AP-Engineering

Larry - When cutting the valve notch's in the pistons like these guy's are. They are only removing a couple of grams. So the balance will not be effected that much. Nothing you will ever feel at least. Plus making the same notch on all of the pistons will keep it pretty darn close to a even balance. The only thing that you will have is your crank will be over balanced now, bt the weight difference is so small this is really a moot point.

Thanks,
Chris Gelineau
Diamond Pistons
877-552-2112 toll free

Larry

iTrader: (4)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by DIAMOND:
<strong> Larry - When cutting the valve notch's in the pistons like these guy's are. They are only removing a couple of grams. So the balance will not be effected that much. Nothing you will ever feel at least. Plus making the same notch on all of the pistons will keep it pretty darn close to a even balance. The only thing that you will have is your crank will be over balanced now, bt the weight difference is so small this is really a moot point. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Chris, I am sure a little piston removal is not going to have much effect on balance but I do disagree that keeping all pistons the same will keep it close to an even balance. It will be closer to all pistons being out of balance the same amount perhaps. Each piston is balanced to it own counter weight. Any time you take a balanced engine apart you mark each piston to be sure it goes back to the same journal/bearing.

Slowhawk

iTrader: (12)

Larry, I agree with what you say but it's being a little mental on a stock lower end LS1.It will make more of a affect on a 8000+ rpm motor BUT you cannot balance a motor for the whole rpm range.You just balance a certain rpm range.Since someone from Diamond gave there opinion I would feel very safe with the notches.

AP-Engineering

Larry, what I ment by even balance was that they would all have the same amount out of them. Which would be better than say having all of them at different weights.

TEA Brent

Guys,

Individual piston/rod combos are balanced to each individual journal.... kinda. heh

Larry when a rotating assembly is "balanced" only 1 assembly is weighed... then this "bob weight" is used to balance the crank... the ONLY reason EACH piston and EACH rod are weighed is to assure they are within a couple of grams of each other.

as far as Notching the pistons in the block there is an easier ( and cleaner) way.. use Duct tape.
2 pieces vertically 2 pieces Horizontally over the piston ( including the gap to the cylinder wall) THEN while cutting stick the nozzle of the shop vac into the exhaust port of the head you are cutting with and turn it on. No shavings in the motor no grease on everything and no scratches except where the cutter ate thru the tape. once you do this you just tap the cutter down till it makes contact with the piston... use a Feeler guage between the top of the guide the cutter is in and the collar on the cutter to determine the depth of the notch you wanna cut and then use the drill on it... that simple.

LS1derfull

Proper balancing requires weighing all pistons with pins , rod weights(total and big end), pin locks and rod bearings, allowance for oil weight also. The bob weight is figured using the lightest cylinders weight, than all parts should be weight matched to that "lightest weight" As for imbalance from valves being notched, this would in a sense leave short block overbalanced.
Many race engine builders such as Bill Grumpy Jenkins believe in over balance as best method to keep bearings in tact at hi horsepower levels.
No problem in our scenario IMHO, if you want to get nervous about balance issues you should look into how well these aftermarket reduction pulleys(crank balancer) work! They make me nervous! <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />