Re: New to the BBC...
 

I dont know about you guys but I get nervous when I cant get 91 no less have to mix it myself. Some stations on the water dont even have 91. The pistons wil be like ballpark franks, THEY PLUMP WHEN YOU COOK THEM.

Re: New to the BBC...
 

I am already alittle ahead of you.. I have a 98 22' Scarab and Im already in the process of building it. I have the same motor 454 lx 315hp carb :rolleyes: . Here is what I have done so far.

Im planning on keeping the stock short for this season because Im buying all my hard parts now.

Here is what I have already :

Edelbrock Performer Large Oval Marine Aluminum heads with the 100cc chambers
Lunati 1.7 roller rockers
TorkerII intake
Holley 750 CFM Marine Double pumper
HVH Super Sucker Carb Spacer
Full MSD Guages with 100mph GPS Speedo

Here is what I still have left to buy :

Crower Custom Grind Cam
Hardened Pushrods
MSD Ignition (coil, box, and distributor)
Gaskets

I also am trying to find a BlackHawk Drive and possibly a Stern Jack to go along with it..

Re: New to the BBC...
 

Ok so we are saying that the engines are acctully the same... but the difference is the demand that a marine application puts on a motor is much more high RPM for prolonged periods of time... so that has considerable implication on the accuracy of the rotating mass (Crank and Pistons).

I do know some shops localy that are great builders... but the build race motors for Drag racing. I am trying to educate myself in understanding the difference so that I can maxamize my money for the best results.

So besides the High RPM requirement... and Cam selection (Due to exhaust I belive) the motors themselfs are the same?

Thanks again guys!!!

Re: New to the BBC...
 

If you want to read up more about the 22' Scarab.. Go over to www.speedwake.com .. There are many threads about the 22 started over in the Scarab section by myself and others. Just figured I would pass it along :cool: . You may have to look back a few months in the Scarab section.

Mike

Re: New to the BBC...
 

Ok guys.. I have talked to a couple marine engine places on the phone. All of them are convinced that building a marine engine is so much harder than a normal performance engine.

What I dont understand is what is the difference besides that you need to build the engine to maintain 3000-4800 RPM consistantly and that you cant have a real agressive cam with exhaust if you have a through prop exhaust.

And something that nobody has been able to answer for me yet.... if I do heads, intake and cam on my existing '96 454 Carb 330 Merc will it hold up to the increase (Prob around 425???)

Re: New to the BBC...
 

TO MAKE 425HP YOU NEED A SEMI LARGE CAMSHAFT, IN TURN REQUIRING SEMI DRY EXHAUST. BIG CAMS HAVE LOTS OF OVERLAP THAT GIVES IT THAT GREAT SOUND BUT WILL SUCK BACK WATER INTO THE MOTOR AT IDLE. THATS CALLED REVERSION. TO MAKE 425HP YOUR GOING TO HAVE TO SPIN THE MOTOR OVER 4500 RPM AND IT JUST A MATTER OF TIME UNTIL YOU BREAK THE CRANK IN 1/2. IVE SEEN IT TWICE.THE QUESTION IS NOT IF BUT HOW LONG. i ALSO HAD A FRIEND WHO SUCKED SOME WATER ON HIS 330 AND BENT A ROD TRYING TO START THE MOTOR.

Re: New to the BBC...
 

It's not hard to make 425 hp with a 454. The weakest link is the cast pistons. If you can, replace them with forged. The rods are ok, better rod bolts are good insurance. I'd limit the rpm's to 5000 with these rotating parts though. Edelbrock heads are a good deal and they come with good valves. They will flow well enough for good power and oval ports make good torque. For 5000 rpm the biggest cam you want is the old Merc 420 cam, Crane #132561. .530/551 lift, 228/236 duration at .050. Holley 800 on an Airgap intake. Msd ignition. You can use stock centerrise exhaust with this and it won't revert.

Re: New to the BBC...
 

Im gonna be using the stock merc exhaust manifolds for the time being till I can get a set of Lightnings .. I think before I buy those im gonna do the outdrive mods. I just want it to rip outta the hole with people on it and do atleast 65mph.

Re: New to the BBC...
 

Longrange, The example of my cousin's engines in post #16 on page #1 within this thread is probably about as close as you're going to get for your answer. Like I have said, I and many of the guys on here are saying; ARP rod bolts, and forged pistons or at least hyperutectic pistons would be the wiser way to go, however, my cousin's engines does not have ARP rod bolts, and is only using cast pistons and his boat is still running (40 hours) with cast pistons @5000-5100rpm WOT, but he had good machine work done by a reputable, precision machine shop familiar with marine engines. For the most part, most machine shops will tell you or suggest that you use the parts that only they feel comfortable with because their name, and repuatition goes on it.

