56 Chevrolet 3 Bolt Heat Riser?

[Gary C.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

Mark,

3725981 was the 2 bolt 1956 exhaust manifold heat riser. It was discontinued 7/1/56

Gary
....

[Joe L.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

I looked up the 3731396 in the GM Parts Books and it comes up for a 56 Corvette only. This would be the one with "TOP on it. The one that I have pictured has "UP" on it, so I am guessing that it might have been used in late 56 Chevrolet passenger cars or early 57s before the donut was used. This has been a tough puzzle to solve.

[David B.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

The 2nd design 3 bolt heat riser #3731596 was originally designed late '55 early '56 for use with exhaust manifolds cast 3731557 & 3731558. These manifolds had larger ports and were installed on the passenger car 240 HP "GT" motors used to "juice up" Chevrolet's efforts at '56 Daytona Speedweek" . Several of these "GT" engines were also used on the Corvettes at Sebring. Later 240 HP engines designated "GU" were installed in production Corvettes. The flat 3 bolt heat riser & exhaust manifolds were redesigned for '57 production. If I had to guess I think Mark's 3 bolt heat riser marked "UP" is a later service part.

[Mark S.]

Re: 56 Chevrolet 3 Bolt Heat Riser?

Thanks David! This adds a bit more information to my puzzle!