Basic rebuild 440 with steel crank and speed pro flat top pistons. ARP rod bolts and main studs. Mopar Performance 528 mechanical cam with crane rockers and lash caps. Iron stock heads with 2.14 intake and 1.81 exhaust valves with felpro blue gasket. Should be about 8.8 to 1 compression.
Motor was assembled and broke in before the blower was installed, Mobil One oil with a premium type filter. Testing before the blower at LV Raceway produced a 13.58 at 103.71 mph with tire spin in first and into second.
6-71 Hampton Blower Setup
Complete Don Hampton Blower set up with a 1:1 ratio. Found it had a death rattle with too much boost? Tried locking the timing. Welded up a dist. for NO advanced and set it for 25° total timing. Boost would jump right to 10 pounds and still rattle the engine even at part throttle.
Changed pulleys and dropped the blower down to 12% under driven. No more rattle and a solid 6 pounds of boost. Was only able to fit a small fan in front of the blower, so hopefully this summer cooling will not be a problem.
The addition of the blower dramatically changed the sound of the exhaust to a loud roar. This is not even taking in account the new whine coming from under the hood.
Two 750 Holley Carbs
Tuning the carbs turned out to be interesting with the blower. First I set them rich and tried them out. Found out fast that they were not doing their job. A lean out back fire and death rattle from the motor under boost is a fast way to destroy a motor.
So , I bought a lean-rich gauge and found it was way lean at part throttle. After doing some reading, I changed the carbs over to manifold reference vacuum by blocking the power valve air vacuum port and re drilling for a side fitting. Now a line runs down to the base of the blower for power valve vacuum. It now gets a true engine reading and opens and keeps the power valves open at part throttle.
Next I drilled the PVR [power valve restriction] out for a richer mix. Started with .063 holes now up to a .073 holes and using a 8.5 power valve. The engine now stays rich at all times and throttle positions.
Right now I have 73 jets with # 28 50cc shooter in the primaries. In the secondaries are 94 jets with a 30cc pump with a # 32 shooter. Most of this was done late fall with colder temps so once warmer weather gets here this may need to be leaned out a little.