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454 Cracked Block

agitator

Contributing Member
"Guys, I just bought a 1998 bo

"Guys, I just bought a 1998 boat with a 454. The engine has a crack. (I knew that when I bought it!!) In trying to find a replacement block I get differing opinions on what will and will not work.
Is there a difference in marine and auto 454's? Aren't marine engines lower compression? If so, where do they get the lower compression? I've been told there are no differences in the block.. I've been told 1996 and newer will work, but anything older will not, I've been told any 454 with one piece rear main and hyd roller cam will work. What's the real truth?"
 
"BBC is BBC. You will need the

"BBC is BBC. You will need the marine parts to go with it.cam,core plugs, etc. Most likely the dished piston lowers the compression vs the flat top."
 
"Used to be that way. when the

"Used to be that way. when the gen V and gen VI stuff started showing up, mixing of parts from one vintage to another is possible but you have to be careful, especially with heads.

The one piece rear mains are definitely the newer GEN style, not the older Mark IV stuff. Gen V started in the mid 90's so the timeframe offered sounds correct to me. The compression ratio changes are most easily accomplished by changing the pistons - BT identified to two most common types. A good machine shop can set you up with what you need; given the local economy, they may be willing to work you a deal where you bring them the old "stuff" and you come back in a week and get the replacement long block."
 
"Ayuh,....
While I agree a BB


"Ayuh,....
While I agree a BBC is a BBC,...
Vintages Do matter,... All the pieces aren't interchangable between Vintages...
Donno where you heard the boats run lower compression ratios,...
Basically, that's Not true...

Mark is Right on, in that you should find a Machine Shop to work with,...
They can walk you through it all..."
 
"Unless you are doing the rebu

"Unless you are doing the rebuild, I would just get a reman. long block or a good used engine and be done w/it. Trying to cut corners to save a dime could cost you alot more in the long run. JMHO"
 
Where are you located?

I ha


Where are you located?

I have a very good complete rebuidable GenV with MPI if you're interested. It's not such a great deal if you have to pay to ship is across the country though.

It was in a '95 Formula I bought. I was going to rebuild it but stumbled across a deal too good to turn down so I replaced it.

PM me if you're interested and I can email pics.
 
"The power of the internet,nev

"The power of the internet,never ceases to amaze me.

I would go for the motor Rick has, marine motor mpi can't be beat."
 
"As a welder/mechanic,I have t

"As a welder/mechanic,I have to ask,where is the crack?is it external and repairable,I've done QUITE a few cracked blocks,some can even be epoxyed rather than welded,I have four that were epoxyed in the last 3 years,all are doing fine,7 were welded,they also are fine,now I reflect and think ,maybe they can ALL be welded,let me know.E-mail me ,PLEASE! [email protected] (this is not an ad for work,I may have a good answer to share)"
 
"Thanks guys. I found a comple

"Thanks guys. I found a complete engine, same vintage, at a local marina. The price was not bad at all.

Rick, I am in Alabama so shipping would have been an issue, I think.

Danny, Cracked is too mild a word to use for this block. I should have said busted!! It has a 5" long, 3/16" wide crack from the valley to the top of the cylinder on both sides. I'm pretty sure I can see a smaller one on one of the cylinder walls. After that I just quit looking for them.

Guy, I agree. Buying a long block would have been better and cheaper in the long run. (Ran across the same thing on a 318 last year and learned my lesson).

I did learn that all BBC are not the same, especially if you start swapping parts. Luckily, I found a complete engine.

Thanks for all the input."
 
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