305 balancer?

[TugOwar]

Hi guys,

I need to know how to tell the correct harmonic balancer for a 305? Is it a measurement or a number of some sort?

All help appreciated.

[TugOwar]

*catchs post before it sinks into the abyss*

I realize it's a newb question. I'm a newb you see. Someone take pity on this newb?

[Fred T]

Don't know for sure. They are measured by diameter. One thing to check is the distance from the crank to the timing indicator. Add that to the crank radius (half the diameter) and double the result. The balancer diameter should be just a bit smaller.

You can use about any size you want, as long as it will fit and you have the right timing pointer. Bigger is usually better, 8" max. Look in Summit or Jegs for the different sizes available.

[TugOwar]

Thanks very much for the reply Fred.
So size makes no difference. What about the balance issue? How do I know if the balancer I have is balanced for a 305?

[JimKshortstep4x4]

All balancers will work except the external balancers like for the sbc 400 engines. The catch is to have the right timing tab which can be separate or welded to the timing chain cover. I believe the 305's came with a 6" balancer.


Jim

[TugOwar]

Thank you Jim. That simplifies the issue somewhat.

Now maybe someone could tell me how to tell an external balancer from an internal balancer? That way I can be assured the one I have on my 305 is for an internally balanced engine.
Then I can eliminate the balancer as a possible cause for vibration.

[arkracing]

External balance will have a "weight" on the backside - it will also be 8" diameter - there is only 1 small block external and that is the 400cid.
Bigblock external is 454. the flexplate/flywheel will also have a "weight" on it in an externally ballanced motor. the external balancer will also have a "cutout" section on the diameter part - the part that passes by the timing mark (and that is most visible to you)

305 balancer is approx 6"diameter..and 2" width
350 balacer is approx 6" or 8" diameter and 1-1.5" width

You can see the differance if you have a "wide" balancer and and "skinny" balancer. see if you can find a stock one off of a 350 and compare it to your's.
either one will work on a 305 though....so if it isn't the wider of the two on there don't worry. (aftermarket ones only come in the skinny style i think)

Anyway you can get a picture of it???...I could probably tell you from looking at it

[TugOwar]

Ok finally got the cotton pickin camera working enough to get a couple of pics.

Arkracing and I did some PM'ing back a forth when I started this thread and he said he could tell if I had a couple pics, so here they are. Sorry it took so long.

Please tell me if I have the right balancer. I'm almost convinced my vibration is coming from the engine.

[arkracing]

looks like a typical 305 balancer to me (6" diameter and Fat (1.5-2" thick or so))

i'd be able to tell better in person...but i would say typical 305 - which will work on a 350 but the elastometer may be worn or the balancer may be crack. it you can stick your finger inbetween the waterpump and the top of the balancer and have plenty of room... and if you stick your finger around the back side of it and it feels like it has a "lip" before you can touch solid it is a 305. the 305 should be solid all the way around - hope that makes sense somewhat. if the inner side (facing the block) is "recessed" then it is a 305 - the 350 won't be you'll be able to touch it without sticking bending your finger underneath the top edge (Most visible Part)

The BigA$$ Arrow i made in Paint points to the "backside" where it will either be recessed or not.

did you check the fan blades? - are they all there? if you are missing one the motor will have a vibration too.

[wannabeburbowner]

Do all or most 305's have the timing mark at the top?? Would the balancer's be the same?? Aren't 305's and 350's balanced a little different?? That's what I have always heard.

[TugOwar]

I can't get my finger between the balancer and the timing cover, there is only like 1/4" space there. But, around on the other side, near the bottom where the timing cover narrows down I can, and it does have a lip, maybe 1/4" thick.

As I stated in a PM, the balance measures 6" diameter and 1 3/4" thick. From what you've told me this would seem to be the correct balancer.

All fan blades are present and accounted for and in good shape.
New water pump.

I know it needs a timing chain and the distributor has some loose play in it but I can't see either of those causing the type of vibration I'm getting. But I could be wrong.

Before, I was convinced it was a drive shaft problem. I've replaced all three U-joints and the hanger bearing and I still have this vibration. Two of my U-joints are longer one way than the other and someone on another thread suggested that meant the drive shaft has been modified, so I guess it could still be a drive shaft thing.

Today I had to run into San Antonio and noticed that the vibration SEEMED to increase with the rpm and decrease when the tranny shifted up. Which is why I'm thinking engine.

I'm at a loss. This is my daily driver. I'm not working right now so don't have alot of money to spend and this truck is my way of getting around to apply for jobs and hopefully soon, to work. If push comes to shove I can take my sons truck but thats a last resort.

[TugOwar]

Just out of curiosity I went to Jegs and started pricing a new distributor, timing chain set and balancer.

Found the first two easy enough. I did a search for "sbc balancer" and this is the one that came up.

809-364709 8'' HIGH PERF BALANCER SBC

Is this correct?

