Just scored a HF 212 with Hemi head... want to buy performance parts

[frostyflammable]

So as the title suggests I bought a 212 Predator with the Hemi head for $95 with coupon and since I have a working engine on my kart now figured before I mount this one next year I would do some upgrades. I will get the performance kit from gopowersports (intake, exhaust, valve springs and bigger jets) but also wanted some better push rods and rocker arms... figured since I will be taking the head off might as well swap for better rockers and rods. The governor will obviously be gone.

So my question is anyone have any recommendation on which rockers and rods I should get?

Edit: Is there also a better spark plug wire to get some more spark?

--Dan

 

[Poboy kartman]

You BETTER get a billet rod.

 

[frostyflammable]

You BETTER get a billet rod.

Billet rod it is, I want to do this right. I am not going to crazy horsepower, but if I can get it somewhere to 12 or so I will be a happy camper.

--Dan

 

[Bbqjoe]

Billet rod it is, I want to do this right. I am not going to crazy horsepower, but if I can get it somewhere to 12 or so I will be a happy camper.

--Dan

I'd bore it out to 475cc.
http://milwaukee.craigslist.org/mcy/5822901764.html

 

[frostyflammable]

I'd bore it out to 475cc.
http://milwaukee.craigslist.org/mcy/5822901764.html

Maybe one day , for now just looking at suggestions for rockers, rod and spark plug wire upgrade. gopower has the rods.

--Dan

 

[bob58o]

Performance Spark Plug for Hondas / Clones / Predators

Not sure about the Spark Plug wire. Maybe a Honda Coil and wire?

The spark plug some claim makes more HP is AR3910X. It is everywhere online or NAPA will have it by lunch if you call in the morning.

I like the AR3911 better for my Predator.
I have an E3 spark plug in my Tecumseh. I don't remember what E3 plug cross references with the Honda / Predator plug, but if you look at what you have, type the number and type E3... you'll find something like E3.18, E3.10, or E3.22 (Should have it at HomeDepot)

---------- Post added at 09:52 AM ---------- Previous post was at 09:48 AM ----------

212cc Hemi Chrome Molly Push Rod (Need Two)
$12 ea
http://www.nrracing.com/product-p/cmpr-55.htm

---------- Post added at 09:58 AM ---------- Previous post was at 09:52 AM ----------

1.2:1 or 1.3:1 Ratio Rockers
You may need to get the shorter pushrods with these. Call NR or ARC and ask. Read the descriptions.

"Like all roller rockers, may require valve cover spacer or minor grinding on valve cover grinder for clearance.

Due to canted valve arrangement, Hemi's may have valve to piston clearance issue with high lift cam, esp with 1.3 Ratio

These Rocker Arms require shorter Pushrods, typically 5.260 or 5.340 depending on cam and head milling."

http://www.nrracing.com/product-p/hemi-rollrcks.htm

Need better valve springs.

---------- Post added at 10:01 AM ---------- Previous post was at 09:58 AM ----------

Here are some 26lb valve springs.

http://www.arcracing.com/dj-1056-valve-spring-26lb-hp-white-stripe-sold-individually/

---------- Post added at 10:04 AM ---------- Previous post was at 10:01 AM ----------

Stock Length 3.308" Connecting Rod
http://www.arcracing.com/6254-arc-billet-rod-hf-predator-212cc-3-308-std/

+0.020" 3.328" Connecting Rod (For increased Compression and better combustion and flow and stuff)
http://www.arcracing.com/6256-billet-rod-hf-predator-020-3-328/

 

[ironbutt]

I'd bore it out to 475cc.
http://milwaukee.craigslist.org/mcy/5822901764.html

What the heck!

 

[bob58o]

You might need the SS valves with valve spring retainers if you get ratio rockers.
I have only used the stock rocker arms.

 

[KartFab]

Maybe one day , for now just looking at suggestions for rockers, rod and spark plug wire upgrade. gopower has the rods.

--Dan

Might want to go for upgrades that make sense and do some more research on what does what before you spring for some rockers.

Rockers are for higher top end power, I wouldn't get rockers unless I was shooting for power in the high RPM range. Things to consider before you even think about rockers are

everything else those are like the last thing you should be thinking about.

Everything else would include, but is not limited to

figuring out what target rpm you want to run at
e.g. 3600, 4000, 5500 6000 7000 8000 9000? from there you can decide which camshaft will give you the optimal power at your target max/operating RPM (keep in mind that camshafts cant give you everything, you get like a torque, or mild or wild cam, torque gives good torque up to maybe 5500 rpm max, mild gives overall boost in torque/even performance curve maybe getting you to 6-7k rpm with the right upgrades, and a wild cam destroys bottom end torque and you get lots of high end torque and the ability to rev higher.
performance camshaft
timing
crank/connecting rod length/piston combination (e.g. stock length, stroker, or long rod, short piston combination)
compression ratio
fuel octane rating, pump gas or methanol
carburetor, stock is restrictive, lots of people use the 22 mm mikuni carb
billet flywheel if going to higher than 5500 rpm,

THEN after you figure out at least all of this stuff, THEN you should look into the rockers, spring height, custom chrome moly pushrod length. Then you gotta clearance the valves from the piston top (or at least know what cam will let the valves clear the piston top, then double check it)

At least thats my opinion on how it should probably go (I dont know much but i know enough to get into trouble)

Then if thats not enough, you could look into getting some headwork for flow done (if you are wanting high flow head that is important at high rpm) so then you could look into valve size, porting/polishing, multi angle valve job, etc etc etc so your rockers can actually do you some good other than being an expensive thing you have on on the engine. Good rockers are like $80-$150

 

[frostyflammable]

Thanks for the good replies... well I am not trying to make it a 9000RPM monster, just something with nice torque that will go comfortably 30mph or so. I doubt I will ever need to go past 5500rpm as most of the riding will be off road where I will need torque more that top end power. I will also match the sprockets to get me my wishful result. I guess what I am getting is go for the cheap/easy stuff first and them build up if needed. Heck if I screw up another $100 will get me a new engine .

