79formula

I built my 525sc last winter. I did it with a 134561 crane hydraulic flat cam.

Intake Duration at 050 inch Lift: 236
Exhaust Duration at 050 inch Lift: 246
Duration at 050 inch Lift: 236 int./246 exh.
Advertised Intake Duration: 296
Advertised Exhaust Duration: 306
Advertised Duration: 296 int./306 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.553 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.571 in.
Valve Lift with Factory Rocker Arm Ratio: 0.553 int./0.571 exh.
Lobe Separation (degrees): 114

I am always nervous about the flat cam. I run good high zinc oil. I have 60 trouble free hours on it so far. Would anything be gained by switching to say a 741 cam?

Intake Duration at 050 inch Lift: 236
Exhaust Duration at 050 inch Lift: 244
Duration at 050 inch Lift: 236 int./244 exh.
Advertised Intake Duration: 298
Advertised Exhaust Duration: 306
Advertised Duration: 298 int./306 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.610 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.632 in.
Valve Lift with Factory Rocker Arm Ratio: 0.610 int./0.632 exh.
Lobe Separation (degrees): 12

The springs crane specd for both cams are the same, so I'd just need cam and lifters. Would it be worth doing or just run it?

Black Baja

iTrader: (2)

30hp + reliability

sutphen 30

call Bob.

sorry,,I couldn't resist

Griff

I picked up about 100 rpms going from the stock 525SC cam to a Crane 731. It did have better midrange acceleration.

The 741 is on the large size for a 454 and unless you want to spin it to 5600+ rpms, I wouldn't go that big.

79formula

This is stock 525sc

UPC: 021174039900
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 2,800-5,800
Intake Duration at 050 inch Lift: 228
Exhaust Duration at 050 inch Lift: 236
Duration at 050 inch Lift: 228 int./236 exh.
Advertised Intake Duration: 298
Advertised Exhaust Duration: 306
Advertised Duration: 298 int./306 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.530 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.551 in.
Valve Lift with Factory Rocker Arm Ratio: 0.530 int./0.551 exh.
Lobe Separation (degrees): 114

I am running a touch bigger already with the 134561. I am also running 8.75 compression.

Intake Duration at 050 inch Lift: 236
Exhaust Duration at 050 inch Lift: 246
Duration at 050 inch Lift: 236 int./246 exh.
Advertised Intake Duration: 296
Advertised Exhaust Duration: 306
Advertised Duration: 296 int./306 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.553 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.571 in.
Valve Lift with Factory Rocker Arm Ratio: 0.553 int./0.571 exh.

mcprodesign

I thought I would chime in. I have 575 sci and I did a motor rebuild to merc specs./ I had to get better pistons made cause they don't sell the pistons any more. The only reason I did it is because i have tons of hours in testing and did not want to do that all over again. IE remapping testing and possible a new arsenal of props. I know a roller set up would net more horsepower and reliability. As it turned out . I have 2 engines that are still Stock merc 575 for the most part. And My boat is fast enough

For you tough, I think, It's a no brainer. Roller is the way to go. ( especially if you are out every weekend.)

TomZ

iTrader: (2)

I'm running the Merc/Crane 525 EFI roller in my 454. It's similar to the 741 but on a 114 LSA. It seems to work really well with my 250 blower, but it does require spinning it harder. We made peak power on the dyno at 5900, though I'd say the test was skewed because of the tired blower. The engine makes great power, gets on plane with a 26P Bravo easily, and cruises right around 50 MPH. I haven't had her to WOT in the boat, but we've been 70 so far at about 4900-5K.

getrdunn

iTrader: (7)

Haven't had to WOT. Come on tom... Let's get on it. Lol. I've never been able to do that but have respect for those who do. On the other hand it was wot on dyno.

TomZ

iTrader: (2)

I've been a little gun-shy! Getting anywhere near WOT kept breaking other stuff!! LOL

MILD THUNDER

iTrader: (3)

I'd have to disagree. I say, leave it alone and run it. If you want to go faster, save the 1200 plus dollars you'll spend on roller cam and lifters, sell the 177 blower, and take the 1200 bucks, and proceeds from the 177 sale, and put on a bigger blower.

Having played with a similar engine over the years, in many forms, I could tell you first hand, the power lies in the induction and heads.

Don't get me wrong, if you were rebuilding, and tearing it all down, a roller upgrade is nice. But, to tear it all apart, to gain maybe 25-30hp, IDK. As far as reliabilty, in case anyone missed it, there has been tons of issues with hydraulic "roller" lifters. They are not without issue. If you have 60 trouble free hours now, I'd say you're probably doing ok with the setup. jmo