First Predator Build, I have lots of questions.

Mini Bike & Go-Kart Parts

#1
First off I have been reading for a couple months but I am a new member and this is my first post. I appreciate the tons of info I have already found but I still have some questions. I am building my first Hemi 212 Predator. I will include a build list of what I plan on doing and then ask the questions I have.


Oil Sensor Delete
Governor Delete
Performance Header
Billet Flywheel
ARC Connecting Rod +.02
Black Mamba Jr. Cam
26lb Valve Springs
Mikuni 22 Carb Kit
Stainless Valves
Titanium Retainers
Chromoly Push Rods
GX160 18cc Head

My questions are,

Is the GX160 18cc head a direct swap if it is unmilled?

Will I have to worry about clearance issues from valves to piston if the piston is flush to the deck?

Do I need different length pushrods?

Can I swap the valves, lifters, retainers and etc from my Hemi Head to the GX160 head?

On the compression ratio chart I found on this forum it says with the piston flush at deck and the 18cc gx160 head I will be at 10.1 compression. Is this correct?

What is the highest compression ratio I can run on 93 octane pump gas?

Thanks!
 
#2
I can't answer your specific questions as I only built up one Pred Hemi.
I like your parts list. That should be a Very stout Hemi.
Can you take the time to list the prices for each of those items?
Thanks
Danford1

PS mine only made a quesstimated 10-11 hp but with the torque converter, it needed a wheelie bar Real bad. It ran great with plenty of power on tap and it wasn't anywhere near the build yours will be. I'm anxious to read how well this runs. It should be a fast MoFo.
 

trinik7597

Active Member
#3
You will still probably be in the hole 3 to 5 thousands with the plus twenty rod .. you want to maintain about 30 thousands piston to head clearance with your gasket . You won't have any valve to piston issues with a .275 lift cam .. the Honda head bolts right on but the dowel pins are bigger on the predator are larger so you either have to drill to accommodate them or not use them . 10:1 sounds about right with that combo .. valve train hardware is not interchangeable from the hemi to the Honda head
 
#4
Interesting, I am also curious whwat is the highest compression engine you can pull start? I'm a pretty strong guy but at what point does it get rediculous?

Here is the pricing list you asked for,

Billet Flywheel $100
ARC Connecting Rod $84 +.02
Black Mamba Jr. Cam $70
26lb Valve Springs $20
Mikuni 22 Carb Kit $98
Stainless Valves $30
Titanium Retainers $33
Thin Head Gasket $10
Chromoly Push Rods $20
GX160 14cc Head $30
 
#5
Is the rod you're buying a .020 longer rod ? If so and this is a hemi engine, I would not use a .010 head gasket you need at least .030 piston to head clearance.
 
#6
I have thought about that. And I would like to use a .02 longer rod and a factory .045 gasket. Would I have clearance issues with this setup? And with a compression ratio of 14:1 can I just use race gas? Will I be able to pull start 14:1?
 
#7
If its a .02 longer rod and the piston is .020 in the whole then use the .010 head gasket....not the .041 I just thought you might have had you rod length numbers punched in wrong.
 
#8
If its a .02 longer rod and the piston is .020 in the whole then use the .010 head gasket....not the .041 I just thought you might have had you rod length numbers punched in wrong.
I'm sorry I'm confused. Why is it that you want .030 distance between the head and piston? If my piston is flush with the deck wouldn't I still need a .045 gasket to get the .030 clearance between the piston and head?
 
#9
Didn't know your piston was flush with the top of the block.....I missed that somewhere !!:shrug: Most of the Hemi's I've fooled with were about .020 in the hole from the factory.
 
#10
As far as pull starting this engine I think you can, as long as the compression release lever is on the cam that you are using. But [MENTION=3072]ole4[/MENTION] can probably tell you for sure.
 
#11
Didn't know your piston was flush with the top of the block.....I missed that somewhere !!:shrug: Most of the Hemi's I've fooled with were about .020 in the hole from the factory.
I am sorry OND I think explained that wrong. I have not taken the head off of my motor yet to see where the piston is, but wherever it is I plan on making it as close as flush to deck as possible with a longer ARC rod.
 
#12
Did you already buy the rod before checking the in the hole measurement? If you did then you will need to get a head gasket thickness that will net you .030 clearance from the piston to the head deck. That is the optimum squish clearance. As far as pull starting the decompressor tab is anything but precise. It keeps exhaust valve open during compression stroke until motor starts. I do not think you will have any issue pull starting it unless it is not working or is not lifting enough. Be sure to set exhaust valve near .000 to .001 clearance to get the most decompression.
 
#14
Awesome thanks for the info Ole4!! Very helpful. Does anyone know what the highest compression I can run on 104 octane Sunoco race fuel is? Can I run 13.5:1?
 
#15
Yes you could if you are running a 246 degree duration cam which will lower dynamic compression. Are you running a 14cc head? You would have to to get that compression.
 
#17
Intake valve closes on the compression stroke. The longer the duration (this can vary depending on lsa) the later the intake valve closes. When the intake closes the compression begins. This is why you can have high compression ratio but low cranking compression. With long duration cams compression needs to be raised to regain the lost low end power. At higher rpms the inertia helps cylinder filling.
 
#18
So if I am going to run the 14cc gx160 head how do I know what kind of valves, springs and retainers to order for it? Is everything the same as the Hemi besides the diameter of the valves themselves?
 
#19
Actually I was doing some research and I found out that the 18cc head milled .050 will result in more horsepower due to its better flow design. You can order one from NRRACING FOR $310 and it comes with a .050 milled head, 28mm SS Intake valve, 25mm SS exhaust valve, titanium retainers, dual springs and has had a porting job done to it. Would this be a better option for me?
 
#20
If you do not have any experience with setting up a head and do not have the tools to grind seats, set installed height, check seat pressure then buying the head would probably be better although that price is kind of steep and I am not sure you need the dual springs. I am also not sure about your statement on the 144cc vs 18cc head flow design, due to the fact they both have the exact same port runner valve bowl. The only difference is when installing large valves you have to do a bit more unshrouding on the head. But if you do buy the head for $310. the weight reduction on your wallet will surely improve acceleration.
 

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