Advice on 468 BB

[SS MAYFLOAT]

Seriously thinking about going with the BB to replace the SB in the 27' Bayliner. A friend of mine that owes me some money has a 468 that he hasn't put together yet. Was asking if I was interested in it for my boat. This engine was the start of a twin turbo setup. All machine work has been done. It has the one piece oil seal, steel crank, dished pistons for about 8.2 compression. Also has steel connecting rods. The oval port heads and block have been "O"ringed, the piston rings that he has is of the gapless style. He is a certified auto mechanic that doesn't no jack about marine engines. But it sounds like this would be a good base to start with. There is no cam, but that is good since what he would have used would be no good for marine use. I can get this for about $1,000. (what he owes me) Does this sound like a good price and good base engine to start with? I know I will need lots of other parts that will end up being more bucks. But hey! thats boating! Hope to find a blown complete 454 for the rest of the parts. Thanks for input, it really helps. <br /><br />SS

 

[coupedeville]

Re: Advice on 468 BB

A thousand bucks? Are you kidding me? <br />You'd be hard pressed to find a good block and crank for that kind of money. It's a steal.<br />Compression's a touch low, perhaps, but better a little low than high.<br />Sounds like he's got better than a thousand in machine work alone.

 

[SS MAYFLOAT]

Re: Advice on 468 BB

Yes sir Coup he does. He was doing all this stuff for his 72 1/2 Camero. That was before marriage and children. Now he's diviorced, and has outragious child support to pay. He is just going to leave the 396 in it and forget about drag racing. I know he paid $600 for just the crank. Machine work was done by him in the shop he was working at. <br /><br />I'm just dreading the idea of finding everything else to make this engine work right and be dependable. Things like alternator brackets, harmonic balancer, flywheel, and then the exhaust manifolds. Then make sure that I have plenty of rise on the manifolds to prevent water ingestion.<br /><br />One question that I'm not keen on is the exhaust manifolds. Do I have to run Volvo manifolds since I have a 280 outdrive? This is my gray area when it comes to marine equipment. My local Merc Dealer is super on helping me get parts and things almost at cost. (of course I help keep his heat/air cond running at his house). One of those scratch my back and I'll scratch yours. Could I get by using merc manifolds? Thanks again....SS

 

[coupedeville]

Re: Advice on 468 BB

Well sir, after having my dinner I've thought of a few other things you may want to consider.<br />1. The short block sounds bullet-proof. Compression's a tad low, but that means you can run cheap gas without a worry. What would interest me is the cylinder heads: Who made them, and have they been ported? If you hog the ports out too big, the low speed airflow is going to be badly affected. This is the problem with adapting an engine from one use to another. If they aren't what you need, they could always be sold/traded for a pair that better suit your application. Maybe even bump the comp up a little.<br />2. If you were conservative with your cam/carb combo, you're looking at an honest 375-400hp. Run like that all day with a premium short block. My question: Is your outdrive going to be happy with that much power?<br />3. Can't help you with the Volvo manifold question. Besides, that's looking a way down the road.<br />4. Cost. Yes, you can get the engine cheap, but that's probably the least expensive part of the conversion! Since you're owed the money, you can consider the engine as "free". Brackets, balancers, marine oil pans and manifolds, water pump, distributor, starter, etc., can be found quite easily, but they're going to add up. Count on maybe 2 grand extra. You can get good used stuff, if you do some scrounging, and help reduce the cost. Is it worth it to you? Only you can answer that. If you need to upgrade your outdrive though, well, that's something else.

 

[Walt T]

Re: Advice on 468 BB

280 or 290 drive should handle it.<br />May have to swap gears though. That engine is perfect for a supercharger.

 

[coupedeville]

Re: Advice on 468 BB

Oh absolutely. That's what the guy built it for; A turbo. But forced induction is forced induction.<br />The thing is, you're looking at another $2500 - $3000 for the blower. That may be more than Mayfloat's looking to spend. And an un-blown 350 - 400 horses will move him right along.

 

[SS MAYFLOAT]

Re: Advice on 468 BB

Thanks for the replies. My friend and I came to an agreement on his engine. I'm calling it even on the money he owes me plus I'm giving in another $500 for it. So now I have got the BB blues. Gonna work on getting the parts I need a little at a time. Doesn't look like I will get to use it this year. Wife got me a new Pool Table for Xmas. (and I'm paying for it!) So the BB is gonna be put on the back burner for awhile until the table is paid for. Maybe if I get good at pool, I can win some engine part money!<br /><br />Again thanks, I'm sure I'll need some more help later, actually alot!

 

[coupedeville]

Re: Advice on 468 BB

Before anyone forgets, ask your friend about the heads. Were they ported? And if so, does he have any flow numbers? My concern is that if the ports have been enlarged too much, it will kill the velocity at low speed, and you won't be happy with the way it runs.

 

[SS MAYFLOAT]

Re: Advice on 468 BB

I'm getting two sets of heads. Both have stainless oversized valves w/3 angle grind. The oval port heads have been polished but not matched to an intake/exhaust, and the square bore hasn't had any work done yet. He said the square bore should increase the compression somewhere around 9.1. So when I get the manifolds I will then match and polish the heads for the best flow.

