Original 66-67 Corvette Choke Thermostat # 3869926 & Replacement #3887148

[David L.]

Attached is a photo of an original 3869926 choke thermostat and NOS 3887148 replacement. The 3869926 was taken off a 1966 Corvette intake manifold with casting "3872783". The 3869926 choke thermostat is stamped "9938" on the coil while the NOS 3887148 choke thermostat is stamped "7149". There is also a slight difference in the frames. I would assume that the difference coils have slightly difference expansion rates. I would appreciate any comments.
Dave

[Leif A.]

Re: Original 66-67 Corvette Choke Thermostat # 3869926 & Replacement #3887148

David,
The original choke spring you took off is for a 300hp engine. The second one you reference is for a 350hp engine. The part numbers for the 350hp are reflected in the picture you posted...right next to the red highlighted area. I'm betting that the springs do have different heat registers based on a cast iron intake vs a cast aluminum one.

[David L.]

Re: Original 66-67 Corvette Choke Thermostat # 3869926 & Replacement #3887148

David,
The original choke spring you took off is for a 300hp engine. The second one you reference is for a 350hp engine. The part numbers for the 350hp are reflected in the picture you posted...right next to the red highlighted area. I'm betting that the springs do have different heat registers based on a cast iron intake vs a cast aluminum one.

Leif,
I know that the 3887148 choke thermostat was original equipment on 66-67 Corvettes w/Sp./H/Per., however, I forgot that the intake manifold was aluminum. The 3887148 choke thermostat is also original equipment on the 1970 Z28 which also has an aluminum intake manifold.

The 3887109 choke thermostat (also stamped "9938" on the coil like the 3869926 choke thermostat, see photos below as this choke opens in the opposite direction) was original equipment on the 1966 Chevelle 327 (275 HP) engines which came with either a cast iron intake for a Rochester carburetor or a cast iron intake for a Holley carburetor.

I believe that you correct about the two different choke thermostats as heat transfer does differ from the cast iron intake compared to the aluminum intake.

The two choke thermostats also differ slightly on the top of the frame on the right side as shown in my first photo in my first post. The 3869926 choke thermostat has a "hook" pointed downward while on the 3887148 choke thermostat it is "straight".
Dave