Greg

Y'know, I've probably had 20 or 30 copies of the Corvette Black Book over the years and never noticed this bit of info before. In the 1953-2007 Edition, at the rear of the book where they show pictures and list the specs for each year, they list the 1970 as having a 20 gallon fuel tank, (just like all other Corvettes back to 1963), except California which had a 17 gallon fuel tank for 1970. No other years show this difference. Now I'm curious why and if anyone else has noticed this or can confirm it? I can't think of any emission related equipment that would account for the one year difference.

Alan 71

Hi Greg,
Did the difference in capacity have something to do with the ECS (Evaporative Control System) that 70 cars being delivered in California had and ALL cars had beginning in 1971?

I believe it was the same tank but the ECS sealed tank couldn't be filled as far as the vented tanks could.

The capacity for gas tanks was given as 18 gallons in 1971, they all had ECS and were sealed systems.
Regards,
Alan

Greg

Alan, you could be on to something there. I can't think of any other reason.
Greg

Iceaxe

70-72 Corvettes all use the same 18 gallon fuel tank. The 1970 49 state cars did not have the evap canister, but they do have the vent valve, which just vented to the atmosphere. Why the black book lists anything else I have no clue.

Dirty Dalton

Given my ancient and infirm state of mind, I may well be misremembering, or maybe remembering alternate facts... I seem to recollect that the 'filler' was extended down into the tank, which would, effectively reduce its capacity, tho the tank would remain the same size.

Alan 71

Hi axe,
What are you referring to as the 'vent valve'?
Regards,
Alan

kenba

I thought liquid reached its own level. How high it is in the filler neck would be at least as high as in the tank unless the tank is full.

See Three

While that is true it is probably not realistic to think that people could pump gas into a small filler neck once the level reaches it and expect the tank level to equalize before the filler neck over-flowed.

Iceaxe

I believe the official name is vapor seperator, which was mounted on the LH side of the tank. The 1970 49 state vettes have no hoses attached to the seperator. It just vents to the atmosphere.

Alan 71

Hi axe,
I asked because I thought perhaps you referring to the 'button' relief valve which both non-EEC and EEC tanks have.
70 non-EEC tanks do not have the nipples or brackets for the vapor separator.
Regards,
Alan

lynnbilodeau

I realize this post is a few months old. Just wanted to point out that not ALL of the 1970 gas tanks have a vent valve on top. I have the original gas tank out of my newly acquired LT-1, and it does not have a vent tube vented to atmosphere. It does have a small overflow tube vented to atmosphere, but it is outside the tank, in the filler neck rubber. I believe the other 350 engines have the vent tube in the gas tank. Mine does not.
Was looking at tanks as mine is rusty on the outside, but clean as a whistle on the inside. I have not yet found one without the vent pipe. Perhaps one made for an earlier year would work?