212 Hemi restoration.

[Rat]

So first off, I'm well aware a wedge head is better for max power tuning, I have a 98%complete engine for free so I'm going to use it; more cost effective to upgrade it a little bit than to replace it entirely with a fresh one and then upgrade that.

Needs:
Conrod (piston?)
Heavier springs and keepers
Carburetor (I plan to get a PWK28 for my 208 and swap over the 24mm)
Side cover (bad threads)
Probably fresh crank seals

I'm thinking about using a longer conrod with the stock dished piston from my 208 so I don't have such low compression, but also not need to mill the head. If I end up having to round the corners off the crown so be it as long as I don't end up hitting and bending a valve or both.

The idea is the dish could or would negate the need to cut valve reliefs, and I do realize that a dished piston will drop the compression more than a pair of notches; I'm going for easy and reliable, not so much killer performance.

Any thoughts from the usual suspects?
@anderkart @Denny @BrownStainRacing @Master Hack @BaconBitRacing

 

[Denny]

If your going to just make a runner I say check clearance as you go and go for it.

 

[Rat]

If your going to just make a runner I say check clearance as you go and go for it.

Oh definitely even if someone said it's been done already.
I took a reading of 0.051 depth of the dish so I'm thinking I could maybe get away with a +0.020 rod, but idk how lucky I feel gambling at the part price.

I only considered it an option because I was noticing the ARC 3.328" billet rods are cheaper than their 3.308" ones... supply and demand deal maybe?

The other option I considered is just getting a 3.308" ARC Rod and flat top piston set for the 208 and put the borrowed 212 stock parts back whence they came.

 

[Denny]

I say put the domed piston in from a (non hemi?) and notch the piston if necessary for valve clearance. I’d also be tempted to try one of those Chineseum rods to get a zero deck (ARP bolts).

 

[bob58o]

The intake valve size is what? 27mm? It’s been a while so I forgot. Do you plan to machine the seats for larger valves? Or are you planning on using a carb larger than the valve?

I try to keep the carb about 2mm -3mm smaller than the valve.

27mm gets 24mm carb.
32mm valve gets 30mm carb
30mm valve gets 28mm carb
35mm valve gets 32mm carb

 

[Rat]

The intake valve size is what? 27mm? It’s been a while so I forgot. Do you plan to machine the seats for larger valves? Or are you planning on using a carb larger than the valve?

I try to keep the carb about 2mm -3mm smaller than the valve.

27mm gets 24mm carb.
32mm valve gets 30mm carb
30mm valve gets 28mm carb
35mm valve gets 32mm carb

Yes 27/25 and I'm not doing ANY work I don't have to.
I've used the head on my 208 so the ports have mild work (mostly just casting ridges knocked down) but my goal isn't to go wild with it, just make it run good and stay together.

As for the carb, I was planning to get a 26mm or 28mm for my 208 (27/25 wedge) and swap over the 24mm I have on it.

If I decide to go nuts with it, won't be til much later. As it sits now its an all stock mill with no governor.

 

[Rat]

I say put the domed piston in from a (non hemi?) and notch the piston if necessary for valve clearance. I’d also be tempted to try one of those Chineseum rods to get a zero deck (ARP bolts).

Non Hemi runs dished like anything else, I've only ever seen domed in 2cycle. I was considering using a dished piston I have, with a slightly longer than stock rod, I'm just not sure if +0.020 is going to be a severe issue and require some crown shaving to regain the head chamber clearance at the perimeter...taking a little bit off the corner isn't a big deal, taking a lot is not gonna do it

 

[BrownStainRacing]

Non Hemi runs dished like anything else, I've only ever seen domed in 2cycle. I was considering using a dished piston I have, with a slightly longer than stock rod, I'm just not sure if +0.020 is going to be a severe issue and require some crown shaving to regain the head chamber clearance at the perimeter...taking a little bit off the corner isn't a big deal, taking a lot is not gonna do it

@RLS_Underground

I've done a few pred 212 hemi builds. They usally closer to .040" piston to deck height.
But that .051" doesn't surprise me.

I shoot for a .030" piston to head, with the head gasket that will get me close.
.030" is plenty of room for rod stretch and block flex.

The hemi ft piston will set .020" further in the hole then the non hemi dished piston.

DJ-1285PH OEM Hemi Predator Flat Top Piston Kit

www.arcracing.com

So that'll put you .071" in the hole with a stock length rod (3.308").

With a +.020" longer rod (3.328), you will still be .051".

