Broke a valve spring. Not looking good@
Pac 1518 springs.
From what I have gathered.. The springs should be replaced once a year depending on miles and track use. I have a very aggressive intake lobe 267@595 lift and have over 40 passes with a lot of hard driven miles. I will be replacing the springs with tea gold duals. I will check the pressure with a spring checker once I remove them to verrify my findings.
So.. I broke a rocker, lifter, smashed the push rod tip, bent the intake valve, shattered the valve guide, and cracked the guide boss. Piston has some pressed valve reliefs that are half as deep ad the piston forward dot. The motor spins freely so hopefully the piston skirt, pin, bearings, and Rod is ok. I will assume yes, based on the fact that the motor spins with ease and that the bore looks perfect. It still has cross hatch marks from honing.
I have a pair of heads coming so I will my machinist check it over and
Make it match the other head specs. Mill, and backcut.
Even with dual springs I will pull one every 6 months or so to check seat pressure. I love beehives... But don't like the fact that if one breaks the valve drops. With duals there is less if a chance.
Again.. My aggressive cam caused the spring to ware. Nature if the beast. If I was running more duration with less lift, the springs should last longer. I'll post up the spring numbers once I remove them
From what I have gathered.. The springs should be replaced once a year depending on miles and track use. I have a very aggressive intake lobe 267@595 lift and have over 40 passes with a lot of hard driven miles. I will be replacing the springs with tea gold duals. I will check the pressure with a spring checker once I remove them to verrify my findings.
So.. I broke a rocker, lifter, smashed the push rod tip, bent the intake valve, shattered the valve guide, and cracked the guide boss. Piston has some pressed valve reliefs that are half as deep ad the piston forward dot. The motor spins freely so hopefully the piston skirt, pin, bearings, and Rod is ok. I will assume yes, based on the fact that the motor spins with ease and that the bore looks perfect. It still has cross hatch marks from honing.
I have a pair of heads coming so I will my machinist check it over and
Make it match the other head specs. Mill, and backcut.
Even with dual springs I will pull one every 6 months or so to check seat pressure. I love beehives... But don't like the fact that if one breaks the valve drops. With duals there is less if a chance.
Again.. My aggressive cam caused the spring to ware. Nature if the beast. If I was running more duration with less lift, the springs should last longer. I'll post up the spring numbers once I remove them
TECH Regular
Joined: Aug 2010
Posts: 446
Likes: 0
From: Midland MI
Good luck with the rebuild as well. Sorry to hear it happened. It's awesome that you jumped right in to get it fixed!
Just grab a
and 
and get to work. (There was no bratwurst smiley so popcorn will have to do!)
Just grab a
and and get to work. (There was no bratwurst smiley so popcorn will have to do!) LS1 Tech Stories
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Verdad Gallardo Motor is ready to come out. Wish I could post some pics. My lap top is down and I'm stuck with my phone.
I love my car too much to see it hurting like this. Most of you can't wait to get out of the ls4 and I'm all about it. I do hate speeding money though
I love my car too much to see it hurting like this. Most of you can't wait to get out of the ls4 and I'm all about it. I do hate speeding money though
A little update:
The intake valve hit the side of the cylinder wall, so I stripped the block down and took into my machinist. The cylinder wall cannot be saved, so I ordered another engine from LKQ that was low mileage. The engine came with a carfax report and was labled as condition A. The engine came from a 2006 GXP (Cool
) I received the engine yesterday morning and stripped the motor down for the cam swap. This engine is pretty clean and came with a AC Declo oil filter, so i will assume.. it was serviced by the dealship. The timing chain was streched pretty bad, so it's getting replaced. I am not going to risk running a factory chain (we have the LS2 chain btw) with dual springs and .600" lift. Too risky!
Piston tops, combustion chambers, and intake ports are coated with carbon and oil (DOD sucks!) My engine was clean as hell.. with a little carbon on the piston tops and had brownish combustion chambers. Turn DOD off guys, and get a catch can people!
New part list:
GM LS6 oil pump
GM head gaskets, head bolts, oil pan gasket and valve cover gaskets
Katech C5-R timing chain. http://www.ls1gto.com/forums/showthread.php?t=286290
New GM LS2 lifter buckets. Replace after 50K
New GM LS7 lifters. Stockers are fine. Being cautious!
