HELP needed. My new 540 is a Dart Sportsman 9.1 to 1 compression, 310 cc Dart alum heads, Edelbrock Performer RPM air gap dual plane. Stainless Marine Gen III manifolds, with wet tailpipes mixing 24" back. 180 psi cranking pressure with prior advised 228/236 @ .050" 113 LSA +3 ground in advance. With best Hardin thermostat controlled cooler, oil temp in pan rapidly increases over 240F over 3700 rpm; jetting plenty fat, timing 32 total. Likely have scuffed piston skirts already. This is a 24 x 7 hull, so probably 625 hp fine. This is a enthusiast boat and not raced. Priorities are reliability and a little spirited fun, and not any more duration than necessary to bring cranking pressure down while not wasting fuel at 2800-3800 cruise. If possible 5500-5700 max rpm desired with labbed Bravo 1 -24 pitch. Lifters are .700" wheel Johnson 2126 BBR limited to 430 lb over the nose. REVERSION avoidance is important as well. QUESTION IS: With similar setup, what hyd roller cam are you having success with? Thank you in advance.

You may get other suggestions, but back in 2003 or so, I had originally had a pair of NA 540cid engines with some JimV fully ported Dart 310cc heads with a Dart single plane Intake manifold and Holley 830cfm spread-bore, annular discharge carbs, 9.4:1 comp ratio---cams were hydraulic roller 236*/244* on a 114* LSA and it idled very nicely and smooth in my 540's. .

I had them dyno'd, but cannot remember the exact power numbers, but was at least 670+hp @5600rpm or so. I would reuse the Edelbrock Air-Gap dual-plane intake manifold especially for a single engine application----Anyway, it was just what I experienced with my 540cid engines about 20 years ago

Thank you.

Kaama, Reaching out once more. Reputable custom cam guy informs any more cam than the 228/236 @ .050" 113 LSA +3 Hyd Roller currently in it will cause reversion. With 540 cubes, there is lots of static pumping pressure. I pulled engine apart, and all 8 pistons are skirt scuffed only on the exhaust side. 850 cfm setting was 81-90 which I think on a dual plane is on the fat side. Going to put another set of pistons in it. Not sure whether to try existing cam again. Question, on your prior 540 build with the 741 cam on 114, what exhaust were you using, and were there any signs of reversion?

1. I would NOT consider 81 main jets and .055 pvcr on a 540 rich by any means, you would know more with actual 02 readings in boat. At this point we're only guessing what your actual tailpipe afrs and HOTTEST cylinder AFRs are . I would still highly encourage you to have this dynoed this time when its back together
2. I still dont grasp how you would have reversion concerns if your actually mixing water 24" back from elbow riser section on a set of stainless marine 3's, if you tell a cam grinder you DO have reversion concerns, they will err on cautious side. you were gonna send me a pic of actual exhaust but never got one.
3. even IF your tune was actually lean and you intially ran 36 degrees of timing which is way too much for majority of 9 and 10-1 aluminum headed bbcs, you should have scuffed/detonated/melted to ring land 2 or 3 hot cylinders. The fact you scuffed ALL 8 pistons evenly lends me to believe you were NOT at the .0061 to .0065 you thought you were at when assembled. How was it measured, who measured it, micrometer and bore gauge or calipers?
4. oil temp, FWIW mercruiser measures return oil temp AFTER cooler on all the 500s, etc that come with factory oil temp gauges. IF your measuring oil temp before cooler or in the pan, its going to show 60 degrees hotter and scare you. Going from 33 to 36 dgrees WILL raise oil temps in my experience as more heat gets transferred thru piston crown to oil cooling the bottom side. IF your measuring oil temp AFTER the cooler and its rocketing up, you got issues.
what octane were you running when you ran it with 36 degrees timing and was there any old gas in the boat?
did you verify the outlet fitting on filter (the one that comes from INSIDE the media before it leaves is connected to the bottom of block adapter going up thru the center. I have seen SEVERAL boats in last few years with center block adapter fitting connected to filter INLET inadvertently which causes block bypass to open and you get hot, unfiltered oil although i think you told me you verified this.
5. Cylinder distribution, do NOT forget there is about a 2.5 point spread on almost all BBC intake manifolds so a tailpipe average of 12.5, 12.2 etc will get your hotr cylinders at least into the 13's, seen MULTIPLE blown up engines that were tuned to 12.8, 13.2 on tailpipes in boat and they cooked a hot cylinder like # 8 which was running at 14.0 + at wot but again, you scuffed ALL cylinders evenly so im not convinced it was tune.
6. Cam, yes, IMO your cam is small, only time id ever run anything that small in a 540 is of guy insisted it idled at 600 rpms and wanted all the power in by 5000, 5200.
7. I dyno simmed your combo based on info you gave me and it shows its all in by 5200 then falls off face of earth.
8. Cranking compression, you stated "cranked at 185" (if i remember correctly), on my sim it shows cranking compression at 155 which is usually pretty accurate, did you perhaps advance the cam on top of the advance thats ground into it and move ICL way deep into the 106 or lower range?

And your small cam did NOT spike cylinder pressure so high that it scuffed your pistons, its small in my opinion BUT ive built similar and stuffs out there living just fine. I also have ran 2618 pistons in a blown 540 at .0055 and did not scuff even under the cylinder pressures generated by nboost. Ive ran as tight as .005 with crown coatings with 4.530 bore blown 540s and pistons still looked almost new after 100 hours of running with boost at refreshen.

The Crane 741 cam on a 114 lob sep is the stock cam in the Merc 525EFI engines, many of which run silent choice diverters. You should not have any reversion issues with it with your SM exhaust with long tails.
Specs of 525EFI cam Teague Custom Marine | BBC Gen V-VI Billet Camshaft - Stage 2

I am running the 525 EFI cam in my 555 with bigger BB2 heads and more compression but I chose this cam because I have restrictive exhaust and it runs pretty good. Definitely not a cam for huge power, but I was surprised at how much power it has and the idle sounds great for the size of the cam. I have no reversion issues.

Yup! What he said ^^^^^ Good Cam for reliable power with good idle sound and good docking manners.

Managed 630hp@5200/700tq@3900 with Dart Iron Eagles 308's in 548's.

Sonic, Confirming that is NA?

Really nice HP/Tq curve. 540s vs 454s and blowers. For me, not yet sure what my max usable twin HP is yet...but if I'm at the 550-600 hp line...then NA 540s seem the better route. Alum heads and no blowers = -300lbs.