Small Block Harmonic Balancer Reinstall

[William G.]

So............ok! I've read all the posts I can find regarding harmonic balancers coming off due to various causes and the tremendous advantage of having an engine/crankshaft set up for the retaining bolt (7/16-20). Why it took Chevrolet so long to come to the conclusion that all engines should have the balancer bolted (screwed on, actually) is beyond me. But I've never found any archival posts regarding the likelihood of internal crankshaft or bearing damage caused by driving the balancer back on the crankshaft nose. My repair manual shows one being driven on with what appears to be some sort of Rube Goldberg type device (factory supplied tool, though) which does not appear to offer any protection to the shaft, thrust bearing, main or rod bearings, etc. So, what is the risk to engine internals by hammering the balancer back on? I should think that significant damage would be likely.......but am I right? I believe my balancer originally was installed at the factory leaving the balancer forward of the crankshaft nose by about one inch, + or- 1/16 inch. That is to say that the crankshaft face was one inch back of the face of the balancer. Bottom line is I'm reluctant to hammer it back on but my neighbor says I worry too much and that perfectionism is an illusion devised to bug the realists and the "get 'er done" folks of the world. Who's right? Ideally the crankshaft should be removed and drilled and tapped by a good machine shop.......but my budget can't stand that and all I had set out to do was replace the timing cover seal.........not overhaul the engine.

Thanks to all the forum experts.

Bill

[Joe L.]

Re: Small Block Harmonic Balancer Reinstall

So............ok! I've read all the posts I can find regarding harmonic balancers coming off due to various causes and the tremendous advantage of having an engine/crankshaft set up for the retaining bolt (7/16-20). Why it took Chevrolet so long to come to the conclusion that all engines should have the balancer bolted (screwed on, actually) is beyond me. But I've never found any archival posts regarding the likelihood of internal crankshaft or bearing damage caused by driving the balancer back on the crankshaft nose. My repair manual shows one being driven on with what appears to be some sort of Rube Goldberg type device (factory supplied tool, though) which does not appear to offer any protection to the shaft, thrust bearing, main or rod bearings, etc. So, what is the risk to engine internals by hammering the balancer back on? I should think that significant damage would be likely.......but am I right? I believe my balancer originally was installed at the factory leaving the balancer forward of the crankshaft nose by about one inch, + or- 1/16 inch. That is to say that the crankshaft face was one inch back of the face of the balancer. Bottom line is I'm reluctant to hammer it back on but my neighbor says I worry too much and that perfectionism is an illusion devised to bug the realists and the "get 'er done" folks of the world. Who's right? Ideally the crankshaft should be removed and drilled and tapped by a good machine shop.......but my budget can't stand that and all I had set out to do was replace the timing cover seal.........not overhaul the engine.

Thanks to all the forum experts.

Bill

Bill-------

The balancers were installed at the factory using a special, large hydraulic press-like device. No such device exists anywhere in the field. Actually, I think that balancers for engines with balancer bolts were also installed this way and the bolt installed after the balancer was fully pressed on. Not that any of this matters in a field SERVICE installation.

For non-drilled and tapped crankshafts the only way to install the balancer is to use "impactive force". Do I like it? Absolutely not, but it's the only way. Fortunately, I don't have any engines that require this and I don't plan on having any.

I don't understand what you mean by "...balancer was originally installed at the factory leaving the balancer forward of the crankshaft nose by one inch...". The balancer should be installed so that the end of the "snout" seats against the crank timing sprocket.

[William G.]

