Technical What would kill every other cylinder????

Hey H.A.M.B.,

1958 Bel Air with original 283, Carter 4G and points dizzy.

Really weak, rough idle so we started pulling plug wires at the cap. Every other one would stall the engine. Every other had no effect. Seems like it is only running on 4 cylinders !?!?!?

What would cause this?

The Points??

Thanks for any sage advice


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Why not start with a basic tune-up. new plugs, wires, points, condenser. cap and rotor? While you have the dizzy cap off, check for shaft wobble. check dwell or points gap. Maybe coil is weak?

 

What were the results of the compression test?

 

Moriarity , I think has it. Had a 312 do this back in the sixties. Had a spider crawl in the vent of a box Ford carb, die and settled down so that his body was in the jet and it’s legs were draped over the sides. As soon as it came up off idle, I’d lose 4 cylinders. Bones

 

New plugs going in now since he had them. Just had the carb off and installed a new accel pump. That helped the stall problem when giving it gas. New vacuum advance installed. Waiting on timing light from a buddy.


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Based on some quick googling, I’m leaning this direction. The draft tube was smoking to beat hell and I don’t think it did before. Car really has ran much at all in the two years my step dad has owned it.


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I’m hoping to get a timing light and compression tester soon. I’ll update the post if we make any progress.


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Why mess around guessing? It takes three things for an internal combustion engine: fuel/air mixture, compression, and spark. Damn easy to check spark and compression and if they are good guess where the problem is.

 

Agreed, while I’m waiting on the proper tools to diagnose this I thought I would see what this experienced group has to say. It’s such a specific problem that I thought someone might know right away. I’ve been saved here before with my bad motor mount making the engine pull the throttle linkage. I would not have even thought to check that until the H.A.M.B. kicked me in that direction. Onward and hopefully upward.


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Had a SBC do that once.... was a bad coil. Doesn't sound logical but a new coil fixed it up !

 

One of the main jets is plugged. When that happens it will idle just great. but off idle with a dual plane intake you have 4 cyls not getting hardly any fuel. with a open pendulum intake you have all 8 running lean.

 

Still waiting on proper diagnosis tools. I think my buddy is at the bar.
New plugs in.
Sprayed carb cleaner in drivers primary and it sped up rpms. Sprayed in passenger side and no change.

1, 7, 4 & 6 do not seem to be firing.


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My F1 has a 60s SBF. I have never successfully used a timing light on it. As a matter of fact, it's impossible with the present water pump. I have always tuned it by ear.
Growing up....timing lights were for sissies.
The truth is most could not afford one or rather were willing to pay for a gadget to do something they already could do.
Too it seemed those who relied on timing lights were not good mechanics. It was as if, they did not have the full package. They could not get beyond it.
My point is this...
This all can be done by ear with nothing more sophisticated than a set of feeler gauges.
Timing lights are a great tool but don't be a prisoner to it or any tool. Use it but build the skill to have that...Full Package.

 

Looks like the carb as posted before..... Typical dual plane manifold layout.

 

As far as using a timing light, I was “taught” to have just a tiny bit of spark knock under load, then retard the timing slightly and it should be reasonably close with the type of gas being used(reg or premium) and the overall condition of the engine and the way the operator drives his car. Any thoughts welcomed pro or con?

 

Smoke & general description of problem suggest intake gasket rupture. That's not a hard item to check.
You don't need a light ... just start around zero & crank it up until it spark knocks on hard acceleration, then back it off ...

 

I'd agree with that - No timing light is needed esp. if the distributor is correct i.e. already curved right for the application, isn't excessively worn, defective advance plate, etc. Advance till it knocks, back off a smidge, lock it down. The initial # doesn't really matter too much, it's where it tops out at is what counts. A lot of people don't get that.

Another shade tree way was to "power time" against an immovable object like say a ... shade tree ... or against brakes... full throttle while your buddy dialed in the distributor. A vacuum gauge works too. A lot of this stuff is just fun too, I like vintage tools, vintage manuals, a distributor machine would be neat, I sure as hell don't need one though.

When I bought the truck I have yet today the distributor was stabbed 180 deg. out, and the damper weight had slipped. Ran like shit too. Had a hell of a time trying to time it, and figure all that out. Now I could do it all blindfolded.

Anyhoo gasoline turns to goo over time. It kinda looks like apple jelly slugs at first and eventually turns to tar, it will screw up a carb. Most guys use a stabil like product and keep the tank topped off. A partially filled old school metal tank will "breathe" like a bellows between temperature extremes night and day and draw in humid air. This condenses as water on the sides of the tank and will buildup a surprising amount over time. With ethanol fuels absorbing this it makes a mess too. Not for sure but it sounds like a buggered carb problem. I run a few ounces of MMO per tank as well, carbs seem to stay better with it.

 

A jet in the carb could be plugged and only getting fuel to half the motor,I had this happen on two motors,

 

Many years ago I had exactly this happen with a '72 GMC van with a high mileage 350. Turned out the timing chain was so worn it had skipped a tooth.

 

We called it a night. I really appreciate all the feedback. Probably be back at it in the morning and let everyone know what we do and do not figure out. Thanks H.A.M.B.ers!!!


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A poorly seated intake valve can screw up the cylinders fed by the same runner as well. A compression test is a good start, but, cylinder leakage testing would be more definite.

 

Yup, I've seen broken intake valve springs cause the cylinders on the same intake runner to not fire, much like a leaking intake manifold gasket kills the other cylinders on that same runner.

 

Does this look familiar????

 

Mine did something similar.
The first time was s vacuum leak at the bace plate and carb main body.
Also the carb adapter didn’t fit the base correctly. Carb is a Rochester 4 jet

The other time one side of the carb was clogged.

 

i was thinking the carb base gasket also.
chevy made an intake in the late 60's that had a weird base gasket set up, if the regular gaskets were used it ran like crap.

 

WHAT WOULD KILL EVERY OTHER CYLINDER????

The Mafia?

 

I love the posts that you aren’t a good mechanic if you use a timing light.....who would want to be precise about this stuff, same as you don’t have to measure anything or use a torque wrench! A real mechanic guesses!!


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The OP of this thread typifies the all too frequent H.A.M.B. member who seek help, admitting he/they do not know how to solve the problem. So far, so good. Then, qualified and experienced members offer very good advice, usually confirmed by other experienced members.

However, the OP goes on and on for several posts, seemingly ignoring the advice they sought, and keep posting how they are going to pursue the path of their (unqualified) pre-conceived notions.....

I don’t get it.

Ray