New to the BBC...
 

Hey guys, I am new to the boating world...

I have a 1996 22 Scarab with the Mercruiser 7.4 454. I have been looking around at different options for the motor to increase the power and rpm capability of the stock 454.

I have also read through the boards and seen bits and peices of stuff to do but not an overall reccomendation from one of you that is more seasoned than I.

If you had the above mentioned boat, and were starting from scratch... what would you do with the engine?

Do BBC rebuilds require specific things for marine applications vs street?

I have seen the 425hp rebuild kits that SDPC have...

Please keep in mind that I am military and I am on a budget... best bang for buck reccomendations only please. As I cant drop 10k for a short block.

Re: New to the BBC...
 

im definately not the expert here but, can i assume your talking a carb motor? or mpi? thatll make a huge difference in some responses here.
its my understanding...if carb.....find out which cyl heads you have, then cam intake and carb can be a good start on a budget.
im sure youll get some great answers from others in your same situation

kevin

Re: New to the BBC...
 

Ummmm It dosent say MPI on the engine... It looks to be carb... Again.... I am kinda new :(

Re: New to the BBC...
 

If you are looking for a few more reliable horsepower, I have a 454 Magnum MPI 385 horsepower @ the prop , 415 @ the crank. I dont need it anymore. I would let it go at a reasonable price.

Re: New to the BBC...
 

ur prob better off findin a good low hour 454 or 502 that someone already put the money into. itll cost more to replicate than to find one done already

Re: New to the BBC...
 

Buy Dennis Moore's book called "Big Block Chevy Marine Performance" before you buy any parts.

Read it cover to cover before you spend any money and you'll be miles ahead in the long run.

This guy literally wrote a book to properly answer your question...plus it's a great text to get you up to speed on BBC performance basics.

Re: New to the BBC...
 

What ECeptor said. Dennis Moores book is a great read. Also, be patient. Lurk here and at other go fast boat sites for a few months and absorb as much info as you can, and ask questions....lots of them. There is a chitt load of knowledge available here. Good luck!!

Re: New to the BBC...
 

I have 330 now in the motor... I dont think I need a replacement, but instead maybe a 496 stroker kit.... a blower.... or hell just a good cam and heads.

I am unfamiliar with what the BBC reacts well to... and I am sure that there are some guys out there like me on a budget.

Re: New to the BBC...
 

Ok I got it... I will look for that book. I am also looking for the good budget things to do... I have seen the 425HP rebuild kit on SDPC... I have heard and read about the 496 stroker kits......

Heads... well budget heads... Edle Marine BBC heads? (750 a peice)

Thanks!!!

Re: New to the BBC...
 

If you have a 330hp 454 then you have cast pistons (just like I do). They will not live long at rpms higher than the max 4,700rpm stock limit.

So, you can leave it as is and have a great bullet-proof engine, sell it as is and use the proceeds as seed money for a build up, or pull it and start rebuilding from the bottom up.

I'm leaving mine as is until I have saved enough $$$ to replace it completely.

If you want to use your current engine as a starting point you will need:
-good heads (oval port Edelbrock marine's would be nice)
-headers or better exhaust (thru hull, of course)
-high rise dual plane or single plane intake (Edelbrock RPM air-gap is great)
-refreshed bottom end with new forged pistions
-new cam (my guru recommends a Crane p/n 134561 236°/246° @ 0.050" duration and 0.553/.571" lift)
-compression in the 9.0-9.5 range with the aluminum heads should allow use of 87 octane unless you go nuts with the total timing.
-carb then tuned for the new engine.

get that book...I pick up on something new everytime I re-read a chapter.

Re: New to the BBC...
 

ECeptor.... Great Post... that is the info I am looking for!! Thanks!

Anyone else have an opinion?

Re: New to the BBC...
 

Another reference book I've read cover to cover several times and recommend is "Horsepower Handbook." It is a compilation of articles from HotRod magazine. I found my copy at the local bookstore (Borders).

Re: New to the BBC...
 

I actually put 250 hard hrs on a 7.4 cast crank/cast pistons after adding a new cam, intake, exhaust, holley 800, a bigger oil cooler, roller rockers and some head work. The peanut port heads will be ok up to around 400 hp. I ran it consistently at 5200rpm for 3 seasons of poker running( ie to the dash stop)
You can make a nice 468cid, add a steel crank, 7/16 rods and forged pistons, decent set of heads, intake, crane 741 cam, exhaust, carb etc and make 500hp all day long for not too much money. Surf the classifieds and the swap shop on this board, you can find lots of good used parts there.

Re: New to the BBC...
 

