Weird Motor Mystery

[teachkenpo]

Hi, I am still trying to get a 66 on the road and having problems with the motor running right. Best I can tell the right side cylinders are not running or not running well. Here is what I know:

Symptoms:
1. Right side carbs sucking air very poorly at idle. At least 1/2 of left carbs.
2. If I cover any velocity stack on left side, the car starts to stall. On the right side, no effect.
3. If I spray starter fluid on the left side, the car starts to stall. On the right side, no effect.
4. If I disconnect plug wires on the right side, very little effect.

Known Facts:
1. Carbs just rebuilt. and squirting properly.
2. Sparks plugs tested and firing properly.
3. Compression 130 to 140 in each cylinder
4. Rocker movement visible when valve covers removed
5. I had massive backfires when trying to start the car this spring. Enough to severely bend the throttle valves on both sides.
6. The left side cylinders appear to be running properly

Questions:
1. Could the timing chain have slipped on the right side enough to cause this?
2. Could there be a vacuum leak? Intake manifolds warped?
3. What other things can be causing this anomaly?

Thanks in advance for any advice you can give.

John

[DanielDudley]

First thing I would do is check the plug wires, to see if they are hooked up out of sequence.

Cracked caps can also have odd symptoms that are hard to pinpoint.

As you said yourself, cam timing is critical. Verifying this would be considered a no brainer with a timing belt. Prehaps this would be a good first step, but your compression ratios seem to imply that you are at least in the ball park.

[T77911S]

plug wires as said above
i assume the carbs have been rebuilt after it was bent?
vacuum leak. check manifold gaskets
miss adjusted crab. you could be running on the one side only.

the way i use to do mine was by dissconnecting the linkage between the 2 sides, put the sync on #1, adjust idle screw for a specific reading, then go to #4 and set idle for same as other side. while it is running, i would turn all air corrections all the way in but keep it running. then i would reset the 2 idle sides again for the same reading. you may find that you will have to idle one side down as you idle the other side up. you just need to get the 2 sides close.
then i would go trhough each side and set the lowest to the highest reading on each side, the sides may be different. then i would reset idle to balance the 2 sides and then go thru all 6 again. you may have to repeat steps above to get it all balanced. you want all 6 pulling in the same amount of air.
then i would do the mixture for each.
then you want to make sure the linkage is balanced. i would idle it up, but not so high the sync would peg, then adjust the linkage so the 2 sides are balanced again. i had a way to iddle mine up and it would stay steady.

[Mo_Gearhead]

Quote: "I had massive backfires... "
______________

If you can place your hand over the velocity stacks on one side, with NO effect,
I would suggest you pull the carbs and look at your carb/intake manifold gaskets on that side.

I would actually do both sides since ;
Quote: "Enough to severely bend the throttle valves on both sides."

You may have blown them out.

Given your compression test results, I doubt your timing chain has slipped.

[teachkenpo]

Originally Posted by DanielDudley

First thing I would do is check the plug wires, to see if they are hooked up out of sequence.

Cracked caps can also have odd symptoms that are hard to pinpoint.

As you said yourself, cam timing is critical. Verifying this would be considered a no brainer with a timing belt. Prehaps this would be a good first step, but your compression ratios seem to imply that you are at least in the ball park.

hi DanielDudley, I replaced the plug wires and distributor cap. I also checked the sequence. All is correct.

I did check the timing with a timing light and it doesn't seem too far off. Also, if the timing was off, wouldn't both sides of the engine be having problems?
Thanks,
John

[teachkenpo]

Originally Posted by T77911S

plug wires as said above
i assume the carbs have been rebuilt after it was bent?
vacuum leak. check manifold gaskets
miss adjusted crab. you could be running on the one side only.

the way i use to do mine was by dissconnecting the linkage between the 2 sides, put the sync on #1, adjust idle screw for a specific reading, then go to #4 and set idle for same as other side. while it is running, i would turn all air corrections all the way in but keep it running. then i would reset the 2 idle sides again for the same reading. you may find that you will have to idle one side down as you idle the other side up. you just need to get the 2 sides close.
then i would go trhough each side and set the lowest to the highest reading on each side, the sides may be different. then i would reset idle to balance the 2 sides and then go thru all 6 again. you may have to repeat steps above to get it all balanced. you want all 6 pulling in the same amount of air.
then i would do the mixture for each.
then you want to make sure the linkage is balanced. i would idle it up, but not so high the sync would peg, then adjust the linkage so the 2 sides are balanced again. i had a way to iddle mine up and it would stay steady.

