Model B intake port porting?

[OHV DeLuxe]

I finally got my block back from machining, what a treat! But i realized that the intake ports on the side of the block is much smaller than the intake i want to use. How much can i open up the Model B (actually a G28T) intakeports without breaking into a waterjacket? Any experiences? is 1 3/4 possible?
Thanks.

 

[Chris in CT]

OHV, Be careful with the B block, the wall thicknesses are sometimes thinner than they were with the A block, and cracks between the valve cavities are notorius. Are you using a cam so hot that the port sizes are the restrictive factor? If the engine can't breathe at the valve openings, increasing the size of the ports is not going to help. Good Luck with your project!

 

[BRENT in 10-uh-C]

While what Chris is saying has merit, as another owner of a G28 I can attest to things being a little different than that of a 'B'. Bill Stipe (Click on his name) is one that has done quite a bit of work in this area is very versed however I think if you look inside the water passages from the deck surface, you will be able to see the port's exterior. Use some Dykem and layout the size port you are seeking on the side and then compare if you have enough material to pull it off.

BTW, most of large aluminum manifolds that you find with big ports and no boss for a throttle bellcrank were actually manufactured for an OHV and not a flathead for the very reason you are working on.