Hemi Predator Build #2

[bob58o]

Well I didn't like how the 1/4 -20 went in after tapping the hole where the shaft that held the gear was. I didn't like it, because somehow I stripped it. So i drilled it out with a 1/4" drill bit and then tapped for and used a 5/16 - 18 (1/2" long) bolt. I like this better (because I didn't strip it.)

 

[tinamcjittles]

Why spend all this money on lawn mower engine when you can dump your savings into something with gears?? lolol, Jokes aside, what will you be doing for the head on this?

 

[bob58o]

Think I still want to do the Hemi Head from NR for $210
(pushrods and gasket not included)
http://www.nrracing.com/product-p/headhemi.htm

Stock Rockers
28.5 mm oversized SS intake Valve (0.070" Longer than stock)
25 mm Exhaust Valve (0.070" Longer than stock)
5.34 or 5.44" Cr Mo Pushrods
3 Angle Valve Job
37lb Valve Springs
Milled about 0.040" (Should be around 17.5 -17.75 cc's, I think)
Ported
0.027" MLS Gasket

---------- Post added at 05:58 PM ---------- Previous post was at 05:47 PM ----------

I do have some questions for Russel tho.

Somewhere I saw on his site that 37lb and Dual springs require the seat pockets to be cut...
If so, is this included with the price of the head since it only comes with 37lb or Dual springs as options.
Also Is the 28.5mm intake valve used on the stock valve seat, or is a bigger valve seat installed for the bigger valve?

My last question is about the powerband for the 285-0211 cam.
.285" lift
250 duration
102 Intake CL
111 LSA
Says small track cam for serious torque, but has 250 duration. That's a whole lot of duration for a torque cam, at least as far as I understand camshafts. The intake center line is 102, so that seems like a torque cam. I just don't know if the cam is good from 2000-7000 RPM or from 5000-7000 RPM????
I planned on using a 4k RPM clutch stall speed cause I guessed that would work nice with the cam, but I'm just guessing here.

 

[bob58o]

I'm thinking it will go on this.
El Lobo
with a 30 series TC and 9T (maybe 8?) jackshaft sprocket to go with the 40T in the Rear.
http://www.minichopperssocal.com/MINIBIKE-EL-LOBO.html

 

[bob58o]

Tried to call, it's too early. Starts work at 12. LOL

I emailed my questtions.....

"Hi Russell,

I plan on building a Hemi Predator with your racing Hemi head and 285-0211 Camshaft.

1.) Is there a bigger valve seat installed for the 28.5mm intake valve, or is the valve used with the original, stock seat?

2.) I wanted to use the 37lb springs, but read on your site that the 37lb springs need the spring pockets to be cut. Do the pockets need to be cut and is that included in the price of the head?

3.) Will be using SS valves (0.070" Longer than stock) and milling the head ~0.040" with stock rockers. I believe that will give me around 17.5cc for the Hemi chamber. Also will be using a 0.027" gasket and a +0.020" Connecting Rod. That should give me around 11.3:1 if my math is correct.

I'm not sure what pushrods to order. Your site says 5.34 - 5.44 with the +0.070" valves. I'll be using those plus milling a bit and using a thinner gasket. Which pushrods should I try. I'm not sure how the cut to fit ones work because I don't know how to measure how long they should be.

4.) Where might I expect to find peak TQ and peak HP with the 285-0211? Seems to be a lot of duration for a torque cam, so I'm trying to figure out what clutch stall speed would work. I was thinking 4k clutch stall speed, but if it will pull hard from 3000-7000 then I'll set it up for 3k clutch stall speed.Planning on running this on a minibike geared 5:1 (or 4.5 :1) with a Torque converter and 13" tires"

 

[ezcome-ezgo]

Russell,

P.S. you've been GAB'ed

 

[bob58o]

Sorry Russel. He never calls me back anyway. LOL

Where's Joe-405? I think he has Russel on speed dial.

---------- Post added at 06:21 PM ---------- Previous post was at 06:14 PM ----------

Russell,

P.S. you've been GAB'ed

There's a kid in my old neighborhood driving around with the original GAB engine. It still has "GAB Nation" stickered on the TC Cover, unless he removed it.

