LY6- bent intake valves- need to know....
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On The Tree
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From: cincinnati
LY6- bent intake valves- need to know.... so i had a mishap with my cam gear after my cam swap- didnt torque the bolt i guess- and the gear came loose. Got that all fixed but it bent four valves apparently. Everything i search says it has a 2.165 valve, 4.9" long 8mm stem- i was thinking of going with some LS3 hollow stem intake valves OR just get a few new stockers but i cant seem to find a supplier that has them or lists them in the correct size. Any ideas? Guess i can call MAST or someone.
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On The Tree
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From: cincinnati
ok so i ended up putting some stock intake valves back in for now and buttoned the car all back up today. Heads looked great, cleaned them up, new gaskets and bolts etc. Not a newby here. Got the motor together and it fired right up immediately and ran for twenty seconds or so. As it started to drop down to an idle the engine died like someone killed the ignition. Tried to restart and will not start up. Here we go.
So i checked the top end, rockers are moving this time, must be getting spark cause itll just pop and spit smoke through the intake sometimes. Decided to check compression and showed 0psi on six cylinders i checked!! Tested my gauge on my riding mower and it works fine. Rechecked a couple and still zero. Ok so im thinking all my valves are bent now right? Decided to do the old school shoot air in the plug hole trick- did cyl number 2 - 0 compression, put air into plug hole and it comes out of the intake with the intake valve spring depressed by the cam. Cranked it over till both valves should be closed and there is no air escaping to the intake or exhaust! Pull the air chuck out of the plug hole and the air all rushes out of the plug hole. WTF.. Am i missing something here? Do i need to retear down the hole front of my motor again...not sure if the timing gear is somehow not on the pin, how else it could possibly be installed. Timing marks arrow down, dot up, heads were off so yes number one was at TDC - i mean even if it was off a tooth it would have compression.
So i checked the top end, rockers are moving this time, must be getting spark cause itll just pop and spit smoke through the intake sometimes. Decided to check compression and showed 0psi on six cylinders i checked!! Tested my gauge on my riding mower and it works fine. Rechecked a couple and still zero. Ok so im thinking all my valves are bent now right? Decided to do the old school shoot air in the plug hole trick- did cyl number 2 - 0 compression, put air into plug hole and it comes out of the intake with the intake valve spring depressed by the cam. Cranked it over till both valves should be closed and there is no air escaping to the intake or exhaust! Pull the air chuck out of the plug hole and the air all rushes out of the plug hole. WTF.. Am i missing something here? Do i need to retear down the hole front of my motor again...not sure if the timing gear is somehow not on the pin, how else it could possibly be installed. Timing marks arrow down, dot up, heads were off so yes number one was at TDC - i mean even if it was off a tooth it would have compression.
Noticed you did a cam swap, What are the specs of the cam? Might have piston to valve clearance issues due to the cam you choose.
Cam gear would be at 6 pointing down and crank gear at 12 so pointing up so it sounds like you have it right.
I have no idea why you are getting the readings you are. You can try to get a cylinder on TDC on the compression stroke and check that valves are actually closed.
Cam gear would be at 6 pointing down and crank gear at 12 so pointing up so it sounds like you have it right.
I have no idea why you are getting the readings you are. You can try to get a cylinder on TDC on the compression stroke and check that valves are actually closed.
Last edited by LLLosingit; Nov 26, 2016 at 01:34 AM.
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I would of switched to LS3 intake valves at that point. But since you all ready went stock, I'd STRONGLY recommend stiifer springs. Stiffer than what they recommend if that cam was spec'd for a LS3. I agree with LLLosingit, contact BTR
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On The Tree
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From: cincinnati
the motor has Mast racing cam, push rods and springs. 585 lift SS cam. All parts from MAST in a "kit" they supply. I believe my problems are all with the cam gear not seating on the front of the cam properly or me leaving the bolt loose- the first time. Havent torn it down yet but im not sure how i can get no compression and also not get tons of air through the intake when i blow air into there with the valves closed. makes no sense- guess i'll rip it back down again. My concern is that i'll never get this cam gear on there correct and just keep doing this over and over. Not sure why this is being so difficult.
Find someone that has done this before and maybe they can figure out what is going wrong.
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Thread Starter
On The Tree
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From: cincinnati
tore the motor down last night and found a sheared timing gear pin. Had only spun a few degrees since the bolt was tight this time. So no biggie i'll pull the cam out and get it repaired- well no. The third cam bearing also seized to the cam and i can pull it forward till the bearing hits the next bearing and then its stuck. Time to pull the motor and send it to the motor shop. Im done. Simple cam swap turned nightmare.
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The pin on the cam could have sheered from the forced of fighting against some bending valves. The problem with installing a cam in a Gen 4 engine is that the VVT engines aren't referenced the same and you need to actually degree the cam instead of installing dot to dot, otherwise the cam will be off by ~7-9 degrees.
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From MAST racing " you do not need to degree a vvt cam as it constantly changes adjustment. We've tried this many times with little advantage. "
Machine shop called today and cam and block are separated and both fine. I do however need a new cam gear and pin. Anyone have a good gear and where do I get a cam pin?
Machine shop called today and cam and block are separated and both fine. I do however need a new cam gear and pin. Anyone have a good gear and where do I get a cam pin?