51 Flathead 8-How Far to Take Rebuild?

[hulleywoodworking]

I,ve posted about my recent 51 F1 purchase, and I have been working on it in the evenings for the past 2 weeks. So far, I've got the Flathead 8 stripped down to the bare block except for the camshaft. I will remove the idler gear and the cam before it goes.

I degreased and powerwashed the block several times as I tore it down so that I could see what I was doing and the washing got most of the heavy grease and sludge out of my way. I have poked and prodded the water jacket and power washed it a bunch of times to remove the built up crud and the casting sand and crap.

Monday morning I am dropping the block, heads, rods, pistons, and crankshaft at a local motor shop. This shop has been around since 1972, came recommended by my regular mechanic, and they have experience with flatheads. They will bake the block then bead blast it clean. After that, they will Magnaflux it. They will also degrease, clean, and Magnaflux the crankshaft, the heads, and the rods.

I found one small crack so far that can be pinned. it is between a valve and the cylynder, and extends down about 1/2". When I described it to the shop, they knew exactly what I talking about and said they commonly pin these, then sleeve the cylinder and install a hardened valve seat. I'm assuming that they will have to bore the cylinders and grind the valve seats, replacing the hardened seats with new. Once they are done, I plan on doing the rest of the build myself.

So after this is all done, I have to decide how far to go with increasing the performance of the motor. It is going to be a daily driver, both city and highway. I like cars with some balls; I don't need to spin the tires off of every light, but I do like to get to speed pretty quickly.

So where do I start? I need to determine what to change out after I get it back. The PO installed a Edlebrock aluminum intake manifold and Edlebrock 4 barrel carb, and I plan on reusing them. What else to do?

New pistons? I have to replace them anyway, so what do I get for a bit more performance?

Valve assemblies? Replace with what?

Tappets (Lifters)? Replace with what?

If the original cam and crank are good, should I reuse them? Or is that a waste of time if I want better performance?

How do I start? Where do I look for more info?

Thanks!!

John

[Ol' Ron]

I think it's time to buy some books. A mild hop up at todays prices will come to %5k min and the cracked block won't be what I'd want to put that money into. I've had a fellow in Mass stitch several engines a d we ran the rings righ ton the stitches his name is Frank Casey. Flatheads need displacement to improve preformance, This will increase compression and a mild cam will give some mid range punch. But this all costs $$$$. Or jst .050 and leave it stock. Mill the heads for .050" piston to head clearance and put 4.1 rear with OD and you'll be able to burn the tires off of it.

[40 Deluxe]

"No replacement for displacement", as Ol' Ron says! Since you're going to rebore anyway, go to 3 5/16" pistons, and since the crank will likely need go be reground, go to a 4" stroke Mercury crank or get a new 4 1/8" stroke crank. Follow Ron's head clearance guidelines with EAB heads. No need for aluminum heads. Add a mild cam and stand back!

[john in illinois]

JWL's book will give you information to plan what you want to do. Must read along with Ron's book.

http://www.flatheadv8.org/jwl.htm

John

[russcc]

If you are fairly close to Mass, stitching cracked blocks is not problem for Frank Casey as Ron mentioned. He does excellent work, and pressure tests them after completion. Reasonable money also.

[Mike51Merc]

Sponsored Links (Register now to hide all advertisements)

I'd get a Merc crank and pistons-- there's some extra cubes right there.

[mikebishop]

Originally Posted by john in illinois

JWL's book will give you information to plan what you want to do. Must read along with Ron's book.

http://www.flatheadv8.org/jwl.htm

John

No better sources for no-BS flathead info than these guys.

With regard to getting the best from your affordable flathead I'd like to add that you consider porting the block to help it breathe a bit better. It's not difficult, just needs some patience and a few hours of your time, plus forty-fifty bucks of expendables -- plus an inexpensive pneumatic die grinder.

There's an old piece I wrote about porting you can find on many of the early Ford V-8 sites, but it's a decade or more out of date; I've learned a lot since then, and recently folded the latest info into a book about rebuilding and modifying the Ford flathead V-8 in collusion with my long-time collaborator Vern Tardel. The book is scheduled to hit the market in a couple of weeks. You can find it on Amazon, or you could purchase it directly from Vern or me.

Mike Bishop

[GOSFAST]

Hi John, it all boils down to the overall budget. If done reasonably well you will see about 150 HP and 250# Torque. Give or take some.

Skip past the 4.125" stroke, go directly to the 4.250". We prefer the Eagle cranks, Scat rods, and Ross' pistons. The "metric" ring pack definitely frees up some HP. Try to find a shop that has a block-plate for finish honing, also important.

