Disclaimer: By no means am I challanging any engine guru with this post. Merely bringing up a few mods I often see for discussion.
I seldom buy used engine but with poor parts availability of K&B and early Picco, I have no choice but to get a few to keep my aging fleet going. It is in these pre-owned engines and what I see at the ponds that prompt me to start this post.
It appears to me that a lot of boaters would either modify or pay to have their engine modified. I can't help but wonder whether many of the mods are effective or counter productive. I will list a few for discussion.
1. Enlarging the mounting hole: Just about every used engine I bought had the mounting lugs drilled out to 8-32, or 10-32 on larger engines. Why would anyone feel that anything less than a size 10 bolt can not harness the engine? It would not cost the engine manufacturer anything to drill to that size hole if they think it was necessary. In my opinion, drilling out the lug to 10-32 would actually weaken the lugs as there will not be much material left.
2. Changing the timing: I have bought a K&B with pretty extreme timing cut into the exhaust and transfer ports. My thinking: if milling out a couple of thou off the ports will greatly increased the power of the engine, K&B would have it? I trust that any manufacturer would have put a reasonable R&D effort to come up with the best timing.
3. Turboing the crank: Will it really buy anything? The crank couterweight is design to balance the recipricating mass of the piston and rod. Most .21 (front intake) engines I own do not have enough counterweight. Cutting away material from the crank will only make it worse and possibly result in more vibration. I do believe in "packing" the crankcase to help fuel draw but I do not think turboing the crank will help in this department.
I believe in blue-printing the engine. By blue printing I mean to take it apart, clean the parts of all debris, check for fits, deck clearance etc and re-assemble it. The only one mod I have found necessary was to balance the rotor of some OS, Picco and K&Bs. Some of those were so out of balance that the rotor pins wore out quickly.
After running some of the "modified" engines I acquired, I have not observed any performance gain over my stockers. I always wonder if Mr. Picco himself run his engine stock. Anyone knows? If he modified them, why would he not implement the mods in his production engines?
Kez
I seldom buy used engine but with poor parts availability of K&B and early Picco, I have no choice but to get a few to keep my aging fleet going. It is in these pre-owned engines and what I see at the ponds that prompt me to start this post.
It appears to me that a lot of boaters would either modify or pay to have their engine modified. I can't help but wonder whether many of the mods are effective or counter productive. I will list a few for discussion.
1. Enlarging the mounting hole: Just about every used engine I bought had the mounting lugs drilled out to 8-32, or 10-32 on larger engines. Why would anyone feel that anything less than a size 10 bolt can not harness the engine? It would not cost the engine manufacturer anything to drill to that size hole if they think it was necessary. In my opinion, drilling out the lug to 10-32 would actually weaken the lugs as there will not be much material left.
2. Changing the timing: I have bought a K&B with pretty extreme timing cut into the exhaust and transfer ports. My thinking: if milling out a couple of thou off the ports will greatly increased the power of the engine, K&B would have it? I trust that any manufacturer would have put a reasonable R&D effort to come up with the best timing.
3. Turboing the crank: Will it really buy anything? The crank couterweight is design to balance the recipricating mass of the piston and rod. Most .21 (front intake) engines I own do not have enough counterweight. Cutting away material from the crank will only make it worse and possibly result in more vibration. I do believe in "packing" the crankcase to help fuel draw but I do not think turboing the crank will help in this department.
I believe in blue-printing the engine. By blue printing I mean to take it apart, clean the parts of all debris, check for fits, deck clearance etc and re-assemble it. The only one mod I have found necessary was to balance the rotor of some OS, Picco and K&Bs. Some of those were so out of balance that the rotor pins wore out quickly.
After running some of the "modified" engines I acquired, I have not observed any performance gain over my stockers. I always wonder if Mr. Picco himself run his engine stock. Anyone knows? If he modified them, why would he not implement the mods in his production engines?
Kez
