Dans55
Newbie
Posts: 28
Reg: 03-03-22
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10-29-23 06:10 AM - Post#2863697
The 55 chevy I recently bought has a 350 engine. The motor mounts are next to the harmonic balancer. What I noticed is that the balancer has a mark in which the washer on top of the mount must scrape against the HB at times. With the engine not running the mount doesn't touch the HB. The engine does not run. I am in the process of pulling of a head as water is leaking between
the block and head. I bought the car and knew it had issues. Question is that if I put on a smaller harmonic balancer will it damage the motor or accessories?
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bobb
Super Senior Member
Posts: 6467
Loc: paradise
Reg: 09-05-03
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10-29-23 10:33 AM - Post#2863704
In response to Dans55
your engine will no longer be balanced. not to say that it was to begin with. would try to find out whats really going on there before replacing it. since you have the head off its a real good time to measure your quench. there are many sbcs that are wrong.
| 70 L camino, grampa engine, g-force 5 spd, road rage suspension. Pray first before all else fails. |
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 Rick_L
Member #409
Posts: 28095
Loc: Katy, Tx, USA
Reg: 07-06-00
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10-29-23 05:04 PM - Post#2863718
In response to bobb
The engine will still be "balanced" if the balancer is replaced with a smaller one. SBC balancers (6" and 8") are "neutral balance" except for the 400" engines, which have a counterweighted balancer.
If you do replace the balancer with a smaller one, make sure that the balancer and the timing tab are correct for each other. '69 up balancers are marked differently from '68 down. You can use either one, the timing tab just needs to match.
The other option is to notch the washer for clearance. I assume the mount bracket is already notched.
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55MAS
Senior Member
Posts: 1685
Loc: North Coast, USA
Reg: 12-19-01
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10-30-23 04:18 AM - Post#2863731
In response to Dans55
The 55 chevy I recently bought has a 350 engine. The motor mounts are next to the harmonic balancer. What I noticed is that the balancer has a mark in which the washer on top of the mount must scrape against the HB at times. With the engine not running the mount doesn't touch the HB. The engine does not run. I am in the process of pulling of a head as water is leaking between
the block and head. I bought the car and knew it had issues. Question is that if I put on a smaller harmonic balancer will it damage the motor or accessories?
Don't waste money on another balancer and timing tab. The 8" balancer is likely the one that GM installed on it originally for a reason, be it a high performance application or HD truck application. If the bracket rubs, notch as need for clearance. I don't really understand the washer issue. The washer I used on my modified mount to clear a 8" balancer never overhung the mount. Use smaller OD washers?
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YOUNG57
Frequent Contributor
Posts: 1376
Loc: Tennessee
Reg: 12-06-10
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10-31-23 06:52 AM - Post#2863766
In response to 55MAS
I have a SBC 400 with its large & balanced Harmonic Balancer and front engine mounts in a ‘57. I notched (cut) both mounts to clear the HB.
After market high performance balancer are smaller and will clear the stock front mounts but very expensive.
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sz0k30
"15th Year" Gold Supporting Member
Posts: 623
Loc: Oakland Co., Michigan
Reg: 10-12-08
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11-01-23 10:52 AM - Post#2863799
In response to YOUNG57
I don't know what in the heck some of the posters are talking about and evidently neither do they. Its been quite a few years ago now, but when I had a 350 built for my 57 with front engine mounts I used a smaller balancer. A 6-3/4" Summit #161350. It worked fine, the engine was still "balanced" & it ran great.
And $65.00 isn't expensive.
Edited by sz0k30 on 11-01-23 10:54 AM. Reason for edit: No reason given.
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55MAS
Senior Member
Posts: 1685
Loc: North Coast, USA
Reg: 12-19-01
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11-02-23 10:51 AM - Post#2863826
In response to sz0k30
Clearly some do not understand the difference between balance and torsional damping and that GM 8" balancers exist for a reason. They are NOT associated with 350 engines and newer. They existed on 327 engines. In '65 the 327 with a 4bbl carb or more (FI) came in HP ratings from 250, 300, 350, 365, and 375 HP. I owned a 365 HP version. All 350, 365, and 375 HP versions came with an 8" balancer and retaining bolt. GM didn't create the balancer as an over-the-counter product, it came on all of the production 327 350-375 HP configurations. All of the 325 balancers were neutral balance, no matter what diameter and thickness. The 8" provides increased torsional damping.
All the above aside, why would anyone want to buy a cheap Chinese small balancer?
Anyone ever see what happens when a balancer comes apart?
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Dans55
Newbie
Posts: 28
Reg: 03-03-22
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11-03-23 06:14 AM - Post#2863841
In response to 55MAS
My 350 is a early 70 model according to the person I bought it from. I confirmed it yesterday by looking at the block I.D. It's a 350 truck engine either 70,or71 or 79. Doubt it's a 79. Made in St. Catherine Ontario Canada. The damper needs replaced. Going to fix the motor mounts. If I put side motor mounts on will it bring the engine more forward.
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acardon
Ultra Senior Member
Posts: 11487
Loc: DFW TEXAS
Reg: 03-25-05
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11-03-23 08:10 AM - Post#2863842
In response to Dans55
If I put side motor mounts on will it bring the engine more forward.
Not if you use "standard location" side motor mounts on the frame. When you fasten (weld or bolt) the mounts to the frame, you want to locate the mounts with the engine in the stock location.
Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)
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