I sold it and the minibike it was strapped to for next to nothing and miss it so much. Why I want to start the next minibike. I'm almost finished with the 420cc Buggy, but the minibike is so much more fun.

 

[bob58o]

I pulled some money out of the fanduel account to make my first purchase.
It is coming from China and should be here by August. LOL

Super Performance Power Jet RACING Carburetor KOSO OKO Carb 24mm

$25.90
http://www.ebay.com/itm/182591308473

And the second purchase is coming from Texas.

10pcs Carburetor Main Jet kit & 10pcs Set Slow/Pilot Jet for PWK Keihin OKO CVK

10 Main Jets
10 Low Jets

$11.95
http://www.ebay.com/itm/371925536732

Third Purchase was an air filter. Pretty sure the carb I got is 49mm on the filter side. Figured I could get a 48 or 50mm to work.

48mm Car Motorcycle Air Filter Cleaner Intake Steel Net Filter Gauze Part Motor

$3.10
http://www.ebay.com/itm/332277831334


I hope this carb isn't complete garbage, I hope these jets fit, and I hope I can gather some scratch to buy some internals for this engine soon. The manifold / adapter is like $38 so I guess the carb upgrade cost about $80 without a throttle cable. And that's buying the cheep eBay stuff.
I had a $40 budget and only went over by $0.95. Not too bad

 

[ezcome-ezgo]

Hope springs eternal. As usual this is fun to watch.

 

[bob58o]

Just got off the phone with Russel at NR.

He said the 285-0211 will pull from 4k to about 7.5k RPM. This is perfect. Exactly what I wanted.

He also said the racing Hemi head comes with the spring pockets cut for the 37lb springs.

The intake valve seat is the stock size, just using a bigger valve on the stock seat.

He said I probably need the 5.44" pushrods but recommends putting it together and grinding down a stock pushrod til I get the right length. I guess I need to research how to find the correct pushrod length. Not a fan of geometry. Probably cause my teacher started off the course with this joke....
"What did the acorn say when it grew up. Geometry."

 

[bob58o]

How to Determine Correct Pushrod Length

http://www.hotrod.com/articles/how-to-measure-for-correct-length-pushrods/

 

[Flyinhillbilly]

http://www.hotrod.com/articles/how-to-measure-for-correct-length-pushrods/

That's how I do it, sharpie the top of the valve, assemble and turn over , then look at the mark, then repeat process until it looks right.

 

[bob58o]

That's how I do it, sharpie the top of the valve, assemble and turn over , then look at the mark, then repeat process until it looks right.

Why would one need to cut seat pockets?

Because the springs are wider than stock? Or because they are longer than stock. I'm assuming longer valves help prevent coil bind. Are the pockets cut for a similar reason?

---------- Post added at 09:37 AM ---------- Previous post was at 09:14 AM ----------

If I do decide to do the el Lobo minibike with its 40T sprocket. This sumnaB is going to be fast. Geared for cruising around at 45 MPH and should be able to touch 60 or 65mph.
Perhaps too fast for a neighborhood bike???? I envision my self driving alone on miles of country road, but I don't live in the country and don't know of any such roads.

Using 40T:8T sprockets for 5:1 (4.5:1 with overdrive).
(Who uses 40T #41/420 rear sprockets? And makes the sprocket the the brake rotor as well. They want me to keep the 40T. They want me to wreck at 65mph.

5000 RPM = 43mph (assuming 0.9:1 Overdrive)
6000 RPM = 52mph
7000 RPM = 60mph
7500 RPM = 64mph

 

[ezcome-ezgo]

I'll say a few kind words at your funeral.

 

[bob58o]

I'll say a few kind words at your funeral.

If they are kind words, they are bound to be few.

I keep going over the powerband, the TC Ratios, the gearing...
How do I keep it drive-able and fun around 30-35 mph and still be able to kiss 60+mph

I'm pretty sure I had the perfect set up before. Well close to perfect.
It had a little too much low end and didn't do 60mph. It did 55, but thats not 60 and 55mph didn't seem scary enough.

