I'm running a '65 283 with a few mild mods. The Harmonic balancer does not have the normal bolt that is in the end of the crank...just an interference fit to hold it on and a key to locate it. My question is will this hold up to some of the mods I made? Cam is a knock-off 327/350hp hydraulic cam. I'm running 9.5:1 .030 over flat top pistons and an Offy dual quad with Carter carbs. I know I'm over carbed for this motor (two 500's) and will need to do some changes here. I'm running and old Mallory marine dual point and the heads are the stock 1.72/1.50 valves, small runner, 60cc chamber heads with a 3 angle valve job. No major big performance parts here just a mild mini-motor that is all brand new. I don't have a clue to horsepower rating now but in stock 2bbl form it was 195hp.I have it mated to a Muncie 4 gear in a 2200 lb truck. Any guesses on what HP potential would be for this combo?
i don't think you will have any problem with the harmonic balancer just pressed on,if you are using the original small 283 one. if you are using a bigger one,maybe you might consider drilling and tapping (7/16"-NF) the end of the crankshaft for the bolt. i've had several mildly mofified 283's in rods abd never had a problem with one coming off..greg
I've witnessed a balancer coming off at about 5500 rpm, and I'm glad it wasn't my car. It tore all kinds of stuff up under the hood, including the hood! I will never run a balancer without a bolt!
If they actually check, I think they'll send you home, but they've NEVER checked any of my cars at either of the tracks I've run at. (I drove to the track, and they reasoned that if it was safe enough to drive there it was safe enough to run)
do you plan on running it at 5500 RPM's?..... if yes,i'd put the bolt in. if you are just gonna criuse around on the street,i'd wouldn't worry about it....but, if the crank is out now,it shouldn't be to much of a problem to drill and tap
i had 283 with a mild cam, intake, carb and headers for a long time. it was a 4 speed car so i wound it up fairly often. i never had any problems. as long as it's pressed on correctly and the key is in place i don't see where there would be a problem. chevy made powerpacks and fuel injected racers that way. mine was a 66
If you are using the same balancer that came with the crank you won't have any problem. The factory didn't use balancer bolts until the HP 327's were introduced and then they still used the press on only method for the rest of the lineup. Frank
For peace of mind, I would drill and tap the end of the crank for the bolt. Years ago I have had TWO balancers come off on two different 327s after hopping them up a little and winding them out. Pressed on balancers do not like "lumpy" camshafts. The crank you have already has a nice center machined in it, so if you are careful you should be able to get a nice straight hole to be tapped. good luck, Dale
Strange factoid: I have a book on the engineering history of the SBC from something like "the musclcar history library"--a very interesting book, by the way. The book says that the bolt actually wasn't directly intended to hold on the balancer--it was a response to crank breakage in the front throw area on early 350's. The bolt supposedly functioned to cure the problem by putting that front area under tension. It didn't give an exact date, but my oldest 350 is a '69 which lacks the bolt and hole.
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