However, with some machine shops it still may not matter how accurately parts are machined or are assembled with either poor care or ignorance, then it still doesn't matter how good of parts you use. If it blows apart then what difference does it make?

My cousin does most of his cruising at about 4000rpm though. Who knows, it could be a ticking time bomb. :( Either way, I guess we'll find out....but at least for now he still has a smile on his face. You could build something like his and only run/prop them to 4800rpm and still make about 425hp or so. I cannot remember what his engines made at 4800rpm, but I would guess it would be close to 425hp.

I really don't know or haven't heard of enough situations with where cast pistons and stock rod bolts have survived in a Merc 330hp engine by just changing cams, heads, and intakes, etc and I don't know how exactly how much lift on the cam that you can use without kissing the tops of your cast pistons like we've experienced that back in the 80's (trial & error). However, that was with a cam that had over .550" of lift and more duration that what my cousin ended up using. A flat tappet hydraulic cam like his with .515".515" lift and 218*/226* duration might work---but you still have to check piston to valve clearences.

Who knows?----Your engine(s) just might survive while making 425hp @4800rpm. To me it seems like it would be fine, but that's one answer I cannot be confindently sure of. There's a lot to consider----it goes on and on.

Re: New to the BBC...
 

Grrreat reply's everyone!! I have learned so much in a short time. Here is the road I think I will go.

I have found a performance engine producer that is going to build me a Gen IV 496 and balance it to the Gen V flywheel. Forged Pistons with a Nodular Iron crank. The cast iron heads are worked over ported and polished with RR and fresh valves and springs. Edle Torqer II intake. We will go with a somewhat mild marine cam.

All this for about 4600 delivered... what do people think? Oh and I will add an Edle 850cfm DP carb.

Re: New to the BBC...
 

A Gen V flywheel will not bolt onto a Gen IV carnk...

I had a 330 in my 1989 24' Pantera.
I changed the cam, intake, and added Imco risers to the stock cast exhaust manifolds, but did not touch the bottom end.
The cam was a Comp Cams, but I don't remember specs. I did not changes the valve springs in the peanut port heads so the cam was not that much bigger than stock. Oh, I did also rejet the carb.
Anyway, the engine went from a max of 4500rpm to 4900rpm with a 23p prop.
It ran great for about 120hours then it lost compression in two cylinders. I pulled it apart; two pistons had melted. Cast pistons can not take the heat of a high rpm engine. I would agree with the others that have said the cast pistons are the weakest link.
My suggestion to building up a low output 454 is to use better pistons, cam for 5000rpm max, and junk the peanut port heads.
I think $1500 for a set of Edelbrock large oval or $1300 for a set of large oval Merlins is $$ better spent than for a stroker kit. If the heads you have won't support the added cubes then it's a waist. And if you have to buy both, just buy a new 502 base engine... :drink:

Re: New to the BBC...
 

496 is a good combo. make sure you get the good valves manley severe duty intake and inconell exhaust. go for the better crank and make sure it has not been cut 3 times. adding a fordged crank and an 850 you will be at 5600. $400 more and I know where you can get a 540 / 625hp.

Re: New to the BBC...
 

Well then ZZ help a brother out :eek: :eek:

Re: New to the BBC...
 

Longrange send me a PM I will see what I can do.

Re: New to the BBC...
 

Cast pistons also can have a piece break off of the skirt. It may have something to do with the manufacturing process, with the steel reinforcements in the skirts. I bought two 330 marine motors. When I cranked one over by hand I heard a knocking sound. Turned out to be a broken piston. Talking to a long established marina owner, this is common especially if motor is lugging (overwheeled). The reversion issue is very true, especially if using a big cam. I would suggest a max of .550 lift, 110-112 lobe seperation. Obviously the duration would be limited to keep overlap down, this will limit your cam selection down. I used the 365 mag cam. With head work, Large oval heads, big valves, porting, Better intake and holley squarebore carb., It really ran great in my 24' Formula, Until I lost oil from a cracked valve cover! and damaged the bottom end. ! Also dont waste money on an msd. They stop MSD'ing at 3000 rpm's anyway. They cost a fortune, have steel mechanical advances that break, due to poor spot welds at the factory. We ran the whole setup on a '38 Scarab with 572's. They provided no increase in power. I like the T-bolt IV. Very trouble free. You would be better off spending the money on the inside of the motor, Or on exhaust. My 2 Cents BBB

Re: New to the BBC...
 

