I've suspected that too early on. But nobody is messing with it besides me.

I too am at a loss as to why this hasn't been solved a long time ago. Everything checks out fine but obviously something is wrong.

 

Ok just checking.

 

Well if you have good ground then your coil is not getting enough amps to fully recharge after each hit. So the spark will be hotter then others and some cylinders not firing at all. All of your plugs should give a bright blue spark, and should jump as much as 3/4 of an inch or more. You can replace the coil, but if the wire feeding your coil, the wire from your distributor are degraded then you will loose spark. Since you have changed your dizzy to EFI, I would suspect the wire from the ignition switch, or even the switch itself as the next location to check. Remember that having enough voltage does not automatically mean your getting enough amperage.

 

I have read this entire thread.
I have also owned many Cleveland's in the past.
Any time you do valve and head work ie: grind the valves and surface the head , you will in most cases need to change the push rod to compensate .
One tool every one of you need to have is a vacuum gauge and the correct way to understand what it is telling you .
There are a number of links around the web that have animated explanations of what is happening , with about every scenario possible with a internal combustion engine.
Even your compression and breakdown tests won't tell you if you have a weak or broken valve spring.
A vacuum gauge will tell you this .
It sounds to me that you may need to get a vacuum gauge , learn how to use it .

My guess from what has been posted is push rod length , or a bad valve spring.
You can determine which valve , intake or exhaust, by listening at the tail pipe and intake manifold.
Good luck.
By the way , all of the 2v intake gaskets are very different from the 4v , and easily noticed that the 4v ones are much different in size .
The catalogs listings , have more to do with other gaskets for that manifold , such as an egr.
I also have never found a Cleveland intake runner to crack , so as to cause an internal leak .

 

No head or block surfacing was done. So deck height and head height are stock. So stock pushrods are what I used. There are no broken valve springs, and all the springs are new.

I do have a vacuum gauge and it bounces between about 12-17 at idle. Indicating a severe misfire problem. And there is a severe misfire. Both 4-7 are dead.

We have 9 Cleveland engines at my place, 2v and 4v. All years in all conditions. There is no way to mistake the 2. The port sizes are radically different.


As for the amperage getting to the coil. I ran a hot 10ga wire straight off the battery to power it. No difference in how it ran. I don't believe it is an ignition problem. I've had 3 sets of plugs, 4 sets if wires, 3 distributors and 3 different coils.

Mechanically speaking, the first engine was worn, but well worthy of operation. The current engine has been completely rebuilt using all new parts. Everything inside checks out fine.

Fuel... Gone through 4 different fuel pumps ( they were all good). I now have used 3 different carburetors. Never any improvement. The intake is the only thing that hasn't been changed.

Truthfully, I don't expect changing it will solve the problem, but I lve got nowhere else to go now. And I wanted one on it anyway.




What may happen soon if I so decide, is another engine swap. My brother has a fresh cleveland on the stand that has been 100% rebuilt new. It is a ready to run engine. I might drop it into my pickup to break it in and see how it runs then. I can't fathom that I would still have problems then, but the way things have been going the past year, I would expect it to be still be wrong. This is a true nightmare.

I have seriously thought of saying to hell with it and buying a different truck. But I can't. Buying a different truck would wipe me out and it would probably still need some work. I have too much time and money invested into this one to walk away. It's sink or swim and I'm holding my own, just under the water. Plus, for some reason, I still like my truck! Even though it's pissed me off to no end. I'm past the angry stage now. I'm in that stage where there is no emotion left.

SNAFU

 

99% of you, including the OP are overthinking and guessing.
It's not a ground issue. It's not a fuel delivery issue, although it may be a lean condition. It is something visually and mechanically related to the two affected cylinders. It's not gremlins or ghosts.
Too bad you're not in L.A.

 

I have read enough to have 100% faith in you Bobby. But I also know Randy (boss 429F100) personally. If he couldn't find it, it's got to be something wild/different. I agree we are now overthinking and guessing but it is only because this has been going on for 351 for So long. It's almost become a lottery to see who comes up with the answer. I can't imagine a cast iron intake being it but it's the only thing left. I truely hope it is the answer.

 

Trying to diagnose without pulling it apart was tough. I figured I would give him an hour or so of my time. But it turned out basically go from scratch and try to eliminate all possibilities prior to pulling intake. Suggested something with dist but that never happened either.

With limited amount of time and he had to drive truck home . . .

No doubt with a bit more time would have figured it out there are only so many things it can be.

As I have said multiple times a vacuum leak or something in the distributor is the issue.

Kind of like a doctor looking for issue with heart patient but patient will not let doc open him up . .

Just because a part has been replaced it does not mean its not the issue!

If the vehicle would have been left here it would have been fixed long ago.

Hard to fix when you cannot do what you want to do to fix.

I have heard it a zillion times before with problems. its not this its not that and it is not this or that.

 

True story. You cannot do a thorough assessment with half of a diagnosis. I agree, the motor needs to come apart.

 

BINGO!

Could be multiple issues but a vacuum leak is one of them . .

Always the same 2 cyl is the dead giveaway. Common cylinders at that.

Intake gasket issue is my guess. I have said that numerous times.

Oh by the way to OP. My 180.00 flashlight was gone that night. Did it get left on seat during test drive?

 

I did not find any flashlight.

I wish we were not so far apart... It would be much easier to work on if we were close and I could leave the truck behind. I am not sure yet when I will have another FULL day to come back and repay you the favor.

Right now my plan of attack is to remove and replace the intake manifold and carb with my new edelbrock sometime late this week or early next week. Depending on when exactly it shows up and when I have enough time to do it. I will be using new high performance fel-pro gaskets as they are what is recommended by edelbrock.

 

If you use the dark colored felpro with the blue seal they are called printo-leaks
vs printo-seals. Last for a while then leak although I have had only one issue out of dozens of sets used. with no coolant in intake it would be different story . .

It is a long drive . . . This week I drive south 3 times for doc visits.

Are the new plugs on 4 & 7 still getting wet? Is it coolant?

We should have pressure checked for kicks too when hot.

only 2 or 3 things possible left it could be.

Has it been same cylinders with each combo?

 

It has been the same 4 and 7 all along. Originally he didn't catch 4 was bad also. Was mainly keyed on 7. Except I remember Once he mentioned something about #8. I want to say plug came back out totally clean. Like brand new. Curious that 4 and 7 are 180 degrees apart in firing order. And 7 and 8 next to each other ..................

 

Yea I just caught 4 red handed. Before I thought it was just 7. And that maybe 8 too. But now that I know it's 4 I've determined that 8 is fine.

 

Well my intake just showed up. So now I'll finish my carburetor and I'll put it on probably early next week.

I'm hoping to heck That this thing will run better with them.