Quote:
Originally Posted by Jay S
He state he checked the cam timing and it was running 107* to 108*. That was also confirmed when it pumped 190 lbs compression. There should be no reason to advance if more than that, especially with a 2800 stall.
With how it is set up, it should not be a dog at the 2800 stall converter with the low first gear in a 200R4, it should roast the tires. If it can’t do that, it probably is pretty unimpressive up top too. I can’t say what that the issue is, whether it is an issue in the season short block or something else. But overall, I really don’t see the mix match of parts in this build.
.
|
I have to agree with just about all of this, there are tens of thousands of 350 SBC's running around with similar combo's with great low end performance.
The 350P has a basic flaw as compared to the SBC 4.00" bore, the 3.875 bore is small enough, and the factory valves are big enough, that valve shrouding is a significant issue. This shows up specifically as a loss of low end torque.
I'm dealing with this right now with a 350P I'm building.
The stock 350P block (usually) has eyebrows cut into the top of the cylinder to try and help with this. However, the factory eyebrows are not really suited for high lift cams, as you are severely restricted in valve lift due to the potential for the valve to hit the block. And if the lift is small enough to clear the block (say .490"-.510" max) shrouding comes into play- which hurts low end torque. Note the exhaust valve block clearance is much worse than the intake valve clearance.
The 350P I am working on has about .600" exhaust valve lift. I made a fixture to mount a Goodson grinding wheel above each cylinder to dress the block eyebrows. I 3D printed parts of it and machined other parts. It's driven by a handheld drill.
I put a 3D printed plug with O-rings in each cylinder to prevent any grinding dust from going into the ring pack. The plug presses all the down to the bottom of the cylinder on top of the piston, with the eyebrow dressing taking place above it.
On the subject of valve shrouding on a 0.030 oversize bore 350P from ChatGPT:
