Sbc 350 harmonic balancer

[Toolman78]

I need to replace the front seal on my 81 Malibu. Car has a 350 swapped in. I don’t know what year the engine is. Best guess is late 70s. I noticed the balancer ring widths vary. Is it ok to use a thicker one? Will the belts line up still??? Also is this a hard job to do with the engine in the car? Never pulled a balancer off so thanks for any help!

Tim

 

[Sweet_Johnny]

The casting number on the rear of the block will give you an idea of the year it was cast. The balancer could be for internally or externally balanced engines so getting the right type does matter, as does the diameter. The elastomer ring thickness will not be an issue if you're just buying a stock replacement part.. I recently swapped in a new Dorman 6.75" balancer on my 305, in the car, and it's a fairly straightforward ordeal but you're gonna remove multiple things. You'll want to get the car as high in the air as possible but you'll be switching back and forth working from the top and bottom of the car.

If you measure the diameter of the balancer and have the engine size and year you can be certain that the correct balancer is used.

 

[pagrunt]

I'll add my 2 peso's cause my pennies are wothless. I'm guessing you're using the original pulleys & accessories so that'll simplify things. Look up a balancer listed for your year with a 305. I have a '70 L48 for my car using the pulleys & accessories (serpentine type belt for the alternator) from an '86 305. I ordered one from Summit in the same diameter as the LG4 305's which was the same I used on the old 305 I was using. I do have the earlier V belt alternator set up which uses the same p/s pump & A/C compessor with no line up issues. Now those thinner balancers are for early SBC's like the 283 & 327 which used different pulley set ups. Most '69 to '85 internal balanced SBC's use the same thickness balancers. I'm not sure the '86 up one piece rear seal blocks used the same balance so I'm not including those for reference but are the same thickness.

 

[pagrunt]

I almost forgot, the one important things is getting a balancer to match the timing tab on the engine along with the right diameter to the tab's position.

 

[78Delta88]

Easy is a relative term, with the engine in the car, it's not that difficult. For some of the guys here that have done this several times on the driveway, OR at the track, it's easy. For someone that has n't done it yet it could be a little daunting. But all said and done it's not that difficult of a task. You might need to remove the radiator just so you have a little bit better clearance.

For something like a project car that you're fixing up over time, you can pull the balancer measure it up and match it up with a replacement. A lot of times RockAuto will have these that are OEM and much better price than what you could get over the counter at your typical Auto parts.

If you want to improve on what you have, then after you take it off measured up, you can get with summit or jegs and see what they have available, and a lot of times they'll have the higher quality balancers with timing tape and all that already built into them.

Typically whenever I do a rebuild for somebody or restoration I'll use the timing tape, a lot of people don't like them because they do sometimes fall off over time. But I like the professional look of the balancer with a nice paint job and timing tape on it, that's just me.

You need a good quality half inch breaker bar, good quality half inch ratchet, good quality half inch torque wrench, and a puller and a press. If you have an O'Reilly's or AutoZone in your area you can rent that as a kit. Once the job is done you return the kit and you get your money back.

If you have the 305 or 350 with the probe pickup, you won't have the slot on the balancer where you need it to be for a timing tab. If that's what you have, you can still set it up properly cut a slot in the new balancer with a hacksaw just enough to make a groove lay some paint in that groove and then add a timing tab to your cover. This will make it easier when you get ready to time the engine.

The absolute most critical is prior to pulling the balancer off make sure you know where zero TDC is also pull the distributor cap to see where the rotor is pointing. If you don't do this your timing could be messed up when you get ready to start it, and it's going to be a little bit of an effort to get it re-timed. So just make sure your #1 piston is at TDC and your timing mark is at zero TDC. When you put it all back together and you should be fine.

 

[Toolman78]

I'll add my 2 peso's cause my pennies are wothless. I'm guessing you're using the original pulleys & accessories so that'll simplify things. Look up a balancer listed for your year with a 305. I have a '70 L48 for my car using the pulleys & accessories (serpentine type belt for the alternator) from an '86 305. I ordered one from Summit in the same diameter as the LG4 305's which was the same I used on the old 305 I was using. I do have the earlier V belt alternator set up which uses the same p/s pump & A/C compessor with no line up issues. Now those thinner balancers are for early SBC's like the 283 & 327 which used different pulley set ups. Most '69 to '85 internal balanced SBC's use the same thickness balancers. I'm not sure the '86 up one piece rear seal blocks used the same balance so I'm not including those for reference but are the same thickness.

Thank you for the info!!!! It helps!!!

 

[Toolman78]

Easy is a relative term, with the engine in the car, it's not that difficult. For some of the guys here that have done this several times on the driveway, OR at the track, it's easy. For someone that has n't done it yet it could be a little daunting. But all said and done it's not that difficult of a task. You might need to remove the radiator just so you have a little bit better clearance.

