Is a 2004 6.2mpi internally balanced?

500dollar744ti

Senior Chief Petty Officer
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Jul 23, 2012
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I got a deal on the crank, rods/pistons and heads from a 2004 6.2mpi, I only have these items and I'm looking to build a 383 stroker with vortec heads using some sort of roller cam (truck maybe?) and a 350 block. I'm going to need to get pistons that are 0.030 over but right now I'm trying to see how this thing is setup.

All these older guys keep telling me I need a 400cid chevy crank pulley and flywheel but I think that's just old school hotrodding back when people ground down 400 cranks and put them in 350 blocks to make a 383 stroker.

I can't imagine mercruiser would put together a motor that wouldn't use the normal 5.7 parts?

I need to know how the 6.2/377 crankshaft is balanced, It looks like the front may be balanced internally but the back may be balanced externally? I got to find out if I can use my 1990 350 magnum flywheel and crank pulley on the engine I'll be building.

Thanks to anyone who knows. I'm already pretty sure I can use my 350 magnum flywheel and crank pulley but I wanted to run it by you guys and see if you can confirm.

Thanks.
 

achris

More fish than mountain goat
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May 19, 2004
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27,468
Take the entire rotating assembly (crank, rods, pistons, flywheel and balancer) to a machine shop and have them balance them. use what you like, but once it's balanced as an assembly, those parts must stay together, in the same position. Number the pistons and rods. And if the flywheel isn't keyed onto the crank, mark that too.

Chris....
 

Bondo

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Take the entire rotating assembly (crank, rods, pistons, flywheel and balancer) to a machine shop and have them balance them. use what you like, but once it's balanced as an assembly, those parts must stay together, in the same position. Number the pistons and rods. And if the flywheel isn't keyed onto the crank, mark that too.

Chris....

Ayuh,.... It ain't keyed, but the bolt pattern only allows to to go on it 1 spot,....
 

500dollar744ti

Senior Chief Petty Officer
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Jul 23, 2012
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691
Does anybody know if I can use my current Thunderbolt-IV distributor with the engine I'm building that includes a roller cam? I'm pretty sure my current ('90 350 magnum) is a flat tappet cam engine. When I went from a flat tappet cam in my truck (Ford 302) to a roller cam engine, I had to change my distributor to use a steel gear. I was told the cam would otherwise eat up the distributor gear if I used the old one.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
It's the same distributor, TB-IV or TB-V.... The ONLY difference is the module, and some of the V8s have a knock sensor....

Chris........
 

NHGuy

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May 21, 2009
Messages
3,631
The gear on the dizzy is determined by the material your cam is made of. Get a new distributor gear if in doubt. If it's wrong you fill your motor with gear metal.
You can use the same ignition. If going carb you might have to fatten up the jets and metering rods. Use truck specs for that stuff, boats operate under similar loads.
If it starves for fuel you might need a performance fuel inlet size. Drill out the seat a tiny bit. OE seats are .100" to .125". To drill it take out the seat and drill from the bottom side, start with .110", then if it still starves go .117" or .125". The needle will fit fine. Some big HP motors use a .149" seat. You should not need it, that's kind of a big displacement motor thing.
 
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