We just built a pair of 454's. Replaced rotating assemblies with a stroker kit.
Eagle Rotating assemblies (496 Stroker kit)
JE 10.4:1 pistons
Merlin "Grumpy" cast iron heads (raised exhaust ports), Team G duel plane hi rise intakes
Lightning headers
Comp cam Pt No 11-775-8,
Duration 224/232 @ .050
Lift .348/.354
Peak power is 675hp w/36 deg advance and can run on 91 with less advance but we run 110 leaded.

Nothing real special with the built except the heads where "massaged" by Tim Morgan.

Re: New to the BBC...
 

The cheapest move would be get a set of closed chamber heads, have bigger valves put in them. Get a flat hydraulic cam that will not have too much overlap or lobe seperation. Add a cast Iron holley hi-rise intake , and a 750 Holley. Get the parts on e-bay. You will have to keep the revs. down below 4600, in order for the rod bolts not to stretch, and wipe out the bottom end. You would be better off finding a 365 Mag motor short block of the '91 and older variety. Like others have said, go with the 7/16 rods, forged pistons, (TRW 2399) and #7416 forged steel nitrided cross drilled crank. 2 bolt main block will be fine. I suggest Arp main studs. This equivalent of a Mag short block can rev to 5500 or more if balanced, and rods resized, with perfect machine work, assembly, etc.... BBB

Re: New to the BBC...
 

I agree with much of what is being said here by some of the others...

My cousin's 454's engines were originally stock Merc 454cid 330hp engines. Actually, his engines are now 461cid, 218*/226* on 110* lobes, .515".515" lift hydraulic flat tappet cams, 8.6 comp ratio, dual plane hi-rise aluminum intake manifold, Holley 830cfm carbs, bowl/pocket ported GM junk large oval port, 3/8" rods, semi open chamber heads with larger valves, cast pistons/cranks. He also had a cylinder bore notch job done which is very benificial in unshrouding the valves in 454cid engine. It is usually worth about 30hp/tq. I call them "the poor man's hi-performance 330".

We used to upgrade the old Merc 454cid 330's all the time back in the 80's. Some we still used, and modified the parts it already had internally except for the cams, rod bolts. You can still use the 3/8" rod bolts, but would strongly suggest replacing the stock rod bolts with the ARP rod bolts. My cousin decided to use cast pistons, but I wouldn't recommend it. Forged pistons would be the way to go or even hyperutectic ones. When replacing the ARP rod bolts you will need to recondition the rods with those bolts and if you replace the bolts with studs in the main saddles of the block make sure you have the main saddles align honed. The 7/16" rods that come from GM are a forged rod. The 3/8" rods are not really a forged rod, but a good thing to do is have them shot peened which stress relieves them and makes them a little stronger, them have them reconditioned with the new ARP rod bolts. I have seen several guys do this in hi-perf marine applications without any problems. Over the years I have also seen several guys using the stock cast crank in marine applications up to 5500rpm.

Just make sure you have accurate machine work done with the correct clearences for a marine application engine. Also, measure EVERY rod/main bearing with a micrometer that goes in the engine, and balance the complete rotating assembly.

Anyway, my cousin's engines were dyno tested with dyno headers, and made 461hp @5100rpm and 510 lbs of torque @3600rpm and stayed pretty flat up to 5000rpm. In the boat he runs the engines with an aftermarket GIL (dry) exhaust system which is much better than the stock cast iron system. A better breathing aftermarket exhaust system like a Stainless Marine or GIL, etc, will help your engine when doing performance upgrades/mods. We could have run a larger duration cam, but with cast pistons we wanted to try and make peek power around 5000rpm or so. Using a GPS he picked up at least 10mph in the midrange, and is still testing different props---but he's very happy with the results.

What kind of exhaust system are you running?--stock cast iron Merc??? Hope this helps--- Have fun!

Re: New to the BBC...
 

I think the 330hp is a cast crank and 2 bolt main so superchargers and high rpm are out of the ???

Re: New to the BBC...
 

The 330 is cast crank, 3/8" rods, and cast pistons. The pistons are the limiting factor. From what I've researched, I would not put a blower on mine or rev above 4,800rpm.

The rods and crank will handle a lot more power than 330hp.

Re: New to the BBC...
 

