Predator 212 Hemi Build

[bob58o]

I will also buy a 2 degree timing key and install it backwards to get my 32 degree advanced flywheel retarded by 2 degrees to approach the 30 degree suggested ignition timing according to my camshaft.

You probably got this but...

 

[bob58o]

I am also about to buy some genuine Honda valves to replace the stock Predator ones but I am not sure if they will fit because I don't want to change the size of what I already have.

The Hemi Predator has 27mm intake and 25mm exhaust valves.
I got the SS ones from ARC with the retainers and lashcaps. I think they were both labeled as either intake or exhaust. They explained a valve is a valve and pay no attention to that.

The Hemi can take up to a 28mm intake for sure and I think I saw a 28.5mm. Work to the valve seats would need to be done. 3 angle valve job would be nice.

---------- Post added at 12:35 AM ---------- Previous post was at 12:23 AM ----------

And in response to the 1.2:1 rockers comment, How much more lift in the valves am I looking at if I install these?

Lift on your cam times 1.2 =
.224 * 1.2 = .267" intake

.231 * 1.2 = .282 exhaust

Something like a .275 cam with 245 degree duration.
Lift of 275 grind and duration of 308 cam.
Ask a pro about this.... Sounds like a screamer to me!

---------- Post added at 12:42 AM ---------- Previous post was at 12:35 AM ----------

What is the next part to on these motors to "govern" the rpm? I have a billet connecting rod, 26lb springs, working on better valves, have a new cam, billet flywheel, new jets and carb, etc. What is next on the list to get me to rev sky high?

Port and Polish
Chrome-molly pushrods
+0.020" Connecting Rod or Decking the block
Thinner Head Gasket
Milling the Head / Swapping the Head for Higher Compression(gx160 head)
Running on Methanol
Bored Cylinder / Larger Piston
Head Stud Kit......

I'm sure I'm forgetting some stuff. It can get really expensive.

Your cam, carb, gearing, and tire size will ultimately govern your RPM.

 

[thebozz]

Wow, that is quite a difference!! Would I get any bind in the springs? Also, how could I find out how much clearness I have from the valves to the piston?

---------- Post added at 12:49 AM ---------- Previous post was at 12:43 AM ----------

Port and Polish
Chrome-molly pushrods
+0.020" Connecting Rod or Decking the block
Thinner Head Gasket
Milling the Head / Swapping the Head for Higher Compression(gx160 head)
Running on Methanol
Bored Cylinder / Larger Piston......

I'm sure I'm forgetting some stuff. It can get really expensive.

Can I run a stock gx160 head? Or would I want to fit it with larger valves, intake and exhaust ports? I do plan on getting chromoly push rods soon, but I'm not too worried about it at the moment, I am fully comfortable porting and polishing the head myself with my trusty demel, I wouldn't mind bumping up compression a smidge with a thinner head gasket (what is stock thickness?), and I would prefer to stay on pump gas. I think I'm getting pretty dang close to making one cool ride

 

[bob58o]

Wow, that is quite a difference!! Would I get any bind in the springs? Also, how could I find out how much clearness I have from the valves to the piston?

I have the 26 lb springs with no bind and my cam is .275 lift 230 duration. Not positive how the ratio rockers change that but I think you would be fine. Some cut reliefs for springs, or shim the springs, use longer valves, custom pushrods... but I think this is for extreme lift cam / rocker combos. Best to check with the seller first though.

I used +0.020" ConRod and thinner than stock gasket. Some people use longer conrods, high lift cams, ratio rockers, and mill the head a bunch. Just have to check!

If you are using stock length Rod, you are probably fine, but I don't know for certain. You can put clay on the top of the piston and turn the engine over by hand. The valves will impress in the clay and you can take the head back off and measure it. Might have to use geometry to figure out how increased lift actually changes P2V clearance.


---------- Post added at 01:02 AM ---------- Previous post was at 01:00 AM ----------

Can I run a stock gx160 head? Or would I want to fit it with larger valves, intake and exhaust ports?

YES! and YES! You might have to run without the dowel pins, or enlarge the pin holes on the 160 head. I don't know what size valves the seats could take on the 160cc and not sure how much work is involved there. Its a compression vs flow trade off I guess.

---------- Post added at 01:05 AM ---------- Previous post was at 01:02 AM ----------

I wouldn't mind bumping up compression a smidge with a thinner head gasket (what is stock thickness?), and I would prefer to stay on pump gas.

Something like 0.041" or 0.045" Composite is stock.

I think I saw the following available for aftermarket.

