365 or 400 engine? F101 . C001

it is a beautiful car. Use it in good health. Always

 

I've been told that matching numbers stopped in the early 70's. How early? I don't know...there is supposed to be a record at the factory of the engine # that was in your car at production.
400 engines share nearly every part with the 365 and I don't know of any external clues.

 

The 400 engines are F101C and the 365 GT4 2+2 engines are F101AC ? At least that was what I thought

 

Scott,
Looking into my database, your engine would likely have come from a 400 built in late 1977. As an example, s/n 22505 had engine number 169 and 22517 engine number 180.
As to the original engine number, s/n 18013 had #F101AC00100904 so yours would likely have been in the F101AC001009XX range.
Hope this helps. David

 

My 400 is chassis 21557 and has it's original engine, number F101.C001.00101. The car is dated by Ferrari as May 1977 in the Heritage Certificate they issued al long time ago when you could still get these.

 

Scott,

As to what I know 365 GT4 2+2 first two production years 1972-73 had 340HP/6800rpm and 422Nm/322ft-lb at 4600rpm. 1974/75/76 had 320HP/6200rpm and 432Nm/319ft-lb at 4200rpm.

So in Your case the 400 engine would give a a 20HP advantage and 39Nm/28ft-lb over the stock engine. I would sacrifice that gladly to have the original engine back ;-) Like You said,one could wonder why the engine left the car at so low milage. Likely something serious happened as mechanical failure or out of oil.

Could be a entertaining anecdote if You where to pursue its history.

Arvid

 

No, the engine number was never the same as the chassis number, but it does appear that vehicle licensing authorities often make this mistake. In the UK, most 365s and 400s have the serial number recorded for engine number by the authorities.

 

Scott, there is no doubt that the engine number in your photo is a 400 carby number. (actually, it is 21 before my carby 400 number).

365 and 400 engines actually use the same pistons, conrods and cylinder heads (400I heads are different), but the 400 block is taller to account for the extra stoke plus an extra amount to keep the compression ratio at 8.8:1. When you look into a 400 cylinder, the pistons stop well short of the top of the block at TDC. Without actually measuring, we can guess that the difference in block height between a 365 and a 400 is maybe 5-10mm (3.5mm plus delta). If we could be bothered, we could accurately measure the difference in the distance between the heads on each version and use trigonometry to actually calculate the difference in block height. It is simply not feasible to deck a 400 block back to 365 height.

A 365 crank will fit in a 400 block but the pistons would stop 3.5mm further down the block than with a 400 crank (in the same block). So with the same pistons, the compression ratio would be significantly lower than 8.8:1 - maybe as low as 5 or 6 to 1. This would mean that developed horsepower would be around 200HP - maybe lower.

So, the bottom line is that you had better hope that the stroke of your 400 engine is actually 78mm or you will not be winning any traffic light drag races!

Regards

WM

 

I think the 365 pistons have 3 rings while the 400 pistons have 4 rings.

 

That's correct, but the geometry is the same - also the same rod and piston geometry as a 308.

The same pistons are used in 365's and 400's to get to 10.5:1 CR

WM

 

Would a 365 crankshaft - presumably delivering a 71mm stroke - installed in a 400 block produce the specified 8.8:1 compression ratio if connecting rods and/or pistons were properly selected (to be "longer" than originals of a F101 AC engine)?

The other item is about the webers. On a F101 AC engine the webers are theoretically 38 DCOE 59/60 and on a F101 C engine the webers are theoretically 38 DCOE 110/111.

 

As you say, either bespoke rods or pistons (or both), dimensioned to put the piston crown at the original 365 deck height, would give the original CR. It's only in recent years that these parts have become relatively cheap to make with modern NC equipment and there are a number of small details that would need to be sorted out.

Actually,400 engines in 365s are more common than you would first think. There are at least 2 C4s and 2 GT4 2+2s with 400 engines that have surfaced in the last couple of years. It's not so long ago that you could buy a rusty run down 400 Auto with a good complete engine for a lot less than the cost of a 365 engine rebuild.

Some years ago, the Australian Ferrari importer sold off a number of brand new 400I (and 308) crate engines as surplus stock. One was fitted to one of the nicest local 365s which was burning oil. That's a much trickier retrofit than a 400 carby engine, but it was logical in the context of the times and the cost of an engine rebuild. Nobody cared about matching numbers in years gone by.

Times change.

WM

 

So if a 400 has a taller deck height, bigger block, than a 365 then the engine should also be wider than a 365 and the valley (where the oil filters are) should also be wider on a 400. Maybe some of you guys can take some accurate measurements of your engines widths and then compare. I'd measure my 365 but am out of town for a couple of weeks. I'd be glad to check it out when I get home.

 

It is quite difficult to find a place to measure in a car because of all the other stuff in the valley. Anyway, I just just measured the difference as just under 4mm at the top machined face of the heads. Since the v angle is 60 degrees, the deck height difference is the same, so about 3-4mm.

WM

 

Scott,

The Eng. No. is absolutely a 400 carby number - there is no doubt about this.

You are sure that the stroke is 71mm and that the car arrived in the U.S. with the engine that we are discussing.

There are 3 possibilities;

1. During 400 carby production, the factory found an un-numbered 365 engine on the shelf, numbered it as a 400 engine and shipped it out the door in a '77 400. At some time later, someone took this engine from the 400 and, by a miracle of circumstances, it found its way into your 365.

2. Some guys in Lebanon built a hybrid 365/400 engine using some specially made parts including at the very least, a set of longer con rods (maybe out of cedar?).

3. The stroke is really 78mm and you have a good 400 engine in a very nice 365.

If 2 is what really happened, it would make the car worth a lot less than a 365 with an original 400 engine since it would require a lot of non-original parts and it is not possible to know what work was done (or how well).

I know what I would be hoping for (and what I would be checking again).

WM

 

512 boxer has a longer stroke than a 365, same deck height. Same for a 308-328-348 and so on, same deck heights as each other. Wrist pin location changes in the piston, rod stays the same center to center, rod ratio changes.

Why not look up a gasket for a timing cover and see if the part number interchanges 365 to 400? That will tell you if the deck height is the same. The timing cover itself might even share the same part number.

 

Scott,

Another lead to the puzzle is what Rovexienus mentioned earlier. The Webers are different between the 365 and 400. They are both 38DCOE but 365 uses 59/60 and the 400 has 110/111. Should be easy to check as this is visible on top of carbs.