Is it timing, carburetor or something else?

[Grumpy old man]

post 3 pictures one of each side of the engine and one of the carb from the top , All with the air filter off and engine off.

[Steeveedee]

Originally Posted by RichardJ

>>RustyPile, Before you pull the head, do ALL the "easy" stuff first. A leaking intake manifold gasket will produce the same "dead cylinder" symptom as a burned valve. <<

X2

Spray carb cleaner around base of carb and intake manifold.

A carb problem can cause it to blow black smoke, but you said you tried three carbs. I see too many wires. Loose that piece of crap pertronix. A really weak spark with those plugs may be giving you the smoke. Ignition Points are far more reliable, they just need more maintenance.

Those plugs are so grungy, it's hard to see what I'm looking for. The head does appear to have plugs for A.I.R. smog tubes, but that alone doesn't tell me it's a later head that uses tapered seat spark plugs. You should inspect the spark plug hole to see if it is supposed to have the earlier style gasketed spark plugs.

That's a good observation. I noticed a lot of slag(?) on plug #6's seat. Maybe it has the wrong plugs.

OP- Add a pic of the head where the plugs screw in, we can verify what plug type is proper.

[maverickmk]

Originally Posted by Grumpy old man

post 3 pictures one of each side of the engine and one of the carb from the top , All with the air filter off and engine off.

It's a 292. Only one "side."

[Grumpy old man]

Originally Posted by maverickmk

It's a 292. Only one "side."

Well...

Actually 6

drivers side
passengers side
bottom side
top side
in side
out side

[RichardJ]

From OP's video on post #17.
Blue paint and dimpling on block indicates possibly mid 80's Mexican block. No big deal.
Plugs in head for A.I.R. smog tubes. No big deal other than '67 or newer 250 smog head. Again, no big deal.
I think they started with taper plugs in 1970, but that's not written in stone as far as I know.

Looks like two wires from coil to-distributor indicates some kind of non-points ignition module.

Start with checking for the correct plugs and replace with new. Start engine and check for vacuum leaks. Then check out ignition system.

[maverickmk]

Originally Posted by Grumpy old man

Well...

Actually 6

drivers side
passengers side
bottom side
top side
in side
out side

Lol, I almost said "middle side"

The 80 psi on #4 is concerning. There is obviously an issue there. Rings and/or valves. Putting new plugs in won't fix that issue.

[dmjlambert]

My Dad put anti-foulers on his 74 Chevy pickup and it worked for years after that. I wonder what would happen if you put anti-foulers and new plugs, and then check the plugs again after a few thousand miles.

[strummin67]

Originally Posted by RichardJ

From OP's video on post #17.
Blue paint and dimpling on block indicates possibly mid 80's Mexican block. No big deal.
Plugs in head for A.I.R. smog tubes. No big deal other than '67 or newer 250 smog head. Again, no big deal.
I think they started with taper plugs in 1970, but that's not written in stone as far as I know.

Looks like two wires from coil to-distributor indicates some kind of non-points ignition module.

Start with checking for the correct plugs and replace with new. Start engine and check for vacuum leaks. Then check out ignition system.

Sharp eye. I do have a Pertronix system. I've run then in three different vehicles over 13 collective years and no issues with them.

I figured I had a Mexican block since the casting number wasn't listed in any of the books I own or have looked up. I think they're supposed to be better anyway.

As far as the age of the head I could pull the valve cover off and run the casting number and find out.

[strummin67]

Originally Posted by Grumpy old man

post 3 pictures one of each side of the engine and one of the carb from the top , All with the air filter off and engine off.

Let's try one at a time.

[strummin67]

The next one:

[strummin67]

And the top.

[strummin67]

Originally Posted by dmjlambert

My Dad put anti-foulers on his 74 Chevy pickup and it worked for years after that. I wonder what would happen if you put anti-foulers and new plugs, and then check the plugs again after a few thousand miles.

I'm probably not going to be driving it until this acceleration problem gets solved. Kinda dangerous when you can't move any faster than 20mph until you clear 1500rpm.

[strummin67]

I guess this thread is ready for a fork.

[dmjlambert]

stick a fork in the road, it's done?

[strummin67]

Originally Posted by dmjlambert

stick a fork in the road, it's done?

I guess. It was quiet for the last couple of days. Someone requested three pics of the engine and I posted them. I haven't heard anything since.

[maverickmk]

Originally Posted by strummin67

I guess. It was quiet for the last couple of days. Someone requested three pics of the engine and I posted them. I haven't heard anything since.

Yeah, I'm not quite sure why that was requested. In my humble opinion (aka means nothing) I think the head needs to come off. That is what I would do, but, again, I'm sure there will be others that will disagree, given some of the advice already posted.

[HO455]

A couple of things to check. Has the Harmonic Balancer slipped? It not uncommon for the outer ring to move in relation to the inner hub. Find TDC of #1 piston and verify that the mark on the balancer lines up with the pointer correctly.
From the video you posted you have some definite valve train noise. I would adjust the valves. Actually first since it is a I-6 you can remove the side covers and inspect the camshaft for bad lobes and if everything looks good then go ahead and adjust the valves

[strummin67]

Originally Posted by HO455

A couple of things to check. Has the Harmonic Balancer slipped? It not uncommon for the outer ring to move in relation to the inner hub. Find TDC of #1 piston and verify that the mark on the balancer lines up with the pointer correctly.
From the video you posted you have some definite valve train noise. I would adjust the valves. Actually first since it is a I-6 you can remove the side covers and inspect the camshaft for bad lobes and if everything looks good then go ahead and adjust the valves

I'm going to say no on the harmonic balancer slipping. I checked the timing that day and I can still see the timing mark where it should be and no wobble of the balancer itself.

