Has anyone ever heard of running a SBC (except the 400) without the dampner on the front? From what I have found out, SBC, with the exception of the 400, are internally balanced. The large weighted piece that bolts to the crank is a dampner and not a balancer. Now, the OEM setup is in two pieces. There is the piece that bolts to the crank and has 3 holes for the pulley. Then there is the weighted piece that is pressed onto it with a rubber sleeve seperating the two. So, would there be crank damage running the piece that bolts to the crank, without the dampner or weighted piece? It seems like I read somewhere that guys used to remove the dampner to save weight. Application would be a street motor running less than 6,000 RPM's.
I dont know about running just the inner hub of the OEM damper, but I have thousands of miles on mine with just a billet steel crank hub
The harmonic balancer's job is to absorb shock waves that are generated every time the crank is fired upon (damper). It also plays a role in the dynamic balance of the rotating ***embly. You can remove the balancer and run a billet flange provided the new part is balance matched to the old part (a good crankshaft balancer can do this for you and don't ***ume that because a motor is internally balanced that the flywheel and damper are zero balanced and will match another similar part). Without the balancer Vibration and harshness will be noticably higher and bearing and crank life can be noticably shorter. You may also see increased timing chain stretch/wear, cam timing drift and spark ****ter due to the increased level of shock/vibrations sent through the camshaft by the crank. Many supercharged motors (often roots type) do not run balancers due to space issues and the fact that the giant gilmer belt and blower drive absorbs much of the harmonics generated by the crank. Is it worth it on a 6000 RPM street motor? Absolutely not. You'll gain more out of using a lighter flywheel (GM has an OEM lightweight wheel available) and clutch ***embly than removing the damper. -Bigchief.
I relate this to removing a water pump pulley for an extra .05 on the strip... you CAN, but why put your baby through the pain? If I remember correctly, you can save 4-6 lbs with a *****in' Fluidampr. They aren't cheap, but are a fraction of the price it would cost to get that weight out of the rest of the rotating ***embly.
There is a good book called, IIRC, How to build SBC's on a budget, by David Vizard. Really interesting how little is necessary to get 400hp out of a 350... but anyway, according to his tests, the bigger the damper is, the better. Running light weight parts on a street engine that doesn't see more than 6000rpms isn't going to get you anything...
All, Here's a good article about how harmonic dampers (harmonic balancers) work and why they are necessary in the vast majority of cases. It is on BHJ's website, written by the head of damper development, and it covers the various designs of dampers available (elastomer, mechanical, fluid, etc.). Let me clarify up front that I work for BHJ and though you might see BHJ branding on this tech sheet, it is not written with a "BHJ vs. the compe***ion, and why you need to buy a BHJ harmonic damper" approach. Rather is intended solely as an educational do***ent. Crankshaft dampers can be a difficult subject for even some of our most sophisticated engine builders to grasp completely and I spend a lot of time on the phone helping folks sort it out. That said, I am offering this to help anyone interested to understand, and hopefully, save a few premature bottom-end rebuilds (or worse) in the process. I'll always encourage a customer to run a damper, even if it means they have their old OEM unit rebuilt at Damper Doctor.: Click Here (230K PDF) Cheers, chrx
I'm gonna run an Iron Duke 151 from a midget, with a crank mounted water pump, am also interested in replies, who's done it?
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