[arkracing]

i'd go with the 6" if that is what yours is and you can't get your finger between the waterpump and the top of the balancer (which is odd to me) - but non the less i would go with a stock 350 type:
http://store.summitracing.com/defaul...5232&x=16&y=10
for your daily ride...and it's only $60 - not too bad

[TugOwar]

I'm sorry bro I misunderstood. Plenty of room between water pump and balancer. I was thinking between balancer and timing cover.

And thanks for the link to the balancer, I just wish sumit wasn't such a pita to order from.

[TugOwar]

actually, now that I click on the link, it doesn't work. at least not directly to the balancer. I'll find it eventually.

[zooza]

I had a terrible vibe once in a 69 truck that i owned. 400 engine with a 350 flexplate shook terribly. so maybe you have the wrong flexplate? just thinking & typing

[TugOwar]

I wondered about that Zooza, and it could be. But the PO swears he never had a vibration problem. And all that part was together when I bought, but the front of the motor I put together myself from parts that were in the back of the truck so thats why I'm doubting that its right.

Thanks for the input though. I think I'm gonna go ahead and make my credit card company rich and order balancer, timing set and distributor just so I can eliminate the front of the motor as a possible culprit.

[rustyold72]

Make sure the flexplate isn't cracked before going to the trouble of replacing the balancer, a cracked FP will also cause vibrations

[arkracing]

summit part#

SUM-161350

I'm sure Jegs has something similar.
I would think that a timing chain or a distributor will give you a vibration.

has to be a drive shaft out of weight...a warped rotor, bad balancer, bad w.p., bad fan, bad tires.....think of that one yet??, out of balance tires.
i wouldn't put a distributor in it - that isn't going to solve it i don't think. - pull the flywheel cover and disconnect the batt and turn the motor over by hand see if you can see any cracks in the flexplate or if you see a big weight spot welded to one side of it close to the ring gear

[TugOwar]

Thank God, I ordered the right one.

The timing chain was noticably worn when I put the front of the motor together but at the time I was more worried about just getting it running. Same with the distributor, but I noticed the other day when I replced the cap that it is getting worse, lots of side to side and up and down movement, so they are both in need of replacing.

I will definately check the flex plate, I take there should not be a weight on it right?

I did think of out of balance tires, actually mentioned it in another thread. But to be honest, I have some unbelievably crappy tires in my life and never had a vibration like this. And the ones I'm running now are nearly new, and I have checked them for broken belts, bulges, knots, etc.

[wannabeburbowner]

What year is your motor?? is it a 305??

[arkracing]

No it should NOT have the weight on the flexplate - that would be for a 400 motor - 454's and i think 502's also use external blance...and probably the new 572.
anyway anything BUT a 400 or 454 should NOT have the weight on the flexplate.

distributors normally have some up and down movement....side to side??? probably not so much and if they do there shouldn't be much.

let us know how you make out after replacing that stuff.

you may also want to try going to a bone yard and getting another driveshaft, putting your new joints in it and trying that - i know it is a lot of work....but i'm trying to brainstorm some ideas to help you out.....
cause I can't stand vibrations and rattles!!! that never go away

[TugOwar]

Wannabeburbowner - I have the casting number wrote down here some where but if I remember right its listed as a 80 - 84 305.

Arcracing I really do appreciate the brain storming. Replacing the drive shaft is a good idea. I may go look around this weekend.
I can handle rattles better than I can a vibration. Vibrations indicate a problem and eventually cause more rattles. lol

I'll keep on keepin on with this let you know what happens.

[TugOwar]

Well I'll just be damned. Went outside and jacked the old girl up, slid under to check the flex plate for cracks, weights, whatever.

First thing I noticed is the torque converter bolts are too long, whoever put it in used washers as spacers to make the bolts work. Not alot really, only about 1/4" too long, but just that might cause a minor balance problem. Started turning the flexplate and low and behold.....there is a weight on it. About 6-8 inches long right against the ring gear. *sigh*

I've pulled trannys before, I've replaced flex plates before. Neither is a job I enjoy very much. I'm wondering about removing the weight from the flexplate and avoid pulling the tranny.

The weight appears to be held on by spot welds through 4 small holes in the flexplate. If I can drill those welds out the weight should come off.

Let me know what you all think. In the meantime I have an old beat up flexplate laying here with the same kind of weight on it. I'm going out and see if the welds can be drilled out.

[TugOwar]

Removed weight, no more vibration. Gotta love POs I guess. I can see making a mistake, I didn't know any better until I was told, but the guy told me he had no vibration. I can only imagine the damage thats been done to the crank, main bearings, tranny, etc.

Oh well, I have a 350 4 bolt main sitting here in need of rebuild, when it goes in I'll put the correct flex plate on it. That is if I don't opt for a manual tranny.

I want to thank everyone who had ideas on the subject and especially ArcRacing. I owe ya one bud, if I can do anything for you just say the word.

Thanks.