454 died, now it sounds like it's eating itself!

Hi Keith;

Bear in mind that this is my son's boat, so he's been watching the receipts, not me. That being said, I believe we have close to $2300 invested at this point. The best deal on a commercially re-manufactured long-block 454 engine we could find was $5200 when you included the shipping. And that would not have included the cost of the new fuel pump, the new exhaust manifolds, or the new flappers for the exhaust Y-pipe that we replaced. (Not to mention all the ignition components we replaced.)

So we basically saved a little more than half the cost vs a commercial rebuild (to say nothing of the cost of a new crate motor!), and he was back in the water in 6 weeks vs 3 weeks. Granted, we still have a problem with the carb, but after another run over the holiday weekend we are now certain that it is either a clogged jet or a stuck needle valve. (I pulled the breather off and looked down the carb throat while we ran up from idle to ~ 3200 RPM, at which point it wouldn't go any higher.) It's clear that the fuel spray pattern on the secondaries is terrible. The butterflies are open, but we aren't getting proper fuel flow. (One bowl has no fuel at all!) We plan to take it apart and clean it this weekend, after which it should be fine.

As for how much time we have invested, that's harder to gauge. Part of the problem is that we discovered other issues as we were taking things apart, and that delayed us. (Every time you find something new, you have to wait for more parts to arrive.) This also drove the cost up, since we didn't buy everything at once but rather piece by piece. Anyway, I'm guessing that we have a solid 24 hours in just engine work, plus another 12 hours invested in pulling and re-installing everything. Maybe tack on a few more hours for troubleshooting here and there, and I'd say a good estimate would be 40 hours total. Bear in mind that we worked slowly so as to make fewer mistakes, and it's been 15 years since I last rebuilt an engine, so I purposefully took my time. A more seasoned mechanic could no doubt shave some time off that estimate.

But I have to say that just like the first time I did it, this was a very rewarding experience. Nothing makes you happier than hearing the engine fire up the first time you hit the key after a lengthy rebuild!

Adam
 
Thanks for sharing. Definetely the route I would have taken had I had the time to put into it. Good luck tracking down what is hopefully the final issue. It is very rewarding to know that you completed a job yourself!
 
Steve;

If the fuel pickup in the tank was partially plugged, the fuel pump would still be able to fill the bowl while the engine was idling (and using very little fuel). That would mean when we throttled up it should rev up fine, at least until the bowl ran dry.

We're not seeing that. No matter if you've been cruising for 10 min at 3000 RPM or if you've been idling the whole time, when you throttle up and the secondaries open, you can see that there isn't enough fuel flowing through those secondary bowls and the RPMs refuse to rise much above 3200. Note also that the fuel spray pattern in the primaries looks great and stays constant while this is going on. So the problem just about has to be in the carb somewhere, and after (or downstream) of the bowl at that - which rules out the "rock" filter on the inlet port. (We're thinking clogged jets or stuck metering rod, but we won't know for sure until it comes apart.)

The rebuild kit was ordered on Monday, and I'll probably pull the carb off either tomorrow or Thursday so I can start disassembling it.

Adam
 
Adam, you mention the cost of "a new crate motor". Are they even available as GM hasn't produced a 454 in some years.
 
quote:
Originally posted by Gregory S

Adam, you mention the cost of "a new crate motor". Are they even available as GM hasn't produced a 454 in some years.

Click to expand...


MichiganMotorz still advertises new carbed (Holley) 454ci/7.4L turnkey crate engines for a little under $11k.
 
Gregory;

As Sandy mentioned, there are a few retailers who still have brand-new 454 crate engines in stock even though they are no longer being produced. But yeah, they've no doubt been sitting in a warehouse for many years.

We just couldn't justify the cost of a new motor at this point.

Adam
 
don't blame you, had one rebuilt when I holed a piston. wow, $11,000!
 
Greg, I didn't answer before when you asked where new 454's were coming from. I just knew they were for sale, but I still don't know the source. I hear "GM Marine" but that doesn't mean much to me. There's no "gm_marine.com" or the like as far as I can tell. My speculation is GM sold the tooling and/or the license to somebody who's producing them for the aftermarket. Speculation... I really do not know. Will ask around. There are 454 marine "base engines" for closer to $5000, some tagged as "new."

What caused one of your 16 pistons to hole through?
 
A vacuum leak caused a lean condition and holed it. I believe it wa # 5.
 
The good thing is the cause was found and not built back into the rebuilt engine. I'd expect that from you and from anybody you'd hire to do the repairs. I talked with Geo/GVP about replacement engines and he said he hated to sell them. The owner would install the rebuilt, short block, base engine, whatever. Using all the components from the engine that had failed. Bringing the COD from the old engine to the new. Say the old was MPI and one Injector caused it to go lean and hole that piston. Same Injector causes engine damage on the new engine. Owner blames engine supplier, wants warranty replacement. Yada Yada. I was thrilled when Admiral said, Just get a Complete New Engine.
 
The builder started the engine after rebuild and install, then sat in the bilge watching and listening as the engine was brought up to pwer under load. Found the vac leak that way, shut it down and fixed it. That question nagged at me all the while the engine was being rebuilt. He assured me he'd find the reason once he ran the rebuilt engine.
 
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