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14CSR top end on a 8 bottom?
Posted: Mon Oct 17, 2016 9:01 pm
by ade
I have a 14CSR in bits with lots missing but a good top end. I also have a 350 model 8 complete.
Is it possible to put a 14CSR barrel/head on a model 8 bottom end? only things I can think may be a problem is that the 14 barrel is shorter and the cylinder barrel studs of the 8 will be too long and the pushrods longer.
Having said that my engine casings on the 14 match the frame and I would like to keep it that way. Can I use the 8 to rebuild my 14?
What's everyone's opinion?
Re: 14CSR top end on a 8 bottom?
Posted: Mon Oct 17, 2016 9:28 pm
by Rob Harknett
If no replies are received and you have all the parts handy. Try putting it together loosely and let us all know how you get on. You could be the first, to advise others.
Re: 14CSR top end on a 8 bottom?
Posted: Mon Oct 17, 2016 9:40 pm
by clanger9
I don't think that'll work!
The 350 / Model 8 is a long-stroke motor (85.5mm), the 250 / Model 14 is short stroke (64.84mm). So quite a big difference in the bottom ends...
I think the big end is the same on a late-model CSR, so you might be able to re-use that.
Re: 14CSR top end on a 8 bottom?
Posted: Tue Oct 18, 2016 8:04 am
by ade
Well I will keep you all updated how it goes. but probably won't start the project for a few weeks.
Re: 14CSR top end on a 8 bottom?
Posted: Tue Oct 18, 2016 9:26 am
by clive
clanger9 wrote:I don't think that'll work!
The 350 / Model 8 is a long-stroke motor (85.5mm), the 250 / Model 14 is short stroke (64.84mm). So quite a big difference in the bottom ends...
I think the big end is the same on a late-model CSR, so you might be able to re-use that.
If one is short stroke that explains the difference in the barrel length. Putting a shortstroke barrel on a bottom end with a longer stroke would simply result in a piston which rises out of the barrel or impacts on the flywheels or both depending on the positioning of the gudgeon pin. You might be better to stick with the complete model 8 motor.
Re: 14CSR top end on a 8 bottom?
Posted: Tue Oct 18, 2016 12:37 pm
by ade
Yes that makes perfect sense.
Re: 14CSR top end on a 8 bottom?
Posted: Tue Oct 18, 2016 1:34 pm
by Rangy65
Hi Ade a better fix and one that would work is to find a G5 350 barrel & piston use that as your head should work with this set up. The taller motor will be a tight fit in the frame so you might not be able to take the head off in situ.
there was a couple of barrels on ebay recently - i know i brought one!!
Cheers
Steve
Re: 14CSR top end on a 8 bottom?
Posted: Tue Oct 18, 2016 1:36 pm
by Rangy65
Forgot to add to my last post you will need longer push rods too
Cheers
Re: 14CSR top end on a 8 bottom?
Posted: Tue Oct 18, 2016 6:18 pm
by clanger9
So a 350 motor will fit in a 250 frame? With a 250CSR head on, that should give a healthy compression ratio too.
Hmm, interesting.
Anybody got a 350 short motor lying around..?
Re: 14CSR top end on a 8 bottom?
Posted: Tue Oct 18, 2016 6:49 pm
by ajscomboman
clanger9 wrote:So a 350 motor will fit in a 250 frame? With a 250CSR head on, that should give a healthy compression ratio too.
Hmm, interesting.
Anybody got a 350 short motor lying around..?
Nope but I've got a spare 350 barrel and +60 piston that will go into it after boring.