ok im finally modding my predator hemi engine already have exhaust and header and carb. billet fly wheel,connecting rod,mod 2 cam,aftermarket Japanese tk carb with adjustable idle screw now I just need help finding the parts to upgrade the valve train I know I can run 10.8 or a 26 lb valve springs just need help finding what else I need or will I be good with just springs.
predator hemi valve train help needed
- Thread starter shaggy340
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KartFab
Active member
If you plan on running super high rpms, you might want to look into chrome/moly push rods. Stock rods flex at very high rpms. Probably not necessary though.
Roller rockers (very very expensive) give added help on the top end, probably not necessary.
Race cut valves improve flow.
Port/polish improves flow.
Just a general lap the valves would probably be the only thing I'd do with that cam, maybe a mild port.
Springs should be 18 lb (like it says on the cam card for your cam).
In/exhaust lash should be .003" per tge cam card.
Roller rockers (very very expensive) give added help on the top end, probably not necessary.
Race cut valves improve flow.
Port/polish improves flow.
Just a general lap the valves would probably be the only thing I'd do with that cam, maybe a mild port.
Springs should be 18 lb (like it says on the cam card for your cam).
In/exhaust lash should be .003" per tge cam card.
ok thanks how many rpms can the stock push rod take and what aftermarket push rods can I put In it? And I got a Chinese torque converter on ebay for 74 bucks on its way to but says it only goes to 8 or 9 hp and it may not work for my application I'm thinking now the seller said it was built real well but he couldn't guarantee it wouldn't break so what would you recommend as an alternatives?
bob58o
SuckSqueezeBangBlow
I am curious about this too as some people claim over 20 HP from these engines fully built out. They make a 44 series Driver for 8-18 HP engine that fits a 3/4" shaft but its pricey. Is it needed??? I have no idea.
https://www.gokartsupply.com/4044seri.htm
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comet 44 series driver.jpg
KartFab
Active member
the drive unit can fly apart at high rpms. I would either install a heavy duty steel cover (if they even exist?) That is what I will be doing to my mini bike.
You will just need to investigate it some more. I dont think it is necessarily a question of 'HP', but RPM. With higher HP sure your shred belts faster, but id be more concered about the drive unit flying apart and injuring yourself. I saw a video of a guy that put a 30 series on some insanely tricked out drag mini bike and it literally blew the belt to pieces from the HP.
Some thoughts (look into it yourself)
race clutches, built to engage around 4200 rpm, but can engage sooner. these handle all the rpms you can give them. pricey 160-350
junior dragster torque converters. They have a much broader range of gearing, and are super expensive though.
the old comet 340 series is similiar to the model 780 but for lower hp applications, it may be starting to be produced now (check GTC manufacturing).
then what bob said above.
You will have to make sure that the max rpm is not exceeded. 30 series is probably the most susceptible to flinging the weights at high rpm
You will just need to investigate it some more. I dont think it is necessarily a question of 'HP', but RPM. With higher HP sure your shred belts faster, but id be more concered about the drive unit flying apart and injuring yourself. I saw a video of a guy that put a 30 series on some insanely tricked out drag mini bike and it literally blew the belt to pieces from the HP.
Some thoughts (look into it yourself)
race clutches, built to engage around 4200 rpm, but can engage sooner. these handle all the rpms you can give them. pricey 160-350
junior dragster torque converters. They have a much broader range of gearing, and are super expensive though.
the old comet 340 series is similiar to the model 780 but for lower hp applications, it may be starting to be produced now (check GTC manufacturing).
then what bob said above.
You will have to make sure that the max rpm is not exceeded. 30 series is probably the most susceptible to flinging the weights at high rpm
Denny
Canned Monster
The 44 and 94 series are pretty good at flinging pucks at high rpm. Had one on a golf cart fling out knocked me out cold. 
Denny
Denny
thanks thats good to know im sending back the cheap torque converter and went with a norma world formula raceing clutch that engages from 4100 to 4300 rpm with the orange springs in it so should handle what im dojng plenty well enough.The 44 and 94 series are pretty good at flinging pucks at high rpm. Had one on a golf cart fling out knocked me out cold.
Denny
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