Cam change with motor still in boat
 

Is there any reason not to change out a cam with the motor still in the boat if there is space in front of the motor to remove and replace it? Seems to be a lot less work involved if it can be done this way because most of the accessories can stay on the motor and the motor and drive do not need to be re-aligned. Thinking of changing stock 454 mag cams to hp425/hp450 specs, porting heads, new intake anc holley carb, new rocker arm studs with roller rockers and aftermarket exhaust.

Re: Cam change with motor still in boat
 

How many hours currently on the engines as they are now?

Re: Cam change with motor still in boat
 

280 hours - 1993 454 Mag's Gen V

Re: Cam change with motor still in boat
 

What horsepower were those rated at?---365?

Re: Cam change with motor still in boat
 

365's

Re: Cam change with motor still in boat
 

Sounds like the hours aren't too many without having to totally rebuild the engines just yet, but to answer your question, "yes" we have done mods like this several times. Just make sure you have enough room to get the cams out of your blocks, etc. I have seen some guys cut a hole out of the firewall with a hole saw to do this. Just be careful when doing all this stuff.

Also, when porting those GM heads just do some minor bowl/pocket work----especially on the short side radius's. This is especially true of the exhaust ports of GM heads as they are very crude. I would also especially install a dualplane intake manifold with the rectangle port heads as they are too large for a 454cid engine. I know that may not be what you want to hear, but it will give you better torque, single to the carb, and throttle repsonse. A good 750cfm Holley carb would be adaquate. Aftermarket exhausts will help enhance all the power mods that you are adding.

Are you replacing the cam with a hydraulic roller or flat tappet? What aftermarket exhaust system are going with?

Re: Cam change with motor still in boat
 

KAAMA - Not sure yet if going flat or roller cam...depends on price vs. benefit....going with gil exhaust with ss risers.... thinking edelbrock rpm airgap intake....Merc used holley 800's on the 425 and 450. Why would you suggest a holley 750?

I will put 50+/- hours per year on the boat so these upgrades should last me 4+ years before I will need to look at the bottom end of the motors.

Re: Cam change with motor still in boat
 

An 800 Holley will be fine---I just wouldn't go any more than an 800cfm for sure. I think the Air-Gap intake is a wise, and excellent choice for your application. The GIL's will help your engines breath much better, just make sure you do NOT over cam the engines and make sure you check piston to valve clearences. You can do it either way, but I also agree with Formulaz583 that pulling the engines would be much easier to inspect all the stuff on your engines and can get at stuff much better. Leaving the engines in your boat while adding mods is probably the last route I would take and only if really have no other recourse. I think pulling your engines to do the mods would be a good experience as well.

Re: Cam change with motor still in boat
 

PG,
Just get a Cig... :D

Re: Cam change with motor still in boat
 

Powerguy,
I'm having something similar done right now. 454 EFI motor that's getting a bit of a face lift. Same vortec heads with a fair amount of machine work. New inconel valves, springs, blah blah blah. Comp roller cam, Edelbrock Air Gap, and a Barry Grant Sea Demon 750 on top. Went with the Revolution Marine manifolds as the budget was running thin towards the end of the project. She should be back in the water in a couple of weeks for a trial run and to figure out what to do with the prop. If you drop me an email, I'll let you know what kind of results I get out of it, since it seems like you're doing something very similar. [email protected]

Re: Cam change with motor still in boat
 

Hey G.L - You having experience the past couple of years pulling motors what are your thoughts on the subject? Think I have the right boat for me just want to go a little faster....... as we all do. How much time did it take your mechanic to pull the motor, strip off the accessories, put all accessories on, and reinstall in the tiger?

Just does not make sense to me to pull motors and deal with all that for relatively minor upgrades.

Re: Cam change with motor still in boat
 

PG, I'm doing my 454mag now too.
Going for a complete rebuild. Should have the teardown done by the weekend.
Not too sure what I'll do to it yet.

