Rods hitting camshaft? Using LS3 rods... Help needed...
08-30-2011, 04:15 PM
#1
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Rods hitting camshaft? Using LS3 rods... Help needed... Hi All,
I have an interesting situation. My builder is currently putting together my longblock and has come across a couple of items, I was curious if perhaps you could give me some insight:
Shortblock specs:
OEM LS6 block
AutoTec 3.903 pistons
OEM LS3 rods
Katech rod bolts
OEM polished crank
Comp Cam 228/230 114 LSA cam - off the shelf cam, nothing special.
So essentially, the title says it all - when he went to spin the shortblock, the rods hit the cam!?! Is there any logical explanation for this - my build is fairly simple, nothing over the top. I know the LS3 rods are beefier than the LS1 rods, but I didn't know by that much - my friend has the same build and his block spins just fine... is it an issue with the cam? He's going to see exactly how much it's hitting to see if it can be clearanced, but I want to see what insight do you have on it.
I've run that cam before in my old stock setup, so the cam itself has been proven true. But when he removed the cam from the shortblock, the engine turned just fine... Could he of installed something backwards? (I'm not too savvy with putting together engines, so I don't know if that was a dumb question...)
Thanks guys.
I have an interesting situation. My builder is currently putting together my longblock and has come across a couple of items, I was curious if perhaps you could give me some insight:
Shortblock specs:
OEM LS6 block
AutoTec 3.903 pistons
OEM LS3 rods
Katech rod bolts
OEM polished crank
Comp Cam 228/230 114 LSA cam - off the shelf cam, nothing special.
So essentially, the title says it all - when he went to spin the shortblock, the rods hit the cam!?! Is there any logical explanation for this - my build is fairly simple, nothing over the top. I know the LS3 rods are beefier than the LS1 rods, but I didn't know by that much - my friend has the same build and his block spins just fine... is it an issue with the cam? He's going to see exactly how much it's hitting to see if it can be clearanced, but I want to see what insight do you have on it.
I've run that cam before in my old stock setup, so the cam itself has been proven true. But when he removed the cam from the shortblock, the engine turned just fine... Could he of installed something backwards? (I'm not too savvy with putting together engines, so I don't know if that was a dumb question...)
Thanks guys.
08-30-2011, 04:58 PM
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How so? You're saying I should be using a different crank?
Prior to making this thread, I noticed a lot of 383 SBC builds have had this issue, but I could not find a single LS1/Gen III engine coming across this issue - I also see that I am one of the few people using LS3 connecting rods in my build, so that might be why...
He said he's clearanced rods before, and depending on just how much needs to be taken out, it won't be a big issue, but if it's too much, we'll have to get different rods. But why? Is it because the rods are beefier? But why is it that my friend has the same setup as me, built by the same builder, and yet we're having clearancing issues? I would suspect the cam, but I believe he is running a GM road race hot cam, which I believe is a little bit more wild than my cam...
He said he's clearanced rods before, and depending on just how much needs to be taken out, it won't be a big issue, but if it's too much, we'll have to get different rods. But why? Is it because the rods are beefier? But why is it that my friend has the same setup as me, built by the same builder, and yet we're having clearancing issues? I would suspect the cam, but I believe he is running a GM road race hot cam, which I believe is a little bit more wild than my cam...
08-30-2011, 06:56 PM
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Since the cam to crank centerline spacing is the same between both blocks and the fact that they both use the same stroke crank and the same rod length would lead me to believe there should not be a clearance issue here. Something seems wrong here but without seeing the issue first hand I couldn't tell you why.
FWIW, I have never had this issue with a gen III/IV block before.
Shane
FWIW, I have never had this issue with a gen III/IV block before.
Shane
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08-30-2011, 07:27 PM
#8
I just talked to the builder, and he is going to go through everything again, but it does not sound like the root cause was rod to cam interference. He is going to let us both know if it ends up being something that has to do with the LS3 rods.
I dont know how it could be the rods, given that the LS1 and 3 are nearly identical dimensionally aside from the bore, and that mine spins ok.
I dont know how it could be the rods, given that the LS1 and 3 are nearly identical dimensionally aside from the bore, and that mine spins ok.
09-01-2011, 03:40 PM
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Well, my builder said that he figured it out - he tore it all down and he said it was something "stupid" - not something you really want to hear, but whatever, he said it's fixed. He won't tell me what it is, he said he has to show me in person... I'll keep you all updated once he tells me what happened in there.
09-06-2011, 12:46 PM
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So I picked up the engine and all is well:
It seems that the bolts for the cam retainer plate go THROUGH the block, and if you use bolts that are too long, they will protrude INTO the area where the crank spins and will block the crank from making a full revolution - you will only be able to go 90 degrees in each direction before it stops. He used the wrong bolts... they were too long.
I'm just glad it wasn't anything major.
It seems that the bolts for the cam retainer plate go THROUGH the block, and if you use bolts that are too long, they will protrude INTO the area where the crank spins and will block the crank from making a full revolution - you will only be able to go 90 degrees in each direction before it stops. He used the wrong bolts... they were too long.
I'm just glad it wasn't anything major.
05-25-2017, 02:06 AM
#15
Thankyouthankyouthankyouthankyouthankyou
I bought an LS3 shortblock that was fresh from the machine shop and went to install and degree the cam, and after I got it in the thing wouldn't turn more than 180°. I had reused the cam retainer and ARP bolts from my LS1 and guess what -- they were too long. Guess they're different between the LS1 and 3?
I bought an LS3 shortblock that was fresh from the machine shop and went to install and degree the cam, and after I got it in the thing wouldn't turn more than 180°. I had reused the cam retainer and ARP bolts from my LS1 and guess what -- they were too long. Guess they're different between the LS1 and 3?
