What's New. Warranty Registration. CPG Nation. Warranty Policy. Privacy Policy. Support Information. Clean the combustion chamber and the top of the piston and valve reliefs.
The cleaner the piston, the better the clay will stick to it. The strip should be long enough to run across both the intake and exhaust valve reliefs. Applying a small amount of oil to the clay will prevent it from sticking to the valves as they press into it. It is not necessary to torque the head yet. All head gasket manufacturers can tell you the compressed thickness of their gasket.
Measure the gasket before you install it permanently and add the difference to the piston to valve clearance. Install enough head bolts to secure the head in place while you rotate the engine. Install the pushrods, lifters and rocker arms on the cylinder you have prepared for the clearance check. If the camshaft uses hydraulic lifters, you must temporarily use solid lifters in their place. Hydraulic lifters bleed down and will provide a false measurement.
Be sure to rotate the engine over two times. Next depress the exhaust valve. Note the distance traveled. Now subtract the difference in the gasket thicknesses and you should have an accurate measurement of the piston-to-valve clearance. For this example on a turbocharged SBC, the exhaust clearance was. Rotate the engine to 10 degrees after top dead center on the intake stroke. Repeat the procedure with the intake valve and compute the clearance.
For this valve, the clearance measured. East Coast Outlaw Written by Mike Magda. Top Blog Posts. Subscribe to the Diamond Pistons Newsletter. Therefore we choose not to push the piston to head clearance issue on those types of engines, but that is another topic.
However, lets just say the safe piston to head for theoretical engine "A" is. Meaning that at. True enough that the intake valve is chasing the piston while the valve is opening and the piston is 'going away'. Whilst 'wiggling' the vertical clearances will be decreasing on one side of the valve or the other. The piston is also 'wiggling' around in the bore causing the same effect.
The head itself does not 'wiggle' so the pistons dont hit at. I can guarantee that if the valves rub they will eventually break at the stem from the flexing that occurs when they touch the piston. I have seen it and I have broken them from it. Based on that we have since followed the piston to head plus. On the exhaust side things are a bit different. Valve loft and float can possibly allow the exhaust valve to 'stay in the way' of the piston and get hit.
The piston is chasing the valve on the exhaust side so any 'delay' in the exhaust valve will allow the piston to strike the valve. As with the intake side there are a lot of factors that come into play but hands on experience has shown me that. Have seen valves rub at. Lately we have been sticking with. I must respectfully disagree with valve bounce causing valve contact on the exhaust side.
Even with a very mild ish degree cam the. Valves cant bounce before they first close onto the seats. If there is that much valve bounce there are several other problems going on in the valvetrain system that would cause a failure before piston to valve contact would. I do and have always used soft springs and checking pushrods to check valve to piston clearances for a very long time.
So what if the clearnce increases with real world valvesprings and real pushrods. I gave up on clay way back in and began using dial indicators and have ever since.
Clay was just too inaccurate for me. It is ok to think about checking with the real springs if those springs can be compresed in some way by hand. Waht if you are using very strong springs that will not compresss by hand? Example for instance to on seat with to even open?
I know of not any way to compress these by hand. Any ideas? Only other thing is once it is all in place I do stick a piece of solder wire through the plug hole to get the valve to squash it.
Takes several times to catch the right place to stick it to catch the valves though. That is just a last check for safety on my part though. I wouldn't think it would be more than maybe a. For what it is worth. Sometimes proceedures you use do work well for you and are eventually endured by you. This is how I feel about using the soft springs with good aluminum checking pushrods. I never did like the thin flimsy cut off pushrod with threaded ends that well, but have used them for years. That all ended for me a few years ago when I bought the complete Manton pushrod checking kit.
Every size graduated right to the next size requirement with no gaps in-between and they go long enough to even cover blocks of over 12 inch decks. I ended up liking them so well I bought another set so I could have two of the same lengths at the same time when I needed them.
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