I've ran them all kinds of ways. I've tried the 3/8 rods with arp bolts. I've ran the the stock 7/16 rods. All with balancing ! Don't waste time and money on the arp resized weak 3/8 rods. Any real performance atempts in a boat, will render them poop ! Sure the bolts give the rods more clamp , but the rods still suck ! You cannot build a champagne motor on a beer bankroll ! It's like making chicken salad out of chicken S#i+...
I've been there and done that, and am still starting to begin to smarten up. Life is too short to f around to rebuild a short lived motor to get another two hundred rpm's out of. And still not be happy. People all the time are trying to make more power from what engineers spent countless hours on. The end result prooves the engineers right ! I'm sorry to let you guy in on this, but you can only get a certain level of performance from cheap parts and only for so long. Sure they could have built it better, but only did for big $$$ and still held back. !!! I don't want to see anybody have to learn the hard way. I used to think , "wow it's a 454" It's awesome. These motors stock have far more torque than anything normal. But each has it's own limitations. BBB

Re: New to the BBC...
 

Perhaps I should clearify that these are 454cid engines in the 450-500hp range and I have yet to see 3/8" rod with ARP bolts come apart. It is what I have witnessed, and experienced since the early 80's back when we didn't have much of a choice in rods. Also, there have been times where the 7/16" GM rods have been known to have cracks around the cap areas because the material is thin in that area where the bolts are---but it's still the stronger rod. The 3/8" rods have more meat/material around the cap area than a 7/16" rod does. Whatever rod you use have them magnafluxed. I am not a rod and bolt expert, therefore perhaps they may eventually fail at some point, but from what I have seen, it has not happened to my knowledge.

Again, I'm not trying to be dogmatic here or upstage anyone here, neither am I trying to lead anyone astray----just giving testimony as to what I have witnessed in the past 25 years or so. If someone else has experienced poor results using the 3/8" rods with ARP bolts that's fine, let it be known what you have experienced here---that's what this forum is for as I would certainly like to know for myself---hey, I'm okay with correction. It's just a hobby guys, have fun. :D

Re: New to the BBC...
 

AWSOME Feedback... Ok now I have been doing some reading and have found allot of kits on E-bay and the like to stroke to a 496. Now some have the Eagle 4340 crank in them.. and some with the Cast crank... I am looking for a 500HP engine... that is all. Do I need the 4340?

Re: New to the BBC...
 

No, not based upon what I've researched.

Are you going to sell you current engine and start over or are you going to re-build it? Is it EFI or carb?

I assume you'd like to get 500 reliable hps as cheaply as possible...or do you have a fixed budget?

Re: New to the BBC...
 

No you are right... I would like to do 500HP as reliable as possible... within my budgetary constraints. The Army dont pay well... so I am limited at what I can throw at it.

Re: New to the BBC...
 

Sounds like we are in the same boat...pun intended.

Here's the advice I got from my v-drive racer buddy.

"Properly set up stock stuff can easily turn 6000rpm and live for years. Take my first set up for instance: Production 2 bolt block with good machine work and ARP main studs. A good cast crank, deburred shot peened, magnafluxed and index ground .010/.010. Stock 3/8" connecting rods, deburred shot peened, magnafluxed, resized and ARP bolts. TRW forged pistons. This short block was built 14 years ago and ran between 6000-6500 for the first 3 years and then ran 6500-7100 for the rest of its life."

That's my short block plan. 0.060" over gives 468ci. So, I'll get the extra hp by spinning up near 6,000rpm. According to my research and the advice from guys I trust, the plan I outlined above will get me there.

I think that's the cheapest route to a solid, reliable 500hp from where I'm starting.

Here's my power data from DeskTop Dyno:

rpm hp
2000 150
2500 210
3000 260
3500 321
4000 386
4500 452
5000 505
5500 542
6000 556

Re: New to the BBC...
 

Back to the stroker thoughts...assume 1.1 hp/ci and the cost of the stroker kit (crank + rods + block clearancing machine work) would only net you 31hp. I don't know the cost of a stroker kit, but I'd assume $1,000 for everything would be cheap. Far better to put that cash into getting good heads and double wall true headers, imho.

Re: New to the BBC...
 

Another one in the same boat....

ECeptor, which heads are you running to get those numbers? I have a 200 Hour, GenV 454mag (carburated, non roller cam) and I am looking for the flow numbers for the Heads (Square Port). I think Mercury says the 1995 engine has 350HP. I know the engine has forged internals, thinking about re-ringing the pistons and putting in a different cam to boost performance. Any suggestions? I am looking for the 500HP mark as well. Does anybody know if 350HP is at the crank or prop? If it is at the prop, what would my crank HP be? I am running a Bravo outdrive. How much HP does a Bravo1 eat up?

I'm sorry, I have a lot of questions...
Thanks,

Re: New to the BBC...
 

If you decide to use 3/8" rods, get the thumbprint truck rods.

Re: New to the BBC...
 

