MONGO510 Posted November 25, 2008 Share Posted November 25, 2008 Hey Guys, I am building a chev 350 V-8 to put in my Z-car and I need to pick your brains. The rotating assy. has balanced pistons and rods. The 327 crank is new to this setup and has been reground 10-10. My question is this; do I have to rebalance the entire assy., or can I get away with a neutral balance of the crank, flywheel, and damper? If I can get by with a neutral balance of crank, what do you think of balancing the crank on a set of knife edges? It will be used for occasional street use only. John Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted November 25, 2008 Share Posted November 25, 2008 Ok first,If I understood you, your looking to to build a 350 chevy with a slightly undersized journal size 327 crank? Im forced to point out the 350 has pistons designed for a 1.560 pin height and a stroke 3.48" stroke the 327 for a 1.675" pin height and a stroke 3.25" stroke, if you use 350 pistons on a 327 crank youll find your running a VERY low compression 327 combo. with around 6.8:1 -7.5:1cpr http://kb-silvolite.com/calc.php?action=piston_comp http://kb-silvolite.com/calc.php?action=comp Quote Link to comment Share on other sites More sharing options...
jt1 Posted November 25, 2008 Share Posted November 25, 2008 You can't knife edge balance a V8 crank. You can knife edge the counterweights, which is done to reduce windage, but is different from balancing the rotating assembly. Read thru this, it explains it better than I can: http://www.circletrack.com/techarticles/ctrp_0504_engine_balancing_tech_terminology/index.html Bottom line is that if you're using anything other than stock components, plan on getting it balanced. jt Quote Link to comment Share on other sites More sharing options...
MONGO510 Posted November 25, 2008 Author Share Posted November 25, 2008 400 block, Brg. spacers, 6" rods, and appropriate forged pistons. The original 327 crank was scored more than I wanted to deal with, so I got a replacement forged crank and had it ground 10-10. The pistons and rods have already been balanced and are good to go. What I am wondering, is if I can neutral balance the crank, flywheel, and damper and have a balanced assembly. Knife edge referal was to use as a bearing surface to hand balance the crank assy. Thanks Quote Link to comment Share on other sites More sharing options...
jt1 Posted November 25, 2008 Share Posted November 25, 2008 Knife edge referal was to use as a bearing surface to hand balance the crank assy. No. That fundamentally doesn't work with V8 cranks like it does with 4 cyl. cranks. You must use bobweights and spin the assembly. Read the article. jt Quote Link to comment Share on other sites More sharing options...
MONGO510 Posted November 25, 2008 Author Share Posted November 25, 2008 Thanks! Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted November 25, 2008 Share Posted November 25, 2008 Pretty straight forward actually, if you have the bobweight information then take the crank with that bobweight sheet and get it balanced. If no sheet then take one set of bearings (rod), one rod, one piston, one set of rings and take that down and get it balanced. Some people take the harmonic and flywheel/flexplate also. Depends on how anal retentive you want to be. What that does is tie the flywheel/flexplate to that motor only, not a good idea especially if you have to change flywheels/flexplates later. The balancer only if your using a stock type can you do that. Quote Link to comment Share on other sites More sharing options...
MONGO510 Posted November 26, 2008 Author Share Posted November 26, 2008 Thanks fella's. I am off to the machine shop! John Quote Link to comment Share on other sites More sharing options...
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