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LQ4 head question

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Old Jul 4, 2016 | 12:38 PM
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Default LQ4 head question

If i mill a set of 317 heads down and run a thinner gasket, will i need to swap out my stock push rods?
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Old Jul 4, 2016 | 07:12 PM
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Well don't know how much your thinking of mill but .030 to .040 you'll fine.
Did you finish your harness.
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Old Jul 4, 2016 | 10:52 PM
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Thats a vague question to ask without listing other specs like the cam and how thin of a gasket will be used.Many have gotten away with milling .030 on a stock gasket and still run stock length pushrod but im sure if yo use a pushrod length check you probably would need a shorter length.Just because most have gotten away with doing things doesnt mean its 100% correct way to get things done..and I include myself in playing the assumption game matching parts based on things I read online and not physically measure them..sometimes it will bite you.Most vendors will tell you to measure..regardless how many times they sell common parts when it comes to selecting a pushrod..any vendor is asked stated that a stock length with a particular cam/head combo was ok with 7.4 rods but for a optimized setup..measure the length and order accordingly...if the stock length tends to be a tad too long..dont complain later you didnt measure the first time!
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Old Jul 5, 2016 | 06:21 AM
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Originally Posted by omc8
Well don't know how much your thinking of mill but .030 to .040 you'll fine.
Did you finish your harness.
Got most of the harness cleaned up. Won't get it 100% done until i get the motor in and final location for the PCM set.
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Old Jul 5, 2016 | 06:23 AM
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Originally Posted by Redbull87
Thats a vague question to ask without listing other specs like the cam and how thin of a gasket will be used.Many have gotten away with milling .030 on a stock gasket and still run stock length pushrod but im sure if yo use a pushrod length check you probably would need a shorter length.Just because most have gotten away with doing things doesnt mean its 100% correct way to get things done..and I include myself in playing the assumption game matching parts based on things I read online and not physically measure them..sometimes it will bite you.Most vendors will tell you to measure..regardless how many times they sell common parts when it comes to selecting a pushrod..any vendor is asked stated that a stock length with a particular cam/head combo was ok with 7.4 rods but for a optimized setup..measure the length and order accordingly...if the stock length tends to be a tad too long..dont complain later you didnt measure the first time!
Stock cam, no parts changes just yet. Just going from old iron heads to 317s. Figured since they were off, i could mill them down .030.
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Old Jul 5, 2016 | 11:17 AM
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What gasket are you thinking ? So you have a early 99- 00 LQ4 what tranny are running behind that ? Have you heard the engine run yet ? A mill of .030 should net you a cc of approx. 67 cc , nice little bump in cr and a weight savings advantage to top.
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Old Jul 5, 2016 | 01:22 PM
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Originally Posted by omc8
What gasket are you thinking ? So you have a early 99- 00 LQ4 what tranny are running behind that ? Have you heard the engine run yet ? A mill of .030 should net you a cc of approx. 67 cc , nice little bump in cr and a weight savings advantage to top.
It's from a 2000 GMC 2500, I heard it run and helped pull it out. I am having a 4L80E rebuilt to put behind it. Should be a fun cruiser!
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Old Jul 5, 2016 | 09:10 PM
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Stock cam with stock gasket you "should" be fine with milled 317 heads which is a healthy bump up in compression.If you go thinner than stock gasket and have a target c/r your trying to achieve..measure for proper pushrods.They are cheap for hardened rods and peace of mind.We are talking $100 vs damaging valves,pistons etc.And keep in mind the stock pushrods are known to bend easy..Id opt for hardened replacements anyway.
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