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Discussion Starter #1
Hi guys,

i was wondering if any of you that have experience with the Falicon 70.4mm stoker crank could let me know their thoughts on it. I have a line on a New-Old Stock crank built for the early DRZ Kick-Only engine and i am considering picking it up as part of my engine build and running it with either just a stock bore at first or an athena 94mm cylinder which works out to 448cc's or 489cc's. My dilemma is the Kick-start only engines use a different LH crank half (its a bit shorter) so i will have to run a custom crank regardless and i believe Crankworks is the only shop around that currently does custom crank work and will run me around $700, and well i came across the NOS Falicon 70.4 knife rod crank for about $100 more.

I have seen a thread or two that indicate longevity isn't great with this crank but there were quite a few early versions of this crank design out so im not sure if the crank being offered to me will be a ticking time-bomb. Some Preliminary calculations show that with this crank Mean Piston Speed at 10,500 rpm will be 4,850 fpm with Maximum Piston Acceleration at 186,127 ft/sec^2, that is if my calculations are correct. At 10,500 rpm is the Mean Piston Speed and Max Piston Accel at acceptable levels?


any other thoughts or input would be much appreciated on the Falicon 70.4mm stroker crank.
 

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What is the rod length? That will be the key, I think.

I have an old Hotrods +5 in my 490. I have my rev limiter set at 11,000 and it will pull itself right to the limiter in 5th. That makes 4878 fpm mean piston speed with 193,576'/sec^2
If that lives, and if your math is right, you should be fine to 10,500. It will need a damn good head and custom cams to feed it, which I can help you with. I have +1mm intake valves, and +2 exhaust valves which I had to have custom made, and I have found that I have to make my own pistons to clear the cam timing that I have found to work, and my own cams, because shelf parts just weren't intended for this level of performance.

I'm fairly sure that you will have to trench the crank case, and the counterbalance shaft to clear the big end of the rod, so keep that in mind.
 

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Discussion Starter #3
Thanks CFM, your numbers are pretty dang close to mine for 11k rpm and a +5 crank. suspension is at the top of my list right now but if the guy still has the crank once i re-spring/re-valve i may pull the trigger on it. do your custom pistons utilize a lower timing edge or deeper pockets to clear the valves?
 

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Thanks CFM, your numbers are pretty dang close to mine for 11k rpm and a +5 crank. suspension is at the top of my list right now but if the guy still has the crank once i re-spring/re-valve i may pull the trigger on it. do your custom pistons utilize a lower timing edge or deeper pockets to clear the valves?
The pistons that I just ordered are for a +5 crank. I was thinking that I ordered them for stock compression height, but I was thinking wrong. However, they do have deeper pockets than anything else out there. I can order anything that I want though. I wouldn't be opposed to stocking a spare at stock compression height. It would give me an excuse to turn my 462 build into a 482.

Another thing that I get custom, is +2 exhaust valves. I think that would be a big help on a build that size.
 
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