Offshoreonly.com - Cant get RPM out of a 454, 330hp

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Quote:

Originally Posted by 35thls1ss19 (Post 3167716)

i looked on the gear case and nothing is there. i will take some pictures. would it be stamped in?

I wouldn't go by any numbers found stamped on the gear case- quite possible that over the years the gears were changed whether intentionally or unknown to the owner. Need to do the math based on number of engine revolutions to drive's output shaft revolutions.

Good luck hopefully you only blew a head gasket on the 454.

Quote:

Originally Posted by Fixxxer22 (Post 3168968)

you sound like you have my old problem. I have a gen 5 engine (1992 build) it had a flat tappet cam. They took alot of the zinc and phosphorous materials out of standard oils. those additives made it easier on the cam and flat tappet assys. i kept running less and less pitch. the boat kept going slower and slower. tore the engine down for a build up and found (count them!) 5! 5 flat lobes. i wanted to scream! when i got it to the machinist we both sat there and guess horsepower with a cam like that... we both know it couldnt be over 200. you need to retro-fit over to a haydraulic roller setup. Bob Madera can help you there. im sure your engine needs freshening up. and from here on out run race oil.

I got all the way down to an outboard vensura 19p 4 blade prop. i think it had a 13.5 diameter. compared to the props i am running now.... itys little. the holeshot was crap and i got 49 mpg out of it at the end of that season. pretty sad.... i got 74 once this year with a Bob Madera engine!

You wouldnt happen to still have that prop would you??

Quote:

Originally Posted by rchevelle71 (Post 3169622)

You wouldnt happen to still have that prop would you??

no, i ebayed it. but it was a mercury vensura 4 blade. you can get them pretty cheeep.

Quote:

Originally Posted by Fixxxer22 (Post 3169734)

no, i ebayed it. but it was a mercury vensura 4 blade. you can get them pretty cheeep.

Jus checkin', doesnt hurt to have a spare, or try another prop, so far the mirages have been best.

so i got the motor back together. I put on an air gap intake, edelbrock carb and a new head. re adjusted my valves. Checked comp and all cyl are 130+. Still getting 3800 rpm!?!? I got my advanced timing set at 32*. I am lost now.

Can it be the drive? I read somewhere that BBC alpha combos cam with the 1.32 gears to put less stress on the drive? I will go buy a 1.50 if you guys thinks that the problem, there all over cragslist. Over the winter i am thinking of upgrading to bravo.

Or buy a smaller pitch prop.

but a BBC spinning a 17 pitch?! sounds stupid does it not?

i have read alot of bravo 223ls guys spin a 21 is this bc of the 1.50 gear drive?

How is your exhaust routed, thru prop?

Quote:

Originally Posted by 35thls1ss19 (Post 3180148)

but a BBC spinning a 17 pitch?! sounds stupid does it not?

i have read alot of bravo 223ls guys spin a 21 is this bc of the 1.50 gear drive?

the 1.32 is for sure holding you back. i have a 1.36 and i switched to 1.50 and i will never go back. my boat was custom order by an idiot. it had a factory 502 mag with the "claimed" 415hp. i was running 19p props and not even getting up to the right rpm. but keep in mind that the number on the prop has no effect on how bad ass the boat is. it is all about getting to your target rpm and if you cant get there with your current prop and drive setup.... the props will be cheaper.

i had bad gauges. last year i was running a 500hp and i thought i was getting 5600rpm with a 24p bravo1 4 balde with a 1.36 drive. guess what i was wrong. i got a 1.50 drive now and 570plus hp with a marine kinetics (bob madera) engine. running in the low 70s with that same prop. that 24p bravo1 and running 5500-5600 with a new set of livorsi gauges. plaining is amazing and the boat is better than ever.

also, if i had the correct gauges i would have known my WOT rpm was low. i would have propped it correctly and gone from there. which is what i reccomend from here. prop it right and you will be happy as long as you have no base engine issues.

happy boating buddy and i really hope you get her whipped.