251 Valves

[No Bux Rod]

Does anyone know the diameter of the intake and exhaust valves used in the 237, 251, 265 flathead motors? Are the ports any larger than the 230?

Thanks,

N B R

[Plymouthy Adams]

could not find that data in either of my motors books.

[Don Coatney]

I sent No Bux Rod here from another forum in hopes that he could get his questions answered. I did not measure my valves and ports when I had my engine apart. I know some of you guys have your engines apart.

[PatS....]

I just put the head on my 251 industrial on Monday, but I can dig out the old 251 engine and measure the valves. Might take a day or two.

[Phill Powell]

1.5" ex. & 1.9 in. valves & port size is about 1.5".

Some small block chev valves fit. This is off the top of my head & may vary fractionally engine to engine. Hope this helps.

[No Bux Rod]

Phil,

Thanks for the info. It looks like the extra effort of using the 25" long engine will pay off with 1.9" intake vs. the 230s 1.53"

By the way which Chevy valves do you use? 350 or other??

Thanks,

N B R

[martybose]

Phil,

Thanks for the info. It looks like the extra effort of using the 25" long engine will pay off with 1.9" intake vs. the 230s 1.53"

By the way which Chevy valves do you use? 350 or other??

In my bored out 230 I used cut down 350 Chebby exhaust valves in all positions. They were cut down to basically stock valve diameters.

Marty

[Phill Powell]

N B R,

I'm honestly not sure which Chev valves fit, I know several who have used them but never bothered to find out exactly as I've never had any trouble getting factory replacements which are of a high quality. Also I should say that the valve/port sizes I stated have only applied to 251 & 265 engines.

My experience is the 237 motors had valve/port sizes similar to 218/230 motors.

[james curl]

I used Chevrolet 235 I/6 stainless steel exhaust valves in all locations. You have to use chevy keepers with the valves.