I have a basically stock 454 magnum w/ an ultradyne 288/296 advertised, 231/239 @.050, .550/.575, 112 LSA cam. If I were to remove the low water Lightning headers and install the stock merc manifolds and elbows, would I be creating a reversion problem?

It seems that most in previous posts said it (reversion) happens when you get at or around the 240* at .050 mark and your close, but let some of the experts come in to answer this one, why are you taking the good pipes off?.....Fred

ttt

bringing this back to the top since it I have the same question now.

I would say that that cam would most likely have reversion with stock merc exhaust.

Our guideline is 224 @ .050" for 'freeflowing' exhaust, and 235 for merc castiron.

BGIII,
That cam is the second version Ultradyne that Harold did for Mercruiser in the mid 80's for the 440/460 cyclone engine package.
!st version:
288/296 at .0045"/.006"
231/239 at .050"
.550"/.558" valve lift, 1.7:1 rockers
110 LSA.
2nd
After several years, Harold changed the exhaust to the 296 at .0045, 239 at .050, .575" valve lift.

Mercury ran these cams successfully without reversion on a 110º LSA where yours are set on a 112º, giving you less overlap and a reduced likelihood of reverting. They are also soft lobes.
That being said, there are never guarantees when it comes to reversion due to multiple factors involved other than cam design. Intake/exhaust port velocities, combustion chamber design, and exhaust backpressure all play a part.
The history of this cam would indicate that set up correctly, you are good to go.
Bob

Thanks for all the info Bob!

Jesus, Bill,,,,,you get into some bad reefer or something? You sniffin' the RAID again?

What brand risers do you have? Had a problem with reversion & it was Sierra brand risers that cause the problem.