I'm definitely wanting to pull the head but I have no place to put it. With rain coming I don't want to store it on my kitchen table. With that much crud on the plugs it's been suggested that my rings are bad. With the compression readings I've gotten that could certainly be the case.

I'll take a peek at the lifters and if possible see what the cam looks like.

[rpmerf]

I'll ramble a bit...

I would attempt a leak down test before pulling the head to narrow down the location of the compression leak.

I think you can at least narrow it down to rings / valves. Do a compression test, oil the cylinders, and test again. If the number is higher, that points to rings. If the results are about the same, valves or head gasket. Given how wet #3 and #4 looks, rings or head gasket are more likely. However, it is still possible the oil is from valve seals. A puff of blueish white smoke at startup usually points to valve seals. Just try to figure out as much as you can before you rip it apart.

Don't know what is a normal compression test result for these engines. I thought 120psi was typically the minimum, and closer to 150 psi was normal.

I don't think I would be worried about carb, exhaust, or ignition at this point.

[maverickmk]

Originally Posted by rpmerf

I'll ramble a bit...

I would attempt a leak down test before pulling the head to narrow down the location of the compression leak.

I think you can at least narrow it down to rings / valves. Do a compression test, oil the cylinders, and test again. If the number is higher, that points to rings. If the results are about the same, valves or head gasket. Given how wet #3 and #4 looks, rings or head gasket are more likely. Just try to figure out as much as you can before you rip it apart.

Don't know what is a normal compression test result for these engines. I thought 120psi was typically the minimum, and closer to 150 psi was normal.

I don't think I would be worried about carb, exhaust, or ignition at this point.

I really like the leak down test. That's an excellent suggestion.

[Grumpy old man]

Originally Posted by strummin67

I guess. It was quiet for the last couple of days. Someone requested three pics of the engine and I posted them. I haven't heard anything since.

Thee 3 pictures were to get a visual picture of what your working with . Take a picture from the top so we can see inside the carb (remove the spacer ) I'm betting it's black . Your video shows carbon build up in the tail pipe , your plugs look carboned up /worn out . when you removed and replaced the intake did you clean the passages between the intake and exhaust manifold (they get clogged with carbon and restrict heat flow ) To make a long story short I'll bet a Doughnut you have a flooding /mixture problem/ carbon build up along with worn out plugs . and in need of an oil change and new air filter ( does the oil dip stick smell like gas ?)

https://www.youtube.com/watch?v=O1KM_J6zDYs

https://www.youtube.com/watch?v=agAWXnT4-EQ

[Richard2112]

A leak down is useful in this case. Another test you can do to narrow the possibilities is to blow compressed air into the cylinder(s) and listen for any escaping. You'll need some type of air inlet that screws into a spark plug hole. I made one from a compression tester.

To test a cylinder first make sure the cylinder you're going to test is at TDC on the compression stroke (so the valves are closed)

Next, make sure you use a low pressure air source as the air can blow the piston back down into the hole, causing the engine to rotate. Make sure this doesn't happen. Put it in gear, e-brake, breaker bar on harmonic balancer...You get the idea.

Disconnect the PCV line

Blow a steady stream if low pressure air into the cylinder, 10 or 15 lbs should be enough.

Listen for air escaping.

If air comes out the exhaust pipe, it's getting past the exhaust valve

If air comes out the carb, it's getting past the intake valve

If air comes out the valve cover, it's getting past the rings

While you're at it, remove the cap from the radiator and look for bubbles

[Grumpy old man]

Originally Posted by maverickmk

Yeah, I'm not quite sure why that was requested. In my humble opinion (aka means nothing) I think the head needs to come off. That is what I would do, but, again, I'm sure there will be others that will disagree, given some of the advice already posted.

I've played with 250's and 292's before How many do you have ? A leak down test isn't going to give much info if the cylinders/heads are full of carbon .

[maverickmk]

Originally Posted by Grumpy old man

I've played with 250's and 292's before How many do you have ? A leak down test isn't going to give much info if the cylinders/heads are full of carbon .

Jesus Christ, WTF is wrong with some of you and your thin skin? I simply said I'm not sure why. Good lord, some of you need to step away from the computer and get some perspective. You're the second guy to get their panties in a wad because I was trying to gather some info or be helpful.

[strummin67]

Originally Posted by Grumpy old man

Thee 3 pictures were to get a visual picture of what your working with . Take a picture from the top so we can see inside the carb (remove the spacer ) I'm betting it's black . Your video shows carbon build up in the tail pipe , your plugs look carboned up /worn out . when you removed and replaced the intake did you clean the passages between the intake and exhaust manifold (they get clogged with carbon and restrict heat flow ) To make a long story short I'll bet a Doughnut you have a flooding /mixture problem/ carbon build up along with worn out plugs . and in need of an oil change and new air filter ( does the oil dip stick smell like gas ?)

https://www.youtube.com/watch?v=O1KM_J6zDYs

https://www.youtube.com/watch?v=agAWXnT4-EQ

This is the carb that I replaced. And yes, as you can see it's black inside. The mixture screw kept backing off and it would start running rich. I had another good carb so I replaced it. It runs the same so the carburetor is only part of the problem. I'll check the dipstick in a bit.

Edit: I just checked the dipstick and it doesn't smell like gas anymore than usual. It is pretty dark though not due for a change for a little while.