Technical Tell Me All You Know About a Ford Flathead Relieved Block!

1. What Year or years?
2. What benefits if any?
3. Desired or not?
4. Did they ever come in a Merc. block?
5. Do these intake ports look stock?
6. Are these stock domed pistons?
What do I have here so I can advertise it honestly.
Thanks!

 

. What Year or years? Look on top of bell housing and post the number/letter combo.... something such as 59L
2. What benefits if any? Maybe slightly better flow? Cool to boast of relieved cyls
3. Desired or not? Probably desired except wont work with Ardun heads
4. Did they ever come in a Merc. block? Not from factory but done in garage a LOT
5. Do these intake ports look stock? Yes
6. Are these stock domed pistons? Yes

 

That is the makings of a cool, hot rod flattie.

 

You would probably know, you've paid your dues!

 

The relief is the shape that Ford did at the factory for big truck engines. Intake ports look stock. But the extra holes to hold lifters while adjusting them are a later addition.

Any oversize stamping on the piston tops? Are there adjustable lifters in there?

 

Alchemy, All pistons say "std", all valves say "Ford", not much of a wear mark ("ridge") at top of cyl.. It's a complete rotating short block.

 

What markings on top of the bellhousing? Does it have freeze plugs in the pan rails?

 

No soft plugs in that area, see pic of bell.

 

Yup, just a regular post war block that came in a big truck. Great start for a hot rod!

 

Has an aftermarket aluminum cam gear (orig is a fibre material), so guessing it was rebuilt at some point as it also has the access holes drilled to lock the lifters while adjusting the lash as @alchemy pointed out. My C69A truck block with factory relief. Lots of folks prefer the 59 series of blocks. Factory relief is debatable. Supposedly Ford added the relief to truck blocks to reduce compression to eliminate complaints of pre-detonation. However, hot rodders believe the relief improves flow and performance. Note the differences in the shapes of the water coolant openings in the middle of the block. There are differences, but cannot recall the significance of the differences. Mine is a Canadian block, and folk lore says the Canadian blocks had thicker walls and more nickel content.

 

Flatheads don't breathe very well. A lot of people point to their Siamesed center exhaust ports restricting their breathing out, but the real issue is breathing in. It's like going out for a jog and breathing in through a drinking straw and exhaling through a toilet paper tube. Not pique performance. Porting, and larger valves are a help as is relieving the block. Relief alone lowers compression by increasing the combustion area so you stick higher CR pistons in and deck the heads. I used blower heads from Navarro and still decked them a bit to dial it in. The ultimate prescription is a blower to force air into the cylinders, combined with some compression increase and bore that wakes them up and takes them from the jogging trail to the track meet.

I have never ran one but perhapse a Frenzel supercharger or the like would be fun on there. Not the boost of a big blower but it may run well on stock pistons and valves with that relief. Then find some good Canadian heads and laser engrave them. This makes my pants fit funny.

 

My '42 Mercury 239 engine was factory relieved. It came out of a Ford fire truck.

 

Zig, factory relief is proven, not debatable. The subject is a stock Ford factory relief. The shape of that relief is recognizable from twenty paces. And, no hot rodder worth his salt is going to grind in a relief that doesn’t go all the way to the gasket edge.

 

I think it is just the reflection, or my eyes, but the spark plugs look like little people. I swear I see faces on them.

That is just absolutely beautiful. I want to hang that on the wall and just look at it every day.

 

99/99A 39 Merc I believe was the first of the relieved blocks

 

Funny pants? Wait-What? What’s getting relieved? What was the question again?

 

I've had 2 NOS 59L blocks which was clearly marked on the back that had a slight factory relief. I ***umed they were military since they were coated in cosmoline and packed in wooden crates. I had both of them built by the local machine shop, one with dual 97's and one with a Road Runner Blower. The carburated 32 roadster sold to man from Japan and went to CA and the Vintage Hammer Garage where it was replaced with an Ardun. I always wondered if those guys had any idea what they had for a motor. The blown 32 roadster went to Portugal and disappeared. Both ran really well.

 

My '39 runs that same factory relieved block. Pretty sure the "59" is a '46-'48. Add a Merc crank for a longer stroke, a little overbore (if needed), a cam upgrade, adjustable lifters, aluminum heads & 3 carbs & we'll have twins.

 

[QUOTE=" Add a Merc crank for a longer stroke,
Wouldn't you have to change rods and pistons also, pin height on piston the same?

 

Do I have to list EVERYTHING?

 

It would be nice!

 

I always wondered curtain area of 1.5" valve lifted 3/8" versus chamber width and height if relieving actually helps. Is it a choke point?

 

The pistons are different, not the rods.

 

I have owned,traded,built many flatheads over a 60 year love affair with Henry’s finest. My last personal(for my use) was to ONLY RELIEVE the intake side and not the exhaust side. The intake relies on “suction” or vacuum and I believe it is beneficial to relieve that side .080-.120: whereas the exhaust side is expelled UNDER PRESSURE AND IS NOT THAT BENEFICIAL as the intake side. My last engine in my 32 Cab was a .080 over bore and a stock stroke(3 3/4) with a 350 lift cam and pulled 150 h p at the flywheel on the dyno. Flatheads Forever!!

 

Here is a good article from the Fat Spot on 59 series blocks.https://myflatheadford.com/differences-in-59-series-blocks/ I have been running a 59L engine for several years now. It appears to have been factory relieved.


https://myflatheadford.com/differences-in-59-series-blocks/

 

Just in case someone barks at me for hanging the motor on bell housing I thought I better post this picture with a proper mounting of the early flathead block on an engine stand

 

Here is another detailed article from the Flat Spot on Flathead identification.

https://myflatheadford.com/id-your-flathead-v8-block/