- Joined
- Oct 31, 2009
- Messages
- 5,193
Referring to an earlier topic titled “Crankcase superblends revisited” I had mentioned that I was receiving a crankcase set and that I was going to report on my finding. I have finally received the set with some interesting findings. They are mid to late 72 reinforced cases with superblends.
1. The superblend bearings have 1 dot. 1 dot clearance
2. I could be all wet on this but it appears that the cases have been machined with a raised area to receive the superblend. No shims needed? I do not see this in older cases. I would like to know what the dimension is for a older case from base to lip of bearing area. .015 per side
3. There is an additional grub screw adjacent of the sump hole. This was very handy when needing to remove shrapnel. Again, not seen in older cases.
This stuff is ferrous (oil ring). Found in breather cavity and oil channels.
This stuff is piston. Found everywhere, especially oil channels.
1/2 of all this stuff combined was dug from the oil holes and channels.
This opens all sort of questions. The biggest being, what was the true intention of these cases. I presume a racing intent. My opinion is that any maintenance should be concise and complete. Anybody doing a top end has to have concerns.
Another question is how many rebuilds have quickly self destructed due to oil channel obstructions. I am sure the pro’s are aware of this, but many are done by capable amateurs, myself included, who just don’t go far enough.
I know the reinforced cases came around 260000 to 280000 and suberblends around 211xxx, yet this set 2105xx has been machined to take the superblend bearing without shims. Again, I could be wrong about this. It is also said the 230xxx was the last 750 but I have a tranny that is 235xxx. I think that these numbers originated from a best guess at best.
Anyhow, I have a nice set of cases to prepare for next winters revisions.
1. The superblend bearings have 1 dot. 1 dot clearance
2. I could be all wet on this but it appears that the cases have been machined with a raised area to receive the superblend. No shims needed? I do not see this in older cases. I would like to know what the dimension is for a older case from base to lip of bearing area. .015 per side
3. There is an additional grub screw adjacent of the sump hole. This was very handy when needing to remove shrapnel. Again, not seen in older cases.
This stuff is ferrous (oil ring). Found in breather cavity and oil channels.
This stuff is piston. Found everywhere, especially oil channels.
1/2 of all this stuff combined was dug from the oil holes and channels.
This opens all sort of questions. The biggest being, what was the true intention of these cases. I presume a racing intent. My opinion is that any maintenance should be concise and complete. Anybody doing a top end has to have concerns.
Another question is how many rebuilds have quickly self destructed due to oil channel obstructions. I am sure the pro’s are aware of this, but many are done by capable amateurs, myself included, who just don’t go far enough.
I know the reinforced cases came around 260000 to 280000 and suberblends around 211xxx, yet this set 2105xx has been machined to take the superblend bearing without shims. Again, I could be wrong about this. It is also said the 230xxx was the last 750 but I have a tranny that is 235xxx. I think that these numbers originated from a best guess at best.
Anyhow, I have a nice set of cases to prepare for next winters revisions.
