Advanced Hemi 212cc Predator Build

[bob58o]

Two complete revolutions of the flywheel gives all four strokes.
The Intake valve is closest to the piston near TDC during the intake stroke when the valve is chasing the piston down the cylinder.
Should be closest from TDC to 20degress ATDC on the intake stroke?

For the exhaust, it should be closest from 20degrees BTDC to TDC on the exhaust (as the piston is coming up as the valve is closing?).

 

[bob58o]

0.036" gasket (measured)
Lifters
Pushrods
10.8 lb springs
Retainers
(No lash caps? - shouldn't matter?)
ZERO lash setting
Rockers with pins, but no clips

A final squirt of lube..

 

[bob58o]

And it looks like this..

 

[bob58o]

After cutting with a feeler gauge....

 

[bob58o]

SS exhaust valve (thicker)
.275 lift
0.036" MLS gasket
Milled 0.037"
0.004" deck height
+0.020" connecting rod

0.090" Piston to exhaust valve clearance.

 

[bob58o]

Stock intake valve (thinner)
Everything else is the same.
0.080" Puston to intake valve clearance.

 

[FreeRunner15]

Thanks for showing the clay pics and measurements. It lets me know that i can have a lift around .340 and still have .030 room left over with an 18cc head and +.020 rod. more than that with stock head and rod, around .380

 

[bob58o]

Here are my options....
0.027" Gasket 0.031" P2H (calculated, not measured [0.004" deck height plus 0.027" gasket thickness])
Exhaust ~ 0.080"
Intake ~ 0.070"

0.036" Gasket, 0.040" P2H
Exhaust ~ 0.090"
Intake ~ 0.080"

0.045" Gasket 0.050" P2H
Exhaust ~ 0.100"
Intake ~ 0.090"

Maybe I can use the 0.045" gasket and get some 1.1:1 ratio rockers???? That sounds like fun. Do they exist for the Hemi?

---------- Post added at 05:34 PM ---------- Previous post was at 05:33 PM ----------

Thanks for showing the clay pics and measurements. It lets me know that i can have a lift around .340 and still have .030 room left over with an 18cc head and +.020 rod. more than that with stock head and rod, around .380

Different timing on the cam, will probably make a difference too. I would measure up for yourself as well.

 

[bob58o]

Even though it goes against all things GAB, I think I'll start with the 0.045" gasket and leave room for improvement when I want to show off. Oh you wanna race, let me get my gasket.

 

[Joe-405]

I'm not mad at you anymore cause dyno screwing up made me get alot more hp. Haha


But seriously looks like your on the right track now. Looks good sir.

 

[bob58o]

A little info about the 26lb springs from the NR Racing site...

Spring, Valve, 26 lb at .850, Coil Bind at .425 lift (.425 spring) , 7500 max rpm, Use with F200 and 280 cams. Small diameter spring. Can be used with stock retainers. Reinforced or Billet Rocker arms Recommended.
Fits all GX120 to Gx200 Hondas, 6.5 Chinese OHVs, and Old Style Predators. Can be used on new style Predators, but spring pressure will be slightly higher.
Note: Actual coil bind is dependent on several factors including valve length, retainer style, keeper style, and valve height. Figures given are for reference only.

 

[bob58o]

So the reason for this last post is because when I cleaned off all the vasoline from the exhaust valve, I noticed a small leak.

I was using the SS valve with the 10.8lb spring. I was wondering if the air compressor could be unseating the valve from the port side.

I started to read about installed spring height vs seating force and shims for the valve springs to increase seating pressure.

I will try to lap the exhaust valve again, then install the 26lb springs and go from there.

Also the installed spring height may be differenct with the stock valves vs the SS one. The way the retainers/keepers grab the valve may change the installed spring height, which would change the seating pressure. I will measure.

 

[Poboy kartman]

So the reason for this last post is because when I cleaned off all the vasoline from the exhaust valve, I noticed a small leak.