 

[Bondo]

Re: Advice on 468 BB

hi SS,<br />sounds like you got a good deal....<br />you'll want the oval port heads.. the rectangle ports are Too big.. velocity is lost...<br />Also... stainless valves are NOT acceptable in a marine motor... you Have to step up to inconel valves...<br />seeing as you have the time, you could try to swap pistons with somebody.. you really need to get the comp/ratio up around 9.0 to 9.5...<br /><br />Good Luck......

 

[coupedeville]

Re: Advice on 468 BB

Iconel valves? Hoowee, get out your check book: Intakes are $25 each, exhausts $43. That's $500 right there, not including installation. <br /><br /> http://www.cpperformance.com/products/engine_parts/104.asp

 

[coupedeville]

Re: Advice on 468 BB

You might want some really good flowing exhausts for that bad boy, too. Regular manifolds are really going to back things up.<br /> http://www.cpperformance.com/products/Exhaust/default.htm <br />Better brace yourself when you check the prices though. <br /><br />Yes, the oval port heads are the way to go. Although, if I could get a good price for them, I might sell both sets and buy something like a set of Merlin aftermarket iron units.<br /> http://www.worldcastings.com/docs/catalog/pg16.pdf <br />If you have to start changing pistons though, this is going to get way out of hand. <br /><br />I told you the engine alone would be the cheapest part!

 

[Bondo]

Re: Advice on 468 BB

It's the Exhaust valves you have to worry about.... the stainless won't take the Heat of the marine enviroment.... you can run the "Cheaper" valves in the intake holes....<br /><br />coupe, maybe just me, but i just clicked on the last link you posted in this thread, Locked up my puter... had to restart.... wanted to see how badass those heads are.... <br />just another thought,.... you could find a set of 366cid truck heads... i think they have a small combustion chamber,+ i know they have oval ports.... you maybe able to sell the two sets of heads you have now to a racer kind of guy.... then you may have enough coin to buy the inconel exhaust valves....<br /><br />Good Luck...

 

[coupedeville]

Re: Advice on 468 BB

Yeah bondo, that worldcasting page is kind of odd. It's a pdf file, and it takes a real long time to load. You can probably find other pages with them. Try looking for "merlin cylinder heads". There are others out there too.<br /><br />When you say that stainless valves wont take the heat from the marine enviroment, do you mean that literally, or figuratively? Near as I can tell, boat engines don't run that hot. <br />Please clarify.

 

[coupedeville]

Re: Advice on 468 BB

Here's a site that lists all the avaiable Chevrolet cylinder heads, production & aftermarket, for mice and rat's alike.<br />www.dw1977.cz28.com/photo2<br /><br />Actually, there's a lot of pop ups and crap on there. Try this instead www.flatlanderracing.com/index They have loads of nice stuff, with prices too. <br />The listing for Edelbrock heads has marine heads, complete with iconel valves. $1200 a pair.

 

[coupedeville]

Re: Advice on 468 BB

Mayfloat, the more I look into this, the more your wallet is going to hurt. Using the rectangular port heads may up the compression ratio, but the bigger port size may work against you for low rpm power. it depends on the port volume. The oval ports would probablybe a better choice, but to get the CR up to the 9 or 9.25 to 1 area, you need new pistons. Another $500 or so, not counting installation, rings, etc.. Ouch.

 

[Bondo]

Re: Advice on 468 BB

Boy Oh Boy,..... it might be Cheaper to give your Buddy the $500. + his motor back.....LOL....<br />the Inconel valves are required on marine motors running 80 to 90% power, 80 to 90% of the time.... You know, the poker run guys,+ 468cid bayliners, + such......<br />Coupe, Ya it's the Heat... they usually let go right at the tulip... they are Right In the Flame path... at 15" downstream of the exhaust valves, we're talking 1200* to 1500*... <br /><br />I still think you Maybe able to salvage this project with a set of 366cid truck heads... oval ports,+ small chambers will work...

 

[SS MAYFLOAT]

Re: Advice on 468 BB

Well luck has it, I have an old friend that is into modified tractor pulling. He has offered me $3500 for the 468. I am going to go ahead and sell it and then find a 454 that someone has removed to repower. That way I'll get all the gadgets and gizmoes that I need. Thanks for your help, you probably just saved me a bunch of bucks. And I need to thank the Dirt Doctor for buying my basket case. Gee, boating is alot of fun. (at least when your on the water!)

 

[coupedeville]

Re: Advice on 468 BB

Yeah, that's probably the best solution. It was really starting to get complicated [and expensive] with that 468. It's usually better to start from scratch, than to try to adapt something else.<br />Since you're starting from the beginning though, I'd have to seriously consider a hotted up small block, considering the $$$$$ we're talking. If you're looking for a 454 take-out, suppose it needs freshening? <br />The small block would save you all the money in accesories that the rat would need, therefore more money for the engine.<br />Kinda cold to be worrying about boats today, though. Brrrrrr.

 

[coupedeville]

Re: Advice on 468 BB

Here's something of interest<br />502 Magnum's [used] for $4995.<br />290 horse Volvo 5.7 for $995!<br /> http://www.marinepowerservice.com/