I did rebuild the carbs and used new gaskets for the carbs to manifold, but used the old gaskets for the intake manifold, but they looked fine. Could the intake be warped?

Also, I have gone through all feasible adjustments several times and cannot get anywhere near balance, so I don't think it is the adjustments themselves.
Thanks,
John

[teachkenpo]

Originally Posted by Mo_Gearhead

Quote: "I had massive backfires... "
______________

If you can place your hand over the velocity stacks on one side, with NO effect,
I would suggest you pull the carbs and look at your carb/intake manifold gaskets on that side.

I would actually do both sides since ;
Quote: "Enough to severely bend the throttle valves on both sides."

You may have blown them out.

Given your compression test results, I doubt your timing chain has slipped.

HI Mo, as mentioned above, there are new gaskets on the top and the lower looked fine, but since you are also suspecting gaskets, I will remove everything, check for warpage and see if I can reseal everything better. It didn't occur to me that it could be leaking so bad that it would have this effect. Thanks,
John

[Mo_Gearhead]

Back to square one.

You have had the carbs AND intakes completely off the engine?
You looked into the intake ports and could see they were clear?

I ask this only because I once had a friend rebuild a engine, during which time he had placed clear tape over the intake ports to keep any foreign matter out of the engine as it temporarily sat. He somehow managed to later place the intake manifold back in place ...with the clear TAPE on one bank, still in place!

Are your spark plugs wet/damp on the right bank?

[teachkenpo]

Originally Posted by Mo_Gearhead

Back to square one.

You have had the carbs AND intakes completely off the engine?
You looked into the intake ports and could see they were clear?

I ask this only because I once had a friend rebuild a engine, during which time he had placed clear tape over the intake ports to keep any foreign matter out of the engine as it temporarily sat. He somehow managed to later place the intake manifold back in place ...with the clear TAPE on one bank, still in place!

Are your spark plugs wet/damp on the right bank?

Hi Mo, I did remove both the carbs and intakes and I am sure there was no obstruction. I had big rags in the openings and had to remove them to reinstall. Also, prior to removing and rebuilding the carbs, I was experiencing these problems.

The spark plugs are wet and I have removed and dried them a few times.Why? What are you thinking?

Thanks,
John

[beepbeep]

No vacuum means either leak south of carbs, bent valves or cams which are not timed correctly.
Even if sparks are not firing on one bank, engine should suck air trough carbs anyway.

I would start with possible gasket leaks and work my way down if they are OK...

[Mo_Gearhead]

Quote: "The spark plugs are wet and I have removed and dried them a few times.Why? What are you thinking?"
____________________

If the troublesome (right ) bank is wet/damp they may not be firing? Do all six plugs (both side) appear the same or do the left appear more "normal" (dryer?)

[Mo_Gearhead]

We are also 'assuming' your valves are adjusted correctly? Proper gap.

[304065]

You have an ignition problem. Firing order is 1 6 2 4 3 5 and the distributor rotates CLOCKWISE. See this thread for more:

Before there was BHKZ: SWB engine electrics

If the plugs are wet with fuel on the right side then the engine should at least be running. Since you had this problem before with the carbs and the backfiring I don't think it's the right side carb YET.

