Technical Help me plan and build my flathead (please)?

The time has come to start putting parts together. I just left the machine shop and my block looks good. I think he said pistons would have to be bored to 3 3/16. Only one minor crack that they say is fixable. So, with that its time to start ordering parts! Can y'all check my work and suggest changes? I'm still not sure on the cam so help with that would be sweet. Im looking for a slightly better than stock motor. I have a 4" mercury crank so I plan to use that (if it checks out...thats next for the machine shop).

-1940 flathead block - 59ab
-Cam (need help here...I want slightly better than stock).
-Dual carbs (need help here too. what do you suggest?)
-Crank - Mercury 4" stroke
-valve train - stock (but adjustable lifters) - Deluxe-Flathead-Ford-V8-Valve-Rebuild-Kit-Single-Springs,432060.html
Pistons - 4" stroke pistons, 3.25" bore - https://www.speedwaymotors.com/1939...ing-Pistons-4-Inch-Stroke-125-Over,39155.html
rods - stock (these ok with a 4" crank?)
Bearings - working on these with machine shop
Heads - stock for now. May upgrade later.

What am I forgetting? Any suggestions for the first time flathead builder? I've built other engines, just never a flathead. I have already read several rebuild books and plan to follow along with a couple of them while I am putting it together. As always, thanks for your help!

 

First buy the two books shown in this thread.
Flathead Books 1935 21 Stud - The Ford Barn
2nd. Post questions on Fordbarn as there are lots of folks with tons of knowledge.
3rd. Use a machine shop that has experience building flatheads and is not "learning on yours".
4th. Gives lots of consideration to your cooling system - building one that really works without the use of an electric fan, if possible.
5th. Remember, changing one thing usually results in having to change something else.
6th. Decide if you are going to use the stock drivetrain.

 

A 40 block is not a 59A. The bore is smaller, and usually has tin sleeves in it from the factory. Has your machine shop pulled those sleeves?

I would only bore the minimum required to clean it up. If the block's water jackets were rusty, it's wise to clean those either with sandblasting or baking, then sonic test to see if any internals were rusted away.

A valve kit like you show is wise, but check places like Reds Headers and others too. Sometimes Speedway uses Chinese parts, and getting good guides is hard to do nowadays.

I currently have a Littero 100 cam on order, as that grind has a great reputation and I want to pep up my sedan's flathead.

The 40 rods will work with the late crank if you use the 40 bearings. But finding some 8BA rods will probably be cheaper and easier to find and set up the bearings. Not many are familiar with full floating bearings anymore.

 

Following this, as I may have a Flathead build in my future.





Bones

 

I trust the shop doing the work. They work on all kinds of engines but know flatheads well. I think there are 3-4 in there right now, including a v12. Pretty cool.

In speaking with him today he said the cylinders were NOT sleeved and they were bored out to 3.125 and I’d need to go up to 3 3/16 (3.1875). Does that make any sense to y’all?

I have one of those two books that you linked on ford barn. Have read it front to back twice now. Will follow it as I put everything back together as well.

I plan to keep the stock drivetrain as well. Just looking to build a solid cruiser that can keep up with most traffic.

Thanks for the info so far. I’m taking my stock crank and the Merc crank in tomorrow to get measured.

 

Okay, so if you truly have a 4" Mercury Crankshaft, that will be an 8BA piece which was intended to use the Insert-style bearings. This is good, because I can tell you first hand, the early floating bearings are very expensive and all that's available is NOS ones from decades ago. So definitely would recommend using the new-style rods as well because the money you save on rod bearings alone will make it worthwhile.

In regards to Cam, that's up to individual preference. For street use, I'm running the Isky Max, and I've heard plenty of good things about it. That's equivalent to the Kiwi 100 cam and others. Anything like a 400jr or similar will be too radical for a daily driver and would complicate head clearance and such.

Carbs: I'm a firm believer in original Strombergs or the English new ones. I've had bad experiences with the Speedway 9Super7s, and wouldn't recommend them at all. I've never messed with the Holley or OEM Ford carbs, but I see some guys run them and they do just fine

Heads: yeah, stick with the stock ones. And don't let the machine shop deck them. Just have them do a quick check for warping, but removing material should only be done as a last resort. Same with the Block, these engines weren't designed with lots of extra material in those areas, so it's real easy to paint yourself into a corner with decking/milling.

I've spoken over the phone with H&H Flatheads and Red's Headers about what parts I need and what they recommend for "budget" builds and both outfits were very helpful and never once tried to upsell me or give me the "hard-sell". Definitely recommend talking with either company.

By the way, speaking of Budget, be prepared for $4-6k for a Flathead build, especially if the machine shop will be doing balancing and final assembly. Better to know up front than be surprised at the end.

