replacement engine choices for a 37 plymouth?

[pipebomb]

 not sure if you are still looking but found this on CL today.   http://milwaukee.craigslist.org/pts/4331987550.html

[Tim Keith]

I prefer to stick with a flathead but...

 

If you mostly want a dependable motor the Jeep 2.5 four from a Dakota might be okay.  Its basically a four cylinder version of the Jeep 4.0 six.    These have good torque for their size, but definitely are not a performance motor.   The Jeep 4.0 is a good motor but the inline six is a bit lengthy to easily replace the flathead.

 

I know that few consider a four cylinder motor, but I have wondered how that might work in a relatively light car. The four option wouldn't get positive attention on cruise night, but the 2.5 Jeep should not have steering or exhaust clearance concerns.  The Jeep 2.5 uses a General Motors bell housing pattern, basically a replacement for the "Iron Duke" GM four, so that there are various transmissions options.

 

Some V6s might be a good option as well, if you find a wrecked donor vehicle you won't need much beyond a custom driveshaft and homemade mounts.   The 60 degree V6s should have less issues with clearance than a GM 4.3 or GM 3800.