Back firing part 2

[bearsden]

OK,After going over everything from triple checking plug wires and vacuum leaks,intake and exhaust leaks i still can't get this thing to run longer than a minute and the whole time it still back fires.So i removed the valve cover again and everything looks great except...as i explained in a previous post that the last rocker arm is loose.So i'm kind of at a loss.It was not loose when i took it apart.I have yet to even get the motor up to temp since getting it all back together.any more suggestions would be appreciated..... again! thanks guys

 

[Barry2]

"since getting it all back together"

Are you sure your got the plug wires in the right order?

 

[hole]

I'm still thinking its timing. Have you verified that while on TDC on #1 cylinder that the rotor lines up with #1 plug wire? Also try pulling the plug wire on the cylinder that has the collapsed lifter to see if it makes a difference.

 

[jdarg]

Assuming the timing chain was installed correctly, it sounds like your distributor is too far retarded. I had this problem on a motor and it turned out the TDC timing mark on the crank was off by like 20 degrees.

Try advancing it more than you "should" and see if it helps it idle properly. If so, I'd get a piston stop and validate TDC is in the right place because it probably isn't.

 

[bearsden]

Yes, I marked them all and then re checked again because...you never know...

 

[bearsden]

I'm still thinking its timing. Have you verified that while on TDC on #1 cylinder that the rotor lines up with #1 plug wire? Also try pulling the plug wire on the cylinder that has the collapsed lifter to see if it makes a difference.

I will try to check all that out tonight.And get back with you.thanks again!

 

[bearsden]

Assuming the timing chain was installed correctly, it sounds like your distributor is too far retarded. I had this problem on a motor and it turned out the TDC timing mark on the crank was off by like 20 degrees.

Try advancing it more than you "should" and see if it helps it idle properly. If so, I'd get a piston stop and validate TDC is in the right place because it probably isn't.

Supposedly there's 20,000 on a total rebuild according to the p/o and there has been some stuff done to it I'm not familiar with. The dist. is not stock and it has the weber 32/36 dgav. The plugs when I pulled the head were black and very sooty.So I'm trying to figure out what i have and at the same time get it running.so all your help is much appreciated!

 

[bearsden]

Supposedly there's 20,000 on a total rebuild according to the p/o and there has been some stuff done to it I'm not familiar with. The dist. is not stock and it has the weber 32/36 dgav. The plugs when I pulled the head were black and very sooty.So I'm trying to figure out what i have and at the same time get it running.so all your help is much appreciated!

I will be working on it again tonight and get back with you!

 

[Jimbos76cj]

How are you verifying that its at TDC? every now and then a balancer will spin the outer collar on the rubber part causing the timing marks to be off by a few dergrees. can you take the valve cover off to check?

 

[bearsden]

How are you verifying that its at TDC? every now and then a balancer will spin the outer collar on the rubber part causing the timing marks to be off by a few dergrees. can you take the valve cover off to check?

I'm going to take the valve cover off again tonight. How do you check for TDC ? I've never had to do stuff like this before but this forum has helped me learn alot! I've never even pulled the head off a motor till last month.I just always did the small stuff . but i'm lovin this jeep thing !!! wish I would've bought one long ago !

 

[bearsden]

never mind , a ton of info out there already........

 

[jdarg]

I'm going to take the valve cover off again tonight. How do you check for TDC ? I've never had to do stuff like this before but this forum has helped me learn alot! I've never even pulled the head off a motor till last month.I just always did the small stuff . but i'm lovin this jeep thing !!! wish I would've bought one long ago !

This is how I do it.....

1. Insert piston stop. Wrap masking tape around the damper.
2. Rotate crank one way until piston lightly contacts stop.. Mark tape where the TDC mark is on the timing cover.
3. Rotate crank the other way until lightly contacts stop. Mark on tape TDC again.
4. TDC is -exactly half way- between the marks, measuring the shortest path between the two marks (don't use longest path.) Mark it with a white crayon, paint, etc. and remove the masking tape.

 

[Jimbos76cj]

To check for Tdc I rotate the motor while watching number one exhaust gala e open and close. As the exhaust valve closes the intake should start to open. Keep rotating it until the intake closes.. Now that's where you want to insert the piston stop or I usually a small long Philips screw driver inserted into the spark plug hole to feel when the piston comes all the way back up. When it comes up to the top you are now at TDC on the compression stroke. Once this is done I would pull the cap off to make sure the rotor is pointing to #1 cylinder and the timing mark on the balancer should be at the 0

 

[Hedgehog]

Here's something a bit different. How's your fuel pump? Sometimes it is very difficult to tell the differance between fuel issue and spark.

 

[bearsden]

I'm still thinking its timing. Have you verified that while on TDC on #1 cylinder that the rotor lines up with #1 plug wire? Also try pulling the plug wire on the cylinder that has the collapsed lifter to see if it makes a difference.

okay so i got it running and it was still popping,I pulled the plug wire on#6 and it went away. that was the cylinder that had the loose rocker arm.Took the valve cover back off and double checked everything.the push rod is straight,but the rocker arm is loose.theres about 20,000 miles on the rebuild. Should i just replace that lifter? or am i looking at a full winter project? as always,thanks!

 

[hole]

I would replace all of the lifters

 

[NorthwestCJer]

I still don't think your timing is correct. However, there is 2 rocker arms for each cylinder. Is only one of the two lose? You may have a burnt valve or a bad valve seat or bad broken valve spring. You had it apart, according to previous posts. how far? Did you have the head off?

 

[bearsden]

I still don't think your timing is correct. However, there is 2 rocker arms for each cylinder. Is only one of the two lose? You may have a burnt valve or a bad valve seat or bad broken valve spring. You had it apart, according to previous posts. how far? Did you have the head off?

yes i had the head off,and had it all checked out.they did re-surface the head and replace the freeze plugs(the freeze plugs were rusted and had small holes and i was leaking antifreeze.I didn't do anything to the valves or springs because i figured they were new ,and looked it.And i dont remember that being like that when I took it apart. I didn't have the problem with the lifter /valve before. Is there away to check that valve spring?

 

[bearsden]

I would replace all of the lifters

I didn't really want to hear that but I'm sure thats the way to go,thanks for help! any advice on lifters ? ARe there some better than others?

 

[jdarg]

okay so i got it running and it was still popping,I pulled the plug wire on#6 and it went away. that was the cylinder that had the loose rocker arm.Took the valve cover back off and double checked everything.the push rod is straight,but the rocker arm is loose.theres about 20,000 miles on the rebuild. Should i just replace that lifter? or am i looking at a full winter project? as always,thanks!

Don't just blindly replace all the lifters, esp. if you are on a budget.

Just how loose is it? It could be as simple as a really worn rocker/fulcrum - a very common issue on these engines, esp. engines with one piece fulcrums, and very cheap/simple to replace if that's the case.

Lifters often don't "fail" - they just get dirty and stuck. You can often free them by running the motor w/ the valve cover off and tap the affected rocker w/ a soft mallet right above where the pushrod meets it. Don't be afraid to give it more than a tap but don't go full ape poopie on it either.

If that seems to help I would run a quart of ATL in lieu of 1 qt. of oil for a while and keep an eye on the filter. That should really help clean things up inside the motor.