73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 1976Scottsdale on December 03, 2005, 01:06:00 AM

Title: Building a 350 for next spring.
Post by: 1976Scottsdale on December 03, 2005, 01:06:00 AM
Okay, I have a 350 project beginning now.  The block is from a 1976 K20 truck.  The casting number is 3970010, the block is a 4 bolt main and bares the "010" and "020" casting marks in the timing cover area and bellhousing area behind the flywheel.  I was told that these stand for high tin and high nickel ranging from 10 and 20 percent to 1 and 2 percent.  The block is going to be bored to 0.030 over and bored to fit each piston.  The crank is a forged steel GM crank that is ground to 0.020 on the rods and mains.  The heads are going to be a rebuilt set of "601" casting 53cc heads with 1.94/1.50 valves.  I know little about these heads except that they were just rebuilt.  I removed them from their former engine because that engine is being rebuilt by me for someone else.  I will be sticking with a set of flat top pistons as I want to be able to run pump gas.  I will be using forged I beam rods.  I am not sure about what to do for timing, I may use a gear drive, but I do not know how loud they are.  I will not use the stock 350 timing cover, I will instead be using a 327/283 cover with the "Y" shape in the middle, may have to remove and reloacate the timing tab.  I will give it a 204/214 duration and 420/443 lift cam so that it runs smooth.  I will also run an Edelbrock Performer intake.  For ignition I will be running the HEI setup.  I will not be using any chrome at all.  Any further ideas or suggestions would be appreciated.

Title: Re: Building a 350 for next spring.
Post by: tornadotech on December 05, 2005, 07:28:00 AM
The "601" heads have 58cc chambers are were originally on a 305.  With flat-tops and a 350, they will raise your compression too much for the camshaft you are wanting to run which looks to be close to 10.25:1.  There is a lot depending factors which how far the piston is in the cylinder, how many valve reliefs the piston has and the head gasket thickness.  I would shot for a head chamber that will give you about 9:1 max and shoot for .040-.045 quench to control detonation.  I would also run a double-roller timing chain instead of a gear drive.  Will be money better spent.

Title: Re: Building a 350 for next spring.
Post by: 1976Scottsdale on December 05, 2005, 09:37:00 PM
I am stuck with the 601's as my old engine blew the heads.  Project just got moved up, what would you reccomend for a cam for the 601's with flat tops?  I wanted to get about a 9.5 to 11.0:1 comp ratio anyway.  I agree on the double roller set.  I like chains better than gears.  easy to work on.

Title: cams
Post by: ChevyGuy on December 06, 2005, 09:32:00 AM
I would call Comp Cams or a cam manufacturer. All you have to do is give them information of what you are looking for and the information on the motor like whats in it as heads, intake, pistons, etc. The compression ratio for street to have your motor still streetable with low octane gas would be better off 10.0:1 or lower. flat tops with four reliefs would probally work but you will also have to remember the cam you purchase that the lift isnt to great with the chamber on those heads that the valve can hit the top of the piston.

Title: Re: cams
Post by: H A REDNECK on December 13, 2005, 08:18:00 PM
I would find some other heads. the 305 heads will not be a good choice on a 350. the combustion chamber is smaller not only cc's but bore size, also not a good match for your 30 over 350.. 64 cc'c with flat top pistons will be 10:1 give or take a 1/4 point. Go to comp cams web site they have a question form you can fill out with your information [ truck weight, tire size,gear ratio etc.] fill it out and they will e-mail you a cam spec. suggestion card. good luck choose wisley.