If i use the balancer and the flexplate from my old 305 motor and put them on my new 350 will i have to rebalance the assembly. Will i have any problems i will also use the 305 timing cover or get the correct timing tab.

Thanks,

Leigh

 

Does anybody know?

 

No problems, they will work.

 

actually a 305 has a much lighter rotating assymbly than a 350 so, no.....it wont work without rebalancing.

 

It will work... rotating assembly weight doesn't matter, only whether it's internally balanced or not. And apart from that, the weight and moment of inertia of the rotating assembly in those 2 motors is nearly identical, in fact most 305s have the same crank casting (442) as 350s do, and some have the same rods.

 

Same number, different counter wieght thickness & locations.
Lingenfelter in his book calls it the great imposter.

Ron

 

ok you can try it....but let me know how soon you snap the snout off your crank.......been there and done that my friend.

 

uh hello?????? what do you mean wheight dosen't matter????

what planet are you from??????

that thing will defanantly need rebalancing if it could ever think of being used.......


think of it this way.... if i took say a box fan and removed one of the blade what would happen??

it would vibrate and shake all to hell...

literally thats what your doing...... your trying to get the counter wheights on the crank to equally match the weight of the piston,rod etc.....

total over all weight of the crank dosen't matter but as far as counter weights and balancing, they defanantly matter.....

 

there cheap enough new, just get a new balancer ( they do were out) and flex plate ( they do fatigue and crack)

 

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most 305's and 350's use the same damper.

No GMC-12551537 6.750 diameter(paw) 6272221 (GM)

You can switch and you will be fine. I have a 4 year old Damper that has been on 1 305 and two balanced 355's without a problem

 

As long as the flexplate matches the crank ( I peice or 2 peice rear main seal) you wont have a problem.

 

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lets have a moment of silence before hand for this innocent crankshaft......................

 

Yep I guess you know more than GM

 

This one is out of the GMPP catalog. Should I keep going?

 

FastTHirdGen, you are way out of the water on this one. There are three different kinds of balancers for the sbc, the small dia, the large dia, and the 400 balancer.

You can use either the lrg, or the small balancer for your......283,302,305,307,327,350........... A 350 crank and a 305 crank have exactly the same throws, rod journals are the same, and the mains are the same for the lrg journal blocks. they use the same rods, 5.7.

Your flexplate depends largely on whether your block is one piece seal or two. It also depends on which starter you are using. there are two different diameters of flexplates.

 

Yeah it's lots of fun arguing with people who don't understand what they're doing, but rely only on anecdotes and try to generalize one happening into a universal law, or only know what they've read in magazines... I usually don't bother to argue with people like that... I have kids, I get enough of it at home...

So, for those who think the weight itself is important, why don't you have to get your rotating assembly re-balanced when you change your flywheel weight??? It's because the actual weight isn't important, what's important is the distribution of the weight. If it's evenly distributed all the way around, or even if it's in equal lumps distributed symmetrically around the axis of rotation, it doesn't affect the balance.

As far as the crank damper is concerned, 262/265/267/283/302/307/327/350 are all internally balanced, and can all use any self-balanced damper from the 265/283 pulley flange with no inertia ring at all, on up to the 8" 350 balancer... of course, the longer the stroke, the more harmonic vibrations there are that one would prefer to be damped, which the larger dampers are better at doing; but that's different from "balance" or "what works".

 

I would just have to have someone pull a rotating assembly and spend the money to have it rebalanced for nothing just because someone is giving out bad tech advice.

 

hey i am sorry if i made any splashes in the pool. i know the literature for the balancers state they are for any sbc so long as it is internal or external for the application. but i have witnessed 2 motors snap the snout off of the crankshaft because they used a different balancer and didn't have it rebalanced. just to be on the safe side, when i pull my motor to replace my oil pump this winter i am switching over to an sfi balancer. before i put it back together i'm taking it back to the speed shop and have them double check and make sure it is still gunna be at dead neutral before it goes back together.

 

An issue I haven't heard raised yet...... the FLEXPLATE on late model 305s and 350s ISN'T totally neutral balanced! It has a set of "wings" welded on one side. I am NOT talking about a 400 flexplate here- it's not nearly that much of an imbalance. It's just a standard-looking 153 tooth flexplate with a smidge of imbalance designed into it.

I don't know for sure when they started using them but I'll say it's about the same time they went to a one-piece rear main seal type block. Therefore, it's not interchangable with earlier engines anyway, but I thought I'd mention this. I can post pics of both early and late style flexplates that illustrate this difference.

Balancers, I agree, are interchngable between 305 and 350 engines (and between early and late style blocks) as both are truly neutral balanced , although they somtimes have the timing line in a different spot (12 o'clock versus 2 o'clock) which requires an appropriate timing tab to be used.

 

Don't worry about that information about the 1 piece RMS motors being unbalanced, because if it bolts to the crank it must be the right one.....


Alot of mis-info in this one, and this is info that was posted about a million or 2x before

Maybe there was a misunderstanding about using a 305 crankshaft in a 350 block which should NEVER be tried as he counterwieghts are to small. But since "Anything is possible" the 305 crankshaft can be used, but the cost of re-balancing with mallory metal would be rediculous.

He only asked about the damper and flexplate so if your 305 is an 1986 or up 305, it will work! If it's an earlier model only the damper will work as the 2 piece RMS flexplate won't bolt up. And if you need to order a flexplate for a 1 piece RMS crank don't use the information that it's externally balanced.... say it's internally balanced.

This "Over-info" on 1 piece RMS flexplates is prolly costing companies and people money and aggrevation on shippping and wasted time because the person ordering thinks he's so smart by ordering an 'external' balanced flexplate for his 350.

Yes, it's not truly internally balanced. The small amount of counter is added because of the rear main seal change which is perfectly balanced on the 1 piecers, but had an offset balance on the 2 piece flange. I'll quit here before I confuze myself

 

sounds like people are confusing engine balance with torsional damping.

a neutral balance balancer (305 350) doesn't affect the engines balance, it is important because it damps the twisting that occours in the crank. a race engine or an engine that spends a great deal of time at high RPM may benefit in durability with a good damper like a fluid damper.

they interchange on 305,350 onl because they have no real effect on the balance of the engine, this is done inside the motor.

according to Johnny L 305 cranks and rods are different, the counter weights are smaller ( made to work with smaller pistons and rods) and the rods are thinner.

its also good to mention that there are different definitions of balance. There is the Factory balance, all the parts are made to be close in weight to a standard. good enough for production.

then there is the performance balance, where all weights are measured ( pistons and rods ) and the overall balance is adjusted very precisely ( depends on who does it)

my eagle rotating assembly is professionally balanced, i have a card with its specs, and there are several spots that are lightened to achieve this. In fact my kit wasn't available with a flywheel so i had to take the flexplate it came with and have the balance of that transferred to the new fly wheel i bought. there is a minute drill spot about a 1/16 inch deep to achieve this.

also i wasn't able to upgrade from sir rods to the H beams because it would cost about 200-400 extra dollars to add enough mallory metal to the crank to compensate for the extra weight of the rods. I also wasn't advised to change pistons to bump compression for the same reason, it would require a rebalance.

Hope i didn't add to the confusion