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LM7 Turbo Guys: Talk to me about 10:1, slight mill, thinner headgaskets

Old 08-20-2015, 05:16 PM
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Default LM7 Turbo Guys: Talk to me about 10:1, slight mill, thinner headgaskets

So I've got a bone stock LM7 motor and the heads are coming tomorrow off for lifters and cam in preparation for the turbo. I plan to have a valve job and guides done on them at the same time, but I'm wondering about doing a mill or using a thinner headgasket to bring compression up to 10:1. Has anyone done this and what was your method?
Old 08-20-2015, 05:30 PM
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Can't do it with a headgasket, you'd need to mill the heads a lot to make a .5 compression increase unless you had 863's. What head do you have on it now?
Old 08-20-2015, 05:32 PM
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Heads are 862's. A .041" thick gasket will drop the compression quite a bit no?
Old 08-20-2015, 07:29 PM
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stick to 9.5
Old 08-20-2015, 07:39 PM
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Originally Posted by George C....
stick to 9.5
Truck will be run on 100% E85 and I was thinking a half point of compression will help with low end torque.
Old 08-20-2015, 07:41 PM
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not as much as you think it will in that case, choose a different cam to bring torque in

unless you have a good tuner
Old 08-21-2015, 12:53 AM
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Originally Posted by George C....
not as much as you think it will in that case, choose a different cam to bring torque in

unless you have a good tuner
I will be running the Tick Stage 1 4.8 / 5.3 turbo cam which is advertised to help with low end, we'll see. Ok George I'll take your advice and have them do a basic surface and valve job on them. I'm sure they'll need guides at 145k as well.

What headgaskets should I run? I have LS9 gaskets but the bore size is way larger on the LS9 so I think there are more ideal gaskets out there. I also have 5.3 GM replacement gaskets (same as LS1 I believe).
Old 08-21-2015, 08:57 AM
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Ls9 gasket will do job...
Old 08-22-2015, 06:50 PM
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Usually the Powdered metal guides in these heads are ok.
Old 08-23-2015, 03:50 PM
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Originally Posted by 1FastBrick
Usually the Powdered metal guides in these heads are ok.
Even after 150k ?

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