ausmini :: View topic

Just a couple of questions about below conrods.

1. Are they S conrods?
2. Why has the one on the right no groove machined into the cap?
3. Are the nuts on the bolts the wrong ones?
4. Should the rod bolts be changed with a rebuild anyway?

If everything checks out I won't be using the pistons.

5. Would good .040"1275 pistons with 'new'rings be worth anything?

dalmeny wrote:

1. yes, AEG521, same as 1100S

2. the grooves machined in the caps are from balancing, are those rods a 'set'? they should be all the same weight
3. don't think so, but at least one is damaged, see 4.
4. yeah, and the rods 'resized' by the machine shop
5. not once they've been removed from the rods, the pistons are usually destroyed in the process. The gudgeons are pressed out, and the pistons get crushed

That is pretty common, they are 40 years old and accidents happen.
They don't need to be a `matched set from 40 years ago' as long as the weights are equal and they are straight (check this!).
My 1412 stroker has 3 rods out of a Victorian 1100S motor that broke the crank and buggered the 4th, and my 4th rod I bought elsewhere.

If you have a big journal crank handy, sure, a stroke job gives better torque from the extra 50 or so cc.
But by the time you buy a 12G1505 crank, get it crack tested, stroked and reground, get it wedged for smoother running, and balanced, it will cost you a chunk more do$h.

If you already have a small journal crank to go with those S rods I'd use it and save your $$$.
My 1360 (S crank) has more HP than my 1412 stroker (but it's got a bigger cam to get it, and it's all from 5000rpm up).

Are you sure "S" rods are the same as 1100S Rods? Aren't the big ends a different diameter? I was under the impression you can use "S" rods on a 1100S crank,once stroked,but not ,vice versa.

Author:	dalmeny [ Sat Jun 02, 2012 5:20 pm ]
Post subject:	S Conrods
Just a couple of questions about below conrods. 1. Are they S conrods? 2. Why has the one on the right no groove machined into the cap? 3. Are the nuts on the bolts the wrong ones? 4. Should the rod bolts be changed with a rebuild anyway? If everything checks out I won't be using the pistons. 5. Would good .040"1275 pistons with 'new'rings be worth anything?

Author:	simon k [ Sat Jun 02, 2012 5:36 pm ]
Post subject:	Re: S Conrods
dalmeny wrote: Just a couple of questions about below conrods. 1. Are they S conrods? 2. Why has the one on the right no groove machined into the cap? 3. Are the nuts on the bolts the wrong ones? 4. Should the rod bolts be changed with a rebuild anyway? If everything checks out I won't be using the pistons. 5. Would good .040"1275 pistons with 'new'rings be worth anything? 1. yes, AEG521, same as 1100S 2. the grooves machined in the caps are from balancing, are those rods a 'set'? they should be all the same weight 3. don't think so, but at least one is damaged, see 4. 4. yeah, and the rods 'resized' by the machine shop 5. not once they've been removed from the rods, the pistons are usually destroyed in the process. The gudgeons are pressed out, and the pistons get crushed

Author:	michaelb [ Sat Jun 02, 2012 6:39 pm ]
Post subject:
Yes I would not be happy with the fourth rod I would get them weighed to make sure they are all the same weight

Author:	drmini in aust [ Sat Jun 02, 2012 6:45 pm ]
Post subject:
Simon If the guy pressing the pistons off (eg GR) knows what he's doing the pistons won't get crushed. The bottom pad under the piston just has to match the piston shape or curvature accurately. I've built a few 1275 engines with s/h pistons, the last one (my 1412) has 4 hr old Hypatecs, my 1310 had s/h Mahle forged flat tops. Not all the AEG521 rods got the groove cut in the cap (only Mk2s I think?), I just built a 1377 with rods looking like yours. I balanced them all to within 1gm, and the plain one needed a bit out of the cap to make it equal. [edit] typo

Author:	dalmeny [ Sat Jun 02, 2012 6:50 pm ]
Post subject:	Re: S Conrods
simon k wrote: dalmeny wrote: Just a couple of questions about below conrods. 1. Are they S conrods? 2. Why has the one on the right no groove machined into the cap? 3. Are the nuts on the bolts the wrong ones? 4. Should the rod bolts be changed with a rebuild anyway? If everything checks out I won't be using the pistons. 5. Would good .040"1275 pistons with 'new'rings be worth anything? 1. yes, AEG521, same as 1100S 2. the grooves machined in the caps are from balancing, are those rods a 'set'? they should be all the same weight 3. don't think so, but at least one is damaged, see 4. 4. yeah, and the rods 'resized' by the machine shop 5. not once they've been removed from the rods, the pistons are usually destroyed in the process. The gudgeons are pressed out, and the pistons get crushed Thanks Simon They came with the block but disassembled. Also noticed that the marks that identify the cap to the rod (cetre punch marks) were 2, 3 and 2x 4's. Which is looking like one rod is not part of the original set. Thanks

