what is it?

[spanishfly]

i know theres a way that u can use either 1.3 or 1.2 pistons/rods/crank to give a longer stroke thus making the 1.4 a slight hight cc?
does n e one know the exact details? i'm in need of a new crank so while i'm there i will be rebuilding the whole bottem end. I have been told it's not worth gettin it lightened, whats ur opinion as it'll all be out and i can get it done cheap through work:)

[spanishfly]

ok i have done some equations, it seems if i use a set of 1.2 pistons i will get a slight better capacity only around 9 cc????
but the main advantage would be the compression ratio raised! it would be around the 10.1:1 mark if i'm correct! the only prob i see is the fact that it will need a slight rebore as 1.4 bore is 77.6 where as the 1.2 is 77.8!
does n e one have n e coments on the above findings:)

[rallyslag]

As far as i know you can use 1.2 pistons with a 1.3 crank i think, i was hoping to do this myself :D

[spanishfly]

i 1.3 crank!
what would that give me then???

so it means i'm gonna have to find another two 'spare' engines

[Aragorn]

why rebuild the entire bottom end for 9cc ??

skim the head to raise the compression

prolly cost u about ?30 to get it done

slatter got 30thou taken off his which took it from 9.4:1 to 11.5:1

if u take about half that off you'd have around 10:1

[Aragorn]

saying that

simply fitting a 1300 or 1200 head and 1300 inlet manifold would do the same thing assuming your running the standard pierburg - and will give u a nice flow improvement over the 14SR head too

[Nova-Boy]

I have two spare heads and inlets if your interested!! :lol:

[spanishfly]

suppose i should ov said spec atm!
it's a 1.4 sr WITH a 1.3 head portedand polished.
piper 285 cam twin 40's (webber) ashley 4 branch and system (rally spec version)

reason i'm rebuilding is cause crank pulley bolt is broken in crank and been quoted ?200 to get it out etc! so basically i need a new crank, so as i was going to have to rebuild the bottom end (top has been done 3000 miles ago) i thought i'ld look into this!!!

[Stuart]

a 1.2 carbed pistons and block, wiht 1.3 crank and rods will give a 1396cc as opposed to the 1.4 being 1389cc

BUT im not sure if the pistons will protrude above the block.


swapping bottom ends about is all well and good but bear in mind the little ends. on the 1.2/1.3 they are 20mm and the 1.4/1.6 are 18mm

and im not sure about the machinging of the little ends and what inserts to put in them.


but if you can squeeze the bits in a 1.2 with 1.6 crank and rods will give a 1.55 engine lol. but wont rev well but will have a shed load of torque if it would all fit

[mikeoxford]

spanishfly mate email me

mikeoxford@hotmail.com

i will have a rally spec 1.3 bottom end for sale, including worked on crank etc lightened and balanced and all the rest

drop us a line if your intrested and ill detail the work done.

[scott5]

why bother going through all the hassle of a rebore etc for an extra 9cc? if you're going to have a rebore get it done properly and take it up to the 1.4s maximum capacity.
I've seen a couple of SRs that have been taken up to 1.5 which i think is the maximum but i dont know what piston/crank combination is used.

[spanishfly]

scott simple reason is because then u'll need over sized pistons/ large piston rings(which i'ld prefere piston option) which will then mean a load of cost!!! which would be worthless then i should of just went out and bought a 1.6 block:) thing is i wanna keep it a 1.4 so i haven't gone for a 1.6!

[scott5]

what i meant was, to gain the extra 9cc that you mentioned, you have to buy new pistons/rods/crank and get the cylinders rebored so u may as well get pistons/rods/crank to take the capacity up a little bit more than 9cc, cos for a 9cc gain its just not worth the money or the hassle.

[Fester]

nova build manual states the group a engine as having an 11.4 CR - for reference

[scott5]

nova build manual states the group a engine as having an 11.4 CR - for reference
thats a big increase!! the standard engine is 9.4:1 so you'd probably need to uprate the head gasket or risk blowing it within a week. lol

[Fester]

i would scan and put the whole thing up but i cant be arsed lol