1964 Some cylinders not firing

[vbudwick]

oh if only everything was that easy.problem still there,
going to look at the carb now, intake is loaded with gas when i took it off. something is going on there. probably should just upgrade

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[Frankie the Fink]

An old mechanic's trick for a stuck float is to take a plastic handled screwdriver and hold it by the tip and sharply rap the sides of the carb's float bowl a couple of times. Might be worth a try.
IMO - getting the original carb "going" (fixed ore rebuilt) are better than introducing more variables into the mix.

 

[doug7740]

doug7740
1955 Thunderbird Blue

 

[Ward 57]

oh if only everything was that easy.problem still there,
going to look at the carb now, intake is loaded with gas when i took it off. something is going on there. probably should just upgrade

Something you may consider is the intake to head gasket or the faces are not meeting properly. Somebody said to use an unlit propane torch and wave it around all the junctions to see if anything changes. You can also use spray carb cleaner to check also. Could be sucking air enough to throw off the combustion mix.
You have to find the issue before you start throwing parts at it. I don't think it's the carb if only a couple of cylinders are not firing. If there is raw gas in the intake manifold it says there is not enough vacuum pulling the air through it. A stuck float valve should affect all cylinders and not just a couple.
Is there something in common with the non firing cylinders? I think you said 3 & 7?
Two different sides but same orientation. 3rd back. I think air flow is your issue. Could be wrong but something to consider.

 

[vbudwick]

Something you may consider is the intake to head gasket or the faces are not meeting properly. Somebody said to use an unlit propane torch and wave it around all the junctions to see if anything changes. You can also use spray carb cleaner to check also. Could be sucking air enough to throw off the combustion mix.
You have to find the issue before you start throwing parts at it. I don't think it's the carb if only a couple of cylinders are not firing. If there is raw gas in the intake manifold it says there is not enough vacuum pulling the air through it. A stuck float valve should affect all cylinders and not just a couple.
Is there something in common with the non firing cylinders? I think you said 3 & 7?
Two different sides but same orientation. 3rd back. I think air flow is your issue. Could be wrong but something to consider.

did the carb cleaner trick... no leaks. good question though. dont see anything with the carb so far, gonna spray clean the crap out of it and try again. i do have a holley 750 sitting there i may just try to see if it clear out. Vacuum... this hole car is a vacuum... ill see if somthing is clogged.

 

[Frankie the Fink]

I agree the carb is a long shot, you would need to have some sort of fuel distribution problem that only affected a few cylinders... Also significant the problem is on two nearby cylinders. I've lost track but if you haven't already done a compression and "leak down" test it might be good to do so. If you are convinced that the plugs are raw gas fouled then it has to be an ignition issue. Don't know if you've considered one of these:

In-Line Spark Checker

Amazing deals on this Inline Ignition Spark Checker at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

I have one but have never actually used it. Supposedly, it gives you a visual indication of the presence and intensity of ignition spark while the engine is running. The old method (Old School again) was to hold a plug near the engine as a ground and examine the spark HOWEVER, I've read where that isn't a good idea with electronic ignition conversions.

 

[vbudwick]

I agree the carb is a long shot, you would need to have some sort of fuel distribution problem that only affected a few cylinders... Also significant the problem is on two nearby cylinders. I've lost track but if you haven't already done a compression and "leak down" test it might be good to do so. If you are convinced that the plugs are raw gas fouled then it has to be an ignition issue. Don't know if you've considered one of these:

In-Line Spark Checker

Amazing deals on this Inline Ignition Spark Checker at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

I have one but have never actually used it. Supposedly, it gives you a visual indication of the presence and intensity of ignition spark while the engine is running. The old method (Old School again) was to hold a plug near the engine as a ground and examine the spark HOWEVER, I've read where that isn't a good idea with electronic ignition conversions.

yeah we did the compression test... 125 all around. i have seen those and havent tried one either, maybe now is the time. wish i had a 6a box around to intensify the spark to see if thats it.
good stuff thanks

 

[vbudwick]

Now I see this from an old post about 65 & 66 shop manuals that show this. What do you think..?

 

[74 Harley]

It's a typo.

 

[vbudwick]

It's a typo.

