Ok. My lower end is coming together quite well in the searching out of parts...need to buy a couple more things and it's bolt together time. Question 1; I'm running an external balance 406 SBC, I've been told to ditch the balancer and get a hub. ?????? I din't think this is correct but hey what do I know. What's up? Where should I be going with this route? Why hubs over a good harmonic balancer? Question 2; What is a good ring/rings to run in a blown/nitrous motor....I've bee looking at the Speed-Pro Hellfire series Max rpm is 6500 H-beam rods 5.7" full floaters with studs, stroker clearanced, rated @ 700hp Ring size is 1/16, 1/16, 3/16 Keith Black forged blower pistons Eagle ESP crank 3.875 stroke
i ran a balancer for about2 weeks then it split off crank went to an old 283 hub worked great the blower belt will take the harmonics out of the crank same job as a balancer
I run steel hub dampers (fluidamper) with a second 3/16 key cut in the crank .a stock cast one can crack and spin . I learned the hard way. steel hubs are for racing some may say the blower belt dampens the crank harmonics i don't buy into that .400's are hard to seal anyway i've had good luck with total seal rings more $$$ but i think its worth it.
There's a lot of answers/opinions on this topic. Lots of guys run hubs & use the blower itself to dampen harmonics. Does it work? To an extent, yeah. Is it as effective as a damper specifically designed for the combination? Probably not, but you might be hard pressed to tell the difference. The engines I've seen with hubs don't get used enough to really say for certain whether it's a good or bad idea...in terms of longevity of the crankshaft. My personal preference leans towards the ATI dampers, which are not cheap, but work well. Double keying on a blower engine is always a good idea. Plain Chevy dampers can be pinned to retain the outer ring, and if you do this it's best to use one of the ones with the nodular iron outer ring....but it's less h***le to go aftermarket. As a matter of fact, Chevy lists the ATI dampers in their own catalog for performance use, where production dampers aren't required. You mentioned that you are using a Eagle crank. I would check with them before using any of the Fluidamprs.....several of the aftermarket crank companies are refusing to warranty any cracks where a Fluidampr was used....or at least they recommend against using them. Long story as to why, but bottom line is, check first & save some grief. If Eagle is OK with them, then they are another option. So far as rings are concerned, the Hellfire series (pricey) are good, as are the regular "R" series ring file-to-fit sets. Almost any GOOD ring set will be OK as long as you take care & effort to finish the bores correctly (and round).
While not cheap, I decided that nothing quite compared to the ATI and it's truly a case of getting what you pay for in this instance. And for the money I already had invested in my stroker build, it was a drop in the bucket at that point. What I can't help but wonder is why you did not go with a full neutrally balanced crank? I know Eagle makes them in their 3.75" cranks and in the 3.80" one I use. I feel sure they must offer it in the 3.875" stroke too.
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.: Click Here (230K PDF) Cheers, chrx
I use neutral balanced cranks in my 400's and they are wicked expensive. They have to add 'heavy metal' slugs to the front (and rear?) throws at a about $125 per slug. My childs & alberts cost $1600, the crower was less but didn't have all the same machine done to it.
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