I was using the SS valve with the 10.8lb spring. I was wondering if the air compressor could be unseating the valve from the port side.

I started to read about installed spring height vs seating force and shims for the valve springs to increase seating pressure.

I will try to lap the exhaust valve again, then install the 26lb springs and go from there.

Also the installed spring height may be differenct with the stock valves vs the SS one. The way the retainers/keepers grab the valve may change the installed spring height, which would change the seating pressure. I will measure.

Now that is GAB for sure! And....at the same time PAFR! Dude! the reason I mentioned vasoline to start with is that you have a valve seating issue!

Throwing heavier springs on is NOT going to make it go away...you need a PERFECT seal....actually....the easiest, cheapest, part of this whole fiasco.....

Pretend your one of my now deceased dogs at it's water bowl: lap lap lap....

 

[bob58o]

Now that is GAB for sure! And....at the same time PAFR! Dude! the reason I mentioned vasoline to start with is that you have a valve seating issue!

Throwing heavier springs on is NOT going to make it go away...you need a PERFECT seal....actually....the easiest, cheapest, part of this whole fiasco.....

Pretend your one of my now deceased dogs at it's water bowl: lap lap lap....

You have ghost dogs that drink water?
I'm sorry. I love dogs. 10 X more than people! Nothing to joke about.
I need to get a doggy.

 

[Poboy kartman]

You have ghost dogs that drink water?
I'm sorry. I love dogs. 10 X more than people! Nothing to joke about.
I need to get a doggy.

Me too....but Sammy won't let me!

 

[bob58o]

The leak I noticed before, was on the intake. It is now gone. I didn't notice any leak on the exhaust with the 26lb springs before, but I re-lap-sed, now with the 10.8 lb springs (and new air compressor) there is a small leak (when blowing air from the back of the valve).

I plan on lapping the exhaust and hopefully I can get a good seal.

I was just wondering if the 125psi coming from the air compressor, hitting a .75 sq in valve, could generate 10 lbs of force to start to unseat the valve.

125 psi x .75 sq in = close to 100lbs.
It only takes 10 or 11 lbs to unseat the valves right?

I realize it is not a closed system and pressure won't build up.

 

[Poboy kartman]

The leak I noticed before, was on the intake. It is now gone. I didn't notice any leak on the exhaust with the 26lb springs before, but I re-lap-sed, now with the 10.8 lb springs (and new air compressor) there is a small leak.

I plan on lapping the exhaust and hopefully I can get a good seal.

I was just wondering if the 125psi coming from the air compressor, hitting a .75 sq in valve, could generate 10 lbs of force to start to unseat the valve.

125 psi x .75 sq in = close to 100lbs.
It only takes 10 or 11 lbs to unseat the valves right?

Nope....GAB again....if you can do it "statically" do you REALLY think an actual combustion charge is going to be less than 100 psi?C'MON, MAN...YO MAN CARD IS ABOUT TO BE YANKED!

 

[ezcome-ezgo]

Please thumbnail your shouty words.

 

[bob58o]

Nope....GAB again....if you can do it "statically" do you REALLY think an actual combustion charge is going to be less than 100 psi?C'MON, MAN...YO MAN CARD IS ABOUT TO BE YANKED!

OK, thanks. Back to the lapping.
BUT I know that a 26 lb spring, installed at a height of more that 0.85", takes less than 26 lbs of pressure to unseat it?

How does 100 psi, on say a 1" diameter valve, not cause it to unseat?

Maybe the intake change on forced induction engine might see back pressure build up like that? (PAFR 85 psi boost)
On naturally aspired engines, I think the intake valve would be open before back pressure got that high?

And I really don't know what kind of back pressure I would see on the open exhaust header.

 

[Poboy kartman]

Please thumbnail your shouty words.

WHY? The only "click on a thumbnail "you know about is your weekly visits to your manurcurist

.