chevy 427

[bryan73southwind]

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boat is now parke for the winter and motor is out looking to mod it any good ideas? how big can you bore a 427? what kind of hp can you get out a 427 or should i just styart a new motor from scratch???any ideas will help...thanks

[Jetaholic]

Stroke it 1/4" and make it a 454. :D

[SmokinLowriderSS]

Stroke it 1/4" and make it a 454. :D
Somehow I just KNEW................. :D :D :D

[Jetaholic]

Somehow I just KNEW................. :D :D :D
Of course you did. ;)

[H20MOFO]

427 Tall block or std?

[SmokinLowriderSS]

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boat is now parke for the winter and motor is out looking to mod it any good ideas? how big can you bore a 427? what kind of hp can you get out a 427 or should i just styart a new motor from scratch???any ideas will help...thanks
Outside limit, with sonic testing, you can bore a 427 1/8" (.125"), IF the cylinders are dead perfect in place (no core shift in production). .100" is easier, .060" is a no-brainer, but do not expect great cubic inches OR HP ains from a simple boring job.
You'll get arround 5 or 6 inches from a .060" overbore. How much HP you think that'll give you? 2-5.
What ideas do you have, what parts do you have (castin g numbers help a LOT), and WHAT DO YOU WANT most importantly.

[GofastRacer]

Outside limit, with sonic testing, you can bore a 427 1/8" (.125"), IF the cylinders are dead perfect in place (no core shift in production).
Yeah providing it's a genuine 427 block, if it's a 454 block it better be a real early one!..

[SmokinLowriderSS]

Yeah providing it's a genuine 427 block, if it's a 454 block it better be a real early one!..
Exact same for a 454 block, since they are the same, sans crankshaft.

[GofastRacer]

Exact same for a 454 block, since they are the same, sans crankshaft.
One difference, 427 block don't have the cast relief for the 454 crank!.. And the 427 block is more likely to be thicker since it's ealier than the 454 block!..:D

[WannabeRacing]

Correct, young man.
Now the real question, what type of boat is this going in? If this thing is in a light flatbottom, there is no reason a 427 should not be way more than you need. You can make all the horsepower in the world with a 427. Now torque is another question. If this is a heavy boat, or a jet, you are probably going to want to get a bigger crank. Either 4" it to a 454 combo or 4.25" it to a 496. That will get the torque needed to get a heavier boat going. Or keep the rpm bands down in the reasonable jet boat operation area. To make a 427 with the nice horsepower numbers, you have to spin the thing.
So we are back to the question of all questions. What is the application? Because any or all answers are dependent on that.

[bryan73southwind]

the boat is a 73 southwind jet

[GofastRacer]

Another question is, what are the intentions for the boat???..

[bryan73southwind]

i want the boat to be fast but still reliable so im not sure what that means i AM infact new too your world of boating...i grew up at the river but parents sold toys b4 i was able to take advantage of them so i am starting to build this boat for me... the boat goes about 60mph now not sure what is all in the motor sorta bout someone elses problem i no its a chevy 427 with mild came i no it has somewhat of a dommed piston not sure of the compression jacuzzi wj that has been gone threw and also a double pumper 850...boat runs alright i just want more out of it since i have the motor out of the boat and am going to rebuild it anyway what is an ideal speed goal i would be able to acheive in this boat.....thanks for reading my boats life story..and thabks for the help:confused:

[WannabeRacing]

Jet+heavy+general performance=torque!
I would put some cubic inches to it if you have the funds to do that. But a crank with more stroke to get more torque down low where that boat can and will use it. If it were me, I would look for a 4.25" and get close to 500 cubic inches out of it. A 4" stroke would also help, and may be easier to find and possibly less $$.

[River Rat 005]

Well, I have a heavy Kona with a Jacuzzi wj B impeler and an adapted Place Diverter. The engine is a .030 over 454 9 to 1 comp. Iron oval ports with a little porting, 078 casting I think, intake 2.19 exhaust 1.88. Comp cam hydralic roller running solids 244@.050 .623 lift. A Dart intake and 850 carb. Pistons are TRW forged. 2 bolt mains, stock cast crank turned .030 mains and rods. This boat turned 5800 rpm @ 75 mph at the drags. Never had a problem with it.