Just wanted your opinion on this...

http://cgi.ebay.com/ebaymotors/BUDGE...QQcmdZViewItem

Would something like this work for the rebuild... This is budget, but I want reliable as well.

Re: New to the BBC...
 

The heads I used are "Canted/Oval Pocket Ported, Large Valves" selection in DT Dyno with 2.25"/1.88" int/exh valves. I'm assuming Edelbrock RPM oval ports or AFR heads will perform to those flow rates.

Here is a site with lots of head flow data - BBC head flows

Now, you are in a different boat than Longrange and I are. Your 454 Mag has a forged crank, heavy duty 7/16 rods and forged pistions. All you need is to rework your top end (head, intake, exhaust, cam) and you are good to go.

Again, get that book I mentioned earlier and it defines all this for you in much more detail. It's will pay for itself 100x over.

I believe a B1 eats about 5% of the power from the crank to put it to the prop...but I'm not 100% sure on that.

Re: New to the BBC...
 

You just found the limit of what I've learned. I'm not an engine builder - just an engineer who loves to research and has gotten bitten hard by the boating bug hard.

So, my advice at this point is not to buy any parts until you have your whole plan outlined - including knowing and talking to the machine shop who will do the work you need. Before you buy stuff like pistons, you will need to have all your geometry worked out so you get the compression you want with your rods, pistons, block and heads. There's a lot of math to do before you should spend your hard earned $$$.

For me, I'm going to have my crank and rods checked out and if they will work, I'll buy pistons only. I'd rather spend any extra money I have on heads rather than 31 extra ci.

Again, have a plan that includes all your goals (power), limits ($$$) and the parts you currently have then find a shop to really nail down the parts list. Then it's time to shop!

Re: New to the BBC...
 

i know this is prob. a dumb idea and question but what about this with a set of heads. and then we can keep our 330 motors togather for a reliable back up. it seams pretty reasonable but its an auto engine but it is a 4 bolt with forged internals.http://cgi.ebay.com/ebaymotors/ws/eB...tem=4593062770

Re: New to the BBC...
 

Dont know your budget but I have a 540 that makes 625hp @5750 with only 23 hrs on it for $6000, Built by pros not in some backyard garage. With dyno sheet. Flame arrestor to pan . NO exhaust. On longisland.

Re: New to the BBC...
 

Damn...if this was December 2006 you and I would be dealin'.

Too much too soon for my boating budget. Gotta upgrade the tow rig first - must be patient.... :(

Re: New to the BBC...
 

:eek: Wow... 6k in one shot would be a little more than the Army sets me up for. I may have that saved after I come back from Iraq this time around... Thank you for the offer!! And boy would that have been an awesome offer!!!

Nobody answered my question from the above ebay rebuild kit... would that work?

PS: Thank you everyone that is giving me feedback... this old troop appreciates it!

Re: New to the BBC...
 

You should see what you can sell your 7.4L as is. There's a decent market for those engines if they are stock. If you could get $2k out of that, that leaves a balance of $4k.

Don't forget a decent set of ready to install BBC heads are $2k.

Also, my new job is designing and building hardware to help keep you boys "over there" safe...safe and armed!!!

Re: New to the BBC...
 

Ok so someone please explain the difference between Marine engines and Normal.... Can I buy a normal shortblock and put my marine stuff on it?

Thanks guys!!!

Re: New to the BBC...
 

search this forum for "crate engine" and you'll find tons of threads on the subject.

Re: New to the BBC...
 

If you want to build it yourself be prepaired to do it alot. You will have alot of down time and after doing twice how much will you have saved ? All parts and builders are not created equal. You need a builder who does performance marine engines. Anybody can build a big block and have it last for years when the rpm only goes to 3500. 5000 rpm you need a pro who knows the rite parts and installed at the rite tollerences for a marine motor ! For an example try running your car engine at 5000 rpm towing your boat up hill for 30 minutes and see what happens. THATS THE MARINE WORLD

Re: New to the BBC...
 

Well said Z. Engines destined for marine use are in a whole different world of their own.

Re: New to the BBC...
 

That e-bay motor is a good deal, but the pistons have too much dome. 10-1 is too high of compression. 9.4 or 9.5 -1 would be ideal for 93 octane pump gas . I've had trw 2349 pistons which are 10-1 on an open chamber head, milled down to create a piston somewhere between the trw 2349 and the 2399. I did this on two motors. Mostly because I got a great deal on the pistons. Another hot way to go would be to run the higher compression motor, and fuel blend racing fuel. One 55 gallon drum would probably last all season, Ie. 85 gal. tank, 15 gal race fuel 70 gal gas. A 55 gal. drum of race fuel would probably cost $400. BBB