Rebuilding The Flathead 6

[Shawn F.]

Has anyone here rebuild their flathead 6 cylinder themselves? I was going to have a local machine shop machine and rebuild mine for $1400 bucks which seems like a great price but I'm one of those people that like to learn anything and everything I can so want to try it myself. I have built engines back in auto tech classes and such but it's been a while and I always doubt myself andm think I will ess something up if I dont follow something exactly.

I will most likely need some micrometers, bore gauge and things like that but then again if I dont buy them I have a friend that I know who will most likely let me borrow them for a few days. Last year in Concord, NC show you guys put on, I heard a few guys telling me they had theirs machined by a shop and assembled it themselves and it was fairly easy and straight forward.

What are your guys' oppinions on this and if you have any information or suggestions then feel free to post them here. I am not mechanically inclinded by any means, just nervous I will screw something up. I dont like to just tear into things and find out too late that I messed it up (which is the hard way to learn and most times the best way, I just dont have the money to screw up right now).

Thanks!

[Young Ed]

I've done a couple that way. The machine shop cleaned the block and machined it and supplied the parts and we built it. You need a shop manual for all the specs and a good clean place to work. Torque wrench is a must.

[Shawn F.]

I have a lot of hand tools and torque wrench. I would probably buy a nice click type torque wrench though. I mostly need the specialty tools for measuring and that is about it. I have a garage to work in with work benches and tables that is clean as well. What I would like to do is do the machining and get the parts from them and do what you said. As far as rebuilding it and getting some more power out of it, would you guys recommend better than stock pistons and internals or stay with stock? Are there things I can have the machine shop do to help with power such as porting or polishing, etc? I know one thing is to shave the head some for compression but thats about it. I want to keep it reliable but at the same time add some more power to it while it will already be apart.

[Young Ed]

Shawn the couple I have helped with were done without any specialty measuring tools except for a click torque wrench. They were all stock rebuilds so I can't help with the other part of your question.

[Death Dodger]

Micrometer for the journals and plasti-gauge for the bearing clearances. A decent torque wrench to put it all together and you should be in decent shape.

For more power, you may want to see what size engine you have first. Some of the 1950's flat 6's are larger than the older ones. Cam's can be custom ground for pretty cheap and better carbs for more power.

[Shawn F.]

Ok sounds good then thanks! So you did not have to check the bores for out of roundness or the pistons and such? I always thought it's best to double check the machine shops work to make sure nothing is out of round and everything has correct clearance. Of course you know way more than me so I am not questioning you at all.

[Don Coatney]

Shawn;

If you do the disassembly (recommended if you plan on doing the assembly) take pictures every step of the way. There are location specific bolts and washers on the front timing cover. Group your removed hardware in sandwich bags marked with a sharpie. Clean all removed bolts and hardware with a wire brush.

You may need a ridge reamer to remove your pistons. You will need a piston ring expander to install new rings on your pistons. You will need a piston ring compressor to install the pistons in the cylinder. You will need a valve spring compressor to R&R the valves. You will need a good set of feeler gauges to measure and set your piston ring gap. You will need feeler gauges to set your valve lash. As already mentioned plasti-gage is required to check bearing (mains and rods) clearance. You will need a puller to remove the front crankshaft hub. You may need a large socket (measure your nut for the correct size) to remove the nut that secures the front hub to the crankshaft.

Click on my photobucket link below and go to the engine album. Lots of pictures that may help you there. Dont be arfaid to ask questions as you proceed.

I sent my cam to Earl Edgertion in California for a new profile. Cost about a big buck and a half 4-5 years ago. I installed shiverlay valves in my engine. My Desoto long block is bored .030" over and is now 255 CI.

[Don Coatney]

One more thing. A good set of taps, dies, and thread chasers is highly recommended.

[norrism1]

Don't forget a valve lap tool and compound. And don't forget to remove and inspect the water distribution tube.

[Shawn F.]

Thanks for the information guys. I will take your guys' advice and see what I can do when I get to the point of pulling and tearing the motor down. For now I am just planning way ahead in advance. Sometimes I go a little crazy and think very far ahead and have to have every little detail planned out before I start but thats just how I am...

[Shawn F.]

BTW, my engine is the original 251ci (250.6 to be exact) with the fluid drive tranny. I'd like to rebuild the tranny but everyone says to throw a t5 into it which would be nice too but the fluid drive IMO is different

[thejackrabbit]

I don't know if this was mentioned, a clean, well lighted place to work. You know, like your kitchen table:D .

[Norm's Coupe]

For now I am just planning way ahead in advance. Sometimes I go a little crazy and think very far ahead and have to have every little detail planned out before I start but thats just how I am...

Shawn,

Unless you plan on simply replacing every part of the engine with new parts, you can't plan every detail in advance. You don't know what you have inside the engine or how good it is, until you tear it down and look. Then you can forget the planning and just do what needs to be done.

[48mirage]

The 2 most important tools I have are the service manual and the parts book. A lot of times the parts book will have exploded views that give better details than the service manual.

[brian hood]

Most of the tools you need are available from most major chain owned auto parts store's through their Loan-A-Tool program. Unless you want one, you do not need to buy anything including a t wrench.