Helluva plan with one exception - I'd stick with the Thunderbolt ignition if he had one already.

Re: New to the BBC...
 

ECeptor... BBB...Kaama...zz... everyone that has helped me in this board I want to say thank you!!!

Re: New to the BBC...
 

Let us know what you end up doing (in detail, of course!) and how it works for ya.

Re: New to the BBC...
 

These inconel exhaust valves...how important are they? I had a 502 built at the end of last summer by a reputable machine shop in Baltimore and those valves never came into consideration. It's basically stock except for .25 longer rods and a .550 hydraulic roller.

Re: New to the BBC...
 

Inconel is not important until you snap a valve off crush it between the head and piston cracking off the piston skirt and cracking the block. Thats Y they make sleeves.

Re: New to the BBC...
 

Ditto ! Inconnel exhaust ! Marine engines have very high exhaust temperatures because the motor is working hard. @ $200-$300 a set, they are some of the best parts for a boat motor.
Cheap exhaust valves will only result in a future failure. Even the inconnel valves should be changed if pitting is found where the head and stem meet. Like the Stainless headers, the metalurgy eventually changes in the valves, especially if subjected to reversion. Only use used valves that have been thoroughly inspected, and ground. If in doubt throw them out. Same thing with valve springs, buy the best that you can afford, to keep the motor alive. My friend's boat with the 572's dropped a valve. It had a cracked guide, and an intake valve fatigued and let go. In the end, doing things right is the only way to go. Instead of going boating we should have had the heads re-done, or rebuild both motors instead of just one. Now he needs a motor.

Re: New to the BBC...
 

That's exactly what happened to the motor that my present 502 replaced, even cracked the deck on the block...all was destroyed except the forged crank. I didn't hear of inconel valves until this new motor was complete. So I guess now you know why I have this concern about the integrity of the valves. Does Mercruiser use these?

Re: New to the BBC...
 

Mercruiser uses Inconel valves in all of their high perf engines. They used to put them in everything from 370hp up. I'm not sure if they use them in the 496 black motors but everything from 500hp up uses them.

Re: New to the BBC...
 

You're not alone with the 502 having valve failure. They have the same heads as the 454's. And the same Eaton GM 2.19 +1.88 car valves. And make more power which equalls more heat on the valves. Better quality valves should be used with nice big valve margins. forget about necked down "race" valves. It know it would suck, But maybe consider pulling the heads and doing an valve job with the Inconnel's . If you want more power go with the 2.25 intakes. Going with the bigger(1.90 exh.) valves isn't worth it. Especially if you have to have hardened seats installed. Whatever you do durability is better than what it costs, and better than short lived power. I'm still trying to get that through my head. :D Talk to the machine shop and find out what valves were installed. Some inexpensive valves made in Brazil are made from a very good grade alloy, and are better than the GM's. Any good valve should have markings on it near the top of the valve stem. They may have the alloy #, or Manufacturer's name on them. You may get lucky. BBB

Re: New to the BBC...
 

Thanks guys. Actually the motor that self destructed WAS a 454, but since I needed a block anyway I went with a 502 this time. For right now I think I'll run what I've got since it's brand new and only has about 10 hrs since the build, but I'll probably pull the heads after this coming summer. I was thinking about going with more cam anyway. Are you guys saying I should go with inconel exhaust and leave the stockers on the intake? And...do you think there is a noticable increase to be had from going to 2.25 intakes?

Re: New to the BBC...
 

Go with the manley severe duty intakes.

Re: New to the BBC...
 

I second all this valve stuff, having broken my share of motors due to valve failures. Inconel or Feria exhausts and Severe Duty intakes. I went from 1.19 intakes to 2.25. No noticable difference in boat speed for me.

Re: New to the BBC...
 

Thanks for the info. Yeah, I guess bigger intakes is one of those things that makes a small increase on paper but not enough to notice by itself. When I do the heads again I'll probably still go bigger anyway though. It might work better with the bigger cam I'll be using. You know how it is...it all helps in the big picture.

Re: New to the BBC...
 

Like most improvements, what works for you is what you want to do. Unfortunately what works well in someone else's application may not serve you well. All you can do is get some input from others, and ultimately make an informed decision for yourself. Based on the big picture, BBB