MILD THUNDER

iTrader: (3)

Personally, I would NOT use those cams pslonaker recommended . Duration numbers of 244/[email protected] is entirely too much duration for a 454 marine pleasure boat engine. That is unless you plan on turning over 6000rpm.

Using those cams with stock merc manifolds, will more than likely revert water. I think you'd be much better off running less duration, and make better hp and torque through the entire rpm band.

endeavour32

iTrader: (4)

Mild Thunder is right, that grind is too big for a 454. I'm running a 232/238 cam and Bob @ Marine Kinetics said it was a tad to big as an optimal cam but it would work. The cam suggested is way bigger and would not be a wise choice! Now if your running high compression (over 10:1) with really good aluminum heads you could run something like a 236/241 but that would be pushing it.

MILD THUNDER

iTrader: (3)

Pslonaker, be careful running those cheap fram oil filters. They are just garbage. Anything would be better, wix, ac delco , moroso, etc. Fram racing filters are good, but those standard budget ones with the rhino liner grip arent.

Also, liquid filled fuel psi gauges are the way to go. The non liquid ones are just about ImPossible to decipher. I think with some liquid filled gauges you'll be pleasantly surprised how easy they are to read.

According to your videos, you said you had mercruiser 502's you converted to HP500's. That cam you posted is very different than a HP500 cam, and the HP500's came with performance exhaust (GIL).

mike tkach

iTrader: (3)

theres 2 people who give advice that will get you in trouble,and pslonaker is 1 of them,unless u want a john deere engine.

pslonaker

iTrader: (1)

I have never had an issue running fram oil filters. Years ago in my drag racing days running a Hemi...I used them then and they were a paying sponsor...still never had an issue.

The fuel gauges on my motors are more of a feel good thing than anything else so it isnt a big deal, but I do agree with you on the liquid gauges.

If you will look at the specs on the flat tappet Comp Cams that I have (11-244-4) you will see that these cams are alot bigger than the carbed or the EFI HP500 cams from Mercruiser. Mercruiser wants over $1000.00 for their HP500 cam and acording to Comp, Crans and Lunati...this cam is better. The exhaust on a HP500 is better than a regular stock mercruiser, but it isnt that important to me. If I decide to change the exhaust sometime later, I might go with Dana's but will probably go with Eddie Marine. I have used EMI manifolds many times in the past with no issues. According to the dyno, my motors made 550 HP and 553 HP at 5500 rpm which is better than I was expecting so I am a happy camper with the motors. I am not trying to be the bull on the water...just decent sound and reasonable performance. 90% of my boating is at roughfully cruising at 50 mph. I agree that the motors would do better with better exhaust, but for me, the stock Mercruiser exhaust works fine.

pslonaker

iTrader: (1)

I dont turn my motors over 5300 rpm and I have no reversion issues running stock exhaust and neither do some of my friends that are running the same cam in their engines. A couple of them are running 454 mag motors and they have also put this cam in their 454's...no issues and the motors run great. Now if one is trying to be the fastest boat on the lake...you are going to need more of everything...motor, cam and boat.

scarab31

My thoughts were to use Competition Cams K11-451-8 roller cam in my 454 mag engines. .547/.547 max lift with 230/236 duration at 0.050" lift. I plan to use the 496 manifolds and risers. Holley 750 carbs, Edelbrock air gap intake, MSD ignition and Comp Cams roller rockers. Mt fear too is reversion and hopefully this cam isn't to aggressive. Has anyone run a similar set up?

Itsallgood995

I was advised not to run the 731 cam (same duration 230/236) with the 496 manifolds.

pslonaker

iTrader: (1)

What are the lobe centers on this cam. This is where your reversion will come from, but on another note, I have never seen a Comp Cam marine version not start to lay down at about 4600 rpm. I will not use them. You would be better off to use the Crane 731 cam...it doesnt lay down.

HaxbySpeed

I used that exact cam many years ago in 454 with edelbrock ovals and an air gap intake. It was only 8.5:1 comp and made 510hp at around 5200ish. Zero reversion issues.