Pick a cam to complement the weight of the ride! Generally speaking we use Comp & Isky for our cam choice along with the original "Johnson" adj tappets. We also use bronze-lined guides on EVERY unit. Stud the mains at a minimum.

To add, I would prefer not using any "stitched" castings. We've done numerous repairs along this line and will not use it on what we consider a "higher-end" build. Also would avoid "shot-blasting" the block with any media and make certain to have it pressure-tested, "magging" is a secondary option. The pressure testing is mandatory?

On a side note, we machine for the 95% oiling system and we "pin" the heads and gaskets to the block with some .312" SBC dowel pins.

Thanks, Gary in N.Y.

P.S. Unless this becomes an "all-out" track build I would skip any "major" porting, also skip any O/S valves. None of this is necessasry to get the HP/T numbers above!

[hulleywoodworking]

All of the comments and suggestions thus far have been very helpful. I have some reading ahead of me!

Thanks everyone, and keep it coming.

John

[GreenMonster48]

I just rebuilt the one in my avatar and installed it last year.

I was fortunate to have a good block to start. I bought an NOS crank (3.75") and NOS rods from the So-Cal Speedshop. I think they were $275 and $125 for the set, respectively. Egge pistons, Schneider 3/4 cam, Zephyr Springs from Reds and well as adj lifters. I had the engine shop assemble everything except for the heads, oil pump, etc. That all added up to about $3800 out the door, not counting heads, intake, etc.

I'm also running the Edelbrock 4 bbl. Over-all, I'm pretty happy with the performance.

[hulleywoodworking]

Update:

I tore the engine down completely and took the block, crank, cam, pistons, rods, valves to Northeast Machine in Tonawanda, NY. They will start by cleaning and magnafluxing the visible crack to determine if it is repairable. If it is, they will work up an estimate to bake and shake the block, Magnaflux, pressure test, repair the crack and bore and sleeve it, bore the cylinders, grind the valve seats and install a seat at the crack. Magnaflux and mill the cast iron head covers. Magnaflux and turn the crank and cam. Install crank, cam, pistons, rods, bearings, valves, etc. Going with Johnson hollow adjustable lifters. I decided at this point to not change out the crank or the cam, as I am not really in need of more HP.

I should hear from them early next week.

John

[JSeery]

Sounds like you are making progress.

[Ol' Ron]

Be nice to know the cost of doing this, so others will have a chance to see how far they might want to go before the install a SBC.

[hulleywoodworking]

Originally Posted by Ol' Ron

Be nice to know the cost of doing this, so others will have a chance to see how far they might want to go before the install a SBC.

I'll post the estimate when I get it.

John

[Diavolo]

Don't bead blast!

One thing my automotive teacher told me was that you don't ever want to blast something unless you can get to every square inch of it to clean it. I have always been a supporter of this claim. A fine example was when my buddy was over at my house to rebuild the top end of his old Chevy. He bought reman heads to put on it and when he brought them over, assembled, I stopped him.

I bounced them off the porch a few times and then poured out a handful of glass beads out of each one of them. We spent an hour running water through them and brushing them the best we could before putting them on. (We didn't have a way to take them apart at the time)

A month after putting them on, he lost a water pump. A month after that, he lost another one. A month after that, he lost another one. He installed another water pump and sold the truck.

No glass beads.

[Bassman/NZ]

Before you spend a single cent on that engine..... get John W Lawson's book "Flathead Facts". It stands head and shoulders above all others because it's based on dyno results. It saved me a lot of money, and it will save you a lot too.

[chap52]

Read both JWL's and ol' Rons books, decide what YOU want and go for it. There is a ton of great advice on this site,. Bottom line, it is your truck.
Let he who has not spent too much money doing unnecessary things to there vehicle cast the first lug nut.
Keep us posted, and enjoy the adventure.

[chap52]

Another thought. If you go with adjustable lifters be sure to drill holes in the valley for each valve. This subject has been covered on here a few times. Search it out. These holes will make the adjusting process less painful.

[mikebishop]

Originally Posted by chap52

Another thought. If you go with adjustable lifters be sure to drill holes in the valley for each valve. This subject has been covered on here a few times. Search it out. These holes will make the adjusting process less painful.

Good suggestion. Drill the holes just above the camshaft-bearing oil-gallery tube. I'd like to add that it's helpful to cut a relief in the top of each lifter bore to improve wrench access, especially for reground camshafts where the base circle has been reduced and the lifters sit deeper in their bores.

Mike

[Tom Walker]

Mike, you got that block clean enough to eat yr dinner off it and now yr going to fill it full of grindings when you do those ports!!! ��
Can I ask, are those marks for the porting transferred off a gasket? Do you match them to the intake in the same way?
Thanks, Tom.