lq9 with ls3 heads help!! - LS1TECH - Camaro and Firebird Forum Discussion



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lq9 with ls3 heads help!!

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Old 03-29-2010, 10:34 AM   #1
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Default lq9 with ls3 heads help!!

will it work or will the pistons hit the valves and if so what can i do to fix it?

if not what size push rods do it for it to work?

and any other info you have to help me out.

thanks for any help you can give
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Old 03-29-2010, 10:58 AM   #2
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SEARCH, there is tons of information on here that is easy to find.
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Old 03-29-2010, 12:37 PM   #3
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thats what im doing but if anyone can pont me the right way it would help out alot.
im looking for some that may have done this already to tell me some of the tricks to making this work.
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Old 03-29-2010, 03:17 PM   #4
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Pm sent to help boost you along. Good Luck!!!
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Old 03-29-2010, 09:30 PM   #5
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You would only have to worry about PTV clearance with a pretty large cam in it. As for pushrods, you'll have to measure. TSP told me that I'd probably need something around the same size as stock LS1 (7.400) pushrods for my setup (LQ4 and stock L92's), so that's what I got with my cam kit. But, won't know for sure until I get the heads on and can measure for it.
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Old 03-29-2010, 10:31 PM   #6
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my cam is a comp cam w/
--------- intake-----------exhaust
lift.......... .617.................. .623
duration.....231................... 247
lsa 114
some ppl told me that it would hit some sid that it wouldnt. so i guess ill see.
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Old 04-07-2010, 04:37 PM   #7
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I'll say if that fits I need to know your secret. I have an LQ9 with LS3 heads and my cam will not clear.......

.596" intake
.600 exhaust

222/230 @ .050

114 lsa

Tried it initially with CNC LS3 heads (64cc) and no intake clearance at all, hits the piston. Bought some new bare L92 castings, swapped valves in one cylinder, only has .025" clearance intake, plenty of exhaust clearance.

My LQ9 is about .007" out of the deck which is normal. Stock 6.2 GM headgaskets (.054" or so). Cam has been degreed 3 times to verify it's on 114.

Good luck, but I'm gonna say "no workie"............. I'm ordering the flycutter tool tomorrow.........

Jody

Last edited by camcojb; 04-07-2010 at 07:33 PM.
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Old 04-07-2010, 07:44 PM   #8
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Quote:
Originally Posted by camcojb View Post
I'll say if that fits I need to know your secret. I have an LQ9 with LS3 heads and my cam will not clear.......

.596" intake
.600 exhaust

222/230 @ .050

114 lsa

Tried it initially with CNC LS3 heads (64cc) and no intake clearance at all, hits the piston. Bought some new bare L92 castings, swapped valves in one cylinder, only has .025" clearance intake, plenty of exhaust clearance.

My LQ9 is about .007" out of the deck which is normal. Stock 6.2 GM headgaskets (.054" or so). Cam has been degreed 3 times to verify it's on 114.

Good luck, but I'm gonna say "no workie".............

Jody
hmmm.... I milled my G8's L92 heads .030 and installed them on the LS2 short block with oem LS3 head gaskets .051 with a EPS grind 222/230@112+3 and I didn't have any PTV clearance issues. It had .087 clearance on the intake side.

Did you degree the cam in or did you use dot to dot while installing the cam?
Dot to dot may not be a 100% accurate because the actual cam grind specs may differ somewhat from the initial cam specs of the grind #'s ordered.
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Old 04-08-2010, 02:42 AM   #9
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I've got a 227?239 .614/.624 115+3 cam , unmilled heads , and stock 6.2 gaskets on my 6.0 with pistons .008 out of the hole...No problems...
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Old 04-08-2010, 05:57 AM   #10
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It comes down to the valve events, the lift doesn't add much towards PTV issues. Two 230 intake duration cams will have different PTV clearances.

In the engine building software like Performance Trends and Dynomoyion,it will simulate PTV with data that you input, Born2fly's cam says that it loser than my 234/246. You still need to clay it but you get a rough idea and can compare numbers.
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Old 04-08-2010, 09:45 AM   #11
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Only way to know for sure is to do a mock up and clay test it
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Old 04-08-2010, 02:45 PM   #12
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Quote:
Originally Posted by BORN2FLY View Post
hmmm.... I milled my G8's L92 heads .030 and installed them on the LS2 short block with oem LS3 head gaskets .051 with a EPS grind 222/230@112+3 and I didn't have any PTV clearance issues. It had .087 clearance on the intake side.

Did you degree the cam in or did you use dot to dot while installing the cam?
Dot to dot may not be a 100% accurate because the actual cam grind specs may differ somewhat from the initial cam specs of the grind #'s ordered.
I believe the pistons are different on an LS2 than an LQ9......... Mine are flat tops, no reliefs, no dish, and .007" out of the deck. Maybe they're the same, but I don't hear much about valve to piston issues with an LS2 but there's a ton of info about the LQ9's and valve to piston issues..........Yes, cam is degreed and set at 114 #1 lobe centerline as it's spec'd.
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Old 04-08-2010, 02:52 PM   #13
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Quote:
Originally Posted by 69LT1Bird View Post
It comes down to the valve events, the lift doesn't add much towards PTV issues. Two 230 intake duration cams will have different PTV clearances.

In the engine building software like Performance Trends and Dynomoyion,it will simulate PTV with data that you input, Born2fly's cam says that it loser than my 234/246. You still need to clay it but you get a rough idea and can compare numbers.
yeah, had this cam custom spec'd to remove valve to piston issues, but it still has them.
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Old 04-10-2010, 02:31 PM   #14
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Quote:
Originally Posted by BORN2FLY View Post
hmmm.... I milled my G8's L92 heads .030 and installed them on the LS2 short block with oem LS3 head gaskets .051 with a EPS grind 222/230@112+3 and I didn't have any PTV clearance issues. It had .087 clearance on the intake side.

Did you degree the cam in or did you use dot to dot while installing the cam?
Dot to dot may not be a 100% accurate because the actual cam grind specs may differ somewhat from the initial cam specs of the grind #'s ordered.
dont u need .100 to be safe???
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Old 04-10-2010, 03:49 PM   #15
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Minimum piston to valve clearance is .080” on the intake and .100” on the exhaust valves. If aluminum connecting rods are being used, add a minimum of .030” to these suggested clearance figures. Aluminum rods will stretch and expand more than steel rods. courtesy of RHS
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Old 03-16-2017, 04:00 PM   #16
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Question LQ9 With LS3Heads NEED CAM HELP!!! PLEASE

I have a 1987 Cutlass with 3.73 gears, a 2003 LQ9 with the matching 4L60E tranny. I also have a set of LS3 head that will be port and polished that i would like to put on my LQ9. I would like to know if the cams listed below will work for a DD (at least 80miles/day) or if you would recommend a custom grind. Also what Stall Converter would be best for a DD with the cams below. Will a dual spring with the max lift of .650 work? i would like to see around 475whp with at-least 14mpg if possible

Xer 273HR (224/230 .581/.588 114) or
LSr 273Lr HR12 (223/231 .610/.617 114+2)

Which of the 2 cams listed best for a DD lq9 with ls3 Heads?
Will a dual spring with the max lift of .650 work?
Stall size?
Valve Spring size?
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