250 rebuild bore 40 over questions/ - The 1947 - Present Chevrolet & GMC Truck Message Board Network

81square · 03-30-2017, 01:49 PM

I have a 1981 k10 that I'm planning to rebuild this summer just because its rather wore out and is very slow, (which I know is normal for these engines). I have the 250 with integrated heads (I'm pretty sure its the integrated head), and I want to bore it out 40 over. Will I have problems with overheating or will there still be enough cylinder wall left? Also and input about a good mild cam upgrade for a little more performance would be helpful as well. Thank you! My other option is to put a 327 block in it I have lying around, but I want to just rebuild the 250 to save money.

**Warrens69GMC** · 03-30-2017, 02:21 PM

A .040 or 40 over 250 is 254 cubic inches. A 250 will cost MORE than a 350 or 327 for comparable hp and torque. You can use 307 chevy pistons in the 250 to get more compression and you can get an non-integrated head for a 4 barrel or 2 barrel carb option.

With a nice cam, headers , 4 barrel and 307 pistons it will wake up the 250

Speeding Dakota · 03-30-2017, 07:14 PM

Check out Clifford for 250 upgrades http://www.cliffordperformance.net/home.html
I wanted to do a inline 6 for my truck and found any upgrade will cost as much if not more than a SBC. So needless to say I have a SBC

03-30-2017, 01:49 PM	#1
81square Registered User Join Date: Dec 2016 Location: Yucca Valley California Posts: 28	250 rebuild bore 40 over questions/ I have a 1981 k10 that I'm planning to rebuild this summer just because its rather wore out and is very slow, (which I know is normal for these engines). I have the 250 with integrated heads (I'm pretty sure its the integrated head), and I want to bore it out 40 over. Will I have problems with overheating or will there still be enough cylinder wall left? Also and input about a good mild cam upgrade for a little more performance would be helpful as well. Thank you! My other option is to put a 327 block in it I have lying around, but I want to just rebuild the 250 to save money. Attached Images Last edited by 81square; 03-30-2017 at 02:51 PM.

03-30-2017, 02:21 PM	#2
Warrens69GMC Registered User Join Date: Jan 2003 Location: Safford,AZ Posts: 3,625	Re: 250 rebuild bore 40 over questions/ A .040 or 40 over 250 is 254 cubic inches. A 250 will cost MORE than a 350 or 327 for comparable hp and torque. You can use 307 chevy pistons in the 250 to get more compression and you can get an non-integrated head for a 4 barrel or 2 barrel carb option. With a nice cam, headers , 4 barrel and 307 pistons it will wake up the 250 __________________ 1969 307, t350 1950 Chevy Wagon 1978 Big 10 1967 C10, 250,3-OTT

03-30-2017, 07:14 PM	#3
Speeding Dakota Registered User Join Date: Oct 2013 Location: Shrewsbury, PA Posts: 325	Re: 250 rebuild bore 40 over questions/ Check out Clifford for 250 upgrades http://www.cliffordperformance.net/home.html I wanted to do a inline 6 for my truck and found any upgrade will cost as much if not more than a SBC. So needless to say I have a SBC



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