I bought another French Flatty.

Mart

Mart

Well-known member
A friend of mine here in the UK offered this French motor up for sale. I like the French motors, the one I have in my roadster is a great motor, went straight out to 3-5/16" no problem. This one was seized, unfortunately, with rust in one bore. But I guess that was why he decided to sell it.

I drove over (100 miles plus) and picked it up along with some other goodies.

Got it home and couldn't resist having a look at what was going on. I put a tyre lever against the ring gear (pan was off) and while it wouldn't turn, I could feel movement on most of the other pistons (very slight). I backed off the rod cap on the stuck one and tried to move the crank again, away from the stuck rod. It moved. I moved it back and forth a bit and left the crank with some play on the stuck piston.

I had applied some 50/50 atf/acetone mix and he had been dosing it with diesel for weeks. I tried knocking on the stuck piston with a lump of soft wood, and lo and behold it moved!

I stopped messing around and got it onto the engine stand. I stripped out all the pistons and rods and had a good look at the problem cylinder.

Well, unfortunately it is too bad to just free off the rings and try running it. It is quite badly pitted.

Anyhow, when I bought it I fully intended to just bore it out to 3-5/16". I already have the pistons and rings.

I envisage it being a nice 4" stroke motor for my 33 coupe, to take the place of the 21 studder in there now.

Obviously without pics it didn't happen, so just to prove it did happen, here are the pics.

ff201_zps509d75ab.jpg

Water pumps are 59A style, just scrap parts for mockup.

ff202_zps329b1977.jpg

The French motors have a great deal of extra gubbinry on the back, most of which can be taken off. The casting dates from 1967.

ff203_zpsecb77fc4.jpg

Here's the problem cylinder. Pitting is quite deep, about .010" as far as I could measure. After seeing the pic I want to have a closer look at that valve and seat. None of the valves are stuck, though, once the pistons were out the crank, cam and valves all spun over freely.

I have put it on the backburner for now, as I have a few other things to do before I can get to it. By then I will have decided whether to bang it straight out to 3-5/16", go for an intermediate rebore size, .080" possibly, or look at getting the problem bore sleeved back to .030", the size of the other bores. All the other bores and the pistons look great. It was probably running great with low miles on the rebuild when it was last run. The water damage must have happened due to poor storage.

Just wanted to share.

Mart.
 
Last edited:
Looks like a great place to start! What mounts above the oil pump, is that for a full-flow setup?
 
Man I love them french flattys, one day I hope before they are all gone I will own one .I may have to win the lottery first tho!
 
SUMB trucks have a governor pad back there. I've seen a lot of them milled off then grit blasted to look like rough cast. You can barely tell it was ever there.
 
What is the huge bulge on the front of the block and sump area for.?? Kind of makes it look like a front wheel drive trans mount ? So obviously the French blocks SOCAL are selling are different and more like a regular flathead it'd you take away the governor boss etc.
 
I would not sleeve it . as once sleeved the bore wont allow
For a 3 5/16 bore

If you are on a budget, bore one hole 0.045 or 0.06 oversize
And bring the bigger piston weight down to your 0.03 piston
I did that twice and both engines are still running
 
it's simca marmon engine ( 4.2l ) the SUMB ( simca unic marmon bocquet) is a litle 4 x4 military truck . I rebuilt some and i found engine parts to CG and red rods parts .
 
The motor is from the heavier duty SUMB military vehicle. The sump pan is the correct type for this motor, it has a steel pressed pan bolted to the bottom of the aluminium pan normally. the alloy sump pan is handy for storing a block with the steel part removed. I'll probably end up cloning my other french motor, but using the isky cam etc I just took out of the other motor. The block is the same as SoCal (or whoever it is now) are selling.

The block is like a 59A at the back and an 8BA at the front. mains are 59A style, Cam gear thrusts like a 59A, even though the timing cover has a thrust button.

The valve bowls have cast in restrictors which need hogging out to make it breathe a bit better.

Mart.
 
years ago I bought a new unused "frog in a bell" the bell being the huge iron container,a lovely bit of kit and everything was painted matt black and every now and then I would put the hoist on the top of the bell and lift it so I could have a look,i had it for a few years and it looked as if it would never be used by me and took up a lot of room in the corner of my garage so it sold (very well) on ebay,now in a 52 f1 apparently , Jim.
 
Lots of long outlet pumps in England, single belt bush type And double belt sealed bearing type.I've seen them on pilot engines, army stuff and Thames trucks.
Martin.
 
Graeme / New Zealand said:
That's a long outlet on the RH water pump. Why is that?

GB
Click to expand...

Sorry, Graeme, haven't a clue. The water pumps are scrap items just used by the previous owner for mockup. I'll have a look to see if there is a casting number. That might point in the right direction. The pumps are not the French military ones.

Here's what a SUMB looks like

marmon3.jpg


Mart.
 
I have a couple of french flatties still for sale, just in case ;-)

At the moment one 255ci and one 239ci
 

Attachments

  • P1000046.jpg
    P1000046.jpg
    88.5 KB · Views: 116
  • P1000051.jpg
    P1000051.jpg
    55.2 KB · Views: 114
Go to the 3 5/16, those 258 run very well. My favorite engine. Find aset od EAB heads and mill for .050" piston to head clearance and you'll have the best engine in the UK.
Good luck.
 
You must log in or register to reply here.
Back
Top