Today I started checking engine parts again in readiness for assembly and found a slight difference between the 2 distributors I have. The 1 that came with the truck (38) has a tag Delco Remy Canada 649G and the vacuum advance unit has a thumb nut adjustable base, the other (39) has not had a tag fitted and has a oil hole the I doubt oil would get to and the vacuum advance unit doesnt have the adjustment parts. I am using new timing gears that were advertised as 40 and up but (I think it was Gene suggested) give better performance. As I stated 1 is a 38 and 1 is 39 and both seem to work as they should, is there a prefered 1 to use or is it a flip the coin issue???? Tony
The only difference in the 1938 and 1939 US distributors in the vacuum advance. I don't understand the oil hole, have never seen that. The 1937 is the same except for the housing as the 1938 had a flat side where it went into the block for better oil return.
The thumb wheel vac. adv. is a nice feature because you dont need a wrench. Can not be used on a '39 block due to lack of bolt holes.
Attached is a picture of some of my distributors. Most are 1938 with the thumbscrews and are Canadian. Not sure about an oil hole? but I haven't looked that closely.
1938 Canadian Pontiac Business Coupe (aka a 1938 Chevy Coupe with Pontiac shaped front sheet metal - almost all Chevy!) 1975 4-speed L82 Vette
Tim and Gene Looks like I will need to look closer at the mounting to decide. In Tim's photo the distributor on top (and separate vac unit at its base) looks like the 1 that came with the truck the cleaner distributor without cap on the right looks like the 39 but mine never had a tag on it (no rivet holes). Both have the flat face on the mounting area and the 39 has the hole at the top of the flat. I thought the hole was to collect oil splash off the cam but it is on the wrong side and in the mounting bracket so not much oil would get to it. Tony
The "early" distributor had the little plate riveted to the side with the advance adjustment with 2 bolt holes on the mounting plate and only 1 bolt hole in the block casting while the later distributor didnt have the adjustment mechanism and only 1 mounting hole on distributor mount and block but both distributors would bolt to either block with 1 bolt. I may well have to relearn the camera and how to post on here to explain. Tony
Have me scratching my head. Gonna have to dig out my distributors and have a look as my block has 2 bolt holes. I took it apart but can't remember how it mounted. My block is an odd Canadian McKinnon Industries casting from Dec 1937 so might be slightly different than a later dated casting from one of the more common foundries.
Is your casting # Canadian Tony? They are different from the US and I recall some overlap around 1938/39 with some Canadian 1937 (going from memory) casting numbers looking like US 1939 casting#'s.
Last edited by canadiantim; 02/20/1810:39 PM.
1938 Canadian Pontiac Business Coupe (aka a 1938 Chevy Coupe with Pontiac shaped front sheet metal - almost all Chevy!) 1975 4-speed L82 Vette
The blocks have different numbers cast in them, the late block (which is the 1 I am rebuilding) has date code D 11 9 but due to its position I have not found date cast on the early block. They both look to be the same in the distributor area. I will get the camera going friday and try posting then. I am not looking for a factory rebuild but dont want it to big hassle either. Tony
For Us blocks the engine number was just behid the fuel pump like previous models amd in 1938 was on the ledge behind the distrbutor. In 1939 the distributor hardware has only one bolt and is is also used the advance/retard the timing when loosened. The 1937 and 1938 has two bolts to hold down the vacuum advance bracket, one to the front and one to the rear of the opening for the bottom of the distributor housing.