Stage 4 Predator 224 Fully built [Head Exploded]

[RefAlpha]

New issue boys only off 6 - 7 hours runs time. Anyone know what could have caused this? Possible a bad cast? I'll answer any questions you have

No markings on valve cover or lifters to indicate striking.

- Go power sports valve cover
- Go power sports stage 4 head
- OMB valve cover Spacer
- Torqued to 7ft pounds
- 3 pressure lines connected to valve cover <2 to equalize pressure and a third to vent it with a one way pressure release valve>

My guess is a bad cast, I've built car engines and a dirt bike engine but never had this happen to me before. I'd love your opinion.

 

[Denny]

Look like crappy casting.

 

[RefAlpha]

Exactly what I thought. How would I proceed? Because this is completely on the company

 

[RefAlpha]

I didn't get it to long ago and surely you can tell if an engine has been driven with wear and tear on valves and springs surely

 

[Denny]

If it was me I’d just get it welded back together.

 

[RefAlpha]

Where would I go to even do that though? That's also severely lowering the quality of the head. Not sure if it would be able to handle the pressure and eventually it would fail in the same spot again

 

[Denny]

Look up welding shops in your area or contact who you bought the head from and ask them.

 

[BrownStainRacing]

Call GPS, they will tell you, "now....you need a stage 5 kit".

Not trying to be a wise a$$, but get with people that actually know what it takes for these engines to handle the power you are expecting.

Dover Power. email Jerry he will get back to you in day 1.

ECCarbs. Mark don't play with bs. There's no way in heLL he would ever recommend that head to be ran with ANY of his Tennessee Thunderstick Cams.

Small Engine Cams. Isky Racing Cams.... I should not have to explain that name.

If you don't know, .... "put that $hit on the google".

One of these days, I'm start making T-shirts with that saying.

Ah probably not, some lazy "f'er" will see this and beat me too it.

 

[busted_blocks]

I checked the go power sports website, the head is marked LJT168F. They mill the head, port & polish and retails for $335. My head in my engine that keeps blowing up is also marked LJT168F. Retail, including shipping, for my unmodified LJT168F head is $11 (including valves/springs/studs), so how much can you expect from this kind of casting. I'm not saying it should blow up and it's sad your head was damaged. All I'm saying is if you start with $11 casting, it can't perform the same as a CNC billet head. It's still an $11 casting no matter how much you polish it up.

 

[Darren]

If you want to try and fix it yourself, you could use durafix aluminium welding/soldering rods. I've had great results when i can't be arsed to tig or lack of space for the tig electrode holder. Unfortunately it gets a bad name due to insufficient preparation and not enough heat for the parent material to melt the rod. Mapp gas torches must be used to get enough heat into the ali casting. Pre heating the head to 225c will minimise any possible warping.
There are a load of videos on youtube. basically 1) buy Branded rods from a welding supplier, 'V' out the crack from the inside, brush the welding area with a stainless wire brush removing the oxide layer, chuck in the oven and pre heat, remove, wire brush again, heat area up with a mapp blow torch or something as powerful, scratch the aluminium solder rod into the crack, it will melt and start to fill the V, DON'T USE THE TORCH TO MELT THE ROD!!!! continue to heat the area under the crack and melt more rod into the weld, chuck back in a preheated oven and then turn it off to cool slowly.
Take a look at my porting video, the Durafix filler is next to the valve guide in the top of the head:

For an idea of the strength of this stuff:

My clone head was a Cheap of the shelf purchase, the valve guides weren't even put in straight!

 

[RefAlpha]

If I paid someone else to repair the damage and including milling what would be your guess on costs?

 

[Denny]

Probably around $100.00. In the US we have Muggy Weld. Maybe worth a try?

 

[BrownStainRacing]

@RefAlpha

Give Mark a call a see what the cost would be for him to set this head up for you.

I'd say around $200, depends on the valve length, springs and retainers you will need for your build.

He's a very ez guy to deal with, and knows his stuff. Let him know what CR you want and what octane fuel you will be running. A 18cc head might be too much.

Wildcat WC946 Non-Hemi 31mm/25mm Cylinder Head - EC Carburetors

www.eccarburetors.com

 

[RefAlpha]

@BrownStainRacing

Do you think he would be able to get as much power as possible from the build from the current parts i have if i give him a list? If he can do anything with the head ofc.

 

[BrownStainRacing]

@BrownStainRacing

Do you think he would be able to get as much power as possible from the build from the current parts i have if i give him a list? If he can do anything with the head ofc.

I know he could.

Jus tell him what you want and expect.

Check out his site, he's got big valve huge, high flowing heads, 263cc build kits.

Wildcat 223 Engine Builder's Guide

 

[Darren]

America has a much better support network for these cheapo engines, I looked at getting my stuff done by machine shops, loads of $$$$, the setting up is what costs the money, a shop already machining the gx/clone parts would be a lot more reasonable.
Typically the welding is around £100/hr, this would include prepping and cleaning, the shop would have to use silicon Alloy rods, next the faces would require skimming to address any warp or high points, another £100/hr.
Did you use a billet ali cover? It's possible that the cover may have contributed to the stress on the cast.
Do you have a set of tempered glass weighing scales, you can check the faces with the flat glass.

 

[bob58o]

So what caused the valve cover to break?
Deformation and flexing?
Some soft of mechanical interference / clearance issues?

 

[bob58o]

I tried a local machine shop for milling a head.
They told me $200. Most were not interested in my job. Dynocams, at the time, milled them for like $20 IIRC. Like Darren said, they are set up to do work on little gx style heads and able to do it for cheaper. As far as welding, I’m not sure.

I was able to get milling, valve seats opened up for larger valves, bowl blending, and a valve job for under $100.

When I need machine work done, I have to ship things out. A few years ago, I think “Randy” might have been the guys name at Dynocams who used to do this type of work for me.

 

[BrownStainRacing]

I tried a local machine shop for milling a head.
They told me $200. Most were not interested in my job. Dynocams, at the time, milled them for like $20 IIRC. Like Darren said, they are set up to do work on little gx style heads and able to do it for cheaper. As far as welding, I’m not sure.

I was able to get milling, valve seats opened up for larger valves, bowl blending, and a valve job for under $100.

When I need machine work done, I have to ship things out. A few years ago, I think “Randy” might have been the guys name at Dynocams who used to do this type of work for me.

Yea, Randy is his name, they still do machine work.

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Performance Machining

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