Filler Neck Rule

[SpdRcr]

Page 50 of the rules states filler neck must be :

"a) atleast 38 mm (1.5 inches) in diameter. "


Now I am assuming this means inner diameter (according to the sketch in the rules), but can my I.D. be exactly 1.5 inches? Or does it have to be 1.51 inches or bigger? Thanks.

[SpdRcr]

Page 50 of the rules states filler neck must be :

"a) atleast 38 mm (1.5 inches) in diameter. "


Now I am assuming this means inner diameter (according to the sketch in the rules), but can my I.D. be exactly 1.5 inches? Or does it have to be 1.51 inches or bigger? Thanks.

[Bill Kunst]

It can be 1.5 exactly. They have been nice in the past and let 1.5" o.d. through tech. As I look at the rules, it could be interpretted that it is O.D. Rules are a funny thing as there always is some room for interpretation, many of the reasons for rule changes over the years. Good example: Two years ago no fuel system parts could be in a direct line of sight with any exposed portion of the driver. UW-P had a high mount radiator that was in direct line of sight. UW-P almost wasn't allowed to compete because of this, even though cooling system components were never listed in this rule. As a result of this interprtable rule, it was spelled out better in subsequent years that cooling system be included.

I would go by the O.D. as the drawings show it that way. If they want to change that in the future to I.D., they will state it, as for now maybe you could go to the rules forum and ask that they state I.D. or O.D.

Good luck,
Bill

[SpdRcr]

Thank you for the input Bill.

[Blake_DFSAE]

This seems like one of the rules that there's no need to bend. Who cares whether it's inner or outer, just use it as the inner number to be safe. No need to fail tech due to something stupid.

[SpdRcr]

Agreed, but it is still beneficial to clarify a rule if you are unsure.