Nightlife1970

Ok I have asked before and no one ever answers.

I have 1988 454 mags. I would assume they are gen IV

I want to start buying parts to refresh them as they have hours on them. I don't want to do anything crazy with them. Maybe a bit more power with a cam upgrade and thats it. Will stay with stock exhaust.

So what should I look for to redo the heads?

What cam would give me a bit of a power boost?

All I plan to do is get a valve job done, replace the bearings in the bottom end, piston rings if it needs them, just the basic stuff to keep them running for a long time.

1BIGJIM

iTrader: (1)

The engines would be Mark IV.
I don't think you are being realistic if you don't plan on spending any money.

Nightlife1970

What do you mean by not being realistic? I am not planning on doing any large upgrades. I just want to refresh the engines for the most part? I would assume with the hours I have on them I need to replace the cam.

The rest is just what ever it takes to make the motors good.

mustangmark

If your going to look for more power or even consider new cams that will allow the motor(s) to breath better I would seriously consider upgrading your exhaust. Yes, it can be costly (if you buy new) but your stock exhaust chokes the motor. If you're on a budget I would look around for some stock 496 exhaust. It's better than what you currently have. The next step up from that would be Stainless Marine or Gill exhaust.

cp5899

iTrader: (1)

I owned a 235 force before my current boat. When I rebuilt the 454 I ported the heads, went with a better cam, alum intake, Holley carb, roller rockers, etc. All the work and money I did gained me 4 mph. Wasn't really worth all the aggravation looking back now. My current boat I went with a supercharger and what a HUGE difference. Unless you wanted to pick up two used b&m 177 or 250's I would rebuild it and have fun. If your only plan was a cam swap I don't think you would see much if any gain. I don't know about the older mags, but I know the newer mags come with roller cams. If that's the case I would think they are reusable?

I'm no expert on this. Only speaking from my personal experience with a Baja force.

Budman II

iTrader: (1)

CP, the roller cams were not installed in the mag engines until the Gen VI debuted in 1999 or thereabouts. Everything up til then was flat tappet. That being said, with the diminishing zinc levels today, I would think about upgrading to retro roller cam and lifters with a rebuild if you plan to hang onto the boat for any length of time.

NightLife, most on these forums started out where you are. I know I did. Thought I would just do better cam and do a little work to my heads, etc. Boat sounded great, but little if any gain in speed. Next build got a LOT more serious, with bigger roller cam, AFR heads, Lightning headers, stroker kit, etc. Let me warn you that the slippery slope you are about to tread on gets very expensive in a hurry, and with twins you can multiply the pain x2. My advice would be to drive them until they are ready to drop, unless they are using a lot of oil or making noises that declare impending disaster. With twins you are unlikely to get stranded somewhere - can always limp home on one. I would wait until winter at least before pulling out perfectly good engines. If I had it to do over again I would be dropping a stock replacement long block into my boat, put down the hatch, and enjoy boating rather than turning all these wrenches.

cp5899

iTrader: (1)

Say it isn't so!! I thought it was about building power ad going fast...lol. I think I went over board on this build, but I don't regret it.......at least not yet. New blower, chiller ad carbs get here Friday. Hope it rus as good as the b&m 250 did.

Griff

Without an exhaust upgrade, changing the cam is not worth anything and you risk reversion issues.

Nightlife1970

Like I said guys, I am not looking to make big power with these. I know they are tappit cams, so I am sure they need to be replaced. All I was looking for was getting the engines back to a fresh condition. I did not buy thei boat to be a speed demon, If I was looking for that I would have bought a faster boat.

All I want to know is what cam's I should be looking at? What parts should I be getting to redo the heads? If there was a cam that would give me a bit of a bump from stock great, if not so be it.

The bottom end I really don't know what I will need until I get them apart. But bearings will get replaced no matter what.

The engines run just fine, and are not buring any excess of oil. But I don't want to wait until one of them explodes. They have alot of hours on them is all, and at this point I plan on keeping the boat for a while. Unless someone offers me the right price and I find a 370 for a steal.

Port Monster

iTrader: (1)

I am in the same boat with the same boat! 280 Baja Sport with 454 mags. Had the dreaded bravo one overheat problem and bad manifolds/ risers and the more I took apart the worse it got. So I am down to rebuilding one motor and the heads on the other (all machine shop work as I am a converted outboard guy and have no experience with bbc's). I decided to go back stock everything for reliability - even a simple cam change will test the stock and/ or most inexpensive aftermarket exhaust. If you wanted to get some more reliable ponys out of it (at least from what I read) you need to convert to a roller set up, go with the aggressive cam and install aftermarket exhaust. Not an inexpensive proposition. But if you are not willing to do at least these three things then you might as well rebuild stock and enjoy the boat. If I had to do it all over I would run the motors and look for a nice set of used motors. These guys are always getting cubic inchitis, build good motors, then sell them all painted, pretty and strong so they can put more cubic inches in the boat. And I have seen some nice motors out there for not much more than the cost of my machine shop work and extra parts I bought - forget about all of the hours I have in the project!