what 84mm pistons do i use?
I built a 1660 crossflow and used 1300 pistons, these have a higher compression ratio than the stock 1600. This then meant that with the valve
cutouts compression stayed pretty good.
These were standard cast pistons from Burton power. I think part number: 20552/030.
I used ARP con rod and flywheel bolts, standard end caps, and standard con rods.
All where fully balanced before assembly. With a Piper 285 cam, twin webers its putting out 122hp@6200rpm and still rising (rev limit is 6800, but we
didn't run it that fast on the dyno (yet.))
More is easily possible, I need to change the emulsion tubes, and rejet which is going to be quite expensive, so I'm holding out for fuel
injection.
- Hijack -
Incidentally, what cam are you going for? I've just ordered a Kent 234 cam, but I'm debating if its going to be an improvement or not. The
piper cam is pretty good, but i'd like a bit more power, its got plenty low down, and good torque and im prepared to sacrifice a bit of that for
some more top end still.
I used 18647 pistons from a 1300 in my 1700 build. You will need to get them modded if you intend on a high lift cam.
I built mine on my own apart from the bottom end which burton did for me. With a 234 cam and a modified mexico head I had it rolling roaded at 136
bhp.
what i've got is, 1300 pistons in 711m 1600 block at 40 thou oversize - circlip came out and the gudgion pin made a nice indentation on the bore
kent BCF3 cam, with double chain cam gear. head ported and max oversize valves with double valve springs.
one option is to try and get 90thou oversize and just use existing setup
the other option is using another 84mm piston thats alot lighter with a lower compression hight, then cutting down 5-7mm off the top of the block to
get the correct compression ratio, also need to cut down pushrods with the same amount.
comments?
I'd go the +90 route and see if it gets rid of the scratches in the bores, if not it's a new block. My winter build will be a fresh rebore to +90, a set of 1300 pistons, kent 244 cam with duplex gear. I'm keeping my current head and prob going either bike carbs or TBs.
Marcus,
Why the 244 cam? People keep telling me its too hot for the road, what do you have in now?
quote:
Originally posted by Marcus
I'd go the +90 route and see if it gets rid of the scratches in the bores, if not it's a new block. My winter build will be a fresh rebore to +90, a set of 1300 pistons, kent 244 cam with duplex gear. I'm keeping my current head and prob going either bike carbs or TBs.
quote:
Originally posted by stretch
then cutting down 5-7mm off the top of the block to get the correct compression ratio, also need to cut down pushrods with the same amount.
comments?
Crossflow pushrods are solid steel. You just ground down to the correct length and reshape the end.
quote:
Originally posted by irvined
Marcus,
Why the 244 cam? People keep telling me its too hot for the road, what do you have in now?
What Claire said I was advised by Mr Kent (at the retro motorsports show) that this was the best in my application, ie light car reasonable torque and bike carbs / injection. I believe the 244 is the one Caterham used in the 1700 Super Sprint.
84mm pistons are they + 90 if so you use 1300cc ones +90 and a big valve head 41.3mm inlet an 34mm exhaust thats the max you can go
(can you not get a 2Lxflow engine in south africa,im sure you can)
kent BCF3 cam and aldon dizzy and twin 40 webers.
here is mine
That's a nice looking head Thunderace, and looks to be well ported. Who did it?