Shore Thing

Looking for suggestions...

1996 454 mag carb (350hp all stock except gil exhaust), 225hrs in a Velocity 280. Had some reversion and got salt water in one of the cylinders. Have a budget of 5k. I've read about a lot of different 454 builds on here but wanted to get some direct advice. I'm pretty much a dummy when it comes to engines besides the normal servicing that I do myself. I've basically found that my options are..stroke it to 496 and get ??? HP. Put a blower on it and gain about 100-150 hp. Or fix the current problem and leave it stock.

I want more power, but I don't want ante up for the 502 upgrade. Looking for reliability as I will probably have this boat another couple of years before I move up in size. Keep in mind that the budget is 5k and you have to include labor in that since I will have an engine builder do it for me. So let me have it!!

Thanks,
Lance

1BIGJIM

Fix what you have and save the headaches

Griff

First thing is how did you get reversion?????? and solve that issue.

Depending on your engine builder and what parts you NEED, your funds for upgrades are going to be pretty limited. You don't have enough to Stroke or Supercharge it with your budget.

You can upgrade the cam and bump up the Compression ratio to 9.0-9.25 with little or no additional cost. Also, add roller rocker arms.

A good cost effective cam is the Crane 134241 and it comes in a kit with lifters under part #134241 for about $150. Change the carb to Holley 750 mechanical secondary, add a good Flame arrestor and your budget is probably gone.

Shore Thing

Approximately what kind of HP increase would this net me? As far as the reversion goes, I'm not sure how it happened yet, i'm gonna let my engine guy figure that out. Bad gasket? Can it occur from water dumping into the exhaust? I did have some a$$hole drive by on my last day out. I was beached with ten other boats in a no wake zone where a bunch of people party on the beach, and this a$$hat came through in a 35' sonic at a half plow and pretty much rammed his wake into my pipes. Not sure if that will do it, but it was enough for me to cuss him out when he pulled up to the beach. After that was when i noticed a miss in the engine. Then later pulled the plugs and identified the bad cylinder easily.

BobbyB

Lance,
Give me a call. Have Pat the guy that raced with me in (Driver)cambridge take a look at it. He is getting ready to go through my motors again.
Bobby

bcarpman

I'm currently doing the same upgrade. There's lots of info around here on this. Just do a search.

Have you taken it apart yet? Your budget might depend on whats wrong with it. Also, are you going to do the work or will someone else. I'm spending a lot less than $5K for a major rebuild, but I'm doing it myself.

Things to look at upgrading:

Intake manifold - Stock one is junk and isn't even matched to the carb (square bore carb on a spread bore manifold) Good choice - Edelbrock Air Gap $230

Cam - Personally I wouldn't waste time on an upgrade in this day and age without going roller. yes, it's more expensive, but in my opinion, if you're spending $5k it's worth the extra $500 for the extra power and reliability. ~$700 w/ lifters

Rings/bearings/etc - do a refresh but you can save alot of money by sticking with the stock bottom end components. From what I've figured out, if they're balanced and put together right, they're easily good to 5500rpm.

Heads - Assuming you've got the L-29 heads (which you should), a little bit of bowel porting and you've got heads that will flow with any good ovals (~$800 w/ new springs and stainless valves)

Things to not worry about:

Carb - the stock AFB is a great carb up to almost 500hp. It's easier to tune than a holley (MUCH easier) and with some massaging will flow as good as an 800

Stroker crank forged rods, pistons - the bang for the buck simply isn't there unless there's something broken

Roller Rockers - Unless you're going big lift with lots of spring they buy you absolutely nothing. They're everyone's favorite upgrade because it doesn't take any real engine knowledge to do.

scottc

I have a take out 454 built to @480 hp that runs great. also a match that needs going through. will sell the good one for@4k running. Can show desktop dyno on them. and have parts list also.

Griff

A 96 carbed 454 Mag will have the good high rise Magnum intake. No reason to change it. It will also have rectangular port heads.
A roller cam will add about 30 hp and will cost an EXTRA $1000 over the flat tappet for everything needed to go with it.

With the info I listed, you will make about 425HP.

Here are some threads to read on budget upgrades
http://www.offshoreonly.com/forums/s...ad.php?t=20929
http://www.offshoreonly.com/forums/s...ad.php?t=25932

Payton

I did just what Griff recomended. and really woke my 91 454 mag up. I was a little over proped and could only spin a 25" Mirage plus to 4500rpm.
Now I am about 4950 with the same props. I already had Gil exhaust.
Make sure you don't have a cracked exhaust manifold. That is what caused an exhaust water leak for me.

bcarpman

Opps, sorry for some reason I missed the "mag" in the initial quote. Guess I shouldn't post after an exhausting (and frustrating) day.

Not sure where you're getting the $1000 though to go roller. The cheepest flat tappet cam and lifter set will run you $200 and the most expensive roller cam and lifters will cost you $950 (I found the cam and lifters I wanted for $550). I guess if you're planning on reusing your old pushrods, lifters, and cam drive, a roller cam may cost you an extra $1000, but then you don't have much of a rebuild, and that new cam probably won't last long.

Besides the extra 30hp, you'll also be able to fire up the new engine with zero run in and head out boating, and you won't have to worry about ever present cam failures. That 30hp will also be with compromise. No loss in reliability, no loss in idle quality, no loss in fuel economy,just more HP. Not many mods you can say that about.

Hold on, now that I think about it, shouldn't a '96 already be a Gen VI block?? If so, shouldn't it already be roller? If not (I know mercury does put flat tappets in weird places) at least the retrofit should be pretty painless. Maybe an extra $200 to go roller as long as your not going crazy with the cam.