Cylinder 5 exhaust rocker barely moving...

[Tim Chavez]

Been a while since I posted. Just got back in the garage and noticed air getting shot out of the carb when cranking. Investigated to find cylinder 5s exhaust rocker is barely moving. My question is what is more likely... a bent rod, a busted lifter or did I wipe the cam love? It’s a j head 340

 

[toolmanmike]

Been a while since I posted. Just got back in the garage and noticed air getting shot out of the carb when cranking. Investigated to find cylinder 5s exhaust rocker is barely moving. My question is what is more likely... a bent rod, a busted lifter or did I wipe the cam love? It’s a j head 340

Could be either or all of the above.

 

[dadsbee]

You've got the cover off, that should be an easy self answered question, all can be watched through the gap in the head where the push rod comes up!

 

[Tim Chavez]

Could be either or all of the above.

Did Stock 340s have hydraulic lifters?

 

[toolmanmike]

Did Stock 340s have hydraulic lifters?

yes

 

[MoparLeo]

No point in asking what it could be, just pull the valve cover and you will know. You have to pull the cover no matter what anyway...

 

[Tim Chavez]

No point in asking what it could be, just pull the valve cover and you will know. You have to pull the cover no matter what anyway...

Cover is off.. you mean pull the intake?

No point in asking what it could be, just pull the valve cover and you will know. You have to pull the cover no matter what anyway...

 

[33 IMP]

A badly-enough bent pushrod to barely move the valve, or a collapsed lifter, you would have likely spit the pushrod out of place . I'm betting on a wiped lobe. Sorry.

 

[MoparLeo]

With the cover off, disconnect the coil from the distributor cap so it won't start. If you don't have a remote starter to hook up to the fender mounted battery/starter connection have someone rotate the engine with the ignition key in the car while you watch the rockers while they crank the engine. This is after you manually check that there is no damage to the rockers, pushrods valves that can be seen from looking on the outside. I have seen all of the above happen over the years. If you find bent pushrods you will most likely need to remove the cylinder heads.

 

[Tim Chavez]

With the cover off, disconnect the coil from the distributor cap so it won't start. If you don't have a remote starter to hook up to the fender mounted battery/starter connection have someone rotate the engine with the ignition key in the car while you watch the rockers while they crank the engine. This is after you manually check that there is no damage to the rockers, pushrods valves that can be seen from looking on the outside. I have seen all of the above happen over the years. If you find bent pushrods you will most likely need to remove the cylinder heads.

Ok your like 5 steps back..

 

[Tim Chavez]

Let’s try this.

 

[dadsbee]

As I said an hour or more ago... look down the push rod hole and it should be easily diagnosed as a bent rod, lifter or cam. Is lifter going up and down? You should be able to see everything down the gap if you use a light! Might have to pull the rocker shaft assembly, but I would think not.

 

[Tim Chavez]

The

 

[Tim Chavez]

Pushrod looks straight. How would I diagnose the lifter?

 

[dadsbee]

Is it moving up and down when cranking? Simple as that.. watch the intake lifter beside it for reference. Lifter shell moving well then it's collapsed, not moving you wiped a cam lobe.

 

[Tim Chavez]

Is it moving up and down when cranking? Simple as that.. watch the intake lifter beside it for reference.

I posted a video above showing how much it’s moving

 

[dadsbee]

No you posted a video of how much the rocker was(n't) moving. The lifter shell itself is what you need to watch..

 

[Tim Chavez]

No you posted a video of how much the rocker was(n't) moving. The lifter shell itself is what you need to watch..

Gotcha. Well a video was impossible solo but in watching it. The lifter case did appear to be moving but every time It moved it would squirt oil from the sides

 

[dadsbee]

If it's moving a similar stroke as the intake lifter beside it then the lifter has collapsed. If you had a big block they are easy to pull out, but not sure on that SB if you can get it up through that oil drain back hole. If you can, take the lifter apart, clean it and put it in a cup of oil and use a drill press or brute strength to cycle it and see if it reloads.

 

[toolmanmike]

If it's moving a similar stroke as the intake lifter beside it then the lifter has collapsed. If you had a big block they are easy to pull out, but not sure on that SB if you can get it up through that oil drain back hole. If you can, take the lifter apart, clean it and put it in a cup of oil and use a drill press or brute strength to cycle it and see if it reloads.
View attachment 998074 View attachment 998075 View attachment 998076

Probably a Comp lifter. LOL