Metal 0.009"
MLS 0.018"
MLS 0.027"
MLS 0.036"
Copper .010"
Copper 0.018"
Copper 0.024"
Copper 0.032"

 

[thebozz]

Alright, so what I'm getting out of this is: get chromoly pushrods, a thinner head gasket, and buy 1.2:1 rockers. I want to stay away from taking things to a machine shop because that's where things can get REALLY expensive, so I don't think I'll go the gx160 head route unless I can buy one that is already fitted with larger valves and ports.

 

[bob58o]

Alright, so what I'm getting out of this is: get chromoly pushrods, a thinner head gasket, and buy 1.2:1 rockers. I want to stay away from taking things to a machine shop because that's where things can get REALLY expensive, so I don't think I'll go the gx160 head route unless I can buy one that is already fitted with larger valves and ports.

The Cr-Mo Pushrods wont improve performance but the may stop them from bending or breaking if you go with the 1.2 or 1.3 rockers. I didn't get them...

Sometimes with larger lift cams and and/or ratio rockers, shorter pushrods are needed to keep valve geometry in line.

As for the gasket... You want a minimum 0.025" - 0.030" between the top of the piston and the bottom of the head. I used a +0.020" Con Rod which left my piston 0.003" below the surface of the deck. Deck height varies so this would need to be measured to be safe.
I used this 0.003" to determine I need at least a 0.027" head gasket. 0.003 + 0.027" = 0.030"

If your piston is sitting 0.020" or more below the deck, you might be able to use a single 0.009" gasket.

Look up checking Piston to Valve Clearance because I would hate to steer you towards parts that won't work. Thinning the gasket and using ratio rockers will get the valves closer to the piston.

Call the manufacturer of the Cam and Rockers to verify first. They will still probably recommend checking P2V clearance with clay.

---------- Post added at 03:49 PM ---------- Previous post was at 03:24 PM ----------

I might go this route if I do it again????
Close to $350 for a nice head set up with rockers.
$225 ish with out the rockers.
http://www.nrracing.com/product-p/headhemi.htm
Just an option.

 

[chancer]

Fill us in on the dyno. Everybody always wonders, but nobody dynos.
and
NO. on the fuel pump.

 

[thebozz]

Fill us in on the dyno. Everybody always wonders, but nobody dynos.
and
NO. on the fuel pump.

Of course I will!

 

[bob58o]

Fill us in on the dyno. Everybody always wonders, but nobody dynos.
and
NO. on the fuel pump.

I missed this. I went back and reread it. I know why I missed it.

I read as far as brakes... Then moved on. lol but probably the honest truth!

 

[thebozz]

 

[thebozz]

Governor removed, low oil sensor removed, new carb with new jets installed along with new carb studs and air filter+adapter, throttle plate installed, cam installed. I am still waiting for my flywheel to be shipped along with my stainless steel valves. I will attempt to make the header, if that fails, I will just buy one (I will probably buy one anyways). I am most likely going to buy new valve guides and retainers to hold the new valves. When the rest of my parts get here, I will install new springs, valves, retainers, guides, connecting rod, and flywheel. Today I went out and bought a complete go kart and will take the 3hp engine off of it and put it in the shopping cart and I will end up putting the predator into the new frame. I feel much safer putting this on a proper frame where the center of gravity is MUCH lower than that of the shopping cart's.

---------- Post added at 01:24 AM ---------- Previous post was at 01:22 AM ----------

That governor C-clip was a pain to get out, but I finally got it after a little playing with it. And I managed to keep the inside of the engine spotless. Both the holes are plugged and sealed with rubber O-rings and lock-tight.

 

[Poboy kartman]

Carry on....

 

[thebozz]

When you guys talk about using modeling clay to check valve clearance, how do you do that? Wouldn't that gunk up the inside of the engine?

 

[Poboy kartman]

You put a small amount of oil based modeling clay...(the stuff that never hardens) in the head over the valves...reassemble the engine and turn it over by hand.....remove the head....section the clay...and see how close the valves got to the piston.

Then remove all the clay.....

 

[thebozz]

Ok, so it doesn't leave any residue in the engine at all? I'm sorry for the questions but I'm a little anal about engine contamination from metal shavings, dirt, etc.

 

[Poboy kartman]

Not if you remove it! To clarify : oil based modeling clay is not really sticky and should come right off....

And even if a little bit remained....it would just burn up with no damage to the engine whatsoever.

 

[thebozz]

if I don't remember to take off the clay I don't deserve to own this engine

 

[Poboy kartman]

If you don't remove it...it still won't damage the engine....it just wont run!

 

[thebozz]

Oh, well let's hope it doesn't even come to that. I think I'm going to measure valve clearance after I have all my parts and buy a thinner head gasket accordingly. How much on average does it cost to mill the head down?

 

[Poboy kartman]

You REALLY need to read Bob's Predator build thread.....Anyway...call Dyno Cams..somewhere in the neighborhood of $15-40.