nizs13

I picked up what i thought were a set of JWT S3 cams off of ebay awhile back. I installed them on my fresh 10:1 motor before dropping it in, and just spent the last couple of weeks trying to figure out why the car wouldn't idle and had nothing below 5,000 or so RPM. After troubleshooting every other possibility and replacing almost every engine control sensor/device, I finally threw the stock cams back in and BAM...ran perfectly. I'm positive they are JWT cams due to the "sportcam" stamping on them, my question is, does anyone know the proper procedure for identifying the lift? The characteristics are as follows...Super lumpy idle(can only get it to about 750 before it surges upward and hovers around 3k),hesitation all the way up to about 500-5500 RPM, then like a rocket ship. Any advice would be much appreciated.
Oh, and i tried looking at the "big list of cams", but the page won't load.

jp314

I have S4s on my daily driver - they idle fine IMO, like the lumpy idle.
Seem to be good above 4k RPM, under that, slightly lower torque, but not
a huge difference.
I would set your base idle and timing, re-install the cams, then check/adjust
idle and timing again.


Measure the lobes to see what cams you have.
"high-port intake cam is 1.51". The lobe height of a low-port intake cam is 1.48"
"I was measuring a set of S3 cams yesterday. 39.2mm (1.545") "
S4 should measure larger than the S3.
To be sure, call JWT and ask what they should measure.

Reference threads:
http://www.sr20forum.com/general-sr2...ppose-s3s.html
http://www.sr20forum.com/general-sr2...s-genuine.html
http://www.sr20forum.com/general-sr2...amp-marks.html

nizs13

Thanks for the info guy's, much appreciated, I'll do the measurements and contact JWT to confirm the specs, as far as resetting the idle/timing goes, i did it over and over again with the JWT's in there, and still couldn't get it to run right.

nizs13

Well, Here's the extreme lobe measurements if anyone can tell me what they are.
Intake= 1.584" Stock= 1.512"-1.529"
Exhaust= 1.555" Stock= 1.521"-1.529"

jp314

For your exhaust cam, 1.555 - 1.26 = 0.295 * 1.55 * 25.4 = 11.61mm lift.
JWT S4 = 11.8mm
JWT S3 = 11.3mm
Double check measurement? Worn S4?
Tomei, HKS, JUN, Greddy all have an 11.5mm exhaust cam;
Comp Cams/Zex have an 11.68mm exhaust cam

For the intake cam, 1.584 - 1.26 = 0.324 * 1.55 * 25.4 = 12.756mm lift.
JWT S5 = 12.78mm
JWT C2 = 12.7mm
JWT S4 = 11.8mm

nizs13

Ok, here's what I came out with...
Intake...1.261" x 1.584"...1.584 -1.261= .323 x 1.584=.511 max lift.

Exhaust...1.270" x 1.555"...1.555 - 1.270= .285" x 1.555"= .443" max lift.

nizs13

So it looks like the exhaust cam IS an actual S3, but the intake cam kinda baffles me, it seems to be in between an S5(.503"),and a C3(.526").
If anyone has an S3 intake cam they would like to part with let me know.