What are the differences between the harmonic balancers for 283 FI (1957) and 327 FI (1963). Does it make any difference between Vettes or passenger cars? Thank You.
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Re: 283/327 High Horse Harmonic Balancers
Two totally different parts, 63-5 was 8 inch diameter and very wide, the '57 is much narrower and I believe smaller in diameter than the '63-5Bill Clupper #618 -
Are you looking for the specs for 59-61 HP? *NM*
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Re: Are you looking for the specs for 59-61 HP?
Loren, what I am lookig for is a pretty good description of a 57 283/283 and I assume there is no difference between one for a Corvette or a passenger car. I have been told there is no difference between the 57 283/283 and the high horse 63's and up. When I dig through my old magizine road teste and aritcles I seem to see two differnt ones as addressed by Bill. Any help you guys can give me I will appreciate. Thanks.Comment
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Re: 283/327 High Horse Harmonic Balancers
Bill, I agree and thanks for your response. Good to run across you at Carlisle. I can tell you those air filters you had for a Studebaker wont work on a 57 FI passenger car. Maybe one of these days I will find a Studebaker to put it on. Thanks for your input on the balancer. You guys have to work to keep us straight.Comment
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Re: 283/327 High Horse Harmonic Balancers
keith----
I agree with Bill 100%. The only commonality between a 57 283/283 balancer and the 62-68 327 SHP balancer is that both will fit on a small block crank. That's it. The configuration and dimensional specs of the balancers are completely different.In Appreciation of John HinckleyComment
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Re: 283/327 High Horse Harmonic Balancers
To put an engineering perspective on this, the purpose of these devices is to damp crankshaft torsional vibration, and the vibration modes of a crankshaft are primarily a function of its geometry, so different stroke crankshafts have different torsional vibration characteristics. Material also play a minor role as steel crankshafts are a bit stiffer than cast iron cranks of the same geometry because steel has a slightly higher Young's Modulus and CI.
So one would expect that the different stroke SBs will have different torsional dampers, but this argument somewhat falls apart with 327s. All have steel cranks, and the Tufftride surface treament on SHP cranks has no effect on torsional stiffness, so it must be a high rev vibration mode that motivated the larger damper on SHP 327s, however the "small" damper on 250/300 HP engine does not seem to cause problems if these engines are modified to achieve SHP rev levels.
DukeComment
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Re: 283/327 High Horse Harmonic Balancers
Duke-----
Not all 327's were originally fitted with steel cranks. Through 1967 most, if not all, were. However, after the change to the "large journal" configuration in 1968, most (but not all) 327's used nodular cast iron cranks. The last PRODUCTION use of the 327 for passenger cars was for the 1969 model year.In Appreciation of John HinckleyComment
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Re: 283/327 High Horse Harmonic Balancers
Yes, I forgot about that "oddball" one year 327 with the large journal CI crankshaft, which would have different torsional characteristics than the previous small journal steel cranks.
I'll leave it up to you to tell us if they used different dampers than the small journal 327s or later large journal 350s.
DukeComment
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Re: 283/327 High Horse Harmonic Balancers
Duke-----
1968 with 300 hp engine (both Corvettes and passenger cars), used a unique-to-1968 balancer. It was GM #3914684. As far as I know, it was configured just like the 1966-67 300 hp balancer. It must have been different in some way, but I don't know what it was.
1968 with L-79, which used a forged steel crank but of "large" journal size, used the same 8" balancer as all 62-67 SHP 327's.In Appreciation of John HinckleyComment
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Re: 283/327 High Horse Harmonic Balancers
Interesting. Typical "dual mass" dampers only damp torsional vibration in a fairly narrow rev range. The are "tuned" to the appropriate frequency by adjusting the outer mass and stiffness of the rubber sleeve. Silicone fluid dampers provide a damping effect everywhere in the rev range.
Back in that era torsional vibration problems usually manifested in the form of broken parts. The early 240Z I-6 had a torsional vibration problem that led to a high crankshaft failure rate. (Long crankshafts are more prone to torsional vibration problems than short crankshafts.) The vibration can sometimes be seen with strob lights synchronized to the vibration frequency. Then experience and trial and error are used to design a suitable damper, or the crankshaft is redesigned for increased stiffness. Nowadays, most vibration modes are predicted by structural analysis software.
Given the "one-year" cast iron big bearing 327 crankshaft, I'm not surprised that the '68 300 HP damper was unique.
Theoretically the '68 forged steel 327 SHP crankshaft should be stiffer than the earlier small bearing version due to the larger journals and greater journal overlap, which would push any problematic vibration modes higher up in the rev range, but apparently the engineers deemed that the earlier SHP damper was adequate for the job so they didn't have to bear the cost to design and tool a new one for a one year low volume application.
DukeComment
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Re: 283/327 High Horse Harmonic Balancers
Duke, Thanks sounds real simple doesn't it.Comment
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Re: 283/327 High Horse Harmonic Balancers
Joe,
I have a 57 Chevy passenger car that I am pretty sure came in to this world as a FI car, so says the original owenr.Someone stopped by and looked at the car and told me the harmonic balancer was incorrect for the car and it should look like the 63-65 Corvette SHP engines. I am under the impression all 57 FI engines came from Flint so there should be no difference between a Vette vs a passenger car as far as the engine goes. Then my question is what does a "real" harmonic balancer look like for a "real" FI passenger car? I have gone back through all of my old publications looking for pictures or specs and no luck so I then turn to you guys for your input. Just keep helping me. Thanks you guys are a ton of knowledge.Comment
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Re: 283/327 High Horse Harmonic Balancers
keith-----
I can absolutely guarantee you that the person that said that the 1957 FI engine should have a balancer that looked like the 63-65 SHP balancer is wrong. Absolutely no doubt about it. The 63-65 SHP balancer (actually used for 62-68 with SHP small blocks) is an 8" balancer. No 8" balancer of ANY configuration was ever used on a passenger car (including Corvette) 283 cid engine. It's possible that some were used on trucks, but I highly doubt it.
As far as 1957 FI engines go, keep in mind that there were TWO FI engines used for the 1957 model year. At least, 2 versions were installed in Corvettes. I believe that both versions were installed in passenger cars, but I don't know that for sure.
Anyway, depending upon which version was installed, either the 250 hp with hydraulic lifter cam or 283 hp with mechanical lifter cam, also affects the correct balancer for the application.
The 250 hp balancer was of GM #3712763. I THINK that this balancer is a 6" balancer with integral pulley. I do not otherwise know the configuration of this balancer, though.
The 283 hp balancer was GM #3742986. This balancer was also a 6" balancer but it did not have an integral pulley.
The Corvette or passenger car version of either of the above engines used the same balancer. In other words, there was no difference between a passenger car or Corvette 250 hp balancer and there was no difference between a Corvette or passenger car 283 hp balancer.In Appreciation of John HinckleyComment
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Re: 283/327 High Horse Harmonic Balancers
Joe, Thanks. It is just interesting how some, including me, have opinions that are hard to change. When we have these car we have to deal will all types of opinions. My car has been apart and through a lot of hands, but it appears the vast majority of the parts have been kept with the car. One of the thought to be 57 experts in the state stopped by and he made the comment about the balancer.This put me to doing my research. The enine doesn't have the SHP 63-65 balancer. It is narrow roughly 3/4" and appears to be about 5" with no groves for belts. There are provisions for mounting other pulleys.
The car is a very very late car,first week of Sept. and has a 4960 unit on it. Fuel, air meter and distributor match up.
Thanks to you and all of the guys on the discussion borard for helping me put my mind at ease that what is on the car should be on it. Thanks again.Comment
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