Is This Possible?

[OneTimeUser]

First, Yes I did a search, though how to title the search is a tough one.​

​

I found a flywheel for sale that says for hemi AND non hemi 212s. I wrote the guy and suggested that this was not possible because of the two having different crank dimensions. He wrote back saying:​

"Hi, thanks for your message. This part is designed to fit both by adjusting with a woodruff key (offset key). Please let us know if you have any other questions".​

Is such a thing possible? In other words, have any of you guys heard of a flywheel that will fit both hemi and non hemi based on some sort of "woodruff" key.​

Sounds like snake oil to me, but there is much I don't know and I guess it could be possible, or maybe I missed that day in engineering school.​

Thanks in advance. .​

 

[Grizzlymi]

Got a link to the flywheel? Do you have a hemi or non hemi?

 

[Whitetrashrocker]

Isn't the taper different?

 

[OneTimeUser]

Got a link to the flywheel? Do you have a hemi or non hemi?

No. The guy can't provide a link, just a picture of something that doesn't really make things clear. I was hoping someone else might have a link--if such a thing exists. This would solve a problem for me 'cause I've got a mix of hemi and non hemi 212s and could share some parts.

 

[Master Hack]

I don't think a woodruff key is going to adjust anything. It either fits or not.

Woodruff Key Sizes with Chart (Free Infographic) | Reid Supply

Woodruff keys come in a variety of sizes and it is important to have the right size for all of your machining processes. View our article to get all the different sizing options.

www.reidsupply.com

 

[landuse]

FROM GOOD OLD AI. WHO KNOWS IF THIS IS RIGHT EITHER

You’re right to question that claim—on the surface, “hemi and non‑hemi 212” flywheels being interchangeable sounds wrong, because those engines do have some key differences. But in this specific case, it’s not entirely impossible, depending on how the flywheel is designed.

What’s actually different between Hemi vs Non‑Hemi 212?​

For Predator 212‑style engines:

• Crankshaft taper and diameter:
  Typically the same between hemi and non‑hemi (this is the key point)
• Crankshaft length / threads:
  Usually the same
• Cam, head, valve train:
  Different (but irrelevant to flywheel fitment)
• Ignition timing keyway:
  This is where things can vary slightly

So the critical mating surface (crankshaft taper) is generally shared, which means a flywheel can physically fit both.

---

Where compatibility can get tricky​

Even if the flywheel fits on the crankshaft:

1. Ignition timing differences
   • Hemi and non‑hemi often have slightly different timing requirements
   • Some aftermarket flywheels build in timing advance
   • That can make it run differently (or poorly) on one vs the other
2. Coil alignment / magnet position
   • The magnet placement relative to the keyway might vary slightly
   • This affects spark timing
3. Aftermarket vs OEM
   • Aftermarket billet flywheels are often designed as “universal” replacements
   • They assume standard clone geometry (which both engines share)

---

So is the seller wrong?​

Not necessarily.

• If it’s an aftermarket billet flywheel, it’s very common for manufacturers to list compatibility with:
  

  “Predator 212 hemi & non‑hemi, GX200, clones, etc.”

• That works because:
  • The crank taper is standardized across these engines
  • The flywheel is designed with a “generic” ignition timing compromise

---

Your instinct vs reality​

• Your reasoning (different engine types → possible incompatibility) is solid
• But in this case, the critical dimensions for the flywheel are the same, so dual compatibility is totally plausible

---

Bottom line​

• Physically fitting both hemi and non‑hemi: Yes, usually
• Running optimally on both without tuning: Not always
• Seller claim “for both”: Likely legitimate if it’s aftermarket

---

If you want, tell me the exact flywheel brand/model (ARC, OMB, etc.), and I can tell you precisely how well it works on each engine type and whether there are any timing quirks.

 

[OneTimeUser]

Landuse,

Thanks for the excellent reply. I was always under the impression that hemi and non hemi cranks had different dimensions. It is revelation to me to know that the real problem might have to do with timing. Good to know.

Here is a link to the Ebay flywheel that I messaged about. Hope the link works...

Clint

https://www.ebay.com/itm/358082625560?mkevt=1&mkpid=0&emsid=e11051.m43.l1123&mkcid=7&ch=osgood&euid=9062d852f46743e3ac7ea047705b9bcb&bu=43202569337&osub=-1%7E1&crd=20260609002232&segname=11051

 

[Hellion]

Thanks for the link. Looks just like the $25 Scamazon flywheel.
I’ve got both Hemis and non-Hemis and I should do the dirty work on something like this but meh...

have any of you guys heard of a flywheel that will fit both hemi and non hemi based on some sort of "woodruff" key

Where’s BrownStainRacing or Itsid or ______ to help us make sense of this?!! The brain drain is real.

 

[Edwin Spangler]

I thought it was a matter of matching the flywheel and coil. Hemi with hemi and non with non. Is this not the case?

 

[Grizzlymi]

I don't know man, I wouldn't risk it. I'd save up for an ARC, never had one fail. Big price difference, but worth saving up for one, or just biting the bullet if you have the extra scratch. Could cost a lot more if you don't!