771M v 711M Swap

[beachguy12]

Thought I'd treat my 78 Crossle to something nice instead of reused or recycled. So I bought a fresh Ford 1600 motor from a reputable third party that had been rebuilt with all the good stuff by a major builder. I figured I could swap motors over a weekend and be ready for a race in a couple weeks. When I uncrated the motor I found it was a 771M block. Never crossed my mind to ask the seller about this little technicality (er, duh?).

I am now curious about what I am going to have to do to fit this into my Crossle:

Are the motor mount bosses the same height and location as on a 711M? Or will the motor be further fore/aft then the 711M? Will my motor mount locate the motor in the correct position?

With only two motor mount bosses on the right (oil pump) side I need to pick-up some other locations to secure the motor. Where is the best spot(s)? (Neil Porter feels more than two bolt locations are needed but not sure what pick-up points to use.)

Any mods needed for the bell housing or starter for correct engagement?

Any other pitfalls that I have over-looked that need addressed?

[Malfred]

I think that is a good question. 771M block ? instead of the usual 711 M ?

Maybe the block is a Fiesta Block ? Or possibly a Fork lift engine block ?

Does any one out there know for sure what the different block comes out of ?

Any Ideas on Motor mount security with only 2 bolts on Oil pump side of the engine ?

Hope some one has some answers ?

Inquiring minds want to know ?

m.

[rv greg]

Its a Fiesta block. Not vintage legal. I am not sure about club ford.
http://www.apexspeed.com/forums/showthread.php?t=52251

[scorp997]

The 771M is indeed a Fiesta motor. IIRC the Fiesta block is a legal replacement in SCCA, especially now that the 'new' blocks are available (and better).. Overall size is identical to the 711M with the exception of the side mounts, water pump bolt (one has to be relocated) and the timing area has additional mounting flange/holes. The difference in length is in the timing and rear covers, front pulleys (you don't use those anyway), flywheel is stepped further back towards the motor (again, not used) and the 771M crank has an approx 3/16" step on the flywheel mounting face (aligns the flywheel). most people don't use the stock crank on a rebuild for an FF... Once you use all of the other FF bits (crank, pulleys, flywheel, etc) there is not much, but if you do you need a spacer ring 'Fiesta' left and the modifications to fit are minor - assuming the side mounts fit your application.

I have several Fiesta blocks (both 2 and 4 bolt side mounts) in my garage. If your car uses the side mounts as the main means of support, I don't think there is a good solution to the 2 mount block. I looked at that a while ago and found that most of the decent places to attach a mount to were inline and the oil pump really gets in the way.. I think you are out of luck fitting this in your Crossle. If you find a solution, please make sure and post it.

[beachguy12]

Has anyone acutally installed the two bolt mount Fiesta block? Have there been any kind of mount failures? What was the mode of failure?

After several discussions with some of the aero mechanical engineers here at work (who are also fellow gearheads) they agree the two mount bosses on the right side of the block should be fine to support the block, as long as the motor mount is designed to prevent 'deflection in the cantilever moment of loading with possible resultant failure of the motor mount'. Or more simply, the right side motor mount has to be desiged to take the vertical loading.

Between the aero engineers and my prototyping machine shop manager we have a mount concept but need to know what has been tried, what has worked, and what has failed.

[beachguy12]

No installations of the two bolt Fiesta block???

[provamo]

just saying.......................in the history of Ford based four cylinder formula car racing how many racing miles have been logged where at the end of the "session" one finds a loose/broken/or missing bolt motor mount bolt?

probably enough that might lead to speculation that a two bolt installation would not be the end of the world!