Ficht 800 DI Vs. 700 Marine Single Carb - Block Information

[NCJ0N]

I'm not sure about rod length crank center line to wrist pin center line. The wrist pin is 2mm larger,so its bore will naturally be lower.

Here are some measurements to help get our heads wrapped around this, however I want to clarify that my build, while it will be carbbed, is 100% DI BLOCK, including the jugs, and will have custom heads/caps to accommodate clearance issues. As far as I know the DI Pistons top out even in the DI Block and there will be minimal clearancing, if any. In fact I'm hoping for super high compression from a ultra tight fit and all of the combustion taking place in the cup of the head cap.

Back to measurements...
Here I have the two cranks side by side. In this you can understand that the wrist pin bore is not "naturally" lower, it is purposefully bored where it need to be on special length rods to accommodate a taller piston. Note the visibly thicker top wall of the bore. I am not calling you wrong, there is 1mm further travel in the end....


And here I will show measurement from crank lobe top to top of wrist pin bore...

Bore diameter for DI


And the carbed version

Bore diameter for carb 700 Marine



After reviewing all the measurements one can conclude the DI cranks the piston 1mm further than the carbed ski but this should be mitigated by the slightly longer jug... We will see

Update: is my belief that the rod must sit slightly higher into the piston because both pistons will top out perfectly even with the cylinder...IE the centerline hole bored in the piston must be slightly higher on a DI piston. Measurements to come...

One thing that can be concluded right now is that the bottom-case half as well as the cylinder jugs are 100% compatible between carbs and direct-injected models. Although as mentioned above it's never wise to mismatched case halves

[NCJ0N]

Got these today...


After attaching the bearings, pins, and pistons I can 100% confirm that I can bore any jug from my inventory.
For my purposes I will likely bore the original 800 sleeves just to create less work for my machine shop and the 700 sleeves being smaller give me a wider range of re-use later.

Now that I have the pistons in hand I will get the sleeves out this week... I also believe I will mount the lower block back to the ski and do final assembly in place thus clearing up room in my shop.