Things to think about when doing a Big Bore upgrade to your engine?
Question:
When I decide to upgrade my engine with a Big Bore cylinder kit, what are the other things I need to do or think about?
Answer:
When you upgrade your engine with a Big Bore Kit, you have to choose between normal and high compression. Also you need to think about all the collateral that will make this upgrade successful. Here is a list of things to think about to help in this process as well as some comments/recommendations:
Big Bore, Regular compression (9.1:1 or 9.3:1)
- When upgrading to big bore regular compression, the first think of course is to change Pistons and cylinders. Note that the standard procedure is still to check the piston-valve clearance when doing this type of work on an engine. If other modifications that affect spacing are being done such as cam replacement then this check has to be performed with the other modification implemented.
- You have the option to replace the engine studs with high tensile ones, but this is optional for regular compression (optional).
- Depending on the overall work done on your engine, you may consider to replace the pushrods by adjustable ones. This will allow at later time to access the cams/oil pump/etc. without having to disassemble the top-end (recommended).
- The cams make a big difference on the engine performance, so you may consider to update them depending on the performance goal (optional).
- If you change the cams and go for very high lift, you may need to replace the valve springs in order to handle the extra lift (Not required if you keep stock cams).
- Compression relief valves are not required for standard compression (Not required).
- Since you have a larger air flow, you may consider upgrading the intake manifold to a big bore one (optional).
- Also if you have a carbureted engine, you may consider to upgrade your carburetor to a larger one (optional).
- Since the air flow/air mass will be different you will need to recalibrate you ECM (if injected engine) or re-jet your carburetor for carbureted engines (highly recommended).
- Since your engine will have more power, you should consider to put a stronger clutch spring in order to handle the extra torque (recommended)
- Since you are going through those engine modifications, it is assumed that the exhaust has been upgraded to a free flow exhaust, if not, this has to be taken into consideration (recommended).
Big Bore, High compression (10.25:1)
- When upgrading to big bore high compression, the first think of course is to change Pistons and cylinders. Note that the standard procedure is still to check the piston-valve clearance when doing this type of work on an engine. If other modifications that affect spacing are being done such as cam replacement then this check has to be performed with the other modification implemented.
- It is recommended to replace the engine studs with high tensile ones (recommended).
- Depending on the overall work done on your engine, you may consider to replace the pushrods by adjustable ones. This will allow at later time to access the cams/oil pump/etc. without having to disassemble the top-end (recommended).
- The cams make a big difference on the engine performance, so you may consider to update them depending on the performance goal (optional).
- If you change the cams and go for very high lift, you may need to replace the valve springs in order to handle the extra lift (Not required if you keep stock cams).
- Compression relief valves are recommended for high compression. This will ease starting the engine and will also give a longer life to your starter (recommended).
- Since you have a larger air flow, you may consider upgrading the intake manifold to a big bore one (recommended).
- Also if you have a carbureted engine, you may consider to upgrade your carburetor to a larger one (recommended).
- Since the air flow/air mass will be different you will need to recalibrate you ECM (if injected engine) or re-jet your carburetor for carbureted engines (highly recommended).
- Since your engine will have more power, you should consider to put a stronger clutch spring in order to handle the extra torque (recommended)
- Since you are going through those engine modifications, it is assumed that the exhaust has been upgraded to a free flow exhaust, if not, this has to be taken into consideration (recommended).
Other collaterals to think about:
Since your engine is disassembled, you may think about a few recommended upgrade:
- Oil pump: Newer engines (TC96) uses a new oil pump with increased flow which will definitely be a big help for upgraded engines.
- Hydraulic cam Chain tensioner plate. Also new on TC96 engines, will outlast the genuine spring loaded tensioners.
