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Balancing necessary? #118330 09/09/08 05:34 PM 09/09/08 05:34 PM
Joined: Feb 2007 Posts: 42 Oregon FarDarter OP member
FarDarter OP member Joined: Feb 2007 Posts: 42 Oregon	I'm planning on doing a hone and re-ring of my 318 shortblock that is totally mid-seventies Dart stock. I'm going to top it with some 302 heads and as I understand it, that will lower the compression a small amount beyond how low it already is. So, if I were to go ahead and get some new pistons to bring it up to around 9.0:1 is there any chance I could get away with runnning it without balancing? Since every car build seems to have a name these days, you can go ahead and call this one "Cheap."

Re: Balancing necessary? [Re: FarDarter] #118331 09/09/08 05:50 PM 09/09/08 05:50 PM
Joined: Jan 2003 Posts: 16,376 D dogdays I Live Here
dogdays I Live Here D Joined: Jan 2003 Posts: 16,376	302 heads have smaller chambers than the '68-and-up 318 open chamber heads. As you will most likely be replacing a steel shim gasket with a composition gasket twice as thick, gaining about 4 cc of volume, your net compression will remain the same as stock. Replacing stock LA 318 pistons with KB167s will make necessary rebalancing the rotating assembly as the 167s weigh about 84 grams less than the stockers. R.

Re: Balancing necessary? [Re: dogdays] #118332 09/09/08 06:20 PM 09/09/08 06:20 PM
Joined: Nov 2004 Posts: 2,495 Oregon City, OR Baxter61 top fuel
Baxter61 top fuel Joined: Nov 2004 Posts: 2,495 Oregon City, OR	You dont "have to" have it balanced. But your going as far as you are with boring and new pistons, its only like $180 extra to have it done and it will in theory run smoother.

Re: Balancing necessary? [Re: Baxter61] #118333 09/09/08 06:50 PM 09/09/08 06:50 PM
Joined: Jan 2003 Posts: 8,144 Arkansas 340727dart master
340727dart master Joined: Jan 2003 Posts: 8,144 Arkansas	Quote: You dont "have to" have it balanced. But your going as far as you are with boring and new pistons, its only like $180 extra to have it done and it will in theory run smoother. IMHO, there is no "theory" about it. I won't ever build another engine without having it balanced. Besides, since he is changing to lighter pistons, that almost requires having the engine balanced. Your life is not my fault. My life is none of your business. Speech is free only if you agree with those in control.

Re: Balancing necessary? [Re: 340727dart] #118334 09/09/08 10:10 PM 09/09/08 10:10 PM
Joined: Apr 2007 Posts: 560 MI M marklock I tried too hard for a custom title
marklock I tried too hard for a custom title M Joined: Apr 2007 Posts: 560 MI	Have it balanced, money well spent. my

Re: Balancing necessary? [Re: marklock] #118335 09/09/08 10:43 PM 09/09/08 10:43 PM
Joined: Jan 2003 Posts: 3,624 Ozark Mo. BADBEE master
BADBEE master Joined: Jan 2003 Posts: 3,624 Ozark Mo.	I agree, its no theory, its fact. An engine will perform better, live longer and have less stress on all internal components when its balanced.

Re: Balancing necessary? [Re: BADBEE] #118336 09/09/08 11:01 PM 09/09/08 11:01 PM
Joined: Aug 2003 Posts: 4,463 Rome, PA Ryan_340 master
Ryan_340 master Joined: Aug 2003 Posts: 4,463 Rome, PA	1972 Power Wagon W100 1973 Power Wagon W200 1971 Duster 1972 Dart Swinger 3-1972 Demons

Re: Balancing necessary? [Re: FarDarter] #118337 09/09/08 11:10 PM 09/09/08 11:10 PM
Joined: May 2007 Posts: 209 New Zealand S solidcam enthusiast
solidcam enthusiast S Joined: May 2007 Posts: 209 New Zealand	From the factory a lot of engines weren't balanced that good.You will really appreciate a good balance job and so will your engine.You may even pick up a few ponies in the process.

Re: Balancing necessary? [Re: BADBEE] #118338 09/10/08 12:20 AM 09/10/08 12:20 AM
Joined: Nov 2004 Posts: 2,495 Oregon City, OR Baxter61 top fuel
Baxter61 top fuel Joined: Nov 2004 Posts: 2,495 Oregon City, OR	Quote: I agree, its no theory, its fact. An engine will perform better, live longer and have less stress on all internal components when its balanced. Ive read articles and spoke with an engine builder who was a long time endurance racer and they used to run motors in 24 hour races and do dyno testing on motors that werent balanced and they concluded there was no evidence that not-balancing as no ill effects on on engine life. I dont disagree that its money well spent, but Ive run motors that werent balanced and I had 0 issues with it. Plus, you really think factory motors from that era were balanced all that well? My buddy used to race 340's in the early 90's and he said he would pull motors apart where 1 cylinder was already bored .010 over from the factory, go figure that one out!

Re: Balancing necessary? [Re: Baxter61] #118339 09/10/08 12:56 AM 09/10/08 12:56 AM
Joined: Feb 2007 Posts: 42 Oregon FarDarter OP member
FarDarter OP member Joined: Feb 2007 Posts: 42 Oregon	Well the question has now become moot, as I have been corrected in my understanding of what my compression ratio is going to do. Somehow I had come to believe the 302s had larger chambers than earlier 318 heads despite the quench pads. I'm not sure how that happened but now that I know the truth, I'll be keeping my same pistons. Project Cheap just got cheaper! Thanks for the input, fellas.

Re: Balancing necessary? [Re: Baxter61] #118340 09/10/08 12:58 AM 09/10/08 12:58 AM
Joined: Feb 2003 Posts: 21,318 Manitoba, Canada DaytonaTurbo Too Many Posts
DaytonaTurbo Too Many Posts Joined: Feb 2003 Posts: 21,318 Manitoba, Canada	Quote: My buddy used to race 340's in the early 90's and he said he would pull motors apart where 1 cylinder was already bored .010 over from the factory, go figure that one out! That makes no difference to balance. Piston A is standard bore size and the same piston in a .03 will weigh the same. They make them like that just so you can avoid the rebalance issues if you kill an individual piston/cylinder.

Re: Balancing necessary? [Re: DaytonaTurbo] #118341 09/10/08 01:19 AM 09/10/08 01:19 AM
Joined: Nov 2004 Posts: 2,495 Oregon City, OR Baxter61 top fuel
Baxter61 top fuel Joined: Nov 2004 Posts: 2,495 Oregon City, OR	Quote: Quote: My buddy used to race 340's in the early 90's and he said he would pull motors apart where 1 cylinder was already bored .010 over from the factory, go figure that one out! That makes no difference to balance. Piston A is standard bore size and the same piston in a .03 will weigh the same. They make them like that just so you can avoid the rebalance issues if you kill an individual piston/cylinder. I never knew that

Re: Balancing necessary? [Re: Baxter61] #118342 09/10/08 01:44 AM 09/10/08 01:44 AM
Joined: Jul 2008 Posts: 30,431 Florida STAYcation BeEtLeJuIcE ! The village idiot's idiot
BeEtLeJuIcE ! The village idiot's idiot Joined: Jul 2008 Posts: 30,431 Florida STAYcation	Factory OEM "balancing" ? ..... some I have heard from people I know are as much off as 50 grams ! ...and from a Bud in FL ...as much as 90 grams !!! ......... And a 300$ balancing job OFF as much as 30 grams !!!! It ALL depends on who is doing the balancing job. I did a 383 some years ago with a grams scale and did EACH to within 2 grams. And that did not take that much work to do.

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