SH Cams into a 1951 18s

Fiona69 · Post by **Fiona69** » Fri May 20, 2011 7:54 am

Ok to the all knowing out there I now have a very nice set of lightened SH cams and am awaiting a coil valve spring conversion set. What I would like is the correct timing for fitting these cams into my AJ. Oh and I tried to change my user name to one a little more subdued but no joy so you are stuck with Kiwi Fiona69

itma · Post by **itma** » Fri May 20, 2011 11:19 am

being stuck with fiona and 69 is too stressful and overheating for some of us here to think about so you get no sympathy..........

your cams should be marked

Fiona69 · Post by **Fiona69** » Fri May 20, 2011 9:17 pm

Thanks itma the only marks are 1 dot on the lobe side of the gear lining up with the highest point on the lobe so when in place the dot is not visible, I was hoping for a degre's btdc to time them in with a degree wheel.

itma · Post by **itma** » Fri May 20, 2011 10:49 pm

for that you'll have to wait till the california comp info board wakes up, whe stuck I just used to transfer the appropriate marks from a set of std H cams, not the 1-2-3 dots, just the one you need.
That ought to get you going, there is not a lot of range of adjustment anyway.
you also ought to know if you have SH or the CI cams

SPRIDDLER · Post by **SPRIDDLER** » Fri May 20, 2011 11:20 pm

If you haven't already checked, the Workshop Manual for the '51 500 single gives:
Inlet valve
Opens 32 BTDC
Closes 63 ABDC

Zorst
Opens 65 BBDC
Closes 30 ATDC

But no doubt your SH cams will require different settings.

http://archives.jampot.dk/Book/Owners_m ... Manual.pdf

Fiona69 · Post by **Fiona69** » Sat May 21, 2011 12:48 am

Thanks I agree the SH cams will require a different than standard setting, and yes definately SH cams from Jampot UK.

SPRIDDLER · Post by **SPRIDDLER** » Sat May 21, 2011 2:09 pm

Certainly there's going to be an element of trial and error getting it right but a steer from Don or someone else with 4-stroke performance tuning experience would be invaluable as altering valve timing also has a knock-on effect on carburation and ign timing which will require even more fiddling about.
I've only ever tuned/experimentd on 2-stroke engines in scrambles days. Latterly I've only striven to 'Blueprint' standard spec'n 4-stroke engines i.e. preventing leaks and achieving designed performance and reliability which is about the extent of my fiddling patience.
If I wanted more power for touring I'd probably go for a larger capacity engine. However I can see that if it was for competition use it might not be an option as it would perhaps put the bike out of class.
Let us know how you get on.

Marty · Post by **Marty** » Sat May 21, 2011 6:11 pm

SH inlet opens 59 btdc, closes 69 abdc
Exhaust opens 69 abdc, closes 48 atdc
Marty

Fiona69 · Post by **Fiona69** » Sat May 21, 2011 9:28 pm

Great thanks, just awaiting clutch parts and the coil valve spring kit then I can start piecing it back together.

laxy · Post by **laxy** » Sun May 22, 2011 2:47 pm

could I just ask what does a coil spring conversion kit consist of and what are the advantages of this conversion?