Author Topic: 302 cam placement  (Read 5306 times)

bob69

  • Member
  • ***
  • Posts: 32
    • View Profile
302 cam placement
« on: December 22, 2005, 04:42:27 PM »
I have my 302 motor in the shop and they made a suggestion that I rotate the cam a few degrees to get a little better low end at the cost of some top end,anyone heard of this. ( I'm running all stock ) Thanks Bob

JohnZ

  • CRG Member
  • *****
  • Posts: 4262
    • View Profile
Re: 302 cam placement
« Reply #1 on: December 22, 2005, 06:00:55 PM »
Advancing the cam timing 4* to pick up some additional low-end torque has varying results, depending on the cam; this works quite well on the Chevy "151" (327/350hp hydraulic) cam, but the duration/overlap of the "30-30" Z/28 cam is so extreme, advancing it makes little difference in low-end torque. A far better solution is to swap it for the Chevy factory LT-1 solid-lifter cam; that cam will produce about a 20% increase in low-end torque over the "30-30", with almost no trade-off above 6000 rpm. The LT-1 cam is available from GM as a kit with lifters under GM P/N 12364054 for less than $150.00, and from Federal-Mogul/Speed-Pro as a kit with lifters under their #KC-1145R for a little less.  :)
'69 Z/28
Fathom Green
CRG

pdq67

  • Member
  • ***
  • Posts: 25
    • View Profile
Re: 302 cam placement
« Reply #2 on: November 27, 2009, 08:51:45 PM »
John's right or consider the little-bitty -097 Duntov cam here.

I DD it in my old junk301 for quite a while back then and it was a real hoot in the little engine.

Nowadays, I'd probably opt for an Isky Z-20 or the little Crower.

Or this one that's in my bedroom closet now.

A PAW PN 10341 ACTUALLY per the timing card spec'd at 280/246, 108/108, .498" gross lift and need's .030" hot lash on both sides.  I'm going to install 1.6 ratio rockers so it will be right at .500" net lift.

I'm going to shift the little short-stroke jewel at 8,000 just for the fun of it!

pdq67

pjbizjak

  • Member
  • ***
  • Posts: 215
    • View Profile
Re: 302 cam placement
« Reply #3 on: January 23, 2010, 12:48:19 AM »
Check out Comp Cam cl12-107-3.

Stingr69

  • Member
  • ***
  • Posts: 457
    • View Profile
Re: 302 cam placement
« Reply #4 on: January 23, 2010, 09:28:39 AM »
After running the "30-30" for some time in my 302 I tried a Crane F-278-2 and that one worked a LOT better in my opinion. I don't ever think about switching back. It has about the same opening / closing points and wider lobe separation as the LT-1 but it has more lift. If you try to find another grind with those characteristics "on the shelf" you will have a tough time. The other solids available are all too narrow or too big.

Availability might be a problem right now but you have to think Crane camshafts will come back at some point soon.

-Mark.

opelitis1

  • Member
  • ***
  • Posts: 261
    • View Profile
Re: 302 cam placement
« Reply #5 on: February 14, 2010, 03:02:07 PM »
Used to put engine together run her in nice and warm with just the inner part of a  2 piece timing cover and then get the highest compression readings from the various cam placements using the multiple keyway sprocket..
Gotta be careful here though and be sure of valve to piston clearances prior to having a go at this neat trick, especially when throwing in a high duration/high lift bumpstick.
T.

JohnZ

  • CRG Member
  • *****
  • Posts: 4262
    • View Profile
Re: 302 cam placement
« Reply #6 on: February 14, 2010, 05:32:49 PM »
Used to put engine together run her in nice and warm with just the inner part of a  2 piece timing cover and then get the highest compression readings from the various cam placements using the multiple keyway sprocket..

Advancing the "30-30" cam isn't a great idea in terms of detonation sensitivity. The reason a "30-30" will run on pump premium with 11:1 compression is the late-closing intake valve timing, which bleeds off some cylinder pressure and reduces the dynamic compression ratio. If you advance it, the intake valve will close earlier, which builds more cylinder pressure, increasing the DCR. Not a good idea for a street engine unless you want to blend avgas or race gas with pump premium all the time.
'69 Z/28
Fathom Green
CRG