gustavison

hello all newbie here. I have a 59 with dual WCFBs, runs just ok. When im standing behind it , she sounds like a small foreign car. Ive done some tuning on carbs, but not getting anywhere. I can remove plug wires 1-7-4-6 all at the same time and the engine runs the same . The manifold vacuum is 10" at idle, Ive removed a carb and plated the intake in both positions to no avail. Im really baffled by this and would appreciate any help.




Thanks in advance, Gustavison

SDVette

Welcome to the forum.

Wow - if you can pull 4 plug wires and not effect anything, something is obviously wrong!

I don't know of any magic bullets.. you have to run some tests to try to eliminate potential culprits.

Have you checked the timing?
Dwell?
General condition of the distributor and points?
Run a compression test on all 8 cylinders?

Frankie the Fink

You either have serious internal engine problems or tuning issues/component failure with ignition or fuel.

An idling dual quad car is generally running on the idle circuit of the rear carb and fuel is distributed fairly evenly to the cylinders so I don't know why you swapped carbs around -- that's not your problem.

R66

This is odd. The firing order is 1-8-4-3-6-5-7-2, you are not getting spark and / or fuel to every other cylinder in the firing order 1-4-6-7. Thus you are running on 4 cylinders, but they are still opposing and thus it runs.
Basics to find the problem, compression test, spark at the plugs, fuel at the plugs.
What manifold are you running?

Frankie the Fink

There aren't many manifold options on a dual quad C1 because of the WCFB bore size; he's prob got the figure '8' dual quad manifold...

R66

Looks like a dual plane intake and the plane / cylinders fed by the dog-bone openings are getting fuel and the ones fed by the single round openings are not. Should find this out by looking at the plugs to see if there is gas on them.

One possible problem is if the valves were adjusted cold and the intakes are not opening on the 4 missing cylinders. But then it would rattle with the lifters too loose, or the exhaust valves are too tight and and the cylinders are not drawing thru the intake but thru the exhaust. I've seen people try to adjust the lifters without rolling the engine two complete revolutions and the valves were all messed up.
Don't know how one plane of the intake could be plugged and the other not.
The only way it could be electrical would be firing order (wires at cap) screwed up, but don't see how. I would check it anyway.
Probably over thinking this and I am all screwed up.

gustavison

thanks for the inputs thus far. just to clarify,,,, I didn't switch carbs front to rear, I plated the the front carb mounting then the rear. I truly think there is a manifolding problem(crack in the exhaust crossover?), but haven't found anything yet. I have done all the basic checks , compression is fine, scoped the ignition system and it is fine. also the front carb has mixture screws as well, not sure if it is supposed to. compression is 150 across the board, base timing is set at 8 degrees, mixture screws are set at 1 1/4

gustavison

also when I drive the car, it runs on 8 cyls and has no misfire

SDVette

Interesting.. like it's firing on every OTHER cylinder... and only at idle??
Myself, I would drop in a Pertroinx (!!!!)....

But seriously, it would lead me to think it's something with the dist, coil or wires.
Perhaps the coil is weak?
and you didn't confirm checking the dwell.....???? Or is that what you mean by "scoped the ignition" ?

Fred

gustavison

yes I checked the dwell, its 29 degrees. I have a sun ignition analyzer (scope), primary and secondary patterns are fine

gustavison

Yes Frankie that is the intake.

tbarb

I would be looking at the carburetors, what does I did some tuning on the carburetors mean.

When did this problem start, at idle the engine gets it's fuel from the curb idle ports. What happens if the A/F emulsion screws get turned out further, does it get rich etc. Turned in??

R66

Going to leave you to the experts, It looks to me as if both carbs have the same idle/air mixture screws set the same, you should be idling on at least 6 cylinders even with one carb blocked off.
Sorry I can't help.

Ron

gustavison

UPDATE...................
after some thought went with my gut feeling and removed the intake. Inspection determined a couple faults, slightly distorted , pitted mating surface along with low quality gaskets. Runs and sounds like a small block should now.


Next project is carburation, I'd like to find out the correct jetting and needle combination, and power pistion spring vacuum specs. Does anyone have info on the wcfb carbs for this car?






Thanks again for the help from all

Frankie the Fink

The ST-12 manual for C1s is on line now and this will give you some of the details you seek: http://chevy.oldcarmanualproject.com...62csg1413.html

gustavison

Thanks Frankie, I don't have a carb tag to go by, would you know which carbs im supposed to have.

MOXIE62

Just a long shot but if you or someone blank off the exhaust cross over in the manifold and do not have the front exhaust pipes tie together, it will sound like that.

Frankie the Fink

Do the carbs have 6-1299 air horns ?

gustavison

sorry Frankie im on vacation, will look and let you know as soon as I return

gustavison

Hi Fankie, the number cast on the air horns is 6-1271