Stock 71 340 Pushrods rubbing Cylinder head

[gf7cuda]

Looking to see if anybody might have some insight on an issue I have with my 71 340 engine that I had a stock rebuild with just a little more than mild cam. I just sent engine to be put on an engine run stand to break in before installing in car. The shop told me the push rods are rubbing the stock J head holes. The rocker set ups are stock ( all rockers together on rail shaft) .I'm just checking if anybody has experienced this issue. Are left and right rocker assembly's Thanks in Advance!

 

[moparleo]

You should contact the shop that put it together. If they didn't notice the interference problems there may be other things that they didn't check as well. If you do any mods before they get to look at it they might void any warranty that you may have been given.

 

[gf7cuda]

Thank you for that advice, makes sense. Just didn't expect this after paying what i paid for rebuild. have a good one!

 

[70chall440]

If everything is stock they should not be rubbing, something isn't right.

 

[Chryco Psycho]

Pictures ?
2 thoughts , are the pushrods stock diameter & the rockers in the correct positions on the shafts ?
I assume you do not have the 915 J heads from a TA engine with the offset pushrod holes

 

[gf7cuda]

Chryco, pushrods i believe stock I will check, Can the rockers be in the wrong positions on the shafts? I didn't know they could could be in wrong positions. I will double check , how would i know correct location on shafts?, They are J heads, would 915 be stamped on the heads? I will check. Thanks Chryco....

 

[gf7cuda]

If everything is stock they should not be rubbing, something isn't right.

Agreed, never saw this before, thanks man!

 

[bandit 73]

Sounds like someone got the rocker arms on the shaft incorrectly . They for sure are what I call lefts and rights. If they did that I would be concerned they also may not have gotten to oil holes lined up correctly. Service manual shows the correct order they must be in. Other than that , I would say maybe too long pushrods.......

 

[gf7cuda]

Thank you Bandit, Good to know, are the rockers themselves left and right or the shafts left and right? This could be the issue.

 

[moparleo]

Here are the different Mopar small block factory rocker arm types.

 

[gf7cuda]

Thank you for this, This will help! appreciate it Leo!

 

[gf7cuda]

Pictures ?
2 thoughts , are the pushrods stock diameter & the rockers in the correct positions on the shafts ?
I assume you do not have the 915 J heads from a TA engine with the offset pushrod holes

Chryco, I will get some pics.

 

[Chryco Psycho]

There are right & left rockers , the tip of the rockers will not sit centered on the top of the valve if they are in the wrong position .
The 915 # is cast onto the head , the TA heads used the 915 casting But the holes for the pushrods were drilled further away from the intake runner .
If the pushrods are thicker than stock it can get close to the runner & I have had to grind clearance but rarely with stock heads & never with stock pushrods

Chryco, I will get some pics.

Rockers are left and right not the shafts

 

[bandit 73]

You may know this but in case not, the rocker shaft sits on several cast in bosses on the cylinder head, but only one is drilled to allow oil to fill up the rocker shaft and then to supply oil to the individual rockers. The hole in the bottom part of the shaft MUST be lined up correctly to the boss oil mount. That is why most folks get a drill and prelube the engine prior to fire up.....to ensure all rockers are getting oil.....

 

[gf7cuda]

There are right & left rockers , the tip of the rockers will not sit centered on the top of the valve if they are in the wrong position .
The 915 # is cast onto the head , the TA heads used the 915 casting But the holes for the pushrods were drilled further away from the intake runner .
If the pushrods are thicker than stock it can get close to the runner & I have had to grind clearance but rarely with stock heads & never with stock pushrods

Rockers are left and right not the shafts

Chryco, I found the stock rockers and pushrods. Ill bring them with me and make sure the rockers are in the correct locations. I think this is the problem, I also found out notches on rails go forward on drivers side, and to the rear on passenger side. Pushrods are just slightly touching the holes, if rockers are not correct this would cause issue. I will give feedback. Thanks for all your help!

 

[gf7cuda]

You may know this but in case not, the rocker shaft sits on several cast in bosses on the cylinder head, but only one is drilled to allow oil to fill up the rocker shaft and then to supply oil to the individual rockers. The hole in the bottom part of the shaft MUST be lined up correctly to the boss oil mount. That is why most folks get a drill and prelube the engine prior to fire up.....to ensure all rockers are getting oil.....

Bandit, I was not aware, I will make sure oil holes are lined up. Appreciate this info...

 

[Chryco Psycho]

Glad to help , let me know what you find !

 

[gf7cuda]

There are right & left rockers , the tip of the rockers will not sit centered on the top of the valve if they are in the wrong position .
The 915 # is cast onto the head , the TA heads used the 915 casting But the holes for the pushrods were drilled further away from the intake runner .
If the pushrods are thicker than stock it can get close to the runner & I have had to grind clearance but rarely with stock heads & never with stock pushrods

Rockers are left and right not the shafts

Thank you!

 

[gf7cuda]

Glad to help , let me know what you find !

Will do!

 

[MoparCarGuy]

Here is a good picture of the factory 340 stamped steel rocker arms showing the left and right pushrod "dimples" or "cups".
Where are your pushrods rubbing in the pushrod tunnel through the head? On the sides of the pushrod tunnel?