I own a 67 with correct casting and production numbers for engine, transmission (4 spd close ratio), and differential (AO posi). The engine was rebuilt at some point and the block was decked so parts of the pad stamping are partially ground of or missing. Enough remains of the ID and assembly date that it matchs with the rest of the numbers. The HT however is completely gone. Everything I can identify says it is a 327/350HP. I haven't removed the harmonic balancer but the measurements I have taken on the car are outside diameter 6 1/2 inches and the exposed outside edge is 1 1/4 inches wide with 3 ground in lines. The tab on the timing cover has an R,O,and A which are all 10 degree marking apart. From what I've read this balancer is not consistant with a 327/350 HP motor. Could a different size balancer work with a 327/350HP and is there any other way outside of taking the motor apart to tell if this is a 327/350HP.
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Re: harmonic balancer
Wayne-----
The balancer which you describe was not originally installed on an L-79 (327/350 hp) engine. However, the balancer which you describe is unlike any Corvette balancer that I am familiar with. The 6-1/2" 327 balancers, GM #3896903 and GM #3896904 are 3/4" thick and not 1-1/4". So, I don't know what you've got there.
In any event, any balancer designed for a 327 engine will physically fit on your L-79 engine and will function more-or-less alright. However, here are a few things to look for for further identification of your engine:
First of all, the timing covers for 300 hp and 350 hp 327s were different. The timing tab for both were spot welded to the timing cover, but the position of the tabs was different. Each tab was designed to fit closely to the balancer outer diameter. So, if your engine was originally equipped with an 8" balancer and someone changed it to the 6-1/2" balancer, there would be a large gap between the timing tab and the balancer. Of course, they could also have changed the timing cover, but this is far less likely.
Second, check the redline of your tachometer. If your engine was originally a 350 hp, then it should have a redline beginning at about 6000 rpm. If the redline begins at about 5300 rpm, it was a 300 hp. Of course, someone could have changed this, too, but it's less likely.
Next, check the distributor number on the ID band which is attached below the upper body of the distributor. If the number is 1111194, that would be a 300 hp 327 unit; if the number is 1111196 or 1111157 (TI), then the unit is a 350 hp 327 piece.
There is no other external way to distinguish between a 300 and 350 hp engine since the block and head castings are the same.In Appreciation of John Hinckley -
Re: harmonic balancer
Sounds a little small for a 350 hp 327. Call around and you'll find out you may need an 8" balancer. I've never seen a 6 1/2" balancer but then again I just pulled a 7" off my BB and as you and posted.
Seems someone put a low performace balancer off a 396 on egnine. These cars are old and there is no telling unless you know the cars entire history what all they have had done to them.Not to mention the .478" lift cam I pulleed out without any ID numbers. I had mech lifters (piddle-valve)also, I was wondering why the car was crapping out at around 5000K. My cam measures close to a 390hp hydraulic cam. 7" balancer.I noticed my friends 66 390hp tach yellow line starts about 5000K??????????????????????
Nothing surpises anymore about these cars. You have to take them down and record the numbers for the next guy along with pictures so the next owner won't have to guess like us.
Good luck,grr33570Comment
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Re: harmonic balancer
Thanks Joe and George for your comments. I should have mentioned that this is a late 67, 113 from the last one built. The heads have early 68 casting numbers but the casting dates are correct for my car. Also I didn't mention that the balancer is held to the crank with a bolt and washer. Can I find the part numbers you've mentioned without removing the balancer? If so, where do I look? How much distance should there be between a correct balancer and the timing tab? I measured the edge of the balancer again and it is 1 1/4 inches wide with the 3 1 1/4 inch timing groves in it. Thanks again.Comment
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Re: harmonic balancer
Does the car have the Aluminum Valve Covers. If they are steel it is probably not a 350 HP. The steel covers wont work on the 350 HP because the Cam has a higher lift and this would cause the lifters to hit the steel covers.Comment
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Re: harmonic balancer
Lou I disagree with your above post. My original 68 L79 327/350HP came from the factory with stamped steel valve covers, they are chromed, but they are still stamped steel direct from the factory and there is no interference with the same valve train as previous 327/350HP Corvette engines.Comment
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Re: harmonic balancer
Wayne-----
Usually, there will be no part numbers found on these balancers. Some early original 8" balancers have them cast into the face of the balancer, but, otherwise, I've not seen them. Sometimes, there is a casting number found on the inner hub, but this is not usually unique to a particular balancer.
As far as distance from the timing tab to the balancer, I would say that it's usually 1/4" or less. That's an approximation, though, and may vary a bit by engine. I've never seen an original one with as much as an inch or more clearance.In Appreciation of John HinckleyComment
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