1964 Chevy C-10 283 question

I have a 1964 chevy C10 with a 283 in it. Im not sure if its the original engine but from what I've found on the blocks casting numbers it very well can be the original but thats not really what my question is about. What I am curious about is the fact that the 283 in the truck currently doesn't have a harmonic balancer. Im in the process of replacing the 283 with a newly rebuilt 327 long block I just purchased and Im going to go to the parts store and purchase a harmonic balancer for the new 327 since the 283 didn't have one. Does anyone know why it wouldn't have had one. Unfortunately my truck was bought at a repo auction so I don't have the leisure of asking the old owner what or why but from what I've gathered so far he did some pretty screwy stuff to this truck so i'm trying to figure if the missing harmonic balancer was stock or something he did. And to clarify that YES I should purchase one to put on the new motor?

All 283's had harmonic balancers. I think you can safely assume the original one had been removed for one reason or another. Was the engine run without one or was it not running when you made the purchase? If an engine is run without a harmonic balancer, it might not be very pretty inside. Hopefully, it was removed because it was needed on another vehicle or the balancer failed, and the guy stopped driving it.

Just to help out some of the other newbies on the board, I'll review my take on harmonic dampers.

First off, they are not balancers, they're dampers. The exception would be motors like the SBC 400 that used an eccentric balance weight on the hub along with an eccentric weight on the flexplate to balance the motor, rather than internally balancing like most motors.

A harmonic damper is used to help cancel harmonics which are set up in the crankshaft by the force of the piston/rod slightly twisting the crank in the direction of rotation when the force of explosion in the cylinder is applied to the crank. It will only twist just so far, then will spring back opposite the direction of rotation to the limit of the material involved, then spring back the other way, then the other way and so on and so on. If left unchecked, the harmonic vibrations set up in the crank from all this to and fro twisting will destroy the crank in short order, causing it to crack and fail.

That's the job of the damper inertia ring around the outside of the damper. It's mounted in a slightly flexible material (we call it rubber, but I don't think it's rubber. Damper guys call it elastomeric material). The ring moves back and forth circumferentially on this elastomeric material and helps to dampen the crankshaft harmonics.

It looks to me like there are different outside diameters on dampers based on the crankshaft stroke and power output of the motor. 400's had the longest stroke in the SBC lineup and also used the largest damper diameter (8"). The fact that they also had balancing pads is inconsequential to the subject matter being discussed here. Shorter stroke motors such as 283's and 327's had smaller diameter dampers. Some low output 350's had smaller diameter dampers as well. So, it appears to me that the amount of MASS in the damper ring is what makes the difference in damping the oscillations, depending on stroke and engine output.

Well I appreciate the responses to my question. Apparently Im gonna have to find a harmonic balancer/dampener for my new 327. In my search so far I have found numerous prices listed for a 1960's era 327 balancers. The prices range on summit from $50-$300? Whats the difference? The truck I am putting together will not be a race truck, in fact the motor (internally) is totally stock. The only performance parts on the truck in a Edelbrock performer intake and 600cfm performer carb. Is there a specific balancer I need to put on this motor or will any chevy small block motor balancer set up work?

The 327 engines had several types of balancers ranging from small ones like you would see on a 283 to large ones for the high performance engines. Size really makes no difference in your application since it is basically a stock engine. Check with you local NAPA or other local parts store and see what a replacement costs compared to Summit. I used the street version of the FluidApr for my 383, but you could easily get by with a stock replacement.

You should be OK with the cheapest dampener for a stock application. Just a small note: over the years the location of the timing mark on the dampeners was changed between 2 and 10 degrees BTDC. But I don't know when and how exactly. You might have to check your timing tab location with respect to the timing mark on the dampener before you set your timing.
Max

PS: Dampening needed is a function of the flex and springiness in the crank, so low-RPM low-power applications won't need that much of dampening as high-RPM high power applications. Mass of the dampener ring and the viscosity of the elastomeric material are the determining factors for how well a dampener does it's duty. On the other hand, a dampener has a considerable weight which has to be accelerated rotationally all the time in a street car, and all accelerating uses gas. So if you don't need a lot of dampening in a street car but you need to accelerate it often, a light dampener is OK, in a race-car you'll need a lot of dampening and you don't have to accelerate it all the time because you're operating at more or less the same RPMs all the time, so you buy a big dampener. Crank material is also a factor, some are more springy than others.

Here's a list of rebuilt dampers from Damper Doctor. There are several choices for the 327 depending on diameter and the timing pointer position and location on the timing cover. To get the proper diameter for your timing tab, measure from the crank snout to the bottom of the timing tab with a tape measure. I don't have a small block crank here to measure, but I seem to remember the snout being 1.250" (1 1/4") in diameter, so the radius would be 0.625" (5/8"). Hold the end of your tape measure down against the surface of the crank snout and measure to the underside of the timing tab. If your measurement is around 5 11/16", then the tab is set up for a 6.250" (6 1/4") damper. (5 11/16" plus 5/8" snout radius plus 1/16" clearance would equal 6.250") If your measurement is a little less, then it is probably set up for a 6.125" (6 1/8") damper.

The other variable is to try to determine whether the tab is a 2:00 O'Clock or 2:30 O'Clock position tab. Standing at the center of the motor and holding a clock or watch face against the end of the crank snout with 12:00 O'Clock straight up should allow you to eyeball which one it is.

http://www.damperdoctor.com/Merchant...egory_Code=CHE

If the block has never been decked, then there will be numbers and letters stamped on the passenger side block deck just ahead of where the head bolts on. These numbers will translate into the exact application and year of the motor.

Thanks for everyones input, its greatly appreciated. Im hoping techinspector1 or someone else here could possibly answer this question for me. Im wanting to know what my rebuilt long block came from originally and dont really know where to go. I do know that its a 64-67 era 327 but I dont know what its H.P. was, what kind of vehicle it was in or anything. Maybe you can help me. Also (Techinspector1) would these numbers designate exactly what harmonic balancer/dampener I need for a stock application without having to do the previously descibed methods you posted?
Here is what I have-
Block Casting # 3858174
Engine I.D.#/ VIN CODE FIII7YC
Heads Casting # 3884520

Any more identifying help is greatly appreciated!

3858174 '64-'67 327
F Flint Michigan
1117 November 17th
YC could be either:
1. 1966, manual trans, A.I.R., 220 hp, 4-bbl, C10-C25 truck
2. 1968, manual trans, A.I.R., 240 hp, 4-bbl, C10-C25 truck
3884520 '62-'67 283, 327. 60cc chambers, 1.72"/1.50" valves

That is great! How about the most cost efficient harmonic balancer/dampener?

I gave you a link to Damper Doctor. Call 'em up, tell 'em what you have and get a price on a rebuilt unit.

I just went to put my damper back on and realized there should be a bolt to keep it in place. Problem is there are NO threads in the end of the crank. The end of the crank is knurled. Is this normal? Is it a tight fit th at keeps it in place? I tapped it back on to the approx. location that it was originally but now have to worry that it's in too far and the pulley will not line up with the other pulleys and will need to back it off thus causing it to less tight than it is now.

Is all this normal?

283 cranks were not tapped from the factory for a dampner bolt. you ave to have them tapped. i do it to all of mine.

the balancer needs to be pushed all the way back to keep the timing gear from walking forward and the chain cutting into the front cover....ted