rocker shafts are burnt up

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moparwedden

moparwedden

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Other than no oil getting to them , what else could cause this,

New build and broke engine in. Oil presure good before we broke cam in. Cam and lifters are alright but one shafts is cooked and the other is starting too. Two lifters and one shafts are finished. Any ideas before I phone machine shop. Motor is a 440, 30thousand bore, oil pressure is 70-80lbs.



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I believe the big blocks oil the rocker shafts similar to the small blocks. Oil comes up through the head through a passage in the deck through the head gasket. If the rocker shaft is installed wrong or the wrong bolts are used it will shut off the oil to the rockers. I'm sure someone knows and will respond. I always read through the service manual to be sure.
 
Were the shafts installed upside down?
 
moparwedden said:
Rockers were upside right, but did not know about the stud. The engine builder is a huge mopar guy, I would like too think he new about this though
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The shafts so the oil holes match up, not the rockers.
 
The shafts themselves are correctly installed only ONE WAY. There is a right side up, upside down, forward and backwards for the shafts. If they are installed ANY other way, but right, you will get results like you describe. Also, close attention needs to be paid to oiling bolt as its shaft is a different diameter to allow oil flow as previously stated.
 
Use of a stud in the position where the oil hole comes up can starve the shaft... But it's not common IMO.
More common is a cam bearing that's not quite in right, or slightly off-center drilled passages in the block. Are you getting oil up there at all? There should be enough at 80psi that it's flooding everything up there.
 
moper said:
Use of a stud in the position where the oil hole comes up can starve the shaft... But it's not common IMO.
More common is a cam bearing that's not quite in right, or slightly off-center drilled passages in the block. Are you getting oil up there at all? There should be enough at 80psi that it's flooding everything up there.
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I read his post as he has already confirmed he's getting oil to the rockers. otherwise if he wasn't, why would he need another reason for burnt up shafts?
 
ScampMike said:
huh.. this I did not know.. sooooo what about aluminum heads? is it still a "thing" to make sure the correct bolts are used in those locations?
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Yes, unless magnum heads, in which case oil goes through the pushrods.
 
One of the 5 bolts is suppose to be difference...dam I usually take them off and throw them in a box....than fish them ...and stick them in what ever hole is the closest...
 
man.... now I gotta go check them dang things... is there a visual difference or is it only found by measuring them?
 
ScampMike said:
huh.. this I did not know.. sooooo what about aluminum heads? is it still a "thing" to make sure the correct bolts are used in those locations?
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On the SBM..... the correct bolt (the long bolt) tapers to .420" in the area in its midsection IIRC, where it is in the middle of the head (vertically) to let oil around and through the bolt hole in the head. The Edelbrocks RPM LA heads have the same bolt hole diameter as the stock heads here, so the long bolt goes in there just like for the stock heads. Use of ARP studs puts a stud that is .500" up through that hole in the head, so it makes that area fairly restricted but does not shut the oil flow off entirely. The flow area where the rocker shaft meets the head pedestal is the smallest flow area and the stud in the head makes that bolt hole area small too.
 
Ive never noticed any of the rocker shaft bolts being different from each other. The hole in the saddle, and the hole in the rocker shaft are bigger than the bolt, so oil flows right by there. But the shaft HAS to be installed correctly, as allready pointed out
 
nm9stheham said:
On the SBM..... the correct bolt (the long bolt) tapers to .420" in the area in its midsection IIRC, where it is in the middle of the head (vertically) to let oil around and through the bolt hole in the head. The Edelbrocks RPM LA heads have the same bolt hole diameter as the stock heads here, so the long bolt goes in there just like for the stock heads. Use of ARP studs puts a stud that is .500" up through that hole in the head, so it makes that area fairly restricted but does not shut the oil flow off entirely. The flow area where the rocker shaft meets the head pedestal is the smallest flow area and the stud in the head makes that bolt hole area small too.
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Ahhhh, yes I was thinking of the rocker shaft bolts, not head bolts.........
 
Machine shop is coming over too look at it. Studs are correct and he double checked cam barrings for fit. We will see and thanks for all the info.
 
4th rocker shaft bolt hole from the front on the big blocks is the stock oil feed source on both sides. The 2nd and 4th rocker shaft support bolt holes in the heads are larger for oil flow as the heads can be on either side. Use the long bolt with no sealer to allow the oil to flow on that 4th shaft bolt.
For reference, shaft orientation............
shaft orient.jpg
 
moparwedden good luck. awhile back when I had this happen to me I pulled the cam and head and ran a coat hanger down through the passage in the block and it stopped at the bearing. Hope yours is a simple fix. The machine shop bought me a new set of rockers and shaft setup.
 
Had a no or low oiling issue with my 383 initially as well, after break in. See my Build Thread below. Mine was on the left bank though. Found out after I heard valve clatter. Wore 4 of the rockers near the front and the shaft so bad, I had to replace them. The right side was getting oil fine. So , I'm thinking the cam bearing has to be right if one side is getting oiled. Tried everything from hand turning engine while priming, to probing through the shaft mount down through the bearing and into the camshaft , with a piece of welding wire. Could not figure it out, although it was getting some oil on the left. So before I replaced the rockers and shafts, I wanted to know if the trans was shifting. Took it down the street. Did a burn out, brought it home. Next day was resigned to tearing down and pulling cam, as to see inside cam bore with bore scope. Decided to pull left cover first.. Oh Oh... I got lots of oil there. Fired it up with no cover to verify. Apparently , in my case, passages blocked or partially blocked with who knows what. Thick assy lube, crud, what?
Mines fine now... Good Luck... I thought I would pull my hair out finding mine !
 
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