Flathead question...

I have a '53 Ford flathead with a 4" Mercury crank. It got some water damage in the cylinders. It is now .060 over. My engine man says it will clean up at .080 over. Most piston manf. offer .125 or .188 over pistons.

My question is.... Would you try to get .080 pistons or go out to .125 over and get a on the shelf piston?

Pros & Cons guys, whats your opinion?

Thanks,
Kevin

 

Most like to run the .125 but if you can find .80 go for it. if it happens again you have room for another cut.

 

What brand piston are most people using?

 

Go the minimum .080". Why go larger than necessary and shorten the useful life of the block by reducing the available number of future rebores? As for pistons, I used Silv-O-Lite from Red's. No problems.

Bob

 

I assume your referring to forged coming only in 125 over and larger.

At 125 you still have 2 more larger bores to go if your block is a good casting.

I personally believe if you can afford the best (forged) buy the best.
Iv torn down a lot of flatheads that have had failed cast pistons.
These blocks don’t wear like newer junk …. Its unlikely you will ever be boring it again and there’s no substitute for cubic inches.

 

I always put forged pistons in my other engines, but never had a GOOD flathead. I'm sure forged is the best way to go, but really didn't know if it was necessary on a low rpm, low hp engine like a flathead. That's why I'm asking for your opinions. I'm a newbie on them and my engine guy is too. We just want to do it right the first time.

Thanks in advance.

 

If over 080 over bore you will need the big bore head gaskets.. a little bit more pricey.. I always go 125 but I have had engines 030 over 3 and 3/8..

 

.080 over is a good start

.125 is better
There is no excuse for cubic inches.

Tig

 

Talk to Jim @ Reds Headers.Nice guy .They have .080 over in stock in a cast piston.I just talked to him the other day

 

""There is no excuse for cubic inches.""

CUBIC MONEY!!!!

 

What about compression ratio? Just got off the phone with the engine man and he was asking.

Is there some reason to keep the compression at 8:1?

With MSD ignition seems like you could get up to 9:5 without any problems unless it's heat....?

I know this is probably SBC thinking, and may not apply to flatheads. Thats why I'm asking.

Let's hear it....

 

I also want to put a set of finned heads on it. Is there a head that has a performance advantage?

 

The least expensive set has the advantage. All the aftermarket flatty heads are more about looks in my opinion. Not saying you won't see some gain, but their cost benefit ratio is the worst of all ways to spend money on a flathead.

Bob

 

Be very sure to tell the piston supplier that you have the 4" crank. These pistons have to pin located 1/4 " closer to the piston top in order ro accomodate the longer stroke. All the Ford flatheads used the same length rods.

4TTRUK

 

"Offy" and Edelbrock have heads,.. Mine are Offy 10:1 compression, they make others as well.
4TTRUK

 

That would be 1/8".

 

The larger the bore the more heat is produced as the cylinder walls become thinner..and the center cylinders on each side share a common exhaust port...

just a note...as I know you guys already know this..but some readers may not...

 

+1 +1 That is correct

 

In the days when these blocks were plentiful, would have replied:
"Bore the damn thing to at least 3.313" (.125 over), and most likely you'll have 2 more bore jobs left in her."
But considering the scarcity and consequently higher cost, and the advent of sonic testing for wall thickness, I'd add that step before I ordered new pistons or setup a boring bar.
Then you'll know what you're dealing with as core shifts were more prevalent back then.Dave

 

Thanks guys, this is some great advise. This is why I come here to ask my questions, massive bank of knowledge.

Next question... This engine has a 400jr cam in it with Johnson adjustable lifters. Any advise on where to degree this cam in for street use?

All my stuff has 3 pedals, and the engine will probably end up in my '31 roadster. Just an idea of what it will be used for.

 

Been a loooong time since I modified a flat head, and in those days I didn't have a degree wheel or a dial indicator, much less the knowledge to use them.
But I installed a 400Jr. in a 3/8X3/8 and it ran great installed straight up by the timing marks.
Be sure you have enough clearance in the heads to run a .400" lift cam! Most heads will need flycutting.
Dave

 

If you use forged(Ross) pistions you have to rebalance the whole
assembly as they are around 100g lighter, each.

I love the Ross pistons!!!Always try to use them.

Between 0.080 and 0.125 there is no big difference and with 0.080 you will get
heavy 4- Ring pistons.....

Since you have a 400jr cam already , which will work good in a 276ci engine.

Michael

 

Sounds like this was a well built engine, or at least had some good parts in it. How did it get water damage?

That 400jr is a great sounding cam.

 

I bought it in my old "Rehab Roadster" with the damage, it was supposed to be dyno fresh. When we tried to start it.... Stuck! Then I found the water damage that obviously went down through the carbs. I ended up getting the engine/trans back after another friend bought the roadster. Can't wait to get it back together.

Any tips on valve lash on the 400jr...?