Re: Visiting the machine shop tomorrow
Ahhh yes it is the 460 Ford cut in half - I did rebuild one of these motors 3 years ago- If you have problems finding oil seals look for a business called "motion industries" they had a few seals I need in-stock and were high quality, and best of all CHEAP
Since he is boring your motor over and your replacing two pistons you have a couple options to avoid paying for a balance job OR read what I posted below:
1: have him find 2 pistons that are heavier than what you have now, balance the two new pistons to the old pistons your re-using
OR
I'd say to just replace all four, it is most certainly easier on the motor, everything is the same and the biggest factor with be quench.
Look at it this way -
When a piston is in the bore it could be 20 thousandths "in the hole" it could be "zero decked" or it could be 50 thousandths in the hole.
This can present a whole lotta problems
1. Your compression will be different from cylinder to cylinder which may create a negative vaccum and a rough running motor
2. The flame travel could be different casuing 2 cylinders to make to motor run like your re-tarded or over advanced with detonation depending on your base timing and advance curve.
3. Cylinder temperatures and EGT's (exhaust gas temperature) would be different from cylinder to cylinder - this can cause head gasket failure and or worse a cracked head.
4. This may also cause a power loss due to an im-balance in motor operation - with two cylinders firing differently from the other two it may change the power output (this has alot of factors involved, not up for typing it out right now)
I'm pretty sure you get the point.
As for the headgasket I used a Fel-Pro M.L.S. (multi layer steel) head gasket for better sealing and heat control.
Here is the difference between certain machine shops
some RE-BUILD others DESIGN
Essentially a motor is a motor correct? What alot of people don't factor in is the harsh enviroment, consistently high RPM, high oil temps, fast RPM rises and drops etc...
When a marine engine is gone through it needs to be re-designed in a sense so it can withstand the conditions and vigors of the tasks at hand specifically four cylinders -- with less cylinder and displacement they work harder with less torque, run rougher, and and have to oversome more obstacles than a V-6 or V-8 will.
Careful planning and a machinist who understands your goals will be the ticket to a well thought and designed motor that will withstand many seasons and/or hours with no problems.
It sounds to me like you found that person and I wish you good luck and happy boating with your build.
If you need anymore assistance please ask or send a PM
--Brad
Ahhh yes it is the 460 Ford cut in half - I did rebuild one of these motors 3 years ago- If you have problems finding oil seals look for a business called "motion industries" they had a few seals I need in-stock and were high quality, and best of all CHEAP
Since he is boring your motor over and your replacing two pistons you have a couple options to avoid paying for a balance job OR read what I posted below:
1: have him find 2 pistons that are heavier than what you have now, balance the two new pistons to the old pistons your re-using
OR
I'd say to just replace all four, it is most certainly easier on the motor, everything is the same and the biggest factor with be quench.
Look at it this way -
When a piston is in the bore it could be 20 thousandths "in the hole" it could be "zero decked" or it could be 50 thousandths in the hole.
This can present a whole lotta problems
1. Your compression will be different from cylinder to cylinder which may create a negative vaccum and a rough running motor
2. The flame travel could be different casuing 2 cylinders to make to motor run like your re-tarded or over advanced with detonation depending on your base timing and advance curve.
3. Cylinder temperatures and EGT's (exhaust gas temperature) would be different from cylinder to cylinder - this can cause head gasket failure and or worse a cracked head.
4. This may also cause a power loss due to an im-balance in motor operation - with two cylinders firing differently from the other two it may change the power output (this has alot of factors involved, not up for typing it out right now)
I'm pretty sure you get the point.
As for the headgasket I used a Fel-Pro M.L.S. (multi layer steel) head gasket for better sealing and heat control.
Here is the difference between certain machine shops
some RE-BUILD others DESIGN
Essentially a motor is a motor correct? What alot of people don't factor in is the harsh enviroment, consistently high RPM, high oil temps, fast RPM rises and drops etc...
When a marine engine is gone through it needs to be re-designed in a sense so it can withstand the conditions and vigors of the tasks at hand specifically four cylinders -- with less cylinder and displacement they work harder with less torque, run rougher, and and have to oversome more obstacles than a V-6 or V-8 will.
Careful planning and a machinist who understands your goals will be the ticket to a well thought and designed motor that will withstand many seasons and/or hours with no problems.
It sounds to me like you found that person and I wish you good luck and happy boating with your build.
If you need anymore assistance please ask or send a PM
--Brad