Ok

 

[Ward 57]

yeah we did the compression test... 125 all around. i have seen those and havent tried one either, maybe now is the time. wish i had a 6a box around to intensify the spark to see if thats it.
good stuff thanks

You have spark, You have fuel you just don't have oxygen. #3 & #7 are just opposite of each other and all the other cylinders are firing fine. Every thing else sounds good and healthy. I'd pull the intake manifold and take a look. Not an involved process and a couple of gaskets. I still think you have a vacuum issue there. Seen it before. Getting gas but sucking so much air from other than the carb and tight manifold not getting the right mix on top.

 

[vbudwick]

Ok carb cleaned, check.
Vacuum lines changed, check
No luck, starting hearing the exhaust pop a little, shut it down.
Pulled valve covers and noticed sludge, grit on lifter arm bolt. Just the one, and where I am having the issue.
Push rods look ok but haven't taken any thing apart yet

 

[Ward 57]

Ok carb cleaned, check.
Vacuum lines changed, check
No luck, starting hearing the exhaust pop a little, shut it down.
Pulled valve covers and noticed sludge, grit on lifter arm bolt. Just the one, and where I am having the issue.
Push rods look ok but haven't taken any thing apart yet

Actually those are REALLY clean. You can expect a little on the lifter arms as they are not washed by the oil. Its the base and valleys that will collect gunk and they look clean.
Compression is excellent, you've got spark, engine is clean, I saw on a restoration ( Fantom Works ) they had exactly the same issue more than once. One, the intake was hitting something in the valley pan and not seating, the other was that the intake was not mating to the heads and the attachment angle was just a smidgeon off. Too much that they couldn't be milled to fit. basically the wrong manifold. Even a vacuum gauge didn't detect it.
I still think that is your issue. Either mis-milled surfaces or a gasket that wasn't torqued correctly and left wrinkles and finally failed. couldn't hurt to pull the manifold and take a close look.

 

[vbudwick]

Actually those are REALLY clean. You can expect a little on the lifter arms as they are not washed by the oil. Its the base and valleys that will collect gunk and they look clean.
Compression is excellent, you've got spark, engine is clean, I saw on a restoration ( Fantom Works ) they had exactly the same issue more than once. One, the intake was hitting something in the valley pan and not seating, the other was that the intake was not mating to the heads and the attachment angle was just a smidgeon off. Too much that they couldn't be milled to fit. basically the wrong manifold. Even a vacuum gauge didn't detect it.
I still think that is your issue. Either mis-milled surfaces or a gasket that wasn't torqued correctly and left wrinkles and finally failed. couldn't hurt to pull the manifold and take a close look.

Gotta go there next...
Thanks !!!!

 

[74 Harley]

Before you go any further start the car with the valve covers off. Watch the valve action and make sure they are all moving about the same.
Your engine is incredibly clean. It has no miles on the top end. I used to rebuild engines for a living some time ago.

 

[Ward 57]

Before you go any further start the car with the valve covers off. Watch the valve action and make sure they are all moving about the same.
Your engine is incredibly clean. It has no miles on the top end. I used to rebuild engines for a living some time ago.

It is a start, but the cylinders are getting fuel but the wrong air mix. Too much air causing it not to fire even though the fuel is there. The air is blowing out the flame.

Ok carb cleaned, check.
Vacuum lines changed, check
No luck, starting hearing the exhaust pop a little, shut it down.
Pulled valve covers and noticed sludge, grit on lifter arm bolt. Just the one, and where I am having the issue.
Push rods look ok but haven't taken any thing apart yet

Before you pull the intake manifold, Double check the valve clearance. Popping in the exhaust is either unburned gas firing in the mufflers as in back fire or the exhaust valves not closing all the way. Either way the top end is where you want to focus. Everything else sounds like it may have been recently rebuilt but the job was not finished off correctly.

 

[Frankie the Fink]

Yes, "After Fire" is raw gas igniting in the hot exhaust assembly...
A symptom of your plugs in some cylinders not providing combustion.
(Although it can sometimes be caused by a loose exhaust manifold or blown gasket).

At this point I am wondering about your cam lobes for those cylinders.
Definitely watch the valve action with the engine running, maybe just an
adjustment if you're lucky or a lifter not pumping up.

 

[vbudwick]

You guys are great. I will do what I am capable. Yes I do believe this was rebuilt prior to me getting it. Head gaskets still look clean. Keep you posted

 

[74 Harley]

One of my concerns is that you said the manifold had standing fuel in it when you removed the carburetor.

 

[vbudwick]

One of my concerns is that you said the manifold had standing fuel in it when you removed the carburetor.

Yes it was very wet, not necessarily puddles.