Re: Small Block Harmonic Balancer Reinstall

Joe,
Thanks for the reply. Yes, certainly the back end of the harmonic balancer should be all the way back against the sprocket, but we can't see that upon visual examination. So...the only way I have of knowing when to cease "beating the drum" in reinstalling the balancer is when the balancer is back far enough that the distance from the face of the crankshaft nose is about one inch inset from the face of the balancer. I took this measurement as a reference before I began to use the puller to remove the balancer. Hope that clarifies my initial post and thanks for the reply......but I sure don't like the thought of hammering the balancer back on. As an aside. or side issue. I have an old factory shop manual (for nostalgic reasons, I guess) and it is for a brand X automobile and this company in the mid fifties was building a six cylinder flathead that probably couldn't exceed 3500 rpm running down hill with a tail wind and it had a retainer bolt or screw to keep the balancer from possibly coming off and tearing things up.. For Chevrolet to delete this bolt, or screw actually, probably saved them back in the day about one dollar per engine........which might come out to 50 cents profit lost per stockholder. One old manufacturing edict says that if you could beat the bean counters at their game made for a good day for the engineering staff.

Thanks again, Bill

[Richard G.]

Re: Small Block Harmonic Balancer Reinstall

In the GM world cost was king. If they could get them on and not have them rolling down the road without a bolt that's the way is was going to be.

That said you can make it easier by putting the balancer in the freezer over night. Use a large rubber hammer for the install. Or you will mark up the face of the balancer and damage the threaded holes that retain the pulley. I have also used a piece of oak for protection? Always check before you pull a balancer to confirm it doesn't have the threaded hole in the crank. Sometimes they are installed on cranks with the hole sans the retaining bolt. I have seen many a crank screwed up because the puller went into the threaded hole and messed up the crank nose threads. I have a spacer I made on the lathe I drop into the hole before pulling one. A short bolt (7/16-20) can also be threaded into the hole but then the hex may be in the way of pulling the balancer all the way off. I can't remember for sure on this point.

Send me a picture of the original in a PM, I may have an extra?
Rick

[William G.]

Re: Small Block Harmonic Balancer Reinstall

Running the risk of beating a dead horse (or crankshaft?) to death I'd like to add that in my repair manual in a couple places is stated to tap the crankshaft forward and then after when installing rod bearings or rear main seal (I BELIEVE this is referred to as "setting the register"?) to bring the mating parts into alignment. Then we also are told (in some quarters, perhaps most) to use a BFH to get the Harmonic balancer back on..........and by BFH I believe we are not expected to use a 16 ounce ball peen hammer. Those two diverse statements do not appear to correlate very well.......at least in my mind.

Finally, there are four tapped holes in the front, of a small block anyway. Would anyone care to comment on the idea of using those four holes to fasten a plate to the front of the engine.......with applicable spacers, of course, to bring the plate far enough forward to clear the balancer. Then with a tapped hole in the middle of this plate use a pusher screw (ok..........young guys call everything a bolt even though engineering folks used to refer to them as screws anytime they threaded into a PART) to slowly force the balancer on. One great advantage to this method is that you would know when the snout of the balancer contacted the sprocket instead of guessing at which point your BFH hammer blows were no longer having a positive effect on balancer movement, rather than merely beating the crap out of the crankshaft bearings. Any thoughts?

Also, would putting the balancer in the freezer increase the diameter of the center hole or decrease it? I had briefly thought of applying liquid nitrogen to the nose of the crankshaft......but this is rather impractical, to say the least. I suppose it MIGHT be able to be made to work.

Bill

[Bruce W.]

Re: Small Block Harmonic Balancer Reinstall

Bill, are you sure that your crank isn't drilled and the balancer bolted on? I believe somewhere along the line GM started threading the cranks to prevent the balancers from spinning off? my 57 and 58 were not drilled. My 62 either was already drilled or it was done sometime before I owned the car. I changed mine on my 62 and to install I just need a long bolt and I just pulled it on by tightening the bolt. I agree with the other post you just pull it on until it lines up with your other pully.
Bruce

[Joe L.]