ausmini https://www.ausmini.com/forums/

S Conrods https://www.ausmini.com/forums/viewtopic.php?f=2&t=77031	Page 1 of 2

Author:	drmini in aust [ Sat Jun 02, 2012 7:23 pm ]
Post subject:
That is pretty common, they are 40 years old and accidents happen. They don't need to be a `matched set from 40 years ago' as long as the weights are equal and they are straight (check this!). My 1412 stroker has 3 rods out of a Victorian 1100S motor that broke the crank and buggered the 4th, and my 4th rod I bought elsewhere. [edit] Bin all those old rod bolts and fit a nice new set of ARP ones. I fit ARP `Big Block Ford' bolts because they are ~1/2 the price of Cooper S ones (no S tax) and you get 16 in a set, not 8. p/no is 155-6002. Same material and heat treatment.

Author:	dalmeny [ Sat Jun 02, 2012 7:47 pm ]
Post subject:
drmini in aust wrote: That is pretty common, they are 40 years old and accidents happen. They don't need to be a `matched set from 40 years ago' as long as the weights are equal and they are straight (check this!). My 1412 stroker has 3 rods out of a Victorian 1100S motor that broke the crank and buggered the 4th, and my 4th rod I bought elsewhere. Thanks That's reassuring. I will be getting them all checked for straightness and balanced. I was hoping someone wasn't going to say the odd one could be a different length. btw, if I'm going for a 1360 is stroking of any benefit for a fast road car? And thanks for the bolt tip. Steve

Author:	drmini in aust [ Sat Jun 02, 2012 8:09 pm ]
Post subject:
If you have a big journal crank handy, sure, a stroke job gives better torque from the extra 50 or so cc. But by the time you buy a 12G1505 crank, get it crack tested, stroked and reground, get it wedged for smoother running, and balanced, it will cost you a chunk more do$h. If you already have a small journal crank to go with those S rods I'd use it and save your $$$. My 1360 (S crank) has more HP than my 1412 stroker (but it's got a bigger cam to get it, and it's all from 5000rpm up).

Author:	dalmeny [ Sat Jun 02, 2012 9:31 pm ]
Post subject:
drmini in aust wrote: If you have a big journal crank handy, sure, a stroke job gives better torque from the extra 50 or so cc. But by the time you buy a 12G1505 crank, get it crack tested, stroked and reground, get it wedged for smoother running, and balanced, it will cost you a chunk more do$h. If you already have a small journal crank to go with those S rods I'd use it and save your $$$. My 1360 (S crank) has more HP than my 1412 stroker (but it's got a bigger cam to get it, and it's all from 5000rpm up). Yeah, the S crank has been xrayed and all is good. Just making sure everything is right before I start the build. Don't want too many nasty suprises.

Author:	origmini [ Sun Jun 03, 2012 7:34 am ]
Post subject:	Rods
Are you sure "S" rods are the same as 1100S Rods? Aren't the big ends a different diameter? I was under the impression you can use "S" rods on a 1100S crank,once stroked,but not ,vice versa.

Author:	dodge [ Sun Jun 03, 2012 9:07 am ]
Post subject:
use this to check what size crank u have http://www.minimania.com/web/SCatagory/ ... ticleV.cfm

Author:	dodge [ Sun Jun 03, 2012 9:10 am ]
Post subject:
copy and paste that entire link ok

Author:	drmini in aust [ Sun Jun 03, 2012 9:55 am ]
Post subject:	Re: Rods
origmini wrote: Are you sure "S" rods are the same as 1100S Rods? Aren't the big ends a different diameter? I was under the impression you can use "S" rods on a 1100S crank,once stroked,but not ,vice versa. S rods are the same as EARLY 1100S rods. The changeover for cranks small J/ large J is 12YD/Ta/H10487 12YD/Ta/H10488 Then, the 1100S motors went to the big journal crank and HEAVY 1100S/1275LS etc rods with the big lumps on the caps. As you say, if you stroke these B/J cranks then you want some S rods (but they have to be narrowed ~1/32" to fit in the reground crank).

Author:	TK [ Sun Jun 03, 2012 9:59 am ]
Post subject:
They were used in some 1100S engines, most got the heavy large journal rods. 1275 'small' rods are: 177 - early Cooper S 625 - Midget/Sprite 521 - some 1100S and Cooper S

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Author:	drmini in aust [ Sun Jun 03, 2012 10:06 am ]
Post subject:
Most 1275S rods were 521, only early ones got the 177 (aka 1071S rods). Midget 1275 rods were AEG624 not 625, hardly ever see them about though as not many were sold here. They are dimensionally same as a 521 rod (but slightly lower material spec).