Help quickly please

[Projectmach1]

I'm doing a full resto on a 92 Mach1 Concorde with a Mercruiser 7.4/Bravo 1. I knew the engine had some sort of water intrusion from the start due to milky oil but I was hoping it wasn't something too bad. I got the engine out of the hull finally and found out the block has a huge Crack on both sides which were hidden by the exhaust manifolds. The block casting is 10114182 which I found to be a 91+ GenV 4 bolt main. I found a guy selling a pair of 454 blocks a few hours away, one is from a car/truck and one from a boat. His casting number is 14015445 which I found to be a 78-90; 2 or 4 bolt main.

I'm fairly new to the GM engine game so my question is, are either of these blocks usable? All he is selling is the block and bottom end internals. I would of course be taking everything out and having it cleaned up with new cam bearings and marine freeze plugs. If the older blocks are usable I'd love to jump on this since he's only asking a few hundred per.

 

[tpenfield]

It sounds like the blocks being sold are 'Mark IV' and you have a 'Gen 5'. So I think the heads are going to be different (IIRC).

The thing is that you probably should not use much from the original engine, as all the main pieces, blocks, heads, manifolds are suspect given the freeze damage that you show.

Perhaps you should shop for a more complete engine, rather than just the lower end.

 

[dubs283]

It sounds like the blocks being sold are 'Mark IV' and you have a 'Gen 5'. So I think the heads are going to be different (IIRC).

this is my understanding as well, your heads will not fit correctly on a mark iv block and vice versa, also i believe mark iv blocks have a machined area for a block mounted fuel pump whereas gev v and newer do not, hence the water pump/fuel pump assy on carbed gen v engines

as stated your best option is to find a used or reman gen v long block assy

iirc, mark iv valve covers were ribbed and gen v and newer were smooth, perhaps the seller can send you a photo of the valve covers if they still own them and you can compare

 

[Scott Danforth]

Find a gen 6 motor from a 1996 - 2000 truck. The gen 5 motor has issues, and you have to change too many things to use a mark IV motor

 

[Scott Danforth]

iirc, mark iv valve covers were ribbed and gen v and newer were smooth, perhaps the seller can send you a photo of the valve covers if they still own them and you can compare

Wrong, mark IV has stamped steel valve covers

 

[dubs283]

Wrong, mark IV has stamped steel valve covers

ah, yes. got sbc on my mind. haven't dealt with many 454 lately

mark iv has stamped rounded valve covers, gen v and newer sharp edges/cast covers?

 

[tpenfield]

Mark IV were stamped steel as Scott said, having the rounded shape. The Gen 5/6 had the more beveled/squared-off shape. The SBC's had the ribs.

 

[Projectmach1]

Thanks for the info y'all! I've been looking for marine engines for a while even before I got this one pulled out. Apparently people seem to think they're made of gold or something. I'll just keep looking. Might go hit the pick n pull and see what I can find.

 

[tpenfield]

'Marine' engines will be in short supply as everyone in TX and a few other southern USA states are out buying long blocks after the winter they had. (sorry to say)

 

[Projectmach1]

'Marine' engines will be in short supply as everyone in TX and a few other southern USA states are out buying long blocks after the winter they had. (sorry to say)

There are 350s out there all over, but finding a 454 is proving to be quite the challenge.

 

[dubs283]

finding a 454 is proving to be quite the challenge.

has been for quite a time

 

[Projectmach1]

Another question. If I get a 454 out of a 99 Burban, will my carb intake and exhaust be a direct bolt on? As well as the drive accessories? I found said 454 for $800 in Houston and will definitely make the drive if my bolt ons will fit.