Well, I've had a bit of a set back. I have a high Zoot crank I was using and I've discovered that it turns into a wet noodle above a certain power level. The Zoot crank is a well made unit made from the toughest alloy that can be machined but, the Fox crank is made from high carbon steel then heat treated and is much harder than the Zoot crank. The Zoot crank is slower and is wearing hard on certain areas of the bushing and back plate. The engine is labored and draggy coming up to revs. You put the factory crank back in and the engine is just so crisp and free like it wants to rev. It's too bad because there's less vibration. It's a great sport/stunt crank which is what it was designed for but it's just not hard enough for what I'm doing in fox speed.
Of course the factory crank will spit out the front with this new build I'm working on so, what to do?
MM
Not a noodle... here are a few things you need to know about installing the HZ crank, first the crank does not have the "ditch" cut into it ,a s the FOX ones does as a shortcut to bypass making the bushing in the case clean at the back with a radius cut into it, this is also a WEAK point of the FOX Crank
The HZ crank install requires that you cut , or lap a " RADIUS " into the back edge of the crankcase bushing, part of normal install and is far superior to cutting a ditch in the crank.. IF you do not do this, the crank has a drag to it, and generates more heat drag, and pushes the crankpin back towards the backplate. And will rub on the backplate.
The HZ crank will NOT hit any FOX backplate if installed correctly
Second the FOX Rod should have vent holes cut into it for oiling, and the stock Fox rod has NO chamfer in it at the bottom front, The HZ cranks have a small perfect little radius made into it for strength, if you DO NOT cut a radius into the FOX rod, the rod will not seat all the way up on the crankpin, causing heat drag and pushing the rod farther back into the backplate, It will rub or dig into the backplate, this is very common in engines, and easily done It will NOT rub or dig into the backplate if installed properly
Next FOX bushings are all different sizes, so make sure you start with at least .001 clearance
The HZ crank test I have done all have been as much or most times MORE RPMs than stock cranks
THe HZ crank tested with my Rockwell diamond hardness tester shows a harder surface than stock cranks.
The HZ crank is made of steel and sent out and double Nitrated , very deep then ground to size
Putting the crank in using the correct blue printing techniques will result in a superior engine
Also all of my test never showed the stock backplate to give higher RPMs than the cnc one, the cnc one is not any faster but it does make the engine piston sleeve fit and rod last much longer
Also the ST G21-40 piston and sleeve will fit into the FOX 35 case, and it has a baffle and ring
Randy