Need a compression release on a 212 Hemi.... (2024)

hmm..
pulling it to where it should be (tdc compression) before pulling the rope doesn't work?
the engine has a compression release build in for exactly that reason..
and while it's centrifugal it still works when properly started.
(blindly yanking the rope mostly hurts however )

Anyways if you want to add a secondary compression release...
I'm actually not to sure it'd be easy..
while one could force the exhaust valve open slightly,
one cannot make sure it's not hitting the piston which would be baaaad.
or one would need a secondary cam to prevent that,
and a drilled port in the cylinder head just for compression release
is not actually a great idea either I think.
And I wouldn't know how to tighten that once the eninge is running reliably.

if you haven't bought the predator already.. just buy a ducar 212 instead that is available with electric start

ORRR get the original Rato 210-III (what Horror fraud sells as predator)
but with e-start if you want some of the mods (all, except the flywheel would fit)
(I think they do too on the Ducar 212 but I don't know for sure)

'sid

Have Predator, will yank. (Old B&W TV western......)

Just got the Hemi. Can't erase the memory of my half-sprained wrist from the first time the other Hemi unexpectedly whipped back before getting through the squish. Might have just not been holding tight enough, but it got me again after that too. Tell me about that built-in release, have heard something like that before, don't know how it works. Is that TDC between blow and suck, or squish and bang? Anywhere after the TDC of compression but before TDC of exhaust would provide enough room to get up and go with some momentum. I never yank the rope from where it sits, always gently catch it on the start of recoil first, so my arm needs some distance from there to build up speed enough to easily plow through the full squish stroke. Too slow a yank on that minibike I built would result in yanking the whole thing up off the ground.

This is taken from a Robin Subaru EX Series engine repair manual. Pretty sure they're all similar.

DECOMPRESSION SYSTEM
The automatic decompression system is mounted on
the camshaft. It opens the exhaust valve before the
compression top, thereby alleviating the compression
pressure and reducing the force required to pull the
recoil starter.
During engine operation, the decompression system is
overpowered by centrifugal force and compression is
fully utilized to produce power.

Amazed at that action train......

Really appreciate that built-in release info, will play with the rope to see what I can feel. Other hemi never had the case cracked open, only intake, custom exhaust, jetting got hopped up, plus my secret procedure with Royal Purple break-in oil ($12 per qt.).
This one will get all that, plus PVL flywheel, 22 lb. valve springs, resistor-free coil w/8mm copper wire, possibly a timing advance key beyond the new flywheel's setup.
How the pull-start problem can be overcome will determine whether the remote start setup I'll build is a short-stroke foot-pedal or pull-lever. Will be a pedal if problem not fixed to my satisfaction.
Note: The reason for tossing the governor without getting a billet flywheel on previous hemi wasn't stupidity. I depended on the stock valve springs to start floating before rpm's could get high enough to blow the stock flywheel.