Lets talk Cams- Predator212, GX200, 196/208cc clone engines

#1
Hey all, so I am new here but have been in the power sports industry for many years and have been thinking about building a rocking Predator 212cc, probably a Hemi head as they seem to be the better engine to build off from my research. Thoughts on that are welcome too.

Now to the meat and 'taters... Cam shafts.

What cams do you guys like for different applications and what were your findings? I am looking at a couple cams and want some pretty big power but I do not want to lose a bunch of bottom end and torque so it only makes HP at high rpm. How about the .274 radical grind cams? They have a couple of options and supposedly one of them makes like buku power up high, gnarly mid and good bottom end. The disclaimer is that : "warning, this cam may cause traction issues", what are your guys thoughts and have you tried one in your build? The .274-0607 in specific but they offer two other common grinds as well and one really high rpm specialty order cam.

Thanks in advance!
 
#2
I can speak as a guy who learned a ton from this site and is just dipping into the real-world game. I would not recommend any 260* duration cam because they dog down low, but I would say the NR 280 0611 is in your ballpark. It also depends how big a cam you can actually fit in that Predator. Clearancing work WILL be required to run a cam like that. Also check out the 315 grind from DynoCams. Once again, it all hinges on "what will fit in the crankcase."

Somebody who specifically knows HEMI Preds will guide you much better than I.
 
#3
We used the 274 NR racing cam ( short track oval racing ) in are Honda GX200 when we run the open class ….and it was great ! Plenty of low to mid range grunt and with 37 lb springs that Russell recommended and It hit as high as 8300 to 8500 rpms on any given night . Running the engine on alcohol .
 
#4
Are you using a head with stock size valves unported or a head that has been redone with larger valves? Makes a difference with cam selection. Also compression,
as duration goes up you should increase compression. These are more factors to consider. I have used various isky cams with 230 and 246 durations and various lsa’s Asawell as dyno early .265 lift regrind and 284 0607. All worked well for the particular application
 

moetrout

Active Member
#5
What's this motor going into and what kind of riding are you going to do? I built my motor up for drag racing in a mini bike. When I bought the bike the motor already had a CS cam (.265 lift) in it. I decided to stick with that cam and do what I feel is a mid range kind of build. After talking to some of the faster guys at the drag strip I found many of them are using a 308 cam. Sounds great to be really fast, but there is a lot more to building a motor like that. I should be able to hit close to 60mph in the 1/8 mile with my mild CS cam build. What's your goal? Speed, rpms?
 
#6
Thank you guys for the info! This is good stuff.

So for now I do not have a rig built nor an engine. The build plan is a "mini" mini truck kinda like a small regular cab for ranger sheet metal body to set on a fairly light frame. Mostly just a fun play machine for mainly pavement use possibly some grass racing. I will also make a set of drift tires for drift wars.

Engine goal is as much hp and rpm as I can reasonably obtain without making it a complete dog on the bottom and in the mid range. So it needs balance but geared more towards making big numbers. I will be doing a full build for sure. Billet internals, flywheel, milling the head, porting, GX390 carb or bored stock size, high compression, and of course appropriate cam. I read this cam in the 0607 grind is quite the monster and both pulls hard down low but just absolutely comes alive up high. Especially with high compression. I may end up going with a custom cut piston with valve reliefs to clear the valves at the compression height I plan to be at. I guess the Hemi predator you have to be careful with lift and compression height for the valve tolerances. Once I get one and pulled apart I will obviously doing a full disassemble and assessment of the engine. The Hemi also has a good flat top piston and the guys at ARC actually like that one and run them hard with good success. Just may be a bit thin for cutting the reliefs in so I may need the Wiseco piston as it thicker on the upper portion.

Interested in seeing what I can get with this bad puppy...
 
#7
Thank you guys for the info! This is good stuff.

So for now I do not have a rig built nor an engine. The build plan is a "mini" mini truck kinda like a small regular cab for ranger sheet metal body to set on a fairly light frame. Mostly just a fun play machine for mainly pavement use possibly some grass racing. I will also make a set of drift tires for drift wars.

