69SportSatellite
Well-Known Member
I am curious about something and I am hoping someone here will be able to educate me.
I have three complete engines, a '67 440, a '68 383, and a '73 400. The 440 is in my car, original bone stock with the 915 non-HP heads - out of an Imperial and surprisingly it runs great on the poor 91 octane gasoline we have in CA.
The other two engines I acquired because like many of you I never know when I'll need something to use or swap. I bought them both recently "just in case" since they were complete carb to pan and remarkably inexpensive. If I ever have to replace the 440, I may go with a stroker build using the 383 or 400 block since the B engine (383) was the largest that came in my car ('69 Sport Satellite) from the factory. Many years ago I also bought a forged 440 crank which was checked and then machined to fit the B engine block.
If I have my stock bore diameters for the three engines correct, they range from 4.25" to 4.34". From looking at various stock / aftermarket cylinder heads and their respective combustion chambers, clearly the diameter of the chambers are smaller than the cylinder bores they sit atop. But, does it matter or create any inefficiency when the bore is larger? I assume not a lot, and piston design may compensate for this especially in a stock engine since the factory heads were engineered to work universally across the B/RB line.
I am not an engineer or skilled engine builder to be sure, but it seems to me that the more flat surface or "ceiling" over the cylinder bore/piston, the less efficient the air flow would be?
I have three complete engines, a '67 440, a '68 383, and a '73 400. The 440 is in my car, original bone stock with the 915 non-HP heads - out of an Imperial and surprisingly it runs great on the poor 91 octane gasoline we have in CA.
The other two engines I acquired because like many of you I never know when I'll need something to use or swap. I bought them both recently "just in case" since they were complete carb to pan and remarkably inexpensive. If I ever have to replace the 440, I may go with a stroker build using the 383 or 400 block since the B engine (383) was the largest that came in my car ('69 Sport Satellite) from the factory. Many years ago I also bought a forged 440 crank which was checked and then machined to fit the B engine block.
If I have my stock bore diameters for the three engines correct, they range from 4.25" to 4.34". From looking at various stock / aftermarket cylinder heads and their respective combustion chambers, clearly the diameter of the chambers are smaller than the cylinder bores they sit atop. But, does it matter or create any inefficiency when the bore is larger? I assume not a lot, and piston design may compensate for this especially in a stock engine since the factory heads were engineered to work universally across the B/RB line.
I am not an engineer or skilled engine builder to be sure, but it seems to me that the more flat surface or "ceiling" over the cylinder bore/piston, the less efficient the air flow would be?
