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I think the engine in my truck is an 81A... My new pickup needs an engine overhaul and my first challenge is to pull out what I believe is an 81A 221CI (not original).
It has a 3spd transmission, and a closed drive train (although I was told it is not original - for that matter the chassis and running gear were all swapped out - I think they put car parts in). Question #1: can the engine and transmission be pulled together and is there somewhere I can go for step by step instructions? Question #2: this is not the original engine - is it worth spending the money to overhaul? Flathead parts (blocks especially) are fairly rare up here in the great white North. I know I need to have it inspected for cracks, but can it even take an overbore (and if so what would the max be)? Your comments would be appreciated. Thanks, George |
Re: I think the engine in my truck is an 81A... The 81A 221 CID engine would be 1938 up to the start of wartime changeover to military production in early 1942. I assume your vehicle is somewhere in that era but you didn't indicate that. There is nothing wrong with the 81A and since it is a 24 stud variant with the later in block water pumps, there is a lot of interchangeability with 239 CID and post war 59 series engines. Up until 1942, the passenger cars and commercial pickups shared pretty much the same drive train and frame with exceptions in 1941.
The condition of the engine will determine whether it is worth performing an overhaul. Some of the Canadian manufactured stuff is a bit different than the US manufacture but the 81A may be US manufactured too and most stuff is interchangeable. Most of the Canadian stuff had a C in the part number prefix so you can tell where it's from. There are shop manuals available and each vehicle had an operator's manual which are reprinted now. There is a good shop manual available that is based on the Canadian wartime manual and it is very good but we need to know what year of vehicle you have. Welcome in to the Barn. |
Re: I think the engine in my truck is an 81A... What year truck do you have and what makes you think it is an 81A?
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Re: I think the engine in my truck is an 81A... From your public profile, I see that you have a '39 1/2 ton pickup. The chassis and running gear for your truck is the same as for a passenger car of the same year, with the possible exception of some minor parts carried over from the previous year, as was sometimes done with commercial vehicles. The internals of the transmission are one place that you may find to be an earlier part: A quick check of the large fork within the shift tower will reveal either the much preferred 91A number, or the earlier 81A number, which would have an inferior synchromesh. I assume you found the 81A designation on the heads, which would be the only place you'd find that number, and would be correct, although it would not by itself identify the engine block as being correct. If your truck has a differential from a car, it may also have a lighter rear spring, and in fact, your whole drivetrain may have originally been the optional underpowered 60 hp engine, coupled to a 4.44 ratio differential. You may now have the preferred 3.78 ratio differential? Your hubs would originally have been wide 5, which, with hydraulic brakes on cars, would have only been available in 1939, though carried over on light trucks, as was the closed driveshaft.
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Re: I think the engine in my truck is an 81A... Some of these engines had 81A cast in the bellhousing, but probably would not be visible in the chassis.
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Re: I think the engine in my truck is an 81A... welcome to the 'Barn....got pics??...lol....Mike
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Re: I think the engine in my truck is an 81A... That sounds like the right engine for a 39 My response to question 2 is that if the block is not full of cracks or bored to 060 then its worth investing in...I don't like to go over 060 bore on those as the cylinders are thin and if its already there sleeves is an expensive solution.
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Re: I think the engine in my truck is an 81A... Thanks for your advice, I have some pictures which I will upload this evening.
George |
Re: I think the engine in my truck is an 81A... Are the exhaust manifold ports are extended away from the block about a 1/2 inch? That was a feature of the '38 to around '40 or '41 (24 stud) blocks. After that, they were flush with the block.
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Re: I think the engine in my truck is an 81A... Many of these engines had the thin steel sleeves. It was common practice to knock them out and bore to 3 3/16.
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Re: I think the engine in my truck is an 81A... 6 Attachment(s)
These are the best photos I have (I took them the day I picked the truck up). It is blocked in by snow right now, which is why I am planning my next steps to get it back on the road...
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Re: I think the engine in my truck is an 81A... I'm not sure the pictures will be very helpful, I suppose I need to pull it and disassemble to get a better idea of what it is.
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Re: I think the engine in my truck is an 81A... The 59AB in my 32 looked the same, so I decided to start pulling it apart one piece at a time, oil pan first. Surprised to find no sludge, and spotless bottom end. Next the intake manifold, and it was the same, with new lifters and cam. Pulled the stuck waterpumps and the water jackets were spotless. New pumps, fired it off and it runs cool with great oil pressure. Moral to the story, looks can be deceiving. It might run.
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Re: I think the engine in my truck is an 81A... That's a Ford Canada 81A, lots of those in Canadian post-war trucks and cars as a smaller option because there were no six cylinder options until '56.