Even with a .009" thick head gasket, it'll only be around 8.5:1 CR with the pred hemi head.

The pred hemi head chamber measures 21-22cc. After clean up it'll measure more.

Lmk what other head you have to work with and we'll see if we can't get that CR up a bit.

When I start a build, I'll shoot for 10.5:1 CR, and still be able to run on 87 octane fuel with 28-30* of ignition timing.

Most of them end up with 10.1- 10.3:1, depends on how the rockers are sitting (gasket thickness and lash caps usally corrects that) and how much I had to unshroud the valves.

 

[bob58o]

The hemis I’ve done were usually just over .020 in the hole. The 3.328” connecting rod got me closer to 0.003-.004 in the hole. With a 0.027” gasket it gave just over 0.030” piston to head clearance. Milling the head about 0.035” seems to get the 22ish cc head to an 18.5 ish cc head.

With the flat top piston I think that makes close to 10.5 :1 Static CR IIRC

They make Flattop pistons that have +0.020 compression height.

DJ-1285PH2 STD Predator Hemi Flat Top Piston Kit

www.arcracing.com

You got to measure your unit.
Here’s a cheap head, I think it’s set up for smaller valves. And you might need to blend the bowls to the seats if using 27mm intake.

Head, Cylinder, GX160, UT2, Thai, 18cc: Genuine Honda

We specialize in Honda GX120, GX160, GX200 and 6.5 Clone Performance for Karting, 1/4 Midget, Mini Bike, Mokai, Winch Boarding, Tractor Pulling, and Bar Stool Applications. Championship winning motors for QMA, USAC, BSP, AKRA, WKA, & ASN

www.nrracing.com

 

[BrownStainRacing]

The hemis I’ve done were usually just over .020 in the hole. The 3.328” connecting rod got me closer to 0.003-.004 in the hole. With a 0.027” gasket it gave just over 0.030” piston to head clearance. Milling the head about 0.035” seems to get the 22ish cc head to an 18.5 ish cc head.

With the flat top piston I think that makes close to 10.5 :1 Static CR IIRC

They make Flattop pistons that have +0.020 compression height.

DJ-1285PH2 STD Predator Hemi Flat Top Piston Kit

www.arcracing.com

You got to measure your unit.
Here’s a cheap head, I think it’s set up for smaller valves. And you might need to blend the bowls to the seats if using 27mm intake.

Head, Cylinder, GX160, UT2, Thai, 18cc: Genuine Honda

We specialize in Honda GX120, GX160, GX200 and 6.5 Clone Performance for Karting, 1/4 Midget, Mini Bike, Mokai, Winch Boarding, Tractor Pulling, and Bar Stool Applications. Championship winning motors for QMA, USAC, BSP, AKRA, WKA, & ASN

www.nrracing.com

That's an excellent price for a 18cc head!!!!

They are hard to come by, around here.

I'll usally use a 14cc small valve head, open it up around 15-16cc and use a dished piston in a 212 to get the CR up.

 

[Rat]

@RLS_Underground

I've done a few pred 212 hemi builds. They usally closer to .040" piston to deck height.
But that .051" doesn't surprise me.

I shoot for a .030" piston to head, with the head gasket that will get me close.
.030" is plenty of room for rod stretch and block flex.

The hemi ft piston will set .020" further in the hole then the non hemi dished piston.

DJ-1285PH OEM Hemi Predator Flat Top Piston Kit

www.arcracing.com

So that'll put you .071" in the hole with a stock length rod (3.308").

With a +.020" longer rod (3.328), you will still be .051".

Even with a .009" thick head gasket, it'll only be around 8.5:1 CR with the pred hemi head.

The pred hemi head chamber measures 21-22cc. After clean up it'll measure more.

Lmk what other head you have to work with and we'll see if we can't get that CR up a bit.

When I start a build, I'll shoot for 10.5:1 CR, and still be able to run on 87 octane fuel with 28-30* of ignition timing.

Most of them end up with 10.1- 10.3:1, depends on how the rockers are sitting (gasket thickness and lash caps usally corrects that) and how much I had to unshroud the valves.

My 208 has the Hemi FT and it is deck flush, but that's also a wedge.

I'm trying to get it back together and running with what I have on hand already FOR NOW, which only excludes the Conrod, and the cover since I can't bolt a back plate to it safely due to thread condition.

My neighbor up the road has a project he wants done that will need an engine and fabrication work to pull off (same dude I serviced a Club Car and a 2023 Hammerhead 150LE for).

