340 issue after camshaft change

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Sabremech

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I have a problem I’ve never encountered before when working on or building an engine. I installed a new camshaft (comp cams high energy) in my 340 along with a new intake and carburetor. Adjusted the valves per the published procedure then went to start the engine. Engine spun over like it had no compression. I rotated the engine to #1 cylinder TDC and stuck a borescope in to find that both the intake and exhaust valves were open. Found the same on the rest of the cylinders when rotated to their respective TDC position. So back on to adjusting them again to published procedures written by someone else. Same thing with no compression as valves all hanging open. I pulled the front of the engine back apart to check timing gear marks and all appear to be as required.
I’m beginning to question the camshaft and if it was ground right. Anyone else ever experience this? I put the cover back over it and walked away in disgust!
 
Sounds like an intake and front cover do-over are in your future if you want your 340 to live. What cam you running?
 
Adjustable rockers? Sounds like the valves are being held open. But really need more information.
 
I have adjustable rockers. I’m questioning the adjustment procedure. What procedure have others used with success? Happy to try it before removing this cam and going back to what I removed.
 
Start at TDC, cyl 2 intake, and cyl 8 ext should be at the base circle and adjust. Then rotate 90* and so forth through 2 full spins of the motor and all 16 valves will be done.

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Just pick a cylinder. With intake valve all the way open, adjust exhaust valve to zero. Rotate the engine till exhaust valve starts to open. Then adjust intake to zero. Then take a compression test on that cylinder.
 
If you're adjusting with the engine 180 out, there you go. Don't come back and say "I'm not doing that" without double and triple checking. I guarantee this is operator error. Something all of us as done at one time or another.
 
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SGBARRACUDA said:
Just pick a cylinder. With intake valve all the way open, adjust exhaust valve to zero. Rotate the engine till exhaust valve starts to open. Then adjust intake to zero. Then take a compression test on that cylinder.
Click to expand...
THIS It is known as EOIC

It means you rotate the engine until the EXHAUST valve just starts to OPEN, an you adjust the intake on that cylinder. Then you rotate until the INTAKE opens all the way and is almost CLOSED and adjust the exhaust on that cylinder

Remember the cam only rotates at half crank RPM so at "one" TDC no1 valves are closed and on the next rotation to TDC both no1 valves are both open
 
67Dart273 said:
THIS It is known as EOIC

It means you rotate the engine until the EXHAUST valve just starts to OPEN, an you adjust the intake on that cylinder. Then you rotate until the INTAKE opens all the way and is almost CLOSED and adjust the exhaust on that cylinder

Remember the cam only rotates at half crank RPM so at "one" TDC no1 valves are closed and on the next rotation to TDC both no1 valves are both open
Click to expand...
I’m also referring to if he is spinning the p/r or jiggling it up and down or some other way if hydro lifters. Maybe he has solid lifters but I doubt it. Kim
 
There are two TDC positions. One on compression, one on overlap. On overlap, both valves are open. Maybe this is what you saw with the borescope.
If you are replacing a stock cam with the HE cam, the HE cam probably has a smaller base circle. Meaning longer prods needed, even with adj rockers.
 
This is how I always do it. For me it's just simpler. I copied this info. a while back as my memory sucks these days lol.


Valve adjusting



This procedure is generally called the EO/IC method, which stands for exhaust opening/intake closing. Working with the first cylinder turn the engine until the exhaust valve starts to open. That indicates that the intake valve is resting fully on the cam base circle and can be adjusted. Then turn the engine over until the intake valve is just about to close. That means the exhaust valve is ready to be adjusted. Simply repeat this process with all remaining cylinders.

The process is slightly different with hydraulic lifters. There is no gap to set; rather, the lifter needs a “preload” to ensure that the plunger is in the center of its travel. Basically, the pushrod is rotated with one hand and the rocker arm is tightened until the pushrod is snug in place or at zero lash. Then the adjuster is turned or tightened until there is enough preload. The amount the adjusting nut is turned depends on the type of adjustment mechanism as well as the lifter. Most applications will use a 7/16-20 rocker-arm stud. A full turn of the adjustment nut moves the rocker .050-inch, so a quarter turn will provide .0125-inch preload in the lifter. The adjustment on the pushrod end of the rocker arm can be calculated in a similar manner. Jesel uses a 3/8-24 screw adjuster, which equates to .041-inch movement with each full turn.
 