Re: Cam change with motor still in boat
 

2Quick and Stormrider - what did you get for estimates on parts and labor to do the rebuilds on the motors and labor to remove/strip/replace motors?

Re: Cam change with motor still in boat
 

I believe on the Gen V you will have to drop the pan in order to get the timing cover off. This is true on Gen VI motors; not positive but I think the Gen Vs are the same.
If true, pull the motor(s) out :D

Re: Cam change with motor still in boat
 

DAMM, Notic heat beat me to it. Yup, I think that timing cover would be better if the oil pan was pulled and resealed correctly. I know you don't want any oil leaks at the front cover after all that work!

Re: Cam change with motor still in boat
 

sounds like I may be just doing my exhaust this spring...........if I can find some 6" rise gil ss risers....

Re: Cam change with motor still in boat
 

I got an estimate of $3000 for a complete rebuild.
I'm guessing I'll be adding some upgrades.
I'm hoping I can do 500hp. That should get me moving.
The engine was a spare that came w/ the boat.
So I'll do a swap. I'm gonna try to hire a rigger for a day to do that and help w/ some other odds and ends. Maybe $50-60/hr.
The boat is inside my heated warehouse... so conditions are friendly.

I'll be going w/ either Stainless Marine or Dana for exhaust.
Another 2g.

I haven't added it all up... and won't. :drink:

Re: Cam change with motor still in boat
 

Powerguy,
I'm doing mine on a pretty tight budget. Email me and I'll give you the skinny.

Re: Cam change with motor still in boat
 

Just put a 177 blower and a Nickerson carb on it and go!! The 454 mag has a great base for a small blower and that will net you more power than head porting and minor cam changes, and it will be cheaper! I am not even a big blower fan, but I have seen this work and work well more than once. If you are sold on the new cam, head porting, intake, and exhaust it can be done in the boat, but is easier on the engine stand!

Good Luck!

Craig

Re: Cam change with motor still in boat
 

Yea just be sure to install deckplates instead of glassing it up. This way when you're not happy with your cam choice you can easily change it out :D:D

Roby

Re: Cam change with motor still in boat
 

Powerguy......you've got mail

Re: Cam change with motor still in boat
 

Power guy, just pull the motors, start to finish both motors can be out in 4 hours, it's a pretty easy job to do.

Did you ever try the hydromotives on your boat, and if you did how did it run.

Re: Cam change with motor still in boat
 

Don't you need to change exhaust valves, change head gaskets, decrease compression, add fuel pressure and oil temp gauges?

Re: Cam change with motor still in boat
 

Ron - never ran the 22 hydro's last year.

Re: Cam change with motor still in boat
 

Worst part about doing the job in the boat is having to get in/out of the boat a million times and parts and tools everywhere and wear and tear on the boat ...

Re: Cam change with motor still in boat
 

Those are good questions about going blower. I know there are many bolt-on kits out there from Pro-Charger, Whipple, Vortech and roots type of blowers. Most of these kits are designed for stock type motors and while the changes you mentioned wouldn't hurt I don't think they are all required. As for the oil temp and fuel pressure guages I personally believe those should be standard equipment on every marine engine. A buddy of mine had a 242 Eliminator Vee with a 454 Mag carb and added the Weiand 177 blower and the appropriate carb. He gained tons of mid range and 8 MPH on top end. He then added some gil manifolds and picked up another 2 MPH. The motor ran great for 4-5 seasons until he sold the boat. Easy, cheap and very effective. If you are open to the idea it is worth looking into!!

Craig

Re: Cam change with motor still in boat
 

I don't know how much time but the charge was around $400-$450 in and out and they had to take the hatch off. I'd say an hour or so out and a solide couple in, woth a few guys working on it (2-3)

Re: Cam change with motor still in boat
 

Seems like I should wait to completely rebuild the motors before removing them. I guess that I will have to stay in the Under 70 mph group.......