Engine goal is as much hp and rpm as I can reasonably obtain without making it a complete dog on the bottom and in the mid range. So it needs balance but geared more towards making big numbers. I will be doing a full build for sure. Billet internals, flywheel, milling the head, porting, GX390 carb or bored stock size, high compression, and of course appropriate cam. I read this cam in the 0607 grind is quite the monster and both pulls hard down low but just absolutely comes alive up high. Especially with high compression. I may end up going with a custom cut piston with valve reliefs to clear the valves at the compression height I plan to be at. I guess the Hemi predator you have to be careful with lift and compression height for the valve tolerances. Once I get one and pulled apart I will obviously doing a full disassemble and assessment of the engine. The Hemi also has a good flat top piston and the guys at ARC actually like that one and run them hard with good success. Just may be a bit thin for cutting the reliefs in so I may need the Wiseco piston as it thicker on the upper portion.

Interested in seeing what I can get with this bad puppy...
The flat top piston means just about nothing in a HEMI Pred because the head has a huge volume. It will require quite a bit of milling to up the compression.
 
#8
The flat top piston means just about nothing in a HEMI Pred because the head has a huge volume. It will require quite a bit of milling to up the compression.
Yeah I am very aware of that. Though it is a much better piston than the non-hemi version. I just wonder how much meat is on top of the piston so I can get that sucker way up there and maximize the compression with a big cam. I know that is an issue with the hemi engine due to the valves being on an angle but as long as I clear the piston or have enough room to machine relief cuts into it, I could mill quite a lot of material off that thing and make a super high compression motor. I am shooting for 12-13:1 or so. Probably going to be a straight 100LL fuel which is fine. Kinda what I was after anyways. This might be a pretty mean little monster don't ya think? I was looking into the .308 cam too, as Dyno Cams quotes it for having a really wide power band and good on the valve train. There are a couple guys running that one with good success.
 
#9
If you want high compression wouldn’t it be easier to use a 14cc head modded? I happen to like the hemi heads but they do require more work to weld up the chamber as well as setting it up on mill with pilot straight to the spindle. Milling with the hemi will requirenotching piston. Also excessive spring tension can break rocker towers on the hemi.
 
Last edited:
#10
If you want high compression wouldn’t it be easier to use a 14cc head modded? I happen to like the hemi heads but they do require more work to weld up the chamber as well as setting it up on mill with pilot straight to the spindle. Milling with the hemi will requirenotching piston. Also excessive spring tension can break rocker towers on the hemi.
Yeah that would be easier yes. The big advantage the hemi has though is the valve size. It is a huge difference.

Hemi- 27mm intake and 25mm exhaust
Non-Hemi- 25mm intake and 24mm exhaust

The ports flow better too. Though I agree it is quite a bit of work to mill the head and pistons for the valve relief I was prepared for that as that is what it takes to do a serious performer anyways. I have access to some good tools and machine shops that I can have all this done on. Welding is easy too as I have been a tig welding and mig welding since i was 15-16, aluminum, cast or not is easy. Though I really dis like ever touching cast metal with a welder unless it is complete unavoidable. So machining a piston is a pretty small price to pay as long as I can get a solid motor that runs well reliably.

Just wonder which cam will produce the appropriate power band all the way through with minimal compromises... Ugh I need a bigger wallet and more freaking time!!! :glare:
 
#14
here is what you need a 14cc head with 32/25 valves and ported. It is the head on the right it just needs a valve job head on the left has new seats and has been opened up to the ID of the 23mm seat but still needs porting flowing etc. I have had various issues tigging these heads all are new but some castings give very little trouble others lots of inslusions near the surface. Looks good until you mill it and start grinding then I have to go in and drill the inclusions and reweld. DSC01284.JPG DSC01285.JPG
 
#15
It's a non-hemi 22cc head. The HEMI head is 23.something cc.
Ah K I see that now. Yeah I guess the obvious thing was the picture of the rocker arm mounts...


