Small block (360) pushrod question

[HemiMagnumRTAWD]

I bought a sweet 1966 Satellite with a '70s 360. it was a GTX clone half-heartedly done, or mostly unfinished. The 360 seems recently rebuilt. The block seems late but the heads look like non EGR; they have stout, maybe triple springs and the intake measured 2". These are not 340 or anything, the cast in part number was for 1.88 valved heads. The takeaway is I have a "monkeyed-with" motor.

I was trying to get it running well; idle high, low vacuum. Everything was progressing when my spouse walked behind the car and said "There is nothing coming out of this side of the exhaust." About that time it stalled, with a SMACK. I pulled the valve cover and found a beautiful set of adjustable, roller-tipped, forged rockers and broken rocker shaft along with the five broken off rocker shaft mounting bolts. I automatically assumed that one or more bolt was not properly torqued and worried loose.

Fast forward.

I take out the engine and pull the head off to get the bolts extracted. ( I did give it a short try with my lefties) As I am getting new parts to replace the broken pieces, and reflecting on the cause of the catastrophic failure, I notice the pushrods are marked "5/16 x 7.800" From my research this seems to be quite long, almost a 1/4' since the stockers are 7.550".

I cannot remove any of the pushrods on the other side, even after loosening the adjusters all the way. I realize I could remove the shaft and get them out but two of the valves are under tension ( I have not rotated the motor) so I just stopped to take some more time to reflect.

Is there any case where a mild street rod (car has 904, not tubbed or suspension or anything to suggest a crazy valve lift cam) LA engine would have such long pushrods? Or did this guy put the wrong pushrods (seem to be super nice cro-moly) and they shoved the shaft so hard it broke?

 

[IQ52]

More likely someone torqued the rocker shaft bolts to 30 ft/lbs instead of the correct 200 in/lbs. Some bolts broke and let the shaft flex until it broke and then the rest of the over torqued bolts snapped. There is only one way to know if the pushrods are correct or not, measure what the engine needs. This has been covered many times in previous threads.

 

[PurpleBeeper]

If you cannot get the pushrods out, they're too long.

I suggest you stick a boroscope down one of the cylinders on the bad head side to see if you still have pistons in one piece. If the pushrods are too long, then the valves can't close, pistons hit the valves & the motor is "toast". A boroscope costs about $30 (I just bought one last month).

Hopefully, IQ52 is correct about the bolts on the rocker shaft & your motor is OK. I'm pretty sure the engine builder just used the wrong pushrods.

 

[HemiMagnumRTAWD]

Thanks!

 

[HemiMagnumRTAWD]

More likely someone torqued the rocker shaft bolts to 30 ft/lbs instead of the correct 200 in/lbs. Some bolts broke and let the shaft flex until it broke and then the rest of the over torqued bolts snapped. There is only one way to know if the pushrods are correct or not, measure what the engine needs. This has been covered many times in previous threads.

Thanks for your input; I appreciate the help with this. This is just my third project and only the second deep engine dive.

I am curious about the 200in/lbs specification. My Larry Shepard book says "...the shaft attaching bolts should be torqued to 30ft-lbs using the following order: 3-1-5-2-4." What update did I miss?

As far as pushrod length, he says for high rpm use you need custom made. I have a rev limiter that I was setting to 6200, I felt like that was moderate, not high. Any thoughts?

I live in the 'burbs; it is an old rat rod with drum brakes so I am not trying to go fast...yet!

 

[IQ52]

The 30 ft-lbs is for the big block 3/8 bolts. The small block uses 5/16 bolts and they are to be torqued to 200 in-lbs. Some books in error list the small block as 30 ft-lbs. At 6,200 rpm a custom heavy pushrod will have positive effect on valve train stability. To me, high rpm starts around 5,500-5,800 rpm.

 

[HemiMagnumRTAWD]

The 30 ft-lbs is for the big block 3/8 bolts. The small block uses 5/16 bolts and they are to be torqued to 200 in-lbs. Some books in error list the small block as 30 ft-lbs. At 6,200 rpm a custom heavy pushrod will have positive effect on valve train stability. To me, high rpm starts around 5,500-5,800 rpm.

Thanks; I appreciate you taking the time!

 

[HemiMagnumRTAWD]

So I don't have the time or inclination to try and get some custom length pushrods, and plan on putting in inexpensive Summit 7.500 inchers.

I wonder about the 7.8" that were in the engine and if they could have caused the camshafr and lifter damage shown in the photo.

I plan on using a Lunati Voodoo around 268/276 with .450 lift. Duration is advertised.
Typed from phone...

 

[Shorthorse]

That's not a pretty picture. Looks like lots of metal shavings.

 

[62 Dart Convertible]

So I don't have the time or inclination to try and get some custom length pushrods, and plan on putting in inexpensive Summit 7.500 inchers.

I plan on using a Lunati Voodoo around 268/276 with .450 lift. Duration is advertised.

Not wise to just guess that 7.5" is the right length pushrod! As IQ said, the proper way is to measure and get the right ones. Why risk buying the wrong length and finding out through more heartache? Take the time it needs to do it right.

Nice cam choice.