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Technical: Have A Boat/Engine Question

monkeyswrench

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Have a buddy with a jet bote...with a 455 Olds. (Don't deny it, we all have or have had that friend) Motor in bote froze, cracked and died. He bought a motor from a guy in Phoenix. He asked me to help put it in.
My first question to him was "what exhaust did it have on it?"
Over the transom...his boat is not.

Any ideas on how to determine if the cam will work? I know there's magic numbers, but never had to reverse engineer to find the numbers.
 

DarkHorseRacing

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Have a buddy with a jet bote...with a 455 Olds. (Don't deny it, we all have or have had that friend) Motor in bote froze, cracked and died. He bought a motor from a guy in Phoenix. He asked me to help put it in.
My first question to him was "what exhaust did it have on it?"
Over the transom...his boat is not.

Any ideas on how to determine if the cam will work? I know there's magic numbers, but never had to reverse engineer to find the numbers.
Overlap is what will get you. You can Google search β€œcam selection for boat to reduce water reversion” and come up with several good reads.
 

Nordie

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Damn, they make cams big enough to cause reversion in an Olds motor?

Could you pull the timing chain cover and see the face of the cam and look for a P/N?
 

Mototrig

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Have a buddy with a jet bote...with a 455 Olds. (Don't deny it, we all have or have had that friend) Motor in bote froze, cracked and died. He bought a motor from a guy in Phoenix. He asked me to help put it in.
My first question to him was "what exhaust did it have on it?"
Over the transom...his boat is not.

Any ideas on how to determine if the cam will work? I know there's magic numbers, but never had to reverse engineer to find the numbers.
Id like to know too. I've heard it boils down to valve events and cam centerline, which many people much smarter than me can explain WAY better than I can...
The "magic" number that I've seen reoccurring for marine cams is around the 223 duration #. But there are so many other factors that can blow that number outta the water (see what I did there) haha. Basically it's all FM and no one number can explain it.
 
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4Waters

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Damn, they make cams big enough to cause reversion in an Olds motor?

Could you pull the timing chain cover and see the face of the cam and look for a P/N?
Rarely is the PN# there, it's usually on the end
 

4Waters

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Have a buddy with a jet bote...with a 455 Olds. (Don't deny it, we all have or have had that friend) Motor in bote froze, cracked and died. He bought a motor from a guy in Phoenix. He asked me to help put it in.
My first question to him was "what exhaust did it have on it?"
Over the transom...his boat is not.

Any ideas on how to determine if the cam will work? I know there's magic numbers, but never had to reverse engineer to find the numbers.
I believe you can put a degree wheel on it and a dial on number 1 intake and exhaust rocker and check overlap
 

monkeyswrench

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Damn, they make cams big enough to cause reversion in an Olds motor?

Could you pull the timing chain cover and see the face of the cam and look for a P/N?
"There wasn't a number on the cam" was the response...I figured a pn may be a start. The thing with that, I know of about 20 cams from the 90's that I ended up with that were regrinds and just had x's...so who knows🀣
I believe you can put a degree wheel on it and a dial on number 1 intake and exhaust rocker and check overlap
I think that's what may happen...I may have to pull the front end down and put a wheel on it...if I can find mine...it's been awhile:oops:
 

coolchange

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Tell him to just not lift all they way after WFO.
 

4Waters

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Just tell him to convert to a Merc 4.3 /Alpha combo.
He'll get similar performance and better longevity. πŸ˜πŸ‘

Somebody had to Olds bash here. 😁😁
Put that merc 4cyl with a 460 stroke, bore and cylinder head🀣🀣

All joking aside those run surprisingly well, maybe because it's a 230ci 4 banger😳
 

monkeyswrench

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if the old motor is only froze broke, swap the cams and call it a day.
That would make sense...but the guy had a "mechanic" up here ring and bearing the thing, swap parts over and crap. I Had already asked him if he had the old cam, but didn't get a straight answer as to where the old motor is.
 

HOOTER SLED-

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That would make sense...but the guy had a "mechanic" up here ring and bearing the thing, swap parts over and crap. I Had already asked him if he had the old cam, but didn't get a straight answer as to where the old motor is.
In my good ole days....spun bearing was the thing.... High rev, WOT..all the oil up top. You know, fuck shit up the right way. πŸ˜‚ Mondello restriction kit....10 qt marine pan, perhaps an ignition box with a rev limiter. Only way to keep them damn Olds surviving.
 

coolchange

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That would make sense...but the guy had a "mechanic" up here ring and bearing the thing, swap parts over and crap. I Had already asked him if he had the old cam, but didn't get a straight answer as to where the old motor is.
Is he an Olds guy? Does it have restrictors in it now? If not do it.
 

mash on it

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@monkeyswrench -
You could measure the lift and see if Summit/Jegs has the rest of the specs in the catalog.
Just checked, Summit has ~32 different (flat tappet) cams for olds 455. Shouldn't be too hard to narrow it down.

I've been ok with 235Β° duration at .050" with logs and snails, 1 sbc and one bbc, if that helps.

Dan'l
 

rrrr

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In my good ole days....spun bearing was the thing.... High rev, WOT..all the oil up top. You know, fuck shit up the right way. πŸ˜‚ Mondello restriction kit....10 qt marine pan, perhaps an ignition box with a rev limiter. Only way to keep them damn Olds surviving.
I earned my stripes a long time ago. Blew one up in 1976.

😁
 

monkeyswrench

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Is he an Olds guy? Does it have restrictors in it now? If not do it.
I know the guy that did the motor stuff...and I'm going to say no it doesn't. That said, not sure I want to volunteer to do it either. I should ask/warn him about it.
 
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