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| Stroker Crank https://ausmini.com/forums/viewtopic.php?f=5&t=17512 |
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| Author: | kartbro [ Fri Mar 24, 2006 4:32 pm ] |
| Post subject: | Stroker Crank |
Ok guys I got the large journal crank outta my 1275 block, Chong mentioned stroking it, which I gathered would be by an offset crank grind back to the smaller journal size. Am I right? What rods would be suitable for this? I heard some honda rod works.... No more info on that though. Im boring to the 1360 size what capacity will that give me? I might as well get this done while im grinding the crank. Nathan |
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| Author: | Mini Mad [ Fri Mar 24, 2006 4:57 pm ] |
| Post subject: | |
You will need S rods if you stroke the crank. Many LJ cranks don't stroke too well though...and many break..especially if you get a bit rev happy.. |
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| Author: | dodge [ Fri Mar 24, 2006 5:13 pm ] |
| Post subject: | |
and hit mat up for some 80 under bearings. I have S rods for sale . |
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| Author: | drmini in aust [ Fri Mar 24, 2006 6:21 pm ] |
| Post subject: | |
If you offset grind (stroke) it from std 1.750" to std 1.625" dia pins, you should get ~84.3mm stroke out of it. That will take it from 1360cc (with 73.0mm pistons) to 1412. 
but crack test it first- many of these big J cranks seem to be cracked now. 
re the -.080" bearings (lets you stroke further), they are dodo dung now. Matt is trying to scare some up on the MM board. I wish him luck..... 
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| Author: | TheMiniMan [ Sat Mar 25, 2006 9:57 am ] |
| Post subject: | |
yeah, don`t listen to Dodge, the .080 undersize bearings are for a very long stroke 1510cc engine i`ve had for years you`re building a 1412cc & they`re a GREAT engine If you havn`t started the stroking process yet then PM me as i can take you through what we do to them , it`s a little more costly (not buy much) but makes them a much stronger ccrank,,,provided they`re not allready cracked "DIIIIIIIIIIIIIIIIIIIINNNNNNNNNNNNNGGGGGGGGGGGGGggggggggggggg" or "Clunk" test them first, then send off the best "DDDDDIIIIIINNNNNNNGGGGgggg" sounding one to the crack testers & then PM or e-mail or ring me after that & i`ll set you up with the method we use to stroke em OH!!! & start with an "UN_WORN" std/std large journal for optimum stroke |
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| Author: | TheMiniMan [ Sat Mar 25, 2006 3:55 pm ] |
| Post subject: | |
Oh & you`ll need to "Narrow" the "S" rods that you use for them to fit ,,,.015" (15 thou)per side of each rod |
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| Author: | TK [ Mon Mar 27, 2006 3:19 pm ] |
| Post subject: | |
you don't need Cooper 'S' rods. 1275 Midget/Sprite rods (625) do the job without the hefty price tag. |
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| Author: | TheMiniMan [ Mon Mar 27, 2006 3:57 pm ] |
| Post subject: | |
same rod, except for the factory balancing, same part numbers etc ...just didn`t recieve the "Cooper S" balancing treatment, 6 of one or half a dozen of the other.
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| Author: | smac [ Tue Mar 28, 2006 11:50 am ] |
| Post subject: | |
I've never seen either type of rod for sale...maybe I don't look in the right places.... |
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| Author: | minicranks [ Tue Mar 28, 2006 3:08 pm ] |
| Post subject: | |
stu you need to ask the right people i only have 3 sets. |
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| Author: | TheMiniMan [ Tue Mar 28, 2006 6:14 pm ] |
| Post subject: | |
& it`s the 177 or 521 rods you will need,,,& i would use the 521 rods , they are way stronger than the early 177 rods you can`t use large journal rods at all as the stroker cranks start off as large journal but are then machined offset down to the small journal size, so small journal rods are the only ones to use, Buy some 521`s |
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| Author: | smac [ Tue Mar 28, 2006 6:54 pm ] |
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Geez and I thought I was a hoarder *lol* |
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| Author: | drmini in aust [ Tue Mar 28, 2006 7:14 pm ] |
| Post subject: | |
MG Midget AEG625 rods will work, if you find any. Pretty much a 1275S rod with lower steel spec.
I'm a hoarder too, but sorry, got none... 
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| Author: | kartbro [ Wed Mar 29, 2006 2:49 pm ] |
| Post subject: | |
Ok guys, just got back from the engine shop stripped the head and block and dropped it in the hot tank. Also ordered a rebuild kit with 73mm Hypatecs, Small J rod bearings, all stuff needed to machine it up and dummy build, currently needing some small journal rods, willing to swap for my large J ones + cash. Also does an 1100 cam fit in a 1275 block? (with regrind) I'll need more parts later will keep posted. Nathan |
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| Author: | drmini in aust [ Wed Mar 29, 2006 6:22 pm ] |
| Post subject: | |
Yes an 1100 cam will fit any 1275 block, if it's an 1100S block you may need to tap another hole for the S oil pump. Depends what pump brand. Personally I'd run an S or 1100S cam blank, as they have 1/8" wider lobes..
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