Lunati Dual valve .660" springs with upgraded retainers, and locks. https://ls1tech.com/forums/generatio...e-springs.html
Comp cams rocker trunion upgrade. https://ls1tech.com/forums/generatio...n-upgrade.html
AI stage II heads. http://advancedinduction.com/LSX/AiL...cGMLS2Head.php
Hoping to add more reliability and with an extra 25-30hp.
The intake valve hit the side of the cylinder wall, so I stripped the block down and took into my machinist. The cylinder wall cannot be saved, so I ordered another engine from LKQ that was low mileage. The engine came with a carfax report and was labled as condition A. The engine came from a 2006 GXP (Cool
) I received the engine yesterday morning and stripped the motor down for the cam swap. This engine is pretty clean and came with a AC Declo oil filter, so i will assume.. it was serviced by the dealship. The timing chain was streched pretty bad, so it's getting replaced. I am not going to risk running a factory chain (we have the LS2 chain btw) with dual springs and .600" lift. Too risky!Piston tops, combustion chambers, and intake ports are coated with carbon and oil (DOD sucks!) My engine was clean as hell.. with a little carbon on the piston tops and had brownish combustion chambers. Turn DOD off guys, and get a catch can people!
New part list:
GM LS6 oil pump
GM head gaskets, head bolts, oil pan gasket and valve cover gaskets
Katech C5-R timing chain. http://www.ls1gto.com/forums/showthread.php?t=286290
New GM LS2 lifter buckets. Replace after 50K
New GM LS7 lifters. Stockers are fine. Being cautious!
Lunati Dual valve .660" springs with upgraded retainers, and locks. https://ls1tech.com/forums/generatio...e-springs.html
Comp cams rocker trunion upgrade. https://ls1tech.com/forums/generatio...n-upgrade.html
AI stage II heads. http://advancedinduction.com/LSX/AiL...cGMLS2Head.php
Hoping to add more reliability and with an extra 25-30hp.
David, I know this is a bit off-topic, but can you verify the valve sizes for the stock 243 heads? Some sources say they're smaller than the valves from in the same head from an LS6 motor, and other places say they're the same size as the LS6.
Can you confirm?
Can you confirm?
I have confermed the valve sizes before. The 243 heads are not ls6 heads due to the lack of ls6 valves. The sizes are the same. GM would not cast another another head for smaller valves and call it a 243.
Thanks David...I didn't think GM would use the same casting number, but there's a lot of bullshit on the internet claiming smaller valves for an "LS4" 243.
TECH Enthusiast
Joined: Nov 2008
Posts: 622
Likes: 1
Yours is apart, maybe accuratly measure one is it 1.890 or 1.990 or 2.000 we know it is not 2.165
It does not only depend on casting # but the series too as they are all LS6 heads different ones /casting makes for more or less
they are all capable of the same lift with stock valves but what about wall clearance at certain lifts, hint
what about retainer clearance during higher lift, oops they all require 0.50 between it and the seal too
why is there a max lift with the smaller bore, can someone use smaller intake valves, a 799 casting with smaller valves without compromising to much performance, if it was ported the drop from 320cfm from 340cfm be noticeable on the street,oh and dont forget the tensioner for your chain
It does not only depend on casting # but the series too as they are all LS6 heads different ones /casting makes for more or less
they are all capable of the same lift with stock valves but what about wall clearance at certain lifts, hint
what about retainer clearance during higher lift, oops they all require 0.50 between it and the seal too
why is there a max lift with the smaller bore, can someone use smaller intake valves, a 799 casting with smaller valves without compromising to much performance, if it was ported the drop from 320cfm from 340cfm be noticeable on the street,oh and dont forget the tensioner for your chain
Hey ill, I had the valves and everything checked/confirmed last year so I know. I will pull a valve and post dial indicator pics for you guys. This engine was set up properly and the spring had to have worn out. Over 20 drag race passes shifting at 6800 and 10k street driven miles. Never a hint of future trouble.
So.. I can't give you the rocket scince explainaton.. About it
So.. I can't give you the rocket scince explainaton.. About it