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Re: I think the engine in my truck is an 81A... Another question... was the 239CI used in Mercurys starting in 1939 a different casting or was it the same casting only bored out to 3.1875? Would this engine take an overbore to 3.1875 (239 CI)?
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Re: I think the engine in my truck is an 81A... I'm sure there were internal changes to the cores.
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Re: I think the engine in my truck is an 81A... I believe the Canadian 99A engine blocks have a raised "99" cast into the block on the front right side. The ones made in the US had "99" stamped into a deck surface but only on some. I think the stamping stopped completely in late 1940 or so.
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Re: I think the engine in my truck is an 81A... Thanks to all for your advice and comments, I will post my progress and I am sure I will have plenty of other questions :)
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Re: I think the engine in my truck is an 81A... Where are you in Ontario? I'm in Paris,ON and can offer you some help, if you want to call. 416.886.3454. Bill
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Re: I think the engine in my truck is an 81A... Nice truck!
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Re: I think the engine in my truck is an 81A... I think I am running into a "damned if you do and expensive if you don't" scenario here in that the truck needs some work to get it running and I was told by the seller that several valves were stuck (no compression on these cylinders).
I originally was going to do a full rebuild with new rotating assembly, valve train, aluminum heads, intakes and dual carbs - now... maybe not. This block apparently won't take much of an overbore and the original crank journals won't support much of a grind (for more stroke). Pistons are available, but they end up being fairly expensive and won't give me the cubic inch increase I need for a decent compression ratio. That really reduces the benefit of the cam, heads and induction. I think that my new plan will be just to check the engine out and freshen it up if it the block is not cracked and then wait until I can afford to put in a little more powerful power plant. |
Re: I think the engine in my truck is an 81A... 4 Attachment(s)
Ok, guess I messed the part about won't take much of an overbore. What is the current bore? And what overbore is it currently at? What is the undersize on the crank? If you want a 4 inch crank, you would need to acquire a mercury or aftermarket crank. I'm just not following the concerns yet. The compression can be increased by the type of head selected or milling a head to get what you want.
I might suggest you read some books on what these engines are capable of, a good start would be JWLs and Ol Rons books. Threw in a couple of others I like. |
Re: I think the engine in my truck is an 81A... Well... as an 81A block, most of the advice I have been getting is that the cylinder walls are not as thick as the 239 motors and any re-bore should be limited to .060".
I could put a 4" crank in, but I would have trouble finding .060" over 221 pistons with the correct pin location. The existing crank could be reground, but as it already uses small journal rods, there doesn't seem to be much room for improvement there and finding floating oversize rod bearings could be difficult. Honestly, I'm coming to the conclusion that this is not the right block to invest in if my goal is to build a "midrange" performance motor. The right block would seem to be a 59 series block. In the short term, I could throw some rings and bearings in, do a valve job and spend $2000 for a motor that will probably be pretty reliable for the next few years. this truck still needs: paint, brakes (complete), transmission (clutch probably as well), electrical and all the rest of the unknowns to get it on the road. |
Re: I think the engine in my truck is an 81A... Oh and by the way, I will take JSeerys advice and buy some books :)
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Re: I think the engine in my truck is an 81A... If you can find a block cheap enough that might be the least expensive route.
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Re: I think the engine in my truck is an 81A... It is pretty common practice to bore 24 stud 221's out to 239, actually.
There were 2 81A engines, 1938 and '39 up. Yours, if further examination shows it to be an 81A, is the '39 up, shown by the picture of the crank pulley...it has the long crank. The short pulley extension behind the nut shows this. In the parts book, the differing blocks are shown by the suffixes, 81A-####- A and 81A -####-B...the early was replaced at the very end of '38 production, the late one was necessary for '39 deluxes to take the crank pulley fan... The 1938 24 used the short 68 crank used in '36-7-8 21 stud engines, and the '38 was the only 24 stud using that. |
Re: I think the engine in my truck is an 81A... Ok, being able to bore out to 3 3/16" opens up a lot of possibilities - plenty of piston options.
I think my next step will have to wait until it thaws out and I can pull it apart and check the condition of the block. |
Re: I think the engine in my truck is an 81A... First, unless there were other warnings, unstick the valves and see if that's all it needs! Common storage problem due to oil running downhilll...
See if they will push down, if so just keep oiling down the guide, turning, and pushing. If they can be pushed, they will likely free up in a few cycles and all you'll need is a pair of head gaskets. If not...you've gotten your rebuild underway, or, if cylinders look pretty good, maybe just a new set of valves and guides will get you rolling. Engine has hard seats, things will oft clean up fairly easily. |
Re: I think the engine in my truck is an 81A... i concur. What do you want out of this truck?
Ive been driving a motor that just needed a burnt valve replaced ($7), now been 5 yrs. great compression. Plan at least another 5 or more. Also have another one with a full blown rebuild. . |
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