clean the engine bay, and get order in all my wiring :-)

The exhaust crossover valve is mounted in the exhaust header pipe. when it's closed (cold) it forces the exhaust across the intake manifold underneath the carburator to help cold operation.

Originally Posted by 34_40

The exhaust crossover valve is mounted in the exhaust header pipe. when it's closed (cold) it forces the exhaust across the intake manifold underneath the carburator to help cold operation.

Thank you 34_40, i will go look for that in the weekend !

I got another view at this thing, i will try to adjust the carb before change it to a rebuild one, and not just keep raise the idle speed

Here's how i think to do it:
Start the engine and let it warm up. Set the idle screw so that the engine is idling at a normal RPM. Take a small screwdriver and start turning one bleeder screw on one side of the carb inward until the idle either drops or rises.
If it drops, you are going the wrong way, so turn it the other way until the you hear the engine's idle rise back up again. If it raises, keep turning it SLOWLY until it peaks-out and starts to drop again. So what you want to do is adjust the screw until you get the highest idle.
Then go back and re-adjust the actual idle speed screw to re-adjust the idle back down to the normal RPM again, and repeat what you just did to the other side of the carb.
When you are done with that side, and you have found the highest possible idle, go back again and re-adjust the idle screw so the engine is idling back where it should be

How does that sound? And is it right, that the mixture screw, only has an effect when idle?

Can i use this "guide" or do i need to buy a vacum tester and a rpm gauge/tachometer?
If so, can those do it:
Rpm:
Spark Plugs Engine Digital Tach Hour Meter Tachometer Gauge Motorcycle ATV | eBay
or:
2in1 Handheld Digital Photo Laser Tachometer Noncontact Tach Tool Line Speed RPM | eBay
Vacum tester:
Car Truck Fuel Pump Vacuum Testing Carburetor Valve Pressure Tester Gauge Kit | eBay

And i now it's some cheap China stuff, but i'm only going to use it a couple of time - Max - so i dont want to go all out

Sherlock, on your idle mixture adjustment you are correct that it only has effect at idle. The mixture at speeds above idle are controlled by the jets in the carb body, along with the mixture rods that fit those jets by throttle position. The way I learned to adjust was to turn one screw in until the idle speed drops slightly (lean drop), and back out that screw, counting the turns as you go, until the idle speed drops slightly again (rich drop), and turn the screw back in 1/2 way. Say from the lean drop point you turn the screw 2.5 full turns, you'd turn back in 1.25 turns and then repeat for the other side. Another way is to hook up a vacuum gauge and turn in a screw to the lean drop point or even full closed, and slowly back out to achieve the highest vacuum, then repeat for the other side. Any basic vacuum gauge works for this.

For a tune up type tach, a really good investment IMO is a good digital advance timing light. They let you preset your timing target on the timing light screen, and then simply adjust your distributor position until the display reads zero. Another neat feature is that it has a digital rpm display which is very accurate. An example here, but there are many to choose from at a wide range of pricing - Amazon.com: EQUUS 3568 Digital Timing Light: Automotive

Hi Roger!
Thanks for your reply
So my stalling problem when cold could be caused by wrong air to fuel mix?

That sound rather easy to adjust, just with a vacuum gauge Maybe a dumb question, but can i read out the rpm out on a vacuum gauge? (with some formula?) or do i need a rpm gauge to set the correct idle speed?

An advance timing light, sound very nice ! But a bit out of my range when i only are going to use it once or twice

I think i'm order the cheap vacuumgauge and see how it will do
This: Car Truck Fuel Pump Vacuum Testing Carburetor Valve Pressure Tester Gauge Kit | eBay

The seller also have a cheap (awful design) rpm gauge, would't i just could plug it in, and read the rpm off that?
5 1" Adjustable 12V Auto Meter 7Color LED Tachometer Gauge 11K RPM Shift Light | eBay

Sherlock,
No, there's no direct correlation between vacuum and rpm's. Only a tachometer will give you the rpm reading. The vacuum gauge you pictured looks like it should be OK, but it doesn't list any accuracy class, which is really OK as you're really looking for high point, not a specific value. The tachometer you pictured is one intended for permanent installation, but would work OK for a test tach, too. I would look at something better for a permanent mount, it it were mine. You could also get a cheap digital tach - http://www.amazon.com/0-9999RPM-Univ...ive+tachometer

On your stalling, it's very much normal to start the car and then give it a minute or two to warm up enough that it doesn't die when dropped into gear. That's just the way of carbureted engines.

Hi Roger ! Thanks for your quick reply

I guess you right, i just need to accept the car need some warm-up time in the morning

But i still want to check if the mixture is correct this weekend
I order the gauge, and a digital rpm gauge. I dont want a permanent mount - right now
The one you link to, only suits up to 6 cylinder

Sherlock-------


On this engine and carb you have-----------Over many, many years of fixing them----------there are three common areas that have appeared numerous times on tune ups of that combo of carbs and ignitions------One common one is the carb leaking the gas out the bottom of the float bowl and that is an easy fix but carb must come apart. Most kits have the rubber plug that fits in the cavity and seals them--other than that, with it being a cold start issue---------the choke has a high idle factor that rotates a small cam under an adjustable screw that will effect idle spee only while the choke is holding the choke plate closed. Also combined with the choke like the one you have in those photos is a warm air passage under the carb that has warm exhaust gas routed thru it by a valve assembly that is located on the exhaust flange where the exhaust pipe connects. It was very common after a few years that this valve would get stuck open or even removed by hot rodders and then cold start up issues like yours occurred. Sometimes on an engine that ran very rick cold the passage could get blocked in the area under the carb and then warm up periods were lengthened.
Also, but maybe not effecting your deal, the advance meck in the distributor would get sticky and might stick at the advance position and then some boso would set the dist back to remove timing and then it would retard an d then get set maybe at a high speed for total advance which would give an extreme setting when it did finally move , etc, etc, etc, but I don't think that's the issue you are dealing with.


I tried posting a pic of the exhaust valve but it didn't work out-----


But also, you aren't going to fix this by looking on E bay for a solution-----that tack is not something for your car and will be money wasted. You can fix you problems without any gauges --just by hearing and results-----


And a comment on the idle mixture screws-altho it is commonly accepted that they don't effect anything but idle mixture------if the carb idle SPEED screw is holding the throttle plates open excessively, they won't have much effect at all. If you can't get the carb where it idles at 600-850 rpm you have issues and cranking the screws in and out won't solve it- over the years a good starting point for idle mixture screws on any carb has been one and 1/2 turns open from a very gentle bottoming out of the screw-too hard a bottom will cause a flare out of the mixture orfice and destroy the idle passage.

Hi Again
And thanks for your long post Jerry !
I have read about the leak in the bottom of the carb, but not something i will try fix myself - right now

There is no exhaust valve, as far as i can see

But something "new"
I adjust the idle screw, lowering the idle speed, release the air cleaner screw a bit.
And now, when i start in the morning: 3 pump on the gas, turn the key, the engine starts right away, sound likes it gonna die for a second or two but find a steady idle afterwards. And no need of keeping it alive with the gas !

Maybe it's just a lucky week or the problem is gone, i hope for the last thing.

Anyhow, when the winter comes, and the car is putting away, i will change the carb to a rebuild one, and maybe - just maybe - try to rebuild my own one

Rockauto got this kit:
More Information for STANDARD MOTOR PRODUCTS 1585A
Is that "god enough" or which rebuild kit should i buy for a 4bbl quadrajet?