Thread: help me out please
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10-25-2010 10:30 PM #4
I don't know what you mean by "big valves", but it's not just the valves that make the head, it's also the runner sizes and shapes. The intake runners in those 305 heads were designed to feed 305 cubic inches up to around 5000 rpm's max so that granny could use the motor to drive to and from Bingo. They will be at a severe disadvantage trying to feed 350 cubic inches to anywhere near 5000 rpm's. I'll try to put this delicately....toss those turds over the fence and get some heads that'll work.
Static compression ratio would be around 11.0:1 and you'd have to use a race cam to keep the motor from detonating on pump gas. The race cam would require a minimum 4000 stall torque converter and 4.10-4.30 gears in the differential. You would make no power under 3500 because the intake valve would be closing so late that you would capture insufficient fuel/air mixture to make any power (with the intake valve still open, the piston coming up the bore would push the mixture back up the intake tract and out the carburetor) and you would have no power over 4500 because the heads would stall due to the small runners. Are you beginning to see the futility of using those fosdick heads on a 350? I'm painting a grim picture on purpose so that you will not try to use them and be disappointed.
If this is a small main journal 327 block, the 283 crank will work in it, making a 302. The problem will be finding affordable 4.000" pistons that have the proper 1.800" compression height. You would also need small journal connecting rods to bolt onto the 283 crankpins.
You can't just pick a cam off the shelf without knowing the static compression ratio of the motor. All the parts that go into a build have to be built to a "combination" of parts that work together in symphony with each other.
I don't mean to sound harsh, but you have a lot of learning to do. I suggest that you begin by reading everything you can regarding engine combinations and how they work together. There is a ton of information on the internet and it's free.
Here are some titles I would suggest for you to get started on....
Cylinder head intake runner volume
Cylinder head exhaust runner volume
Cylinder head flow
Cylinder head flow bench
Static compression ratio
Dynamic compression ratio
Piston compression height
Cylinder block deck height
Piston deck height
Squish
Quench
As you wade through some of these, other areas of interest will reveal themselves to you and you'll expand your searches....Good Luck.





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Right after I posted yesterday it was down again, I don't think it's getting better.
Where is everybody?