As yu say there is normaly a fair bit of clearance between small end of rod and piston as can be seen above. (Ignore the clearance between small end section of rod and big end section of rod for now!)
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| Author: | nikkin [ Tue Oct 13, 2009 1:30 pm ] |
| Post subject: | been a long time |
Hi peeps been a while since i have been about got the car finally running right with 356 bhp only lasted 2 weeks the engine died big style total right off. sourced a new engine and had it placed in car and had old engine stripped down. cause of engine distruction forged piston on standard rods only ok if standard rods are milled mine wasnt all for rods had snug fit pistons pushed on them causeing them to wear away the rods giving me a nice mix of oil and steel finaly cause rod to break up. Im totally gutted as i was told the person who done my engine was a good person to use and has cost me 1000's any of you that can remember me from toyota office meet at epson for the slot car championship i hope to see you all again soon now car is back running and for that i havent met hope to see you soon |
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| Author: | TrackToyFour [ Tue Oct 13, 2009 1:57 pm ] |
| Post subject: | |
Sounds very strange if there's a problem running forged pistons with standard rods. I have never heard of this before. The gudgeon pin is normally a floating fit in the rod small end bushing. If the pins were a 'snug fit' does this mean they were binding or a press fit? If there is insufficient clearance and/or lubrication then galling or bearing material pick up can occur on the bushing. I guess this could have led in an extreme case to eventual bearing and rod failure. It does sound rather as though the engine builder didn't check the small end gudgeon clearance during the build. |
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| Author: | Diceman [ Tue Oct 13, 2009 1:57 pm ] |
| Post subject: | |
Hi, sorry to hear of your engine demise & yes remember you from the slot car meet. Where exactly did the rods wear/break-up? Little end on piston gudgoen pin or big end? May be that the end tolerances were set for standard power/heat load and hence once you up the power it became an interference fit. I am in no way an expert on this subject but have tried to listen to reason from those that have gained respect for their work in the past. be interested in further info as sometimes engine strip down diagnosis is very difficult with catastrophic failure to establish cause & effect. good luck m8 & hope to catch up soon. Has been some good knowledge about engine builds from Datajon/Don Boyack & his engine builder about this type of thing. Unfotunately it seems that on quite recently has it become more known to us punters what to look out for and ask our designated builder's. |
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| Author: | nikkin [ Wed Oct 14, 2009 8:55 am ] |
| Post subject: | |
the rod side was snug against piston side instead of a 1/4" clearence allowing no movement on small ends apart from rotating. looking at the piston sides thay have been polished by the rob to a mirror finish with the edges chipped i will photo the piston on my return home next week and will see if i can get a photo of one on the rod itself. but the old engine might be scrapped now. I am far from a mechanic so only going by what the mechanic i am using now is telling me. but when he stripped the old engine to find out cause ( i think more for his piece of mind as he has done a lot of wrk trying to get the car running right ) he came across this fault and was amazed that the engine lasted along as it did. this year the car was rolloing roaded a lot getting it running right Now i have a unmodded engine and need to start all over again so if anyone has any upgraded parts for inside engine kicking about and wanting to sell im your man |
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| Author: | Diceman [ Wed Oct 14, 2009 9:13 pm ] |
| Post subject: | |
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As yu say there is normaly a fair bit of clearance between small end of rod and piston as can be seen above. (Ignore the clearance between small end section of rod and big end section of rod for now!)
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| Author: | TrackToyFour [ Wed Oct 14, 2009 9:45 pm ] |
| Post subject: | |
Diceman wrote: Ignore the clearance between small end section of rod and big end section of rod for now!
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| Author: | Sirius [ Wed Oct 14, 2009 11:13 pm ] |
| Post subject: | |
TrackToyFour wrote: Diceman wrote: Ignore the clearance between small end section of rod and big end section of rod for now! Looks like theres a little bit of play there!
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| Author: | TrackToyFour [ Thu Oct 15, 2009 6:13 pm ] |
| Post subject: | |
Boom boom
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| Author: | Sunny [ Thu Oct 15, 2009 7:28 pm ] |
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Hi, LOL a bit of clearance
greetz |
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