Make sure you have the #1 plug wire on the cap over the spot the rotor points to when cylinder #1 is at TDC on the compression stroke and the rotor is pointing at the notch in the distributor housing and the Z1 mark on the pulley is lined up with the notch in the blower housing. Then CLOCKWISE, 6 2 4 3 5 around the cap with each wire to its respective plug.

Good luck!

[kidrock]

My personal experience is to NEVER re-use any type of intake gasket, no matter what they look like. Just too damn crucial to the well-being of a proper running vehicle.

Instead of removing carbs, manifolds etc to check for leaks...work smart, not hard. With the motor running, spray some carb cleaner or quick start around the base of each intake, as well as the base of the carb where they mount to the top of the intake. Your vacuum is being stolen from somewhere, and you've stated that you've eliminated the problem being derived from spark (spark plug wires are not out of sequence, cap & rotor are supposedly fine.)

[Mo_Gearhead]

Now I'm confused John. He states the engine will run and idle(?)

Backfiring is no longer an issue? Or am I misreading this?

[DanielDudley]

Originally Posted by teachkenpo

Hi, I am still trying to get a 66 on the road and having problems with the motor running right. Best I can tell the right side cylinders are not running or not running well. Here is what I know:

Symptoms:
1. Right side carbs sucking air very poorly at idle. At least 1/2 of left carbs.

John

^^^^^^ Camshaft is not sequenced properly in relation to the pistons. Two cams, one for each side. One side is out.

I am assuming you didn't leave rags in the intake runners. Don't laugh - it happens.

[DanielDudley]

Originally Posted by kidrock

My personal experience is to NEVER re-use any type of intake gasket, no matter what they look like. Just too damn crucial to the well-being of a proper running vehicle.

Instead of removing carbs, manifolds etc to check for leaks...work smart, not hard. With the motor running, spray some carb cleaner or quick start around the base of each intake, as well as the base of the carb where they mount to the top of the intake. Your vacuum is being stolen from somewhere, and you've stated that you've eliminated the problem being derived from spark (spark plug wires are not out of sequence, cap & rotor are supposedly fine.)

That is a lot of vaccume to lose. But this is a good move.

[teachkenpo]

Originally Posted by beepbeep

No vacuum means either leak south of carbs, bent valves or cams which are not timed correctly.
Even if sparks are not firing on one bank, engine should suck air trough carbs anyway.

I would start with possible gasket leaks and work my way down if they are OK...

Hi Goran,
There is some vacuum. Just not a lot. For instance, at idle the left bank are running at 12 or 13 on the velocity meter. The right side are running at 6 or 7. When I rev the engine, the meter pins, so I know the vacuum is increased, but it is still weak compared to the left side.
Thanks,
John

[teachkenpo]

Originally Posted by Mo_Gearhead

Quote: "The spark plugs are wet and I have removed and dried them a few times.Why? What are you thinking?"
____________________

If the troublesome (right ) bank is wet/damp they may not be firing? Do all six plugs (both side) appear the same or do the left appear more "normal" (dryer?)

The left bank appear dryer than the right side. Also, I have not adjusted the valves yet.
Could they be so far off as to cause reduced vacuum?
Thanks,
John

[teachkenpo]

Originally Posted by john_cramer

You have an ignition problem. Firing order is 1 6 2 4 3 5 and the distributor rotates CLOCKWISE. See this thread for more:

Before there was BHKZ: SWB engine electrics

If the plugs are wet with fuel on the right side then the engine should at least be running. Since you had this problem before with the carbs and the backfiring I don't think it's the right side carb YET.

Make sure you have the #1 plug wire on the cap over the spot the rotor points to when cylinder #1 is at TDC on the compression stroke and the rotor is pointing at the notch in the distributor housing and the Z1 mark on the pulley is lined up with the notch in the blower housing. Then CLOCKWISE, 6 2 4 3 5 around the cap with each wire to its respective plug.

Good luck!

Hi John,
I will double check the firing order. I did check it early-on hoping that this was my easy fix, but ruled it out after checking one of my books. I certainly could have made a mistake. I will check it out at noon est.
Thanks,
John