Originally Posted by
Yellowjacket
Don't know how the 25's were built. The change in rod clearances on the four cylinder engines coincided with a change in crankshafts and other changes to the top of the motor. Not sure if they ever tightened up the clearances on the two cylinder motors. The change was made to make the 4 cyl engine more quiet. Probably more important on the bigger motor and not such a big deal for a smaller motor. At that point they weren't racing the 44 and it was probably more important to have the customer feel that he had a quiet and smooth engine as opposed to making a few racers happy.
Just a thought, I really don't know, you would have to ask someone who is building the 2 cyl motors to find out. There is also a reference to this problem in Harry Brinkman's notes on building the 44 for and he states that you need to open the rod clearance on the stock 44xs as well as engines running higher rpms in modified racing so I am sure it is real. I was corresponding with Jerry Wienandt (Trident Racing) and he is the one who recommended that I use an RPM limit of 6,000 for my 1977 stock Merc 500 until I get the rods opened up. Jerry is an expert, when experts talk I listen.