Sabremech said:
I have adjustable rockers. I’m questioning the adjustment procedure. What procedure have others used with success? Happy to try it before removing this cam and going back to what I removed.
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Cleaning up this post..........Let’s first establish what is the “published procedure” you’re using. There are quite a few procedures on valve adjustment. That info would really help in sorting out what’s what.

Looks like you have a hydraulic flat tappet cam and adjustable rocker arms. It may be possible you’re off on setting the lifter preload and that is why you have valves hanging open?
 
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I appreciate all the replies, even the sarcastic ones. Thanks again and I'll just call it good from here.
 
Wouldn't give up so easily... the guys here know a whole bunch all together. Just do what they asked you for... tell 'em your adjustment procedure. For starters...
 
Sabremech said:
I appreciate all the replies, even the sarcastic ones. Thanks again and I'll just call it good from here.
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I assume that you'll get this figured out. I'd like to know where you ran into problems as I am going to be doing this myself......Even a PM if you don't want to post in this thread. Thanks.
 
Kendog 170 said:
This is how I always do it. For me it's just simpler. I copied this info. a while back as my memory sucks these days lol.


Valve adjusting



This procedure is generally called the EO/IC method, which stands for exhaust opening/intake closing. Working with the first cylinder turn the engine until the exhaust valve starts to open. That indicates that the intake valve is resting fully on the cam base circle and can be adjusted. Then turn the engine over until the intake valve is just about to close. That means the exhaust valve is ready to be adjusted. Simply repeat this process with all remaining cylinders.

The process is slightly different with hydraulic lifters. There is no gap to set; rather, the lifter needs a “preload” to ensure that the plunger is in the center of its travel. Basically, the pushrod is rotated with one hand and the rocker arm is tightened until the pushrod is snug in place or at zero lash. Then the adjuster is turned or tightened until there is enough preload. The amount the adjusting nut is turned depends on the type of adjustment mechanism as well as the lifter. Most applications will use a 7/16-20 rocker-arm stud. A full turn of the adjustment nut moves the rocker .050-inch, so a quarter turn will provide .0125-inch preload in the lifter. The adjustment on the pushrod end of the rocker arm can be calculated in a similar manner. Jesel uses a 3/8-24 screw adjuster, which equates to .041-inch movement with each full turn.
Click to expand...

Lastly this. Basically, the pushrod is rotated with one hand and the rocker arm is tightened until the pushrod is snug in place or at zero lash. Then turn 1/2 turn to set preload and call it a day .
 
Assuming a solid lifter cam, back all your adjusting nuts off at least a full turn. If you have the proper gaps and both valves are open, it is possible the cam is ground wrong. If the cam is hydraulic, just use the factory rockers and pushrods.
 
Knowing the setting of hydraulic lifter preload or setting solid lash specs, using the standard Mopar Performance adjustment chart is really all you need. There are other methods, some may disagree with this as being ideal, but it works fine for most. Rotate every 180 degrees and adjust. Then there’s the other one for bigger cams that sets valves every 90 degrees of rotation.
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If, as you say, you spun the engine over and it had no compression, AND the valves are not closing;
what are the chances that every valve kissed the piston, and now all or at least half the valves are bent.

At this stage I would remove the rocker shafts and do a LeakDown test to see if you still have an engine.

if you do;
then I would find split-overlap and see if the cam is installed remotely close to correctly.

After that we can work on the lifter preload.
 
I don’t have the specifications in front of me for the camshaft to quote lift and duration, but it is a hydraulic lifter camshaft. The method I used was what has been posted by 12many. I did back off all of the adjusters and none of the valves are bent. It’s not that high lift of a cam. I’ve been through the being 180 off scenario and that’s possible, but I find it hard that I would have done the same thing twice. Never say never. I won’t be able to recheck everything for a couple of weeks as other projects have to get done first. Thanks
 
I never have used the MP valve adjustment chart. Never have used the EOIC or ABC, XYZ, PDQ or LQBTQA+ method or whatever the hell else there is. I get ONE camshaft lifter at a time on the base circle of the lobe and adjust that valve and move on to the next. Always done it that way and it's always worked well "FOR ME". That means turning the engine to close the valve you're fixing to adjust and turn it "a little" more to assure that lifter is on the base circle of that lobe. Anything else is just too complicated for my simple mind. You have the valve covers off. You can shine a light into the intake valley through the heads and SEE the camshaft lobes and lifters and make SURE they're on the base circle. Simplest way ever to do it, IMO.
 
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