Box Stock

Clone money racing

Scarface5029 said:
I was running the box stock predator 390 class and most people that I’ve talked to and from what I’ve read have said not to turn them past 4800 if they are a true out of the box engine and haven’t been modified in any way because the power and torque curve tapers off after that, but I tried running it close to 5300 n practice and was no difference they still leaving me no matter what rpm I’m turning. I’m moving on from the box stock class, I just ordered the Dover clone engine kit so hopefully will be here this week or next, they said they are really busy right now and backed up with engine orders.
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Im kind of new in clones, been running stock appearing and small block open karts so the required rpm in clones is a lot less than what we run in our other motors. So after checking with the other clone guys I found out that almost of them run 6800 to 7100 rpm.
 
mike97760 said:
Im kind of new in clones, been running stock appearing and small block open karts so the required rpm in clones is a lot less than what we run in our other motors. So after checking with the other clone guys I found out that almost of them run 6800 to 7100 rpm.
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If you don’t mind me asking and telling 😄, what rpms do you turn on stock appearing? I’m turning between 8-8300 on my mild built predator but there is a stock appearing kart at a local track that is nasty, I can gain a little in the turns but he leaves me on starts and coming out the turns down the straights…almost as bad as I get left in box stock! Lol
 
The thing about stock appearing is there are few rules. A few years ago guys were throwing stuff together in their garages and racing it. Then one day a guy shows up with a motor with a stroker crank, high dollar head etc and was lapping most of the field. Sort of ruined the class. now days the class has half the entries it used to and theyre all stupid fast, pretty much small block opens with small carbs. In the beginning we ran about 7500 max and could win. Not so now. I put one together recently, ran about 7900 and was maybe a 5th place kart.
Now, 8000-8300 could be hurting you if you dont have everything to go with it (head, .690 carb etc) it to make it thrive at those rpms, could be youre just making noise at 8000 instead of power.
 
mike97760 said:
The thing about stock appearing is there are few rules. A few years ago guys were throwing stuff together in their garages and racing it. Then one day a guy shows up with a motor with a stroker crank, high dollar head etc and was lapping most of the field. Sort of ruined the class. now days the class has half the entries it used to and theyre all stupid fast, pretty much small block opens with small carbs. In the beginning we ran about 7500 max and could win. Not so now. I put one together recently, ran about 7900 and was maybe a 5th place kart.
Now, 8000-8300 could be hurting you if you dont have everything to go with it (head, .690 carb etc) it to make it thrive at those rpms, could be youre just making noise at 8000 instead of power.
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I forgot to mention mine isn’t a stock appearing motor, it has big header And aftermarket air filter, and I’m running a .690 carb along with all the other bits to turn those rpms, they let that guy run with us because he was the only one there with a s/a engine and again this is at a small backyard track really no rules and no tech it’s all just for fun. But that’s what I was getting at, his ran like an open motor but in a s/a package and I was really impressed how fast it was running with stock air box and exhaust and I know they are modified but is still impressive.
 
So I found out why the engine was so slow this past weekend, the flywheel had slipped and had retarted right much, Idk how it was even running as good as it was. In the first pic is with the flywheel on and just to the right of the black marker line is a white paint mark on the crank and is barley visible but that’s where the keyway groove is so you can tell how off the timing was. And in the second pic you can obviously see where the black mark is representing the key groove on the flywheel in relation to the keyway groove on the crank. I lapped the crank on as always and torqued down the nut to around 50 ft lbs. Now I want to reset it and run it again! 😄
 

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flattop1 said:
Yea that will definitely do it . Looks like afull keyway width .
50# isn't enough .
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All I’ll say is she’s right now! It’s a money race at the same track this weekend so I’m gonna go back and hopefully redeem myself, I was told by Dover the engine kit more than likely will not be here until next week so I figure I’ll run the box stock one more time and should have wayyy better results this time.
And I torqued the flywheel down to 60 ftlbs this time.
 
UPDATE: hey guys, I got my Dover clone engine kit in and excited to put it together, not sure if I’ll have it ready to race for tomorrow but it’s suppose to rain anyways, Wanted to go with the arc flywheel but my pockets weren’t deep enough for that. Also what rpms to most people turn these motors? I’ve seen some people say 6800-7000 but the fact sheet says 5900-6400 for adult unrestricted.
 

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We have 2 pretty good clones built by 2 different known builders. One likes 6950 the other likes 7100. They perform the same on the track.
 
Scarface5029 said:
Either one, I have a head to run both.
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Don't understand how that would work. both my NKA and AKRA engine builders tell me to aim for 6800 rpm. That being said it is best to follow the advice of your engine builder as the target RPM is very cam dependent. if you're not sure you would need to put it on a dyno after it's been properly broken in. An understanding of the HP curve and rpm drop in the corner will determine your gear ratio. the TQ peak is your target clutch engagement
 
J'-remy said:
Don't understand how that would work. both my NKA and AKRA engine builders tell me to aim for 6800 rpm. That being said it is best to follow the advice of your engine builder as the target RPM is very cam dependent. if you're not sure you would need to put it on a dyno after it's been properly broken in. An understanding of the HP curve and rpm drop in the corner will determine your gear ratio. the TQ peak is your target clutch engagement
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It’s an ev-6 cam and From what I’ve read on that cam it’s made to turn 7,000 with “little hp drop from peak at 6,000”, 5900-6400 just seems a bit low to me but I’ll run it at wherever rpms it’s fastest on the track!
 
Well she’s together and I have to say Dover did a great job with everything, she’s running great on the stand, hopefully will get to try it out next sat. Thanks again and again everyone for the help.
Bobs need to update their site to allow videos!
 

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Looks nice but my advice get a tire program for the pro money races. And if your looking to test take it to the world 100 at cross roads motorplex and you'll see what I mean.
 
Scarface5029 said:
Well she’s together and I have to say Dover did a great job with everything, she’s running great on the stand, hopefully will get to try it out next sat. Thanks again and again everyone for the help.
Bobs need to update their site to allow videos!
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You can post a video to YouTube and post the link of the YouTube video on Bobs. That’s the only way I have seen people post videos on here.
 
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