Goto 540 or Tweek out the 489
05-06-2022, 03:15 PM
#41
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Not saying it wouldn't work, I just don't believe it would be the best choice if buying a new cam. If it was sitting on the shelf I would definitely throw it in.
Switched out a straight split cam with one that has a 6° split and it was much healthier and better performing. These heads were optimized and have great exhaust ports. JMO
Switched out a straight split cam with one that has a 6° split and it was much healthier and better performing. These heads were optimized and have great exhaust ports. JMO
I wish I had more time to play around with different splits. Had one even split cam back in the day in a 383 surprisingly worked well with GM heads to boot and poor exh. But never compared. Was 16 then… comp 292 magnum cam called (king of the drive in) 😂
I always thought with the more efficient heads and int / exh ratio less split desired but so many factors. When jones spec’d my current ones he chose a 4 deg split. Remains to be seen yet as I’m sure you heard short blocks gotta be torn down and pistons fly cut. (Slight clearance issue but glad we caught it. One engine about read. Got delayed by a good month plus now.
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getrdunn (05-07-2022)
05-11-2022, 12:02 PM
#43
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-As you add duration you also add overlap.
-Tightening lobe centers (lsa) does also.
-Amt of Exhaust open degrees past TDC on intake stroke is what really means the most when it comes to reversion possibilities since the exhaust valve still open (but closing) when piston going down drawing in air from both valves (intake valve starts opening before tdc intake stroke) at lower rpms.
Look for some of my cam charts comparing the mag 454/502MPI/ HP500/Crane 731/500EFI/525EFI/Crane 741 and you’ll see seat overlap, .050” overlap (including btdc and atdc), etc, etc. Really good info that if studied, paints great pictures. :thumbs
-Tightening lobe centers (lsa) does also.
-Amt of Exhaust open degrees past TDC on intake stroke is what really means the most when it comes to reversion possibilities since the exhaust valve still open (but closing) when piston going down drawing in air from both valves (intake valve starts opening before tdc intake stroke) at lower rpms.
Look for some of my cam charts comparing the mag 454/502MPI/ HP500/Crane 731/500EFI/525EFI/Crane 741 and you’ll see seat overlap, .050” overlap (including btdc and atdc), etc, etc. Really good info that if studied, paints great pictures. :thumbs
05-11-2022, 12:06 PM
#44
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05-11-2022, 05:39 PM
#45
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jeffswav (03-08-2023)
05-13-2022, 08:59 PM
#46
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You were probably on an OSO break during the lobes and or valvetrain gone bad. I don’t wanna get it all started up however if your comfortable with what you have and lobes look good your likely ok. His concept made since however didn’t agree with many endurance HP builds. Short duration / hi lift ratio a tad off compromising lobes and other valvetrain parts.
