I cannot count the number of times that I have recommended using high flowing aftermarket heads on a healthy SB400. It almost seems that some people just do not relate the displacement of a small block to that of a big block.
But, no matter how you slice it 400+ cubic inches is 400+ cubic inches, regardless of whether it is a SB or BB!!!!!!!!!!!!!!!! Consequently, it needs to breathe!!!!!!!!!!!! You wouldn't put mickymouse port/valves in a BB 396-427, so why do it on a SB?????????????? Makes no sense to me.
If you want max output on a SB400+, you really need something like World or Dart heads with 210-220cc ports and 2.05 or 2.08 intake valves! And guess what? YOU STILL END UP WITH THE BIGGEST VALVES THAT ARE STILL SMALLER VALVES IN A SB HEAD THAN THE SMALLEST VALVES THAT COME STOCK IN A BB HEAD!!!!!!!!!!!
Nominally, about the BIGGEST intake valve for a SB head is a 2.08, and the SMALLEST intake valve in a BB head is 2.19. The BIGGEST exhaust valve used in a SB head is 1.6, but yet the SMALLEST ex valve in a BB head is 1.72. Big block heads are well known for their superior breathing ability. Again, 400+ inches is 400+ inches, and to extract max performance from 400+ inches, it needs to be able to breathe! So, give your SB400 a head start!
But, no matter how you slice it 400+ cubic inches is 400+ cubic inches, regardless of whether it is a SB or BB!!!!!!!!!!!!!!!! Consequently, it needs to breathe!!!!!!!!!!!! You wouldn't put mickymouse port/valves in a BB 396-427, so why do it on a SB?????????????? Makes no sense to me.
If you want max output on a SB400+, you really need something like World or Dart heads with 210-220cc ports and 2.05 or 2.08 intake valves! And guess what? YOU STILL END UP WITH THE BIGGEST VALVES THAT ARE STILL SMALLER VALVES IN A SB HEAD THAN THE SMALLEST VALVES THAT COME STOCK IN A BB HEAD!!!!!!!!!!!
Nominally, about the BIGGEST intake valve for a SB head is a 2.08, and the SMALLEST intake valve in a BB head is 2.19. The BIGGEST exhaust valve used in a SB head is 1.6, but yet the SMALLEST ex valve in a BB head is 1.72. Big block heads are well known for their superior breathing ability. Again, 400+ inches is 400+ inches, and to extract max performance from 400+ inches, it needs to be able to breathe! So, give your SB400 a head start!
