Gettin a-head - The 1947 - Present Chevrolet & GMC Truck Message Board Network

petemonster · 10-25-2006, 05:21 PM

Hey kids,
I' new here. I have a question about a 250 inline six.
A friend of mine wants to hop up the 250 in his truck.Does anyone know of a good site on building these engines?
I heard something about using Olds rods and pistons.
Most importantly however,I would like to know about the cylinder head.
My question on that is,what is the wall thickness in the ports?The head uses chevy 1 3/4 small intake valves ,and I was wondering if there is enough meat there to straightbore the valve pockets to accept 1 15/16 large valves...........I do this all the time on small valve 624 and 882 V8 castings and use 3/8 stem 1 1/2 exhaust valves.
Or would it be better to do maybe say a 70 degree taperbore and install new valve seats?

**Captkaos** · 10-25-2006, 06:23 PM

I can only recommend getting the book on the Chevy inlines. It has some info you may be looking for.
As for performance, talk to these guys:
http://www.sissellsautomotive.com/

C&C Chevy · 10-25-2006, 07:14 PM

Honestly? I'd get a $1300 350 crate engine and be done with it..

68Stepbed · 10-25-2006, 08:36 PM

www.cliffordperformance.net has alot of performance 6-cylinder parts and modification info.

PM Sent.

petemonster · 10-26-2006, 05:32 PM

Quote:

Originally Posted by C&C Chevy

Honestly? I'd get a $1300 350 crate engine and be done with it..

Well ,we work at an engine shop, so most of it will be free..maybe $100 for parts, so that's prolly why he wants to screw around with it.I personally don't care to me it's another valve job ,and we kinda work on the you do I do system,so if I ever need anything done........I've just never done that to a six b4.
Thanx for the info tho guys hopefully I can find somethin around... otherwise I'm just gonna chop and watch the look on his face when I hit the water jacket lol.

10-25-2006, 05:21 PM	#1
petemonster Registered User Join Date: Oct 2006 Location: minnesota Posts: 5	Gettin a-head Hey kids, I' new here. I have a question about a 250 inline six. A friend of mine wants to hop up the 250 in his truck.Does anyone know of a good site on building these engines? I heard something about using Olds rods and pistons. Most importantly however,I would like to know about the cylinder head. My question on that is,what is the wall thickness in the ports?The head uses chevy 1 3/4 small intake valves ,and I was wondering if there is enough meat there to straightbore the valve pockets to accept 1 15/16 large valves...........I do this all the time on small valve 624 and 882 V8 castings and use 3/8 stem 1 1/2 exhaust valves. Or would it be better to do maybe say a 70 degree taperbore and install new valve seats?

10-25-2006, 06:23 PM	#2
Captkaos www.73-87chevytrucks.com Join Date: Dec 1999 Location: Birmingham, AL Posts: 6,935	Re: Gettin a-head I can only recommend getting the book on the Chevy inlines. It has some info you may be looking for. As for performance, talk to these guys: http://www.sissellsautomotive.com/ __________________ Chris Lucas 1973 Chevy C-10 1978 GMC Jimmy (2WD) - SOLD 1987 R10 twin turbo LS 1991 R3500 SRW CrewCab 1985 K5 diesel swapped project 1989 K5 2WD conversion w/ Vette susp Project Captkaos Customs 73-87chevytrucks.com

10-25-2006, 07:14 PM	#3
C&C Chevy Registered User Join Date: Feb 2003 Location: Midwest City, OK Posts: 1,001	Re: Gettin a-head Honestly? I'd get a $1300 350 crate engine and be done with it.. __________________ Robert Current: 1986 SWB Silverado 4.3 / TH400 Past: 1985 SWB Silverado 305 / TH350 - sold 1995 1987 1/2 ton Silverado - FI 350 / 700R4 sold 2007

10-25-2006, 08:36 PM	#4
68Stepbed Registered User Join Date: Mar 2005 Location: 10-Uh-See Posts: 5,609	Re: Gettin a-head www.cliffordperformance.net has alot of performance 6-cylinder parts and modification info. PM Sent. __________________ Matt 68 C10 stepside, LS1/700R4, TCI Engineering suspension system



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