I think most likely I'm going to stick the Hauyi on it, rebuild it to factory spec minus governor, sell him the engine as part of doing said project and then get a better engine once that deal is done.
It's going to be a big project so it will be a big bill that I can likely get an engine and upgrades all in one shot.

 

[Thepartsguy]

Non Hemi runs dished like anything else, I've only ever seen domed in 2cycle.

On Facebook they thought this was made with a piston from a 2 cycle boat engine.

 

[Rat]

On Facebook they thought this was made with a piston from a 2 cycle boat engine.
View attachment 144277

My statement remains, and would have to agree despite that being a flathead lid behind it. I've never seen rings positioned so low on ANYTHING that they crossed over the gudgeon hole... I suppose it's as good of a way as any to wet the oil ring set though.

I decided against using the dished piston primarily because the top ring is only 5mm down, I'm not willing to weaken the top land and risk the level of catastrophic failure likely to occur.

 

[Denny]

On Facebook they thought this was made with a piston from a 2 cycle boat engine.
View attachment 144277

That piston is gas ported, note the holes around the crown. They go to ports behind the rings. When the cylinder fires the hot gasses go through those ports and push against the back side of the rings and push the rings tighter to the cylinder wall. Weird, because pop up pistons don’t play well with flat head engines.

 

[BrownStainRacing]

My 208 has the Hemi FT and it is deck flush, but that's also a wedge.

I'm trying to get it back together and running with what I have on hand already FOR NOW, which only excludes the Conrod, and the cover since I can't bolt a back plate to it safely due to thread condition.

My neighbor up the road has a project he wants done that will need an engine and fabrication work to pull off (same dude I serviced a Club Car and a 2023 Hammerhead 150LE for).

I think most likely I'm going to stick the Hauyi on it, rebuild it to factory spec minus governor, sell him the engine as part of doing said project and then get a better engine once that deal is done.
It's going to be a big project so it will be a big bill that I can likely get an engine and upgrades all in one shot.

You'll find these blocks will have different deck heights.

The honda, ducar and tilly blocks are more consistent then others, that I've been into. The specs and clearances are pretty much the same from engine to engine.

I can't say that for the other Chinese 163, 196, 208, and 212 engines. They are all over the place.

The pred 224 block is a decent block and clearances check out fairly good, but its a ducar block. The bolt torque specs were all outta wack, and need to be double checked before mounting and starting up.

1 spun the starter cup with the first pull of the rope.

You planning on running electric start with charging coils on your next engine????

 

[Rat]

You'll find these blocks will have different deck heights.

That's one other reason I considered a longer rod.

1 spun the starter cup with the first pull of the rope.

You planning on running electric start with charging coils on your next engine????

Undecided, but probably not. I'd have to reconfigure some stuff and buy myself a couple more inches to fit the starter, but maybe coils and a to drive a simple led running light setup probably but then I'd need a battery or capacitor to buff the flicker out, that means buying a flywheel I don't have and I'm just not trying to get into this Hemi block like that, I'd rather start fresh with an already electric start engine at that rate.
I'm still scratching my head over a way of driving an electric motor as a genny. One issue is that what I have is 300w rated at 24v but can safely take 36v but it's not brushless. It will output in DC which is fine but it makes things a little more complicated electrically aside from the inevitable brush wear which is more concerning.

I got to thinking and the neighbor project and that will require both, and he'll probably want/need something a bit bigger than a 212 in that electric golf cart conversion He ran by me so flipping this engine for that project isn't likely.

 

[Rat]

The Kohler CH270 is direct fit for parts such as flywheel and starter.

 

[Rat]

I saw mention of a compression calculator somewhere and went looking.
Assuming 100% accuracy of the calculator and my inputs, it shows my 208 has a CR of 11.5:1, the factory spec sheet says 8.5:1 having put a flat top piston under it's 18cc head, in the off chance it's a 20cc head I'm still getting 10.6:1.

The real irony is if I put 93 through it, it runs a lot hotter but not really any better.

I can't seem to find Ethanol free gas like I could up in NY (I could get 90/0 locally and it ran great) So I have half the mind to set up a phase separation table and start pulling that sh¡t out before tossing in something like Heet101 or Stabil to recover some of the lost potency of the process.

 

[Denny]

Heet is methanol! I just wouldn’t worry about it and use blue Sta-BIL.

 

[Rat]

Heet is methanol! I just wouldn’t worry about it and use blue Sta-BIL.

You say that like meth is bad