cylinder planing max spec

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rpatton

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I have a cylinder head that is warped and having it reserfaced. Can anyone tell me what the max i can take off without getting in trouble. The motor in a 1984 mercruiser 120
 
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Re: cylinder planing max spec

rpatton said:
I have a cylinder head that is warped and having it reserfaced. Can anyone tell me what the max i can take off without getting in trouble. The motor in a 1984 mercruiser 120
Click to expand...

Ayuh,.... Yer Machinist will know,... I'd guess .010", maybe .020"....
 
RogersJetboat454

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Re: cylinder planing max spec

All depends on what he's starting with too.
If the cylinder head has already been through the mill, less material is available to be removed. As Bond-o said, the machinist should be able to measure it, and tell you whats up.
 
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rpatton

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Re: cylinder planing max spec

thanks guys' i was just reading in the library in the adult section that .10 was max and i think im going to be right at that spec. my machinest is a performance atuo guy ' not sure how much he knows about boat motors even though a head is a head. just want to be sure i dont take to much off and crack it or hit a valve after i put it back together
 
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rpatton

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Re: cylinder planing max spec

OK guys now im confused . i looked in the library for the torque of the head bolts and found everything else but that. i have a clymer book but i do not trust it for stuff like this . the book says 93 ft pounds which i think sound light. i researched the site and all i found was the 470 and that torque is 130 ft pounds . i asked my machinest and he thought it should be 120 ft pounds. do i trust the book or can someone tell me exactly what it should be. thanks
 
RogersJetboat454

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Re: cylinder planing max spec

Per Mercruiser service manual number 3, for the GM 4 and inline 6, listed torque for head bolts is 93 foot pounds with a 20 hour re-torque recommended.

You can't compare apples to oranges. The 470 is a COMPLETELY different engine.

This is a link to the factory service manual for your engine;
Boatinfo - Mercruiser Service Manual nr. 3 - 1978-1984 - All 4 cylinders, L6 & V8 Engines

Page 649 has torque specs, and page 663 gives the procedure for removing and installing the head.
 
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rpatton

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Re: cylinder planing max spec

Thanks guys i guess im blind cause i looked in that section
 
RogersJetboat454

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Re: cylinder planing max spec

rpatton said:
thanks guys' i was just reading in the library in the adult section that .10 was max and i think im going to be right at that spec. my machinest is a performance atuo guy ' not sure how much he knows about boat motors even though a head is a head. just want to be sure i dont take to much off and crack it or hit a valve after i put it back together
Click to expand...

What's the thickest feeler gauge you can fit under your strait edge?
Machinist will most likely check to see what the lowest spot is, add a couple more thousands to that when cutting the head.

I seriously doubt with .010 shaved off you're gunna be smacking pistons with the valves. You're not exactly running a tight spec performance engine.
 
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RogersJetboat454

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Re: cylinder planing max spec

rpatton said:
Im right at 10 heavy
Click to expand...

Have him confirm, and see what he thinks. If he has to cut .010 off, he has to cut .010 off. There is typically a bit of wiggle room for low spots (if cutting .010 doesn't get it all). Worst case, gunna have to find another head.
 
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rpatton

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Re: cylinder planing max spec

Do think i have to worry about valves and crack if , say he need to take 11 off
 
RogersJetboat454

RogersJetboat454

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Re: cylinder planing max spec

rpatton said:
Do think i have to worry about valves and crack if , say he need to take 11 off
Click to expand...

I won't tell GM or Mercruiser if you take it to .011... :D;)
.001 over spec is someones milling machine with a quarter of a human hair between one of the cutters. I wouldn't sweat it....

Your not running a 0 decked engine, with a paper thin head gasket, domed pistons, and a high lift cam. The valves should be fine.
 
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rpatton

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Re: cylinder planing max spec

Kinda what i thought and that is what my shop is telling me to.
 
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