~Peter

 

Clean the coolant passages. Then clean the coolant passages. When you're done with that....clean the coolant passages! 80 years is a long time to develop corrosion/debris.

 

I didn’t know 59AB blocks were also 221 (3 1/16 bore), because the 239 is 3 3/16th.
I guess nothing to really add, but just getting my mental info up

 

59A means it was designed in 1945, hence the 5.

8BA means it was designed in 1948, hence the 8.

 

I’m now more confused. OP says 40 Flathead 59AB.
So assuming it’s not a ‘40 engine, were 59AB engines 221 and 239 ?

 

My pops has an NOS 59A block with the small bore, but I think it was a post war produced part for use as replacement of a 39-42 block. It does not have tin sleeves. The small bore is probably the reason it’s still unused after all this time.

 

I've had a small bore 59a motor too, theres a few out there

 

As said before clean the coolant passages. When I started on my first flathead I had two pieces of junk 3/4” plywood stacked on one another. I would lift the bare block on one end and drop it then lift the other end and drop. I did this for 15/20 minutes, you would not believe the amount of rust and casting sand that was still in the block.

 

Okay, now it’s making sense to me.

 

Here's info on cam thrust on early and late flatheads.
Camshaft Movement - The Ford Barn

 

If this engine is actually a 1940. It will have 81A cast into the top the rear bellhousing. That's how the 1938-41 engines are marked.

 

I am dropping off the cranks today to be measured and will verify which engine I have. I mistakenly thought there were only two, 59ab and 8ba. Knowing it wasn't an 8ba I just assumed 59ab! I'll verify it today. Thanks everyone.

 

I am following this thread with great interest. I am attempting to gain some knowledge to eventually build my flathead. I see a lot of "59A" and "59AB", what is the difference? I apologize if it seems like I'm hijacking this thread, I'm just trying to learn. This is my block:

What do I have?

Thanks.
Larry

 

I am going to dispute this statement. In my opinion, one of the best things you can do to improve flathead performance and economy is to rework the heads for optimum quench and combustion chamber efficiency. It also increases compression. You want to strive for a consistent .045-.050" over the crown of the piston (I have seen stock heads with over .100" and aftermarket aluminum heads with over .070"). Back in the 1920's an Englishman named Sir Harty Ricardo did detailed research on combustion chamber design in "L-head" engines. His works will explain the theory behind this.

A quick search on this forum using the terms "flathead" and "quench" will produce many threads on the "How's and Why's" of this. (Feel free to ignore those that I have contributed to if you wish.)

 

That's absolutely correct, my concern is that once you deck the block or heads you've now removed that option for the next guy since you've now taken away the little material that was available to begin with. The opposite is also true, if this block has already been decked, then there may not be enough room to do another pass.

In the case of this discussion, the OP is not trying to make the most powerful flathead of all time, so that's why I recommended caution when it comes to removing material. Better to leave that room to experiment for the next guy or for yourself down the road. That's also why in my years of engine building I've never bored an engine to it's max, I always want to think about serviceability down the road. The last thing I want is to take an engine to it's limits and then have no wiggle room for repairs or rebuild.

~Peter

 

I am fully aware of the thin character of flathead block decks. I think it is important to differentiate between surfacing of head and blocks. Blocks are becoming scarer as the years pass. Heads (especially stock units) are much more common.

To clarify my position, I would not machine a block unless it was absolutely necessary. I would always rework the heads for maximum efficiency.

 

If the deck of your block is in good condition, leave it alone.

 

I just took my two cranks to the shop. While there I looked for numbers on the bell housing. There are none. Does this tell you anything?

 

@'34 Ratrod 59a was the ford ID for the block series. 59 ab referes to the heads. Early heads were one side only design, and marked a or b with the part number on the head. Later, the 59ab heads will fit either side, and are marked 59ab.

 

Bus man, show us the front of the block to see if it passes the pencil test

 

Thank you @rusty valley!

 

Yes, I believe it passes the pencil test. Also has the Welch plugs under the oil pan.

 

I’m stalled by my machine shop on my C8BA. Preliminary boring done but still need a couple of small cracks repaired and one sleeve... so I’m following along with interest.

 

Nope. Every '40 Ford block I've had did not have 81A on it. Some had a smaller group of uninterpretable numbers up closer to the valley on the bellhousing, but none have had a big 81 anywhere on them.

 

Came here to say this. In all my years messing with these lumps, I've only come across one of these blocks. I was totally stoked to find a good 59AB. Took the heads off and was like what the heck? Found the small, 3 1/16th bore that can only be bored out to 3 3/16ths max. It also had the 59AB casting loud and proud on back top of the bell.

Turns out these were some odd ball replacement engine sold after WWII for pre-war cars. Makes zero sense why in the world they did this when a 239 would be nice upgrade to the 221. Really odd.