1275 valve train setup

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Erickz

Well-known member
Is there any benefit to setting up a valve train (limited prep 1275) using solid spacers versus springs in between the rockers?
Thoughts?
ez
 
Bit less friction/drag/heat without springs, don't have a clue as to amount. Drawback on solid spacers is you have to pull rocker shaft to "isolate" a cyl. For doing stuff like "huffing"(displacement check by some tech folks) or valve/spring/seal service without pulling head... Pulling rocker assy. only, can disturb the head sealing...best to drain coolant first.

Have done it both ways, Takes a bit of fitting to get solid spacers happy. I found bronze bushings (Bunting) made fair source for spacer stock.

Okie.
 
I've eliminated springs in a Honda valvetrain using aluminum rocker shaft spacers, and use wave spring springs to keep a slight amount of pressure to maintain alignment.
 
Had a rocker arm snap using the spacer set up. Don’t know if the spacer setup contributed to it but never had that problem using springs.
 
There's a chance that some side pressure reduces chatter and harmonics. The bushes would have some side clearance and be able to chatter ,maybe enough to shake out the oil or simple fail.
I dont "up grade "stuff on my car just cuz it's cool. Only if I have a failure.
 
Erick - Ask Hap what he does. The rocker arms look like his with the welds on the top... I haven't seen anything like that from other LP 1275 engine builders.
 
Yes to Jason...rocker arm was from his build. Eric V thought the weld across the top may have made it brittle.
 
Putting a weld across the top of the steel later 1275 rocker arms was an old trick done by many back in the day. I have no idea what happen to Erik's rocker arms, but I know that engine sat for 8 years after being built, and was never ran until Erik got it.
 
Acme Speed Shop":1mfpnxdd said:
Putting a weld across the top of the steel later 1275 rocker arms was an old trick done by many back in the day. I have no idea what happen to Erik's rocker arms, but I know that engine sat for 8 years after being built, and was never ran until Erik got it.
Click to expand...

Yeah it was a chicken or egg root cause speculation as the damage was pretty severe to the one rocker...but in typical form it ended in a destructive failure through the heat effected zone behind he pad. No crack propagation I could recognize after all the beating it took.

With the change to the rules over the past couple years it allows us to better align the rockers over the valve stem with the hopes all the geometry is perfect and side loading is eliminated. Spacers allow for lower friction on the rockers but I'm sure we are talking parasitic levels. Inspection over my limited years of rocker pads and rocker shafts never seem to indicate much axial movement of the rocker arm.
 
We get our rockers, shafts, etc. from Harland Sharp. Beautiful stuff, no failures. They do not recommend using the solid spacers for various reasons that they are more than happy to explain to you if you call them. We pull our 948s well above 9K and have never had a problem with their rockers. One thing they do have is thicker wall rocker shafts that pretty much eliminate shaft breakage. Have broken stock shafts a couple times over the years but not theirs. They also do a great job repairing damaged rockers and replacing bearings/bushings etc..

Bob
 
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