cam profiles

[frank]

a comparison of a piper 285, a 1.3 and a 1.0 cam profile
http://i44.photobucket.com/albums/f47/TomEA/PICT0027.jpg
the timings on the piper appear to be quite inacurate :suspect: time will tell ?
and like ed said the 1.0 is very tame

 

[Low Rider]

Inaccurate? Care to elaborate?

 

[frank]

lowrider

its supposed to be 30 62 62 30 timings, the inlet (only fitted so far) opens at 30+ btdc and closes at exactly the same as the 1.3 cam i took out ??
looks like i,ll have to retard it :doh:
i,ll post the exh timings when i get some more shims (i,ve had to grind my spare ones down to put under the buckets)

 

[sonic]

Thats an odd result Frank, the Piper cam looks like it has a longer duration on the picture.

also the slot on the end of the shaft looks like its at a different angle to the 1.0 cam.

 

[frank]

sonic

yes its puzzling me
the lobe to dowel position was different (hence its overadvanced) which is no problem but i doubt very much there being 272 deg of duration :suspect:
the car goes better but i expected "ultimate" cams to be wilder than this, especially on a 1.0

 

[joelh]

be wild if u get a remap

 

[frank]

joel

i mean wilder timings
now my old 649 ministock, that was a proper cam :devil:

 

[Low Rider]

lowrider

its supposed to be 30 62 62 30 timings, the inlet (only fitted so far) opens at 30+ btdc and closes at exactly the same as the 1.3 cam i took out ??
looks like i,ll have to retard it :doh:
i,ll post the exh timings when i get some more shims (i,ve had to grind my spare ones down to put under the buckets)

Which method have you used to measure the cam timings?

 

[frank]

low rider

3 thou feeler guage under the lobe (biting point) and measured the crank pulley

 

[Low Rider]

I wouldn't expect to see a full 272 on anything less the cam mounted between centres with a drop gauge zeroed on the base circle. If you're getting 30deg+ BTDC and closing as a stock cam, (42 ABDC), which does seem a bit out, (triple check timing just to be sure lol), translates to ~252deg, which although low is quite good considering the method....as there's a fair bit of slop in the system.

 

[frank]

low rider

point taken, but the valve duration will be even less than my measurement, and there,s way too much advance (bearing in mind the chains have done 70000mls), the no1 inlet lobe on a stock cam lines up with the locating dowel, but the piper one was well forward of it

 

[frank]

both cams are in now, i,ve had to advance the exhaust cam and retard the inlet cam
i thought they would be too peaky for a 1.0, but the tickover is dead smooth and the powerband is very linear (its lost the mad surge at 5000 to 7000 that the 1.3 cams gave)
so i,m pretty chuffed and when the flywheel is done i,ll deffo trounce any standard 1.3 :devil:

 

[LordJunk]

@frank
after all these years, experiments and experiences, which are your favourite cams?
Or cam constellations if you are using different ones?

would you stick to your advised 1.3 IN and 1.0 EX?