ole4 here is what you need a 14cc head with 32/25 valves and ported. It is the head on the right it just needs a valve job head on the left has new seats and has been opened up to the ID of the 23mm seat but still needs porting flowing etc. I have had various issues tigging these heads all are new but some castings give very little trouble others lots of inslusions near the surface. Looks good until you mill it and start grinding then I have to go in and drill the inclusions and reweld. Attachment 107847Attachment 107848 [QUOTE said:
See, this is why I cringe anytime someone hands me a cast piece and asks me to weld it.... :thefinger:
I just slowly hand it back and back away very slowly.... Lol
Now I will say those heads look really good. Are they hemi head or the original?
 

65ShelbyClone

Well-Known Member
#16
The pair of heads on the left are regulars and the one on the right foreground with unfinished welds is a hemi.

I did my own sleuthing recently on the hemi heads and I haven't found any reports to suggest that they flow better except maybe in totally stock form. I still want one of the heads for a GX140 project because the layout can fit bigger valves in a smaller bore than the inline heads can.

With the intended use of the engine, have you considered a big block instead? A 212 would be working pretty hard to make 20hp whereas a 390/420/460 could do that with mild mods and will last a lot longer doing it.
 
#17
The latest ones do flow better in stock condition the last two flowing at .400 @ 28" 57 and 58 CFM. The early one I had was 51 CFM at .400. Do not know what changed. The 14cc heads flow stock around 47 CFM. I have not built any hemi larger than 28.5 and those were getting around 78CFM (The best one) ported. The 14cc head on the right with no valve job flowed with the intake valve upside down so no valve head was in the way is flowing 91CFM. Still have to do the valve job install valve and checking springs and do a flow test. I did have to put a vane on the middle of the floor to pick up 4 cfm. Probing with flow ball showed flow increase with ball in the middle of the floor. I have no idea why probing with a pitot showed the floor all the way across over 300 FPS.
 
#18
The pair of heads on the left are regulars and the one on the right foreground with unfinished welds is a hemi.

I did my own sleuthing recently on the hemi heads and I haven't found any reports to suggest that they flow better except maybe in totally stock form. I still want one of the heads for a GX140 project because the layout can fit bigger valves in a smaller bore than the inline heads can.

With the intended use of the engine, have you considered a big block instead? A 212 would be working pretty hard to make 20hp whereas a 390/420/460 could do that with mild mods and will last a lot longer doing it.
Yes I have thought about it but they are more than double the weight. The 212 will also run at higher rpm once built and balanced properly. But yes the 420 would absolutely make 20 with almost no work. Still, I wanna see what I can get out of a 212 and where I plan to mount the engine would work better with a 212 cause it is much smaller. I plan a mid engine chassis where the engine is basically between the drivers legs and run a torque converter and chain back to the axle and an adjustable tensioner for the chain.

That is very impressive ole4, see that is kinda why want to challenge myself at building a monster of a 212 cause I have built RZR xp1000 engines for a turbo application and made well over 300hp at the tires on some of our crazy builds here. They start out at about 110hp at the crank stock. This should a fun little build for me...
 
Last edited:

65ShelbyClone

Well-Known Member
#19
I did have to put a vane on the middle of the floor to pick up 4 cfm. Probing with flow ball showed flow increase with ball in the middle of the floor. I have no idea why probing with a pitot showed the floor all the way across over 300 FPS.
Is it a noisy port as well?

Something I wonder about is the potential for a hemi's angled intake valve to actually impede flow. It looks like both the inline and hemi heads have similar ports that shoot across the valve, but the hemi's valve back is angled upward slightly into the flow path. A larger valve would make it more so. Just thinking out loud.
 
#20
Your valve specs on the non-hemi head are outdated.

The later non-hemi heads have the same size valves as the hemi, 27mm & 25mm.

Because the non-hemi heads are easier to work with, many kart guys are using the hemi bottom end with the non-hemi head in a modified motor.
 
Top