* Incorrectly installed piston: The piston itself might be the wrong type for the engine, or it might have been installed incorrectly, possibly upside down or with the wrong connecting rod.
* Wrong deck height: The block's deck height (the distance from the top of the block to the top of the cylinder bore) might be incorrect for the crankshaft and connecting rods used. This is a critical measurement in engine assembly.
* Wrong connecting rod length: Connecting rods that are too long will cause the piston to travel too far up.
* Excessive head gasket thickness: Using a head gasket that's too thick effectively lowers the compression chamber, leading to piston-to-plug contact.
* Damaged or worn parts: A severely worn crankshaft or connecting rod journal could alter the piston's travel.
How to Correct This:
This is a serious problem that could cause catastrophic engine damage. Do NOT attempt to run the engine again until this is resolved. You'll need to disassemble the engine to find the exact cause. This requires significant mechanical expertise. Here's a suggested approach:
1. Professional Help: Unless you have extensive engine building experience, take the engine to a qualified engine builder or mechanic. They have the tools and knowledge to diagnose the problem accurately.
2. Careful Inspection: The engine must be disassembled, and each component carefully inspected. This includes:
* Piston and connecting rods: Check for damage, correct installation, and proper length.
* Crankshaft: Inspect for wear and damage.
* Cylinder head and head gasket: Verify the head gasket thickness and check for any damage to the head or block.
* Block deck height: Measure the deck height to ensure it's correct for your combination of components.
3. Precise Measurements: Accurate measurements are crucial. Using proper tools (dial indicators, micrometers, etc.) are essential for diagnosing the issue.
4. Component Replacement: Depending on what is found, parts will likely need to be replaced. This could include pistons, connecting rods, the head gasket, or even machining the block to correct the deck height.
Preventing this in the future:
* Precise assembly: Follow the engine builder's instructions precisely during assembly.
* Use correct parts: Employ only the correct pistons, connecting rods, head gasket, and other components for your specific engine combination.
* Professional assistance: Consider professional engine building services for any significant engine work.
* Measure twice, cut once: Double-check all measurements and clearances before final assembly.
Ignoring this issue could lead to a destroyed engine. Get professional help to diagnose and fix the problem.