I keep going over these things and the price of everything. Not sure the 285-0211 will be best option for me. I keep thinking maybe I want to do another Black Mamba Jr instead. It would be cheaper. I'd use stock valves, retainers, and pushrods. 26lb springs so the pocket won't need cutting. No three angle valve job. I'd port myself. Dynocams could mill it for me.

The engine, carb excluded, would be pretty similar to my last hemi. Did I get it right the first time, or am I just developing a pattern now. It would be geared 5:1 now instead of the 5.4:1 I had last time. This should get rid of some of the low end and allow me to hit 60mph. I think.

So Much GAB to get done. Its ok, I've got nothing but time for this.
But this is why I spend so much time planning these things. If the cam isn't right for the application. I'd like to know before I purchase and install it.

 

[bob58o]

So the cheaper option...

Black Mamba Jr Camshaft

$81 shipped from SmallEngineCams


+0.020" Con Rod
Carb Manifold
Head Gasket 0.027"
26lb Valve springs
Valve Spring Shims 0.015"
Timing Key

$149 Shipped from NR

Milling

$45? shipped from Dynocams
___________________________________________________
$275

$275 - SmallEngineCams, NRracing, Dynocams
$35 Exhaust (RLV?) eBay
$41 (Carb/Jets/Air Filter) eBay
$85 Predator 212 Hemi eBay



$436
What am I forgetting????

Stock Valves
Stock Retainers
Stock Lash Caps
Stock Pushrods
Stock Rocker Arms
Stock Piston
Stock Crank
Stock Lifters
Stock Flywheel
Stock Ignition coil
Stock Head Bolts
Stock Side Cover Bolts

Black Mamba Jr Cam
26 lb Valve Springs
Valve Spring Shims (to protect the Aluminum Head)
+0.020" Billet Connecting Rod
0.027" Head Gasket
Advanced Timing Key 8 degrees
Carb Adapter
24mm Carb
Carb Jets
Air Filter
Milled 0.040"
Ported
Exhaust ???

So add in a $14 breather filter for the valve cover vent and call it..............

$450 Total

Not too bad for what should be a pretty powerful little engine.
Hopefully the Valve train and flywheel hold up. I used stock push rods and flywheel in the last one with no issues and also used stock valves/retainers for a bit.

This would be geared for lower RPMs so it should be ok? I Hope.
This makes more sense to me financially and as far as making a bike I can ride around the neighborhood.

 

[ezcome-ezgo]

Can you still find a Predator that cheap on eBay? Seems like the prices have gone up

 

[bob58o]

Can you still find a Predator that cheap on eBay? Seems like the prices have gone up

"Apparently" the JIG is UP.
https://www.youtube.com/watch?v=rz5TGN7eUcM

---------- Post added at 08:39 AM ---------- Previous post was at 08:31 AM ----------

Wake-y, Wakey-y, Eggs n Bake-y, and Duck Dynasty Reggae.
https://www.youtube.com/watch?v=TZaQzSAjczI

---------- Post added at 08:45 AM ---------- Previous post was at 08:39 AM ----------

Randy from Dyncocams said it would be around $75 to Mill the Head, Do a Valve Job, and Cut the Spring Pockets. He said the Milling would be around $15 plus shipping. He also told me they just finished the jig for milling hemi heads. I sent a hemi head there before, I guess they didn't have a jig for it before?????

 

[bob58o]

Piston Pop Out 0.015"

I'm trying to cut every dollar I can.

I'm thinking about getting a +0.040 Rod instead of the +0.020 and running the stock 0.045 gasket with 0.015" piston pop out. Instead of the piston 0.005" in the hole with a 0.027" gasket.

Is this too much pop out? I don't why it wouldn't work. I've read about cars with 0.014 or 0.023" pop out.

Any advantages/disadvantages to one or the other?

 

[ezcome-ezgo]

You'll get a marginal increase in compression? Maybe? I'm more of an expert in pop-tarts.