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01-13-2003, 12:48 AM
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#1 |
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Senior Member
 
Join Date: Apr 2001
Location: Alexandria, MN
Posts: 1,462
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250 cyl head????
welll i decided to pul my head off today after seein some moisture in my oil, and since my head gasket looked good i was gonna bring the head up to my machinist and have them go over it.... so my question is... if i leave the lower end as it is (its a 74 250), how much can i mill the head to get bout 9-9.5:1 compression, up from the stock 8.0???? figure as long as im there may as well do it... might help effeciancy and milage a little bit.... thanks in advance..
--mike
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63 C20 2WD, 230/SM420/4.11 73K 68 C30 dump truck, 327,SM425,4.56 66K original 68 C10 2WD SWB Stepper, 250/3-tree/3.73 66K.... Wifes 68 Buick Skylark Custom Conv., 350/TH400/2.56 In our family since '79 69 GMC 1500 SWB 2WD, 350/TH350/3.73 posi... 70 K10 SWB 4X4 4-sp,ps, pb, tilt, buckets, console, sliding back window (Need AC parts) WIP 72 Chevy K20 4x4 350/350/205/4.56 donor 72 Vette 350/M21/3.70 posi, triple black and super fast 84 Olds Cutlass Brougham 350/2004r/4.11 was Dad's |
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09-24-2024, 09:26 AM
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#2 |
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Registered User
Join Date: Aug 2020
Location: Charlotte
Posts: 53
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Re: 250 cyl head????
It's 2024 and I am in the same predicament.. Anybody out there know an answer?
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09-24-2024, 09:40 AM
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#3 |
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Registered User
Join Date: Mar 2022
Location: Surrey BC
Posts: 874
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Re: 250 cyl head????
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09-24-2024, 09:55 AM
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#4 |
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Registered User
Join Date: Dec 2012
Location: Temple City
Posts: 3,623
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Re: 250 cyl head????
Becareful how much you mill.
You may end up needing new push rods to go with it. |
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09-24-2024, 10:24 AM
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#5 |
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Senior Member
Join Date: Mar 2019
Location: Herculaneum MO (20 minutes south of St. Louis
Posts: 641
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Re: 250 cyl head????
You will never get to that compression ratio with the stock pistons.
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67 C10 283 T5 swapped longbed fleetside = wife's daily driver 67 C20 292 (originally a 250)4speed longbed fleetside w/original wooden bed=my project truck 67 C10 283+.060 (so a 292 as well)T5 swapped longbed fleetside=my DD 72 C1500 Sierra Grande 350 TH350 longbed fleetside=wife's fair weather truck Can you tell we are fans of longbed fleetsides & 67s Chris |
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09-24-2024, 02:07 PM
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#6 |
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Registered User
Join Date: May 2011
Location: Anderson SC
Posts: 3,896
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Re: 250 cyl head????
To figure out how much to mill to get a certain chamber volume, use a graduated cylinder to measure out that many cc of water (add a drop of dish soap), level the head, add that water to the chamber, then measure down to the water level.
Not sure, but there might be thinner head gaskets available that would also help bump the compression up. If you can find them, flat top 307 pistons work great to bring compression up.
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