--Dan

 

[bob58o]

You have done the cheap easy stuff with the Stage 1 kit.
Next if you want more would be, billet connecting rod, camshaft, and valve springs/timing key to match the cam specs.

Use stock valve springs unless you get a billet connecting rod.


Like $175 to $225 for a rod, cam, springs, and key.

 

[Flyinhillbilly]

I'd tear it down and do some measuring. I'd shoot for a rod length that will put your piston about .020" in the hole, and run a .009" head gasket. Port the head, back cut the valves, put a mild cam in it with 1.2 or 1.3 rockers,8 degree timing key, and go like gangbusters. I'd say it should run pretty good with those mods.

 

[chancer]

I have a Stock predator, Gov removed, with intake and exhaust only. Not even a jet.
Geared at 6:1 with 13" tall tires. IT goes 29 mph.

So you really do not need much if you are looking to go 30mph.

15" tall tires and I can go 33mph

 

[Redlig]

Go for it build it up

 

[pRoFiT]

As a hacker i say do it all! but, i wonder if it is all worth it. fun to do, dont let me stop you. but would it just be better to buy a race engine? or the next step up in predator engines?

How much more performance do you get with all these HF motor mods? Like chancer said remove gov hit the +5000k rpm and your golden. and i think he was giving best outcome. calculator shows if you hit 5400 rpm with 15 inch tires and 6:1 ratio you can hit 40mph! add torq converter to smooth everything out.

If i dont die with my stock Pred at 27mph i will remove gov next and go for the 40!

 

[outcrydrummer]

If your going to keep in the stock valve springs for a while you might as well wait to get a billet rod before you remove the governor.
Not that it's hard but why go into the engine twice.
You can adjust the governor on a 212 to pull about 5k rpm without even opening up the side cover or altering the linkage.

I'd do an nr racing stage 2 kit and leave the governor and adjust to 5k rpm.
When you get a rod and more parts than go into the crankcase 1 time and do it all.

Just my .02

 

[mckutzy]

Are you sure that the stock gov limiter inside will handle the rpms past for which it was designed to limit to? 5K seams to be a bit much for it to be left in....

 

[outcrydrummer]

mckutzy it's extremely common to run them in that configuration actually.
They have a lot of kart race tracks with stock predator classes. You can't touch the engine except for the spark plug and the governor. Governor has to be in tact and surge before 5500 rpm.
Most set their governor to restrict engine rpm to 5200 and gear for 4800 rpm (peak hp on stock hemi predator). Those engines get run at 4800 to 5k rpm for, what equates to, about 4 miles a night.
They also have, locally here in NC, predator 200 lap races. That's 25 miles at those sustained RPM's and I've never seen or heard of a governor letting go during a race etc.

Just my experiences, your mileage may vary.

I also look at it as this. If you never go into the motor to do a rod etc and you just buy external easily swappable parts if one day, 2 years from now, your governor gives up the ghost then your only out a 99$ predator core. Swap all your parts to a fresh predator and go on about your karting day

---------- Post added at 07:40 PM ---------- Previous post was at 07:35 PM ----------

As a hacker i say do it all! but, i wonder if it is all worth it. fun to do, dont let me stop you. but would it just be better to buy a race engine? or the next step up in predator engines?

How much more performance do you get with all these HF motor mods? Like chancer said remove gov hit the +5000k rpm and your golden. and i think he was giving best outcome. calculator shows if you hit 5400 rpm with 15 inch tires and 6:1 ratio you can hit 40mph! add torq converter to smooth everything out.

If i dont die with my stock Pred at 27mph i will remove gov next and go for the 40!

He will never hit 5400 rpm with stock valve springs in.
I think the learning experience and pride of building your own motor, not to mention its cheaper, is worth the hassle. Take your time, consider your ultimate power goals, research towards that goal and start putting parts together.

---------- Post added at 07:44 PM ---------- Previous post was at 07:40 PM ----------

I have a Stock predator, Gov removed, with intake and exhaust only. Not even a jet.
Geared at 6:1 with 13" tall tires. IT goes 29 mph.

So you really do not need much if you are looking to go 30mph.

15" tall tires and I can go 33mph

Chancer you really need to rejet that carb brother. If nothing else drill the main jet and richen it up a little. Predators are factory lean like crazy. Under WOT are you not experiencing some cutting out??
Just concerned, not criticizing (spell check??) lol

 

[chancer]

I think it is Valve flutter as you mentioned. Limiting RPMs and therefore top Speed.
Anyway we have almost 2 acres so unless I decide to go to the store 1 mile away, There is no reason or chance to see 30mph.
So it is fine.

 

[outcrydrummer]

I'm not worried about the valve float as much as I am about your engine running very lean. If you've done the air intake and exhaust and not rejetted it's got to be extremely lean now. I'm curious if you slam the throttle from a roll does it pull smoothly and hard? Or does it kind of pull hard but more choppy then smooth?

I just don't want you to burn that piston up when a 5$ jet could have prevented it.