I have a flathead that I took out of a s**** 40 merc. Naturally, I've always ***umed it was a 40 merc block, but would like to know for sure. Can you tell me how to ID it? The heads are marked 81T-6049 (LH) and 6050(RH). From you previous posts, it sounds like those are 6.3 to 1 Truck heads. I have the engine in my 29 roadster now and can't see the bell housing. I'll have to pull the floorboards to see what's marked there. What should I look for?
I ain't Bruce (who else can compare?) but I've learned a lot from him, so I'm gonna comment. Somewhere in my search for flathead knowledge, I learned that a common opinion is that the pre-war Mercury 239 engines had a raised intake mounting surface that followed the intake mounting edge, as opposed to being flat across from deck to deck. I'm building a '42 Merc 99A and it has that feature, along with the "keystone" coolant p***ages in the deck. I ain't swearing this as gospel, but it seems to be a widely held opinion. Bob
The raised deck indicates a post 1940 motor, Ford and Merc. Most prewar Merc motors had 99 stamped into the p***enger side forward area between the intake and the block. I have a 39-40 motor that is missing this though so it isn't 100% rule. The middle water hole is the final indicator.
Guys. Thanks for commenting. Should the "99" be be visible with the intake on? You said "between the intake and the block" which sounds like I'd need to pull the intake. As for the middle water p***age, I tried to pull the heads on this motor and they were stuck tight after sitting for 40 years. I decided to run it for a while and then tear it down. I'm glad I did because it runs like a champ and I will now put off a teardown and rebuild since I have so much other work to do to the car.
Not likely any pertinant data on the bellhousing if not a 59A block. If 99 Merc it would be a 239 cu/in engine. and would have the raised deck. The 19A didn't come out until 1941 so that's not likely it. After 70 years it could be almost anything. With the 81T heads the Service Specifications Manual says the CR is 5.9:1 & also says the cc's of the right head are 84-86 and the left head 82-84. If it does not have the raised deck it could be a 221 cu/in engine like a 81A block. Jim
81T heads are truck heads, in Fordspeak Truck means 3/4-1ton -UP. 81C would indicate Commercial. Pickups are called Commercial in Fordspeak, includes panel delivery, sedan delivery, station wagon, pickup, and others rated at 1/2 ton or le***.
Yup. It's got the 99 stamped on the machined surface of the block just outboard of the intake manifold on the frt left side. The intake manifold surface is flat from deck to deck. So I think, from all your input, it must really be a 40 Merc block but with truck heads. It sure runs strong so I don't plan to tear it down anytime soon to check the water p***age. Thanks for all you help guys. Dan
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