For something like a project car that you're fixing up over time, you can pull the balancer measure it up and match it up with a replacement. A lot of times RockAuto will have these that are OEM and much better price than what you could get over the counter at your typical Auto parts.

If you want to improve on what you have, then after you take it off measured up, you can get with summit or jegs and see what they have available, and a lot of times they'll have the higher quality balancers with timing tape and all that already built into them.

Typically whenever I do a rebuild for somebody or restoration I'll use the timing tape, a lot of people don't like them because they do sometimes fall off over time. But I like the professional look of the balancer with a nice paint job and timing tape on it, that's just me.

You need a good quality half inch breaker bar, good quality half inch ratchet, good quality half inch torque wrench, and a puller and a press. If you have an O'Reilly's or AutoZone in your area you can rent that as a kit. Once the job is done you return the kit and you get your money back.

If you have the 305 or 350 with the probe pickup, you won't have the slot on the balancer where you need it to be for a timing tab. If that's what you have, you can still set it up properly cut a slot in the new balancer with a hacksaw just enough to make a groove lay some paint in that groove and then add a timing tab to your cover. This will make it easier when you get ready to time the engine.

The absolute most critical is prior to pulling the balancer off make sure you know where zero TDC is also pull the distributor cap to see where the rotor is pointing. If you don't do this your timing could be messed up when you get ready to start it, and it's going to be a little bit of an effort to get it re-timed. So just make sure your #1 piston is at TDC and your timing mark is at zero TDC. When you put it all back together and you should be fine.

Thank you for the advise! It definitely comes in handy with tips you guys share!

 

[WanaBa442]

If you're just replacing the seal, why do you not want to reuse the balancer that is on there now?
Barring a groove worn in it, it should work fine and seal up on the new seal, no?
At least you know it'll fit without spending money for no reason.....

 

[Sweet_Johnny]

If you're just replacing the seal, why do you not want to reuse the balancer that is on there now?
Barring a groove worn in it, it should work fine and seal up on the new seal, no?
At least you know it'll fit without spending money for no reason.....

I don't know how many miles are on his balancer but it's common for them to develop a wiggle or even slip rotationally over time due to the elastomer ring deteriorating. If the engine is old enough to need a new timing cover front seal it's pretty good insurance to spend the $65 on a new balancer instead of risking a ruined crankshaft/front bearings when it goes. I personally made that mistake before and have a 350 on a stand because the crank snout is ruined- the keyway stripped off.

 

[CopperNick]

Okay, us Norte Americanos north of the 49th don't use pennies anymore so adding my 2 cents would have to be done in .02 USD. Basically, what you are going to be doing is removing most of the FEAD (Front Engine Accessory Drive) items, leaving the front of the block more or less naked. In addition you should remove the radiator because you will have already drained it of most of the coolant due to having had to remove the water pump to get to that cover.

Getting the rad out of the way also gives you more room to get in there without the danger of smacking the rad with something heavy and hard and dinging the core.

For the balancer you will need a dedicated balancer puller. Yeah it might be possible to do it with something else along the puller line but that balancer, if OEM original, might prove reluctant to move so having the right tool for the job is an asset.

The major thing to be on the lookout for, once you remove the balancer pulley, is the presence of a bolt that secures the balancer to the crank snout. Again, it might come away easy or fight you. If you are restricted by circumstances or budget to using hand tools, then, in addition to the correct puller, you will also need a tool called a flywheel or ring gear turning tool, Lisle Tools among other suppliers makes them. To use that, you drop the dust shield that is screwed to the bell housing on your auto T-box, 4 screws, or to the bottom of the manual bellhousing and expose the flywheel or ring gear. At that point you need your buddy to slide under the car and use the turning tool to grab the teeth on the ring gear and lock the crank from moving so you can go after that balancer bolt and remove it. Don't depend on engine compression to hold the crank in place, it might or it might not. if you do happen to have an electric or battery driven 1/2 drive impact gun then use that and a 6 Point socket. Most tool kits typically come with 12 point but for working with that bolt the 6 is a better bet. A 6 point socket on a hex head bolt means little to no way the socket will slip unless you don't get the socket all the way onto the hex head or the bolt is both old and worn from life in the fast lane.

Oh, yeah, one last point, put all your hammers and blunt engines of destruction far enough away from you that there is no temptation to use one of them to try and bear the balancer off of the crank snout. Three/Four consequences, first that it doesn't work, second that you damage the balancer and make it harder to remove, third that you do get the balancer off but damage the crank snout, or all of the above.

Oh yeah, number two, this is not a half hour exercise, unless you have full access to air driven tools and a clean dry quiet place to operate. Otherwise, I can almost guarantee that you will be interrupted repeatedly by life wanting you to stop what you are doing because "Hunn-y, can you help me do..............or Daa-aad, I think I broke the .................. or ????"



Nick