Re: Small Block Harmonic Balancer Reinstall

Bill, are you sure that your crank isn't drilled and the balancer bolted on? I believe somewhere along the line GM started threading the cranks to prevent the balancers from spinning off? my 57 and 58 were not drilled. My 62 either was already drilled or it was done sometime before I owned the car. I changed mine on my 62 and to install I just need a long bolt and I just pulled it on by tightening the bolt. I agree with the other post you just pull it on until it lines up with your other pully.
Bruce

Bruce-----

The balancer bolt was first used for 1962 with 340/360 HP. Thereafter, it was used for SHP 327 through 1968. For 1969 and thereafter it was used for all small blocks.

Big blocks always used a balancer bolt.

[William G.]

Re: Small Block Harmonic Balancer Reinstall

Bruce..........

No......in the vain hope that you might be correct I just went to the garage and checked again. In the era of my car (mid-sixties) the 300 hp and lesser engines had only a pilot hole in the nose of the crankshaft for centering the shaft prior to machining operations. And yes, I've installed balancers on L79s........piece of cake: too bad bean counters were not engineers or at least mechanics. I know this is vastly unfair but bean counters on my list rate just above attorneys..........vastly unfair to both occupations--just my sick sense of humor at work.

Rick........

I'm certainly no computer guru and therefore couldn't send you a photo of my harmonic balancer. But there is nothing wrong with mine that I might benefit from your kind thought............but it is not totally fair either to say "nothing is wrong with my balancer" because, as with any 50 year plus old part, the rubber could, by tomorrow morning, be deteriorated to the point where attention by a rebuilder might not be necessary. [You may recall my mention on an earlier post about a brand X harmonic balancer detailed in an old factory repair book. That brand X company designed their balancers with two pieces of rubber one on either side of the middle section "weight" and the whole thing held together with six bolts and nuts.......hence any mechanic with a set of hand tools could rebuild a balancer of that design and the two rubber sections back in the day probably cost about 75 cents apiece. Ah, yes the good old days...........course that balancer might have only withstood 5000 revs, at best.]

Thanks to all,
Bill

[Domenic T.]

Re: Small Block Harmonic Balancer Reinstall

If I remember, GM used the bolt only on the steel crank, not the cast iron. All the manual cranks then were steel and the automatic cranks were cast iron till the HP was increased using a automatic trans?

Dom

[John L.]

Re: Small Block Harmonic Balancer Reinstall

Dom
I pretty sure All corvette sm crankshafts were forged steel - bolt on balancer had more to do with the higher RPM of the SHP solid lifter engines

[Domenic T.]

Re: Small Block Harmonic Balancer Reinstall

Yes John,
I think you are right. I was mainly talking about the passenger cars. Also I got a bunch of steel cranks and HI PERF blocks out of trucks back then for about nothing. The trucks used those tough parts, even 4 bolt mains.

Dom

[Joe L.]

Re: Small Block Harmonic Balancer Reinstall

Yes John,
I think you are right. I was mainly talking about the passenger cars. Also I got a bunch of steel cranks and HI PERF blocks out of trucks back then for about nothing. The trucks used those tough parts, even 4 bolt mains.

Dom

Dom-----

I don't think that any 327's were ever originally made with 4 bolt mains. None used in Corvettes ever were.

All 1962-67 327 crankshafts used in Corvettes were forged steel. Only SHP were drilled and tapped for a balancer bolt. For 1968 with the introduction of the large journal crankshafts, the 300 HP was nodular cast iron while the L-79 was forged steel.

All 1969+ Corvette small block crankshafts were drilled and tapped for a balancer bolt regardless of whether the crankshafts were cast iron or forged steel. L-46, LT-1 and L-82 were forged steel. All others were cast iron.

[Domenic T.]

Re: Small Block Harmonic Balancer Reinstall

Joe,
Again I wasn't clear. I was talking about BB and 350 engine 4 bolt mains. By the way, in our circle back in the 265,283,and 327 days we never needed 4 bolt mains. The only thing I saw bad was #1 & 2 turning a bearing at high RPM, usually from lack of oil. Never had a problem at the strip. My solid lifter 365 HP has 2 bolt mains and reved so fast the tach was behind.

Dom