10-23-2016, 08:33 AM
Mc101 AA Question
John Poffenbaugh
I have a 101 AA I think. It has a recessed head gasket seat and a flat exhaust surface. Other than that it is like our 101 B. I have measured the ports and they appear to have been changed some. Would like to know if this block will be a decent runner or temperamental and not worth re-building.
All dimensions from recessed head gasket seat area
EX port is .020 higher and .020 lower than standard
1.065 top 1.787 bottom
INT All 6 round ports 1.424 tops down from seat
2 finger ports 1.435 tops down from seat
Block has cleaned up at 2.319 bore and is straight. Probably .002 more and it will be ready to use
Questions:
Is there a piston out there that is +.035 or +.040 0ver or do I need to go to +.050? Really like to not to go to +.050 if possible.
Is porting o.k. to use? This came from a local racing family that did well but I don't have any history on this block. Has some chain rash and ex port surface where gasket sits is a little rough but I can deal with that.
What is the sealer used over the freeze plugs for the ports?
Do all 101's from A to MC have the same crank PTO to Flywheel side dimensions(between the bearings) so that cranks interchange?
What is the standard/acceptable OD of the crank pin for the rod journal and also the ID of the crankpin area of the rod?
Who would have a piston for this block?
I have rebuilt several of these but not where I have had to sort through parts I have on hand and want to be sure not to use the wrong stuff.
Sorry about the number of questions in this post but I figured it would be better than several posts. Thanks in advance for any help.
John
Steve Ohara
The porting is fine and will run good.
Terry Ives is the man with the pistons you need.
The A, A/A, B, D and M/C Blocks are all basically the same part with minor variations so the cranks will interchange. There are only two version of the crank that fit and the only difference is the PTO end... the B came with no key and left hand threads, the previous versions had a key and right hand threads. There is also a saw crank that fits with bolt on counterweights.
Big end rod ID NOS is .822, they are safe to use up to .824 for casual use but for all out racing .824 will not last long.
The crank journal NOS dimension is .629/.630 if the journal is worn to under .628 it will wear out fast under heavy use. Don't use a worn rod and crank together.
NOS clearance between the rod and the crank is .822-.630= .192 and the needles are .0945 so the assembly already has a lot of internal clearance when all the parts are new.. around .003/.004".
If you use a worn rod that is .824 with a NOS crank the internal clearance grows by 50% or more.
If you use a worn .824 rod and a .628 crank the internal clearance doubles and the assembly becomes a slide hammer at TDC on every stroke.... won't last long.
Steve O'Hara
John Poffenbaugh
We have 4 Mc rods in the accompanying picture. Top one is .100" longer. All measurements are between bottom of wrist pin hole to top of crankpin/needle hole the way the Mc engine specs sheet shows. Lengths as follow:
Top pic 2.063"
g0ld color 1.960"
Gray color 1.963"
g0ld color 1.963"
The bottom three are 101 rods but what is the top rod? Stroker? Other engine?
What does the g0ld color signify if anything?
I asked this in my block questions but what is the acceptable OD of the needle area so the needles stay put?
Anything else you might care to add. These appear to be decent shape and don't seem to be bent. I know I need to use new cap bolts also.
Thanks in advance for any help or info.
John
![[Image: attachment.php?id=13166]](http://www.vintagekarts.com/forum/attachment.php?id=13166)
Steve Ohara
Top rod is Mc 70 if there is no slot in the cap.
If it has the slot in the cap then it is a Mc75/100/first generation 101.
It should have a 9/16" hole for the wrist pin rather than the 1/2" in the others.
Steve O'Hara
John Poffenbaugh
I have a 101 AA I think. It has a recessed head gasket seat and a flat exhaust surface. Other than that it is like our 101 B. I have measured the ports and they appear to have been changed some. Would like to know if this block will be a decent runner or temperamental and not worth re-building.
All dimensions from recessed head gasket seat area
EX port is .020 higher and .020 lower than standard
1.065 top 1.787 bottom
INT All 6 round ports 1.424 tops down from seat
2 finger ports 1.435 tops down from seat
Block has cleaned up at 2.319 bore and is straight. Probably .002 more and it will be ready to use
Questions:
Is there a piston out there that is +.035 or +.040 0ver or do I need to go to +.050? Really like to not to go to +.050 if possible.
Is porting o.k. to use? This came from a local racing family that did well but I don't have any history on this block. Has some chain rash and ex port surface where gasket sits is a little rough but I can deal with that.
What is the sealer used over the freeze plugs for the ports?
Do all 101's from A to MC have the same crank PTO to Flywheel side dimensions(between the bearings) so that cranks interchange?
What is the standard/acceptable OD of the crank pin for the rod journal and also the ID of the crankpin area of the rod?
Who would have a piston for this block?
I have rebuilt several of these but not where I have had to sort through parts I have on hand and want to be sure not to use the wrong stuff.
Sorry about the number of questions in this post but I figured it would be better than several posts. Thanks in advance for any help.
John
Steve Ohara
The porting is fine and will run good.
Terry Ives is the man with the pistons you need.
The A, A/A, B, D and M/C Blocks are all basically the same part with minor variations so the cranks will interchange. There are only two version of the crank that fit and the only difference is the PTO end... the B came with no key and left hand threads, the previous versions had a key and right hand threads. There is also a saw crank that fits with bolt on counterweights.
Big end rod ID NOS is .822, they are safe to use up to .824 for casual use but for all out racing .824 will not last long.
The crank journal NOS dimension is .629/.630 if the journal is worn to under .628 it will wear out fast under heavy use. Don't use a worn rod and crank together.
NOS clearance between the rod and the crank is .822-.630= .192 and the needles are .0945 so the assembly already has a lot of internal clearance when all the parts are new.. around .003/.004".
If you use a worn rod that is .824 with a NOS crank the internal clearance grows by 50% or more.
If you use a worn .824 rod and a .628 crank the internal clearance doubles and the assembly becomes a slide hammer at TDC on every stroke.... won't last long.
Steve O'Hara
John Poffenbaugh
We have 4 Mc rods in the accompanying picture. Top one is .100" longer. All measurements are between bottom of wrist pin hole to top of crankpin/needle hole the way the Mc engine specs sheet shows. Lengths as follow:
Top pic 2.063"
g0ld color 1.960"
Gray color 1.963"
g0ld color 1.963"
The bottom three are 101 rods but what is the top rod? Stroker? Other engine?
What does the g0ld color signify if anything?
I asked this in my block questions but what is the acceptable OD of the needle area so the needles stay put?
Anything else you might care to add. These appear to be decent shape and don't seem to be bent. I know I need to use new cap bolts also.
Thanks in advance for any help or info.
John
Steve Ohara
Top rod is Mc 70 if there is no slot in the cap.
If it has the slot in the cap then it is a Mc75/100/first generation 101.
It should have a 9/16" hole for the wrist pin rather than the 1/2" in the others.
Steve O'Hara