[Tom Skinner]

Shawn,

Did you ever get the brake parts, or break job started?

Good to see you back on the Forum. E-mail me if you need help.

Tom Skinner

Huntersville, NC.

[Flatie46]

Brian's right about the loan a tool program. I wouldnt be so nervous or worried about doing it yourself its a learning experiance. You are the only one you have to worry about pleasing. If you get stuck or have a question just post it. Take it a step at a time, bag and tag like Don said. You can do it!

[Savoy Boy]

Try this post from the HAMB. Probably the most comprehensive post on rebuilding a Mopar 6 that you will ever find.

http://www.jalopyjournal.com/forum/showthread.php?t=315555

[1949P17BC]

A good rebuild also requires about 4 cases of beer!

[realrain]

second that. Theres not an engine out there that a case of Kokanne cant rebuilt (my first Wankle 13B and BBC and my first flat head 6).

I'll take some pics of the one im doing right now, and of the valve spring compressor and lapping tools i use.

If your really into it, check out ebay. i see original mopar dealer tools from the 40's hand crank valve lapping tools and one handed vavle spring compressor, usually they are cheap to.

[realrain]

[aero3113]

$1400 seems like a good deal if that includes all of your parts. A good thing is if the shop does the work you can always go back to them if there is a problem with their work. If you do the work and mess somthing up its your fault. I replaced pistons rings and rod rbearings with no problems with the motor in the car.

[George NU]

Everyone has Givin' you some great advice,Thats what this site is all about so Pass it on !

One thing i did NOT read was the Cyl head...Have it Milled, a lil More then what it takes to clean up ,as this Makes it Snap!! ...Also, "If " ,you have the Bucks ?, have it balanced as this makes it last ! Check every thing at least Twice to besure it is right! These Engines are in," MY BOOK" some of the BEST Engines ever Made!!....SO Enjoy it & take your Time ! Learn and Pass it on ! Make them Live On & On !! and Not Just in a Garage or Museum, but on the road ! NU

[grey beard]

Hi Shawn,

Seems like you have plenty of advice. At the risk of too much of a good thing, I'd like to offer just a few other general pointers, so you don't make any major blunders.

The rod caps are each made to fit one individual connecting rod. Usually they are numbered, but you cannot always count on this. I suggest you never have more than one cap off of any rod at the same time. Pull a cap, get the rod and piston out of the block, and get the cap back on it's own rod. When you put 'em on, the two notches go towards the same side. Any time you ever see a bunch of rod caps laying in a parts pile loose, you know that whoever took that engine apart doesn't know much about engine assembly. Each rod cap must always stay with its own connecting rod.

AND, when you pull those rods, do put short pieces of vacuum hose on each rod bolt, so you don't notch that polished crankshaft. Gentle care is needed here, getting things apart.

Main bearing caps were line bored in position on the block when it was brand new. They will only fit on that one block and in that one position. Usually these are numbered, but again, don't depend on this. It is a good practice to take a center punch and mark each one so you will know without fail exactly which position it belongs on the block. The front and rear main caps are distinctively different - can't be mixed up. The rear one has a seal built into it. It is the center main bearing caps that are all identical and can easily be mixed up. Mark the front one with one mark, the second with two marks, etc. That way you will have no doubt about which goes where on reassembly.

Rod bushings are in the top of each rod, and fit around the piston wrist pins. These bushings are often ignored by novice engine builders. Don't commit this sin. Have the rods trued and rebushed by your machine shop while it's all apart.

You will also want the machne shop to check the valve guides for wear while the block is out. The front valve guide in the block is an eshaust, and is always the one that seems to wear most, because it is at the highest elevation and gets the least oil splash from the pistons and rods. If any guides will be worn, it will always be the exhausts. They wear quicker. They are not expensive and are easy to replace. If they are worn, they MUST be replaced before the valve seats are ground, for they provide the center for the grinding pilot tool. To replace them after the seats are gound would be laughable - and they'd have to be redone.

When you are having the block inspected, someone must check the cylinders with a bore gauge to determine how much taper is present. Cylinders always wear most at the top, so the cylinders show the most wear most at this point. More than 8 or 9 thousandths taper means the block must be rebored. Reboring requires new pistons and a block tanking, which will also require new cam bearings. So it is that if your block must be rebored, you're looking at the neighborhood of an extra $4 or 500 bucks.

When you go back together, make dead sure your conecting rods all have the squirt holes on the sides pointing towards the camshaft. This hole is what lubricates the valve train.

Finally, if you decide to build the engine yourself, keep us posted with your progress. When you have questions, let us help. Some of us have been doing this stuff all our lives. We enjoy helping other guys.

Good Luck.

[NintendoKD]

I am a fairly new member, as in I haven't been here in a while. I have done a fair amount of studying about engines inner workings and etc Now I am ready to move on to build my 54' plymouth savoy's 230 flathead. I will get the block cleaned/hot tanked and line bored/honed at the machinist and do all of the work myself. I realized that when I first came here I was a horrible noob and was rather rude to some folks unintentionally. I must apologise in advance, this is not a thread jack by the way, I am just checking progress and re-introducing myself. Good luck on the build and keep up the good work post pictures when you get a chance and keep everyone here posted on progress.

Happy Holidays,

Kevin