otazup Posted October 9, 2012 Share Posted October 9, 2012 hey guys i am roughly blueprinting my motor before it goes back together. My problem is ive just weighed my rods. (as a whole piece, not the big and small ends individually). 3 of the rods weigh about 9-10gms more than the other 5. these same 3 are from a different motor which may explain the difference?? anyway, am i just being perdantic in thinking i need to linish some weight off? or can i just whack them in and go. I really want to hear from someone who builds there own v8s as im sure itll be different principal to 4 cyl etcs. the 5 originals weigh between 736-738gms each and the other 3 weigh 748gms. i know thats alot of weight to take off a rod so i thought im not gonna start if i dont have to. the motor is a 351 cleveland if that matters and also whats your opinion in painting the lifters valley, ive heard good and bads things. i mostly want to do it for oil return and also cause it looks tidy! any advice much appreciated Jason Quote Link to comment Share on other sites More sharing options...
Jase Posted October 9, 2012 Share Posted October 9, 2012 from what've read the optimal balance can only be obtained when the piston rod combo each way the same, as far as giving them a dab with the drill press or linisher follow this chaps example QLpiF0E0EJU Quote Link to comment Share on other sites More sharing options...
Unclejake Posted October 10, 2012 Share Posted October 10, 2012 am i just being perdantic in thinking i need to linish some weight off? any advice much appreciatedJason The royal flush of Jasons.............. I don't think you are being pendantic at all. A well balanced engine is a delight to drive and produces more power. The trick will be deciding where to loose the 10 grams from. If the crank is already out of the motor then perhaps take it all in to get professionally balanced? They will need a bob weight to do the crank, but in your instance you can't even supply that as you have a choice of weights. As you are using components from different engines you will need to check main bearing clearances very carefully too. Quote Link to comment Share on other sites More sharing options...
Spencer Posted October 10, 2012 Share Posted October 10, 2012 Yea are you getting those rods re-sized? I would add ARP bolts/studs and re-size the rods on almost any stock conrod build accept the most budget slap together job. Sometimes there are pads on the rods where weight is meant to be removed from, a good manual will go over where you should remove weight from. I think I spent around $500 to have all my rods & pistons blanced to with 1grm and then the rotating assembly balanced, ended up with quite abit coming off the flex plate to get it in balance, money well spent though Quote Link to comment Share on other sites More sharing options...
otazup Posted October 10, 2012 Author Share Posted October 10, 2012 cheers guys yea all valid points i had a good talk to an eng reconditioner yesterday, he says to balance the rods, pistons, rings, crank, flywheel and balancer all as one. pretty big job he says can do for $500 which is decent i think. he also said the difference in weight may be from the bolts? i didnt even consider this so im gona remove them first and weigh again and go from there. arp bolts as you say are definately going in, apparently standard nuts are crap. cheers jason Quote Link to comment Share on other sites More sharing options...
Unclejake Posted October 11, 2012 Share Posted October 11, 2012 Sweet. If you go ARP bolts you should probably have the big ends re-sized as the clamping pressure is different than the factory bolts. Quote Link to comment Share on other sites More sharing options...
RUNAMUCK Posted October 14, 2012 Share Posted October 14, 2012 It's a job for a shop. I tried to balance my rods once using a very sensitive digitaal scale. BUt you need a jig to weigh each end of the rod by itself. Vee engines are considerably more difficult to balance that an Inline engine. At the absolute minimum, you'll want to get the foreign rods weight matched to the original rods. Quote Link to comment Share on other sites More sharing options...
Testament Posted October 14, 2012 Share Posted October 14, 2012 it doesnt matter so much if the new rods are lighter/heavier than the originals provided each of the new rods is the same weight as eachother. e.g. in a 4cyl two rods are going up and two are going down at any one time so they balance eachother out. vee engines are a little different unless they run a flat plane crank Quote Link to comment Share on other sites More sharing options...
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