454xli Repower

[Viper]

Source of the post....#3 at 130lbs, still within spec, but -2lbs less and it would be problem......

I wouldn't worry much about 130lbs or 10lbs less!

Source of the post.... After he left......The gauges dropped to ~5lbs......

Again, this needs to be confirmed by a test instrument. You can't assume the sender, wiring and gauge are working properly throughout the entire operational range and conditions. He needs to test it while on a sea trial to mimic the same operational conditions before you condemn the engine.

Source of the post...... The oil was changed 10hrs ago, it smells gassey, which indicates gas is getting by cylinders or the TBI is providing too much fuel.
Going to use it gently over the summer and schedule for a repower.

You really should find out what's going on here as this may be causing the low oil pressure so you need to eliminate that as a possible cause. When fuel is getting into your sump, there is no such thing as "using it gently over the summer" It's not good to have or run with explosive vapours in your sump.

[SanJuanDreamer]

Are you getting a lot of black smoke from your exhaust? Blue smoke
Have you done anything to your motors that would have effected your tune? Nuthin
Is your plug hot enough? Running recommended MR43T 44 would be the next hottest.
Do your plugs look saturated? Most are saturated with fuel.
Plug gap was a little close, we regapped to spec, it did run better.
The hottest the engines run is Port 175\SB 179 and will hold steady there.
The Mechanic and I think its not a miss but misalignment of the prop shaft.
I measured fuel pressure and found it within speac, I think it was 21lbs...but I know it was good.
I replaced the U coolers about 2yrs ago and I just inspected with a borescope, looked good and clear.

For now, I'm going to change the oil\filter and move from 30 to 40 and work it until its time.

[SanJuanDreamer]

" this needs to be confirmed by a test instrument. You can't assume the sender, wiring and gauge are working properly throughout the entire operational range and conditions." understood...but both engines oil pressure behave the same....

[390Express]

Source of the post " this needs to be confirmed by a test instrument. You can't assume the sender, wiring and gauge are working properly throughout the entire operational range and conditions." understood...but both engines oil pressure behave the same....

I would try going to the next hottest plug, gapping at 0.45, and see if your plugs still look saturated. Your cap rotor, wires, etc. are all good, correct?

IMO, you're better off with a slightly hotter spark and a slightly fatter gap (I gap electronic ignition plugs at 0.45, you may already have yours at 0.45) is better than running around with fuel in your oil and the vapors it causes.

[Viper]

Will you rebuild your current engines or purchase others?
Will you end up with complete engines or long blocks and put your current bolt-ons on yourself?

[SanJuanDreamer]

Bud37 - I read you have the 6.2's are they Bobtails?
Viper - Going to have a Mech go with me to see and measure.
Engines are dependent on cost...like most things. Looking at rebuilding the 454's and using the same parts, after some indepth testing, or Bobtails...
At one time we were looking to sell and go bigger. After review of what we want and budget, we we decided to keep what we have as anything else would increase moorage and maintenance cost.
So...why not spend some of that "other" boat bucks on repowering what we....

[bud37]

SJD...they are Mercruisers,hooked to v drives came with the boat.......If it were me and I was in salt I would buy new as a package, more money but you may be getting some upgrades, warranty etc...there are lots of ways to skin this cat but that is the way for me....lets see what comes up...easy to spend your money heh....

[Viper]

Source of the post......Looking at rebuilding the 454's and using the same parts......

I guess I don't have to mention that you need to ensure your current hardware is in perfect condition before doing that. Why there's fuel in the sump for example needs to be determined so you don't transfer the problem to your new rebuilds. That would void any warranty. The most commonly overlooked thing in engine replacement due to failure is not assessing why the engine failed to begin with. The underlying cause is then bolted on to the new long block and it also fails shortly after. This is so common that OEMs have courses on the subject. It covers everything from existing bolt-ons to be used again, boat systems and their contributions to possible failures, as well as owners' boating habits.

[km1125]

Source of the post
I measured fuel pressure and found it within spec, I think it was 21lbs...but I know it was good.

21 might be correct at idle... and if so it should raise (probably to 40-45 or so) when the throttles are opened up. If that's the case then your regulator is working. However, not knowing that engine, I would double-check what the idle spec should be and make sure you're not comparing an idle reading to the WOT spec.

What about your backfire flame arrestor? Do you have one? Is it clean?? Any other possible restrictions on the intake air?

You say temps are 175/179... is that what your thermostats are? Sounds high to me, but I'm running an older raw water cooled and only have 143 thermostats. Not sure what your vintage calls for.