Extreme oil temp while under boost

[78 propduster]

Jet, 454, 671 (17 percent OD), Merlin cast heads, 109* / 7.2 lift solid roller, 2-850's
Just got boat running, runs 150* water / 240* oil while running at 4500 RPM.
When I make 1 run, WOT, 6000 RPM @ 9LB boost. Oil temp. jumps to 290*
water temp holds at 150. ( Climbs to 190* during cool down.)
Timing is at 32* would this cause a lot of heat? Trying to play it safe.
Installed a Hyfire VI today with a MAP sensor, How much retard should I start out with? Should I kick the timing up to 35* now?
Hope to install my A/F sensor before the weekend, Plugs look good but inside the header collectors go from black to white after a hard run. Lean?
Thanks for any thoughts on this!

[DMOORE]

About the timing, I think you need to do a really good reading of the plugs first. The oil on the other hand is too hot. 290 just isnt good regardless of oil type. Are you running an oil cooler? you want to keep it under 230. 215-230 would be about perfect.
Darrell.

[78 propduster]

Got a Dan Olson cooler that I am going to rebuild.

[Infomaniac]

Check jetting
Then oil cooler
And I have seen oil temps too high from no intercooler or not enough intercooler.
When you decide a retard point 1 degree of timing for every additional pound of boost is pretty standard.

[ghittner]

Check jetting
Then oil cooler
And I have seen oil temps too high from no intercooler or not enough intercooler.
When you decide a retard point 1 degree of timing for every additional pound of boost is pretty standard.
Yup! Jetting 1 cooler 2

[1968Droptop]

I would agree, jetting.

[78 propduster]

Thanks for the responces, I'll try jetting first.
Where should I be on the A/F meter readings, 12-14?

[ghittner]

Hard to say, boostpower likes em 1400 Degrees with AFR @ 11.3:1 WOT.
Personally I feel @ 11.3:1-11.5:1 AFR you are safe. Cruising maybe 12.0:1

[78 propduster]

Thanks!