45 ci MODS

[thornl01]

Currently building a 45" (60hp) engine for a river boat for my nephew. Have been out of the loop for a few years so I am going to need & really appreciate some help. Have a '100' block, crank, etc, 15" mid w/ full shift foot. Boat is 13 ft, glass, flat w/ small pad @ rear. @ 250 lbs.
Plans are to bring all ports in block to map on apba spec sheet, add finger ports in block & pistons, & add low water pick-up to foot.

Questions are: 1.could someone please point me in the direction of what port timing will work on a little heavier boat,.2. what cc will work in head ?
recomended deck height ? 3.tuner length . 4. ign timing. who has best nose cone / water pick-up for this foot (nitro). What kind of rpm should I be looking for.5. Prop selection will come later.

I know these questions are a little intrusive to some as far as revealing your secrets, but we will not be racing against any of you guys, we only want to be "respectable" on the river.

thanks:

lawrence Thornton

[thornl01]

Guess I'll make a reply to my own post reguarding the lack of reply from anyone out there.

Seems that there is a lot of secrecy pertaining to any mods on the 45" motors.

Guess that all these guys running "stock" really aren't running so stock after all. LOL

If the 'MODS' or "blueprinting" that is going on in the 45" class is so "stock", then why the reluctance to share ?

Lawrence Thornton
Florence SC.

[ultrafast30]

I did the same thing. I cleaned up the ports, set the port timing at 118 and and 86 degrees. added 3/8" finger ports. Cut the head to get 175 lbs comp. Ran the big bore carbs. Stock 15" tuner and built my own nose cone, no low water pick up but blocked the top two holes. The motor is very strong to 6500 rpm. On an efficient hull it would pull right past that I am sure .I run a 4 blade 18 yamaha for every day and pull water skis with a 17. I really believe there is something left in the tuner a single cowbell would be my guess. I dry stacked the mid but no difference.The boat is just to get to the sand bars and back. Fastest so far is 50.9 with a 23 cleaver but a bear to get on plane. 45 with the 18. Put a trim and tilt from a V6 on it.The boat is a porpoise monster. The pad really ruined it for every day use untill I put a tiny set of adjustable tabs on it. Have fun but be careful. Mine is a bigger handful at 50 than my action marine was at 100 with a 2.5!! I have a 70 triple sitting on a stand for it just don't know if I need it or just want it.

[Mark75H]

Guess I'll make a reply to my own post reguarding the lack of reply from anyone out there.

Seems that there is a lot of secrecy pertaining to any mods on the 45" motors.

Guess that all these guys running "stock" really aren't running so stock after all. LOL

If the 'MODS' or "blueprinting" that is going on in the 45" class is so "stock", then why the reluctance to share ?

Lawrence Thornton
Florence SC.

Or the exact opposite ... everyone IS running bone stock

[thornl01]

Thanks for the reply.

LT

[jeff55vDSH]

All these internal mods seem like a lot of work for a river racer. What kind of HP gain would you like to see? Another 5hp, 10hp? I really don't know.

[thornl01]

Any improvement will be welcome. 5-10 would be great. Built quite a few 49" motors w/ decent success, & would like to apply the same basic mods to this 45" motor. Once a motorhead, always motorhead. Got to mess w/ something.
Just need a little direction as to if the 45" responds the same as the 49" triple. Not looking for a handout of information, just a little direction. If any of you w/45" experience say it will run better left alone, then I'll do that.

thanks

lawrence Thornton

[David Mason]

If you want the 45 to perform like a 70HP 49 incher, you need to do a lot more to it than simple porting and carbs.

There is only one substitution for cubic inches. That would be cubic dollars.

[thornl01]

Never said that I wanted the 45" to perform like a 49" triple. (got one of them that will honk!)
Just want to improve the performance of the piece in hand.
I know that porting only will not do the job, and I have other improvements planned for this piece.

Didn't want to step on someones toes, but seems that I have by simply asking for help.

LT

[river_ratj40]

depending on what you want to get out of it. Carbs, reeds, a little porting, and alot of compression. You can bump the compression up to 175-200#s and it'll wake it up. opening the exhaust will gain you a little bit also. but once you port it, the exhaust will really allow it to flow better. bump your timing up a couple degrees 21-23*. great thing about those motors they are indestructible. seems like they run forever.