I'm back! - AI Cam time! - Rod bolts?
10-08-2010, 05:52 PM
#41
Rod bolts are SUPPOSED to stretch, but people assume that since they are in one piece in their blown engine that they are not to blame.
Fact of the matter is, rod bolt failure usually has NOTHING to do with a broken rod bolt...in fact, a broken rod bolt is usually not the one that caused the break down in the first place, but a stretched rod bolt next to it. They fail to keep the caps seated properly and cause OTHER things to break.
Usually, someone installs them wrong by using a torque wrench all at the same spec, when then they should be installed using a stretch gauge. One rod bolt may take 60lbs to reach proper spec, and the other might take 80lbs. Doing them all at 65 doesn't cut it.
No matter how you slice it, the most stressed fastener in the whole engine should be one of the things looked at the closest.
10-08-2010, 05:52 PM
#42
10-08-2010, 06:01 PM
#43
+1.
Rod bolts are SUPPOSED to stretch, but people assume that since they are in one piece in their blown engine that they are not to blame.
Fact of the matter is, rod bolt failure usually has NOTHING to do with a broken rod bolt...in fact, a broken rod bolt is usually not the one that caused the break down in the first place, but a stretched rod bolt next to it. They fail to keep the caps seated properly and cause OTHER things to break.
Usually, someone installs them wrong by using a torque wrench all at the same spec, when then they should be installed using a stretch gauge. One rod bolt may take 60lbs to reach proper spec, and the other might take 80lbs. Doing them all at 65 doesn't cut it.
No matter how you slice it, the most stressed fastener in the whole engine should be one of the things looked at the closest.
Rod bolts are SUPPOSED to stretch, but people assume that since they are in one piece in their blown engine that they are not to blame.
Fact of the matter is, rod bolt failure usually has NOTHING to do with a broken rod bolt...in fact, a broken rod bolt is usually not the one that caused the break down in the first place, but a stretched rod bolt next to it. They fail to keep the caps seated properly and cause OTHER things to break.
Usually, someone installs them wrong by using a torque wrench all at the same spec, when then they should be installed using a stretch gauge. One rod bolt may take 60lbs to reach proper spec, and the other might take 80lbs. Doing them all at 65 doesn't cut it.
No matter how you slice it, the most stressed fastener in the whole engine should be one of the things looked at the closest.
10-08-2010, 08:01 PM
#44
Stock lifters with 100k on them would probably work just fine on a brand new 0 miles stroker, but that doesn't mean you shouldn't change them anyway.
My stock 10-bolt survived multiple 11 second runs, and others have massacred them in stock cars on street tires. Doesn't mean you shouldn't get an aftermarket rear until you run 10s, but its still a good idea. Is my 10 bolt defying physics because it hasn't blown yet? No, I have just been lucky so far.
Its a fact of physics - rod bolts are the most stressed part in your whole engine, and it will never hurt to replace them. It is very hard to tell if those pieces of piston and connecting rod in your oil pan were from stretch rod bolts or not since they usually stay intact.
10-08-2010, 08:07 PM
#45
Your engine NOT being dead does not really mean anything overall, just that your's survived so far. There are of course examples that can be used to defend anything.
Stock lifters with 100k on them would probably work just fine on a brand new 0 miles stroker, but that doesn't mean you shouldn't change them anyway.
My stock 10-bolt survived multiple 11 second runs, and others have massacred them in stock cars on street tires. Doesn't mean you shouldn't get an aftermarket rear until you run 10s, but its still a good idea. Is my 10 bolt defying physics because it hasn't blown yet? No, I have just been lucky so far.
Its a fact of physics - rod bolts are the most stressed part in your whole engine, and it will never hurt to replace them. It is very hard to tell if those pieces of piston and connecting rod in your oil pan were from stretch rod bolts or not since they usually stay intact.
Stock lifters with 100k on them would probably work just fine on a brand new 0 miles stroker, but that doesn't mean you shouldn't change them anyway.
My stock 10-bolt survived multiple 11 second runs, and others have massacred them in stock cars on street tires. Doesn't mean you shouldn't get an aftermarket rear until you run 10s, but its still a good idea. Is my 10 bolt defying physics because it hasn't blown yet? No, I have just been lucky so far.
Its a fact of physics - rod bolts are the most stressed part in your whole engine, and it will never hurt to replace them. It is very hard to tell if those pieces of piston and connecting rod in your oil pan were from stretch rod bolts or not since they usually stay intact.
And it would definitely hurt if you just swapped out your stock rod bolts to arp's.
10-08-2010, 09:24 PM
#46
So why do all the experienced people have no problem spinning their stock shortblocks to 6800+ when the majority of spon bearings are from people spinning ~6200 rpms. I still have yet to hear 1 reputable person say rod bolts are the weak link in lt1's.
And it would definitely hurt if you just swapped out your stock rod bolts to arp's.
And it would definitely hurt if you just swapped out your stock rod bolts to arp's.
A stock shortblock street car shouldn't even be running a cam that wants anywhere near 6800 rpms, a properly spec'd cam for a street driven 350 won't need to be shifted anywhere near that.
10-09-2010, 02:08 AM
#47
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So pretty much speed_demon is recommending me to get a large cam and some good ported heads and saying he'll pay for my rebuild if my **** breaks spinning it to 6800+rpms because that is his word... if that **** is true, I'm down 
10-09-2010, 03:36 PM
#48
The fast, experienced people also don't recommend that you spin your street car passed around 6300 on a regular basis. They arent running street cars that see 10k+ miles a year. They do not care at all about the stock shortblock - people go crazy fast with it, spray tons of nitrous, then replace it or rebuild it when it goes...no big deal. For a daily driver that gets relied on for work the next day? Not a good idea.
A stock shortblock street car shouldn't even be running a cam that wants anywhere near 6800 rpms, a properly spec'd cam for a street driven 350 won't need to be shifted anywhere near that.
A stock shortblock street car shouldn't even be running a cam that wants anywhere near 6800 rpms, a properly spec'd cam for a street driven 350 won't need to be shifted anywhere near that.
Hell my old gm846 222/230 cam on mild heads wanted 6500 rpm. Last edited by speed_demon24; 10-09-2010 at 07:16 PM.
10-09-2010, 04:58 PM
#49
I think your the only person saying stock rod bolts arent the engines weakest link and most common internal failure. Please post up all the engine builders that told you this. Since everyone I have ever spoken with has said the exact opposite.
Puck has it right. You have been lucky.
Puck has it right. You have been lucky.
10-09-2010, 05:18 PM
#50
10-09-2010, 05:55 PM
#53
10-09-2010, 07:12 PM
#54
What about my old 224/230 107lsa 106icl bre cam that was still gaining hp at 6300 when the valves started floating. I've had 4 different cams in my car so I think I have a pretty good idea of what peaks where....
Last edited by speed_demon24; 10-09-2010 at 07:17 PM.
10-09-2010, 07:36 PM
#56
I didn't say you didn't know. All I said was arguing cam hp peaks off only duration numbers is pointless.
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