55-56 & 57-60 17" 4-blade fans

[David L.]

Could someone tell me the difference between the 55-56 17" 4-blade fan (GM # 3704803) and the 57-60 17" 4-blade fan (GM # 3735314)?
Pictured on the left is a 17" 4-blade fan which I believe is either GM # 3704803 (55-56 Corvette) or GM # 3735314 (57-60 Corvette). The tips of this fan are straight, NOT curved. The 4 domed rivet heads are on the BACK side.

Pictured in the middle is a very common 57-62 Chevrolet w/V8 17 1/2" 4-blade fan (GM # 3739265) which I removerd from a 1958 Chrevrolet with "T1216D" (December 16, 1957) stamped on the 283 engine "pad". The tips on this fan are CURVED (see picture on right comparing the tips of each fan). The 4 domed rivet heads are on the FRONT side. I have at least 6 more of the fans.

The blade width on both fans pictured is 3 1/2" with the 5/8" hub hole and 1 3/4" bolt circle.

[Gary C.]

Re: 55-56 & 57-60 17" 4-blade fans

David, basically the fans are the same except the 57 fan has curved tips, which adds about 1/8" length to 17 1/8". 17 5/8" fan is passenger car fan and not 57 Corvette. Gary....

[Roy B.]

Re: 55-56 & 57-60 17" 4-blade fans

The 55-56 are stright

[David L.]

Re: 55-56 & 57-60 17" 4-blade fans

Gary,
Thanks for the information. It does seem very logical that the 57-60 Corvette fan and the 57-62 passenger fan both have curved tips. When I remeasured my 57-62 passenger fan it measured more like 17 5/8" tip to tip. Based on this I tend to think that my 17" fan is GM # 3704803 used on 55-56 Corvettes (8 cyl.) & 55-56 Passenger cars (exc. 8 cyl. w/C.A.C.).

Even though the 3735314 fan measures 17 1/8" tip to tip my 1957 Chevrolet parts catalog (March 1957) list the dia. as 17". I printed your shop drawing of the 3735314 fan (scaled to fit on a 8 1/2" by 11" sheet) but I can not read any of the print.

Dave

[David L.]

Re: 55-56 & 57-60 17" 4-blade fans

Roy,
Based on your pictures the domed head of the rivet appears to be on the back side of the fan just like my fan.
I guess I have a 55-56 fan.
Thanks,
Dave