Given that there is no performance camshaft options for 6.2/6.5L engines, another avenue to increase air flow in to and out of the cylinder by increasing valve lift and lengthening valve openness is a higher ratio rocker arm. Has anyone ran the Harland Sharp 1.6 ratio rocker arms and what results did you get from them? Is there enough clearance between piston and valve on a stock long block to facilitate this, or should this only be used with thicker head gaskets or shorter low compression pistons?
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1.6 Ratio Rocker Arms
- Thread starter Chewy1576
- Start date
ak diesel driver
6.5 driver
I have a set for my future build I also have a set of 18:1 pistons I got from Chris. My understanding is that there's not enough clearance with stock pistons. Not sure about with thicker gaskets.
My understanding is that generally, every 0.010" over stock thickness will reduce compression ratio by one point. I could have that misrepresented, but this would mean that +0.020" head gaskets should yield an 18:1 compression ratio with only removing and replacing the cylinder heads.
ak diesel driver
6.5 driver
Actually you'd need closer to .030 to get there. My pistons have valve reliefs too.
Valve reliefs would make clearances a non-issue. Hypothetically, without additional reinforcement, thicker head gaskets could create a higher chance of blowing out as well. Without that, lower compression pistons with valve reliefs is probably the more sound option.
A thicker gasket doesn't give you anything to speak about, about .03...
I have made mods to my p motor for 1.7:1's...
I machine these below.... and you will need pushrods and some grinding for clearances ....
I have 1 set left with valve reliefs...
I have made mods to my p motor for 1.7:1's...
I machine these below.... and you will need pushrods and some grinding for clearances ....
I have 1 set left with valve reliefs...
I may have been one of the first years ago with these rockers, they will smooth out and quieten the motor to the extent it doesn't sound like a 6.x.. and as always the valve geometry should be checked, ie pushrod length, and valve springs will provide much better valve control, I also speced springs with PAC racing springs if needed...
If I was looking at an engine teardown and rebuild in the near future, I would be seriously interested in a set of the modified pistons. I either need to put more miles on the truck, or turn up the boost and help it along lol.
I was wondering if the rocker would work on a stock application, or what needed to be changed to accommodate them. It sounds like there isn't enough valve clearance using stock head gaskets and pistons, and other considerations need to be made to accommodate the additional valve lift.
I was wondering if the rocker would work on a stock application, or what needed to be changed to accommodate them. It sounds like there isn't enough valve clearance using stock head gaskets and pistons, and other considerations need to be made to accommodate the additional valve lift.
1 set left, I do machine for others but with the cost of the machining plus someone purchasing pistons these are a deal... but I know what you are saying..