Dono77056

Last year when I purchased my boat the survey turned up low compression on number 2 & 6 and slight tapping sounded like a lifter. Was planning on a top end build this winter, had the boat winterized and the sound evaluated, the shop said they put a stethascope on the engine and said the tap sounded more like an internal knock. Wrist pin or bearing they suspected. Called my mechanic, (seperate shop) suggested a freshening of the engine from a machine shop that built race engines and marine engines.

Upon tearing the engine down nothing catastrophic jumped out. Had a worn cam lobe and lifter and I believe a bearing on the crank that had a flat spot.

The engine has been bored i believe twice over the shop said it was a 468. We had originally talked about building a stroker with a roller cam for about 5K . I think somewhere around 550hp maybe more.

The final suggested build was using the existing crank and a lil hotter cam since it was going to be replaced. Suggested dyno should be around 450hp, for an extra grand we can go to a roller cam a lil hotter and pick up another 50hp. Both the shop and my mechanic said the 450 should work nice and not have to worry about upgrading to a bravo xr.

The main thing i want is good reliable power out out my 454 mag. Bad economy and keeping things budget minded with an emphasis on quality.

Any thoughts.

CIG3

I would go with a nice hydraulic roller on any build, its worht the extra couple bucks up front. Look at a few threads here on OSO about HP500 build ups. That is the direction you are heading. All the parts will be listed and you will be able to run on 87-89 octane and make your 450-500 HP.

The 24 Pantera should run in the mid to upper 70's with that combination all day.

Stormrider

I had 560hp and upgraded the internals on my B1. No problems to date w/ either one that i know of.
But once you start upping the hp, you gotta do an exhaust, and with speed external steering. Which can be another 4-5k.
Btw, the boat ran 75 for me, and now is in the upper 70s w/ current owner.

ziemer

iTrader: (1)

Yep, no problems, knock on wood.

Since you've got the same boat as mine, I wouldn't go for anything less than 500 hp. 500+ will break you into the 70's whereas 450 might leave you right at or just shy of 70.

Hydraulic steering will be a necessary upgrade as you will find the stock steering will become sloppy over time with a bunch of hp. The steel pin that runs through the gimbal eventually wallows out the hole which leads to loose steering and from there the handling suffers.

Don't forget exhaust too, cause ain't much point in raising the hp if you're not gonna let the motor breath.

The motor in my boat has been reliable for me so far. It's got 150 hours on it, and it still fires up and runs like a champ.

TexomaPowerboater

I'd switch everything over to a 502 415hp GM Marine long block. Basically make a 502MAG. I had some engine troubles with my 454 and this was the route I took. It was cheaper to buy the new long blocks than to rebuild. Easy choice, much better for resale too.

Dono77056

I'm going to stick roughly at the 450hp - I do have upgraded exhaust but I dont have hydraulic steering. We'll see what it comes out when the shop does the break in next week. I think the bill is going be roughly $3500 for the shop work and another 1K for take out, install, service and other misc. repairs, cleaning up some of the rigging. The boat was originally Bill Dahl rigged. I dont want to slam the guy but very sloppy wiring, lots of use of the same color for positive and ground. Maybe he a like red wires or got a good deal on them.

IRONMAN

Don't stray too far from the merc HP450 specs and you should see low to mid 70s but the roller cam is necessary for this as is the good exhaust. external hydraulic steering is a must in any 7' beam boat , when you outrun some 30' boats in the rough you will understand