northiam

Can anyone tell me why when two cams of almost identical specs are listed in the cam manufactors literature the solid cam designs are described as fair idle while the hyd cam are stated as rough idle eg: H238 - F238?

Also my stall convertor man reckons the higher the stall speed the better the idle as greater slippage is needed at revs under 1000 rpm to improve idle (the car wont want to nudge ahead as much when you take your foot off the brakes) Is this true??

TruBlu351

A higher stall converter would be a requirement with an auto and that cam. Yes it may assist in idle quality, normal stock converters lock up @ about 1200rpm I think. It's not an on/off rpm set up though. It's a gradual build up to be fully "engaged" by that rpm.......but like you mentioned, higher stall = more slip down low.

The power range in the cam is 3000-6000rpm. If your stock converter locks up at 1200rpm, you'll have a dead range/flat spot (where the cam produces crap power) until you baby it up to ~3000rpm. That's why a 2500+ converter is recommended, to bridge this gap. When you nail it, your rpm will rise rapidly and start hooking up around your stall speed, similar to dumping the clutch on a manual = instant power range.

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XE Falcon
393 Tremec TKO 9"

xdclevo

Well i ran a H238 for the last 3 years and it was a great cam. It does have a lot more lift than the solid F238. I would say that would be it. The H238 has 579 lift and the F238 has 554 lift, but if i am correct and we take off the 22 thou lash, it would be 532 thou lift. The H238 will rev as high as you want it to. I overrevved it one night to 7500 rpm in second. I lost that race.
On the converter question, i did have idle issues only when in drive. When i went from the 2200 converter up to the 3500, i had no more problems.

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10.70 @ 125.00 on the black fun top
408 Cube Cleveland.