Stuffed Crank?

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Marc101885

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So took my truck out a little before lunch ran great for a little while and then just started to get sluggish and then would just stall when it idled, give it a little gas and it would keep going but didnt sound right. So i took it apart and it looks like the plating came right off the cylinder wall and there are a lot of scratches (explains the loss of power). I don't know what went wrong, i run 25:1 synthetic oil, have a well oiled hpi filter, and no crankcase leaks.


Anyway, the top end is toast and i am taking this oppurtunity to upgrade to a bigger setup. I am going to keep the bottom end (i don't see anything wrong with it) and want to put the 30.5 head kit on ( http://www.davesmotors.com/s.nl/c.885035/n.1/it.A/id.4757/.f ). It has 2 options stuffer w/ 2mm crank and just a 2 mm crank. Whats the difference? Which is better off for a monster truck that is just a backyard basher, not looking for top end just grunt off the line? And will this work with the 23cc CY that the rampage came with?
 
you were running too lean. someone my say that cy plating is bad, but those days are gone. what you have is a lean seize. you may see some type of scorching in there too. right before it died, did you notice some stumbling or hesitating at the top end? that was your motor over heating.. check your plug.. its probly a grey color. it should be dark brown. (grey=lean) you fuel mix is useless if your carb isnt set-up right. im running 38:1.
 
i didnt notice any scorching, would that looking like a blueing like when you overheat a rotor or a flywheel on a car. plug is brownish around the tip of the electrode and ground strap, but black everywhere else. i figured i was running rich too, got the some smoke when i ran it wide open.


**EDIT** I just thought about it, the last time i played around with the carb setting was back in september and it was a lot warmer then, could that have messed up my tune now that it was 30 when i started this morning?


anyway the motor is toast and i will take note of the tuning issues, but which would be better stuffer or not
 
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I would suggest the Ported 28.5cc kit many of us are running 28.5's and they are a excellent compromise of hp and torque. I put a stock stroke stuffed race crank in mine, with a Race ported 28.5cc BB kit.


Were you running it in the cold? If so, when I run mine in the cold I open the H needle rite up, and it still runs lean. temperature's around -20


Sounds like it leaned out to me aswell.
 
Clubin said:
I would suggest the Ported 28.5cc kit many of us are running 28.5's and they are a excellent compromise of hp and torque. I put a stock stroke stuffed race crank in mine, with a Race ported 28.5cc BB kit.
Were you running it in the cold? If so, when I run mine in the cold I open the H needle rite up, and it still runs lean. temperature's around -20


Sounds like it leaned out to me aswell.
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yeah it was cold, i just edited that in the last message. I want a torque monster, im not concerned about top speed i like to be able to burn the tires and chew through the deep mud, sand and snow
 
Marc101885 said:
yeah it was cold, i just edited that in the last message. I want a torque monster, im not concerned about top speed i like to be able to burn the tires and chew through the deep mud, sand and snow
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One thing I realy don't like about that kit is the .040 gasket, what that does is lift the jug off of the crankcase .040" so you have the correct squish, now the ports are .040" out. Does that realy matter? Yes, it does. What might be a better kit is one that is machined and ported, like this one.


No gasket stacking with this kit- http://www.oneillbrothers.com/rccar/itemdescription/30_kit_mpp.htm It is more money, but it is ported, so it will perform much better.
 
Clubin said:
One thing I realy don't like about that kit is the .040 gasket, what that does is lift the jug off of the crankcase .040" so you have the correct squish, now the ports are .040" out. Does that realy matter? Yes, it does. What might be a better kit is one that is machined and ported, like this one.
No gasket stacking with this kit- http://www.oneillbrothers.com/rccar/itemdescription/30_kit_mpp.htm It is more money, but it is ported, so it will perform much better.
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i agree totaly with clubin if you want a stroker drop the bore down to a 35 mm if you need to stay on a budget. Or if you do go 36 bore get the cut out one like clubin talked about , but that is lot $$ for not racing. To answer your other question I would go with the stroke stuffed option, it is not much more for stuffed and it does get little more rpm , which you will need to get back after the stroke increase. DDM runs the 35 mm bore plus stroke crank kit on sale often.
 
i didnt think anything about that extra .020" on the gasket. for the extra $40 for the oneil kit it might be worth it.
 
Marc101885 said:
i didnt think anything about that extra .020" on the gasket. for the extra $40 for the oneil kit it might be worth it.
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Absolutely. Then at least it is done properly gasket stacking is only done because people don't have the proper tools to machine the cylinder so the squish is correct. I ahve not ran or do I know any one that has tried that kit, but O'neill stuff is very good. I am curious to hear your review on that kit.
 
I've had stuffed crank failures when running high RPM setups. For example, the attached pic was a stuffing failure from an Oneills race ported head running with a Jetpro. My experience with running my Baja's and fixing other guys Baja's is that stuffing has a decent chance of failure when you start reaching 19k+ RPM.


Trevor Simpson said himself, "I've had reliability problems with the stuffed cranks in the past so I prefer not to run them." My guess is that he has reliability problems on a regular basis cause every one of his engines clear 20k RPM.
 
catchaser said:
I've had stuffed crank failures when running high RPM setups. For example, the attached pic was a stuffing failure from an Oneills race ported head running with a Jetpro. My experience with running my Baja's and fixing other guys Baja's is that stuffing has a decent chance of failure when you start reaching 19k+ RPM.
Trevor Simpson said himself, "I've had reliability problems with the stuffed cranks in the past so I prefer not to run them." My guess is that he has reliability problems on a regular basis cause every one of his engines clear 20k RPM.
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Where exactly did the stuffer crank fail? From the pic it looks like a lean seize.
 
MY two cent's.. take the 23cc cy engine that comes with the Ramp, buy a $105 28.5 (gp290) race ported top end, forget the stuffed this the stroked that and simply slap it on. More punch for the buck then you'll ever need....add a pipe and ........start buying replacement diffs cause you'll need em!
 
IMADMAN said:
Where exactly did the stuffer crank fail? From the pic it looks like a lean seize.
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Look at the 4 corners around the con rod. Those points are supposed to be tapered. Each corner lost about 2-4mm of stuffing. This was an Oneills engine. I had it do the same thing on my DS engine. The inside of my crankcase, transfer ports, and exhaust port had pieces of it all over.
 
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