Jet boat engine 427bbc questions

[kevin400ex]

Go hold a big block at 5500 rpm for 30 -45 minutes with out letting off at all, See what happens to it Just because a motor can put out high power at redline doesnt mean you can run it there for long. Thats why a marine long block costs so much more than a general replacement long block of the same size. Not built the same. Sure you can build one to work. But theres that word again...... BUILT


I'm just saying I've sen it done (more than once) and it ends in carnage

so whats the difference? what makes a marine 454 long block different from any other 454 long block?

 

[shady]

Their not different if you use a forged setup and high perfomance bearings Etc. But you cant go pull a stock 1981 454 out of a c10 and throw it directly into a jet boat. Even if you do change the oil pan. It just the way the internals are in them. If you take that 454 from the truck, tear it down buy good internals and bearings and such then put it in. It would be fine. The difference comes from intended use. Most car/trucks are not designed to run at 3-5k for more than short bursts or just long enough to shift. Boats dont have a choice, jet boats even less. Most general boats with a bravo drive will run 1 mph for every 100 rpm. so if you want to run across the ozarks or down the mississippi at 55-60 mph wheres that leave the motor for that entire trip. If you drove down the highway in your truck keeping up with traffic with only second gear youd worry about your motor wouldnt you But in a boat that would be fine???

I'm not being confrontational or Talking out my a$$ here. I have a dozen or more friends with 50-150k boats and have had a couple (smaller than them) ones myself. I've seen a buddy sink his jet boat and have a shop rebuild the motor since it was out, with a cheap basic rebuild kit. He locked it up in 10 min. Then bought a running truck swapped motors and shelled it the first time out. Meanwhile since the other motor went bad so quik he took it to a different shop, had it rebuilt again. Thought maybe the truck had to have been on its last legs, so he swapped once again to the newly rebuilt again original motor. Died in less than an hour.
he sold the entire thing to a dude for 1500 just to get it out of his sight.

I'm just trying to keep someone from the brotherhood from finding out the hard way.

 

[kevin400ex]

well mercruisers standard 7.4l engine came with a cast crank and cast pistons, 3/8 rod bolts and peanut port oval port heads with a cast iron intake.

the 454 mags and the 502 mag did have forged crank and pistons, and a brass insert in the take water jackets since the intake was aluminum. the magnums also had a little stiffer valve springs for the higher performance cams they had.

in reality the main differences are the freeze plugs, valve guides, head gaskets (for corrosion reasons) cam profile, higher volume oil pumps and oil pans.

 

[K85 Octane]

what it all comes down to is:

clearances
balancing
oiling ability

cooling ability is through the roof with boat engines, at least lake drawn cooling systems

 

[K85 Octane]

well mercruisers standard 7.4l engine came with a cast crank and cast pistons, 3/8 rod bolts and peanut port oval port heads with a cast iron intake.

sounds like my dead motor

 

[ryoken]

feel like I'm at work, stop.. boats bring the suck...

Kevin pretty much nailed it..


oh, ftr.... production reverse rotation motors haven't been made in about 15 yrs now... a replacement cam is about a grand these days...

 

[wasted wages]

Their not different if you use a forged setup and high perfomance bearings Etc.

did you even read the spec's ????




SPECIFICATIONS
425 HP @ 5250 RPM
500 ft/lbs @ 3250 RPM
8.75:1 Compression Ratio
Cast-Iron Four Bolt Main Block
Forged Steel Crankshaft
Forged Steel Connecting Rods
Hydraulic Roller Cam (Lift .510" Int/.540" Exh, Duration @ .050" 211° Int/230° Exh)
Cast Iron Rectangular Port 118cc Cylinder Heads (2.19" Int/1.88" Exh valves)
1.7:1 Rocker Arms
8'' Harmonic Balancer
14'' Flexplate
Recommended spark plug: Accel #111-263 or any spark plug with 14mm, .460'' reach, 5/8'' hex, tapered seat, non-projected tip

 

[wasted wages]

and...BTW, I have one of these crate 454 HO's in my buggy....

I had a 6-71 blower on it for about 3 years and yes, it will hold up to long pulls at 5000 rpms....maybe not 30 minutes at a time, but I have held it steady against the 5200 rpm rev limiter for at least 5-7 minutes-SUPERCHARGED.
I did it many time in mud bogs and pulling thru deep mud trails out in the woods....

once I built my buggy out of the blazer, I pulled the blower off because the 2 - 750 holleys didn't like steep angles very well...It's sitting on the shelf in my storage unit,,,It's for sale if any one wants to bolt it on their boat and go make some real HP...

One of these 454HO crate motors would make a fine squirt boat engine...

 

[shady]

http://www.jegs.com/i/GM Performance/809/12568774/10002/-1?CT=999

and.....It's brand new....with a warranty.....



SPECIFICATIONS
425 HP @ 5250 RPM
500 ft/lbs @ 3250 Rpm

If you read their waranty it wont be warantied for long in a boat.

you cant use just any motor in a boat. It will self destruct. boat motors run at 3000-5000 rpm or more ALL DAY. they have to be built to the gills to take it. Blueprint engines has a good boat motor for decent price through jegs also. I'll find the link in a minute

When I posted this I was trying to point out that there are motors for the same price or slightly more that ARE MARINE motors, built specifically for that aplication.

http://www.jegs.com/i/Blueprint-Engines/138/MBP4960CT/10002/-1?parentProductId=1644208

They came up a little?? but it will last. I'd get the one your looking at if you can hear it run. its already from a boat.

After posting the link (which has more power, is built for a boat, still has a warranty, and is the same price) I noted that he should get the one hes looking at if it runs good. My main statement was about not throwing a Regular run of the mill motor in there. And yes I did miss the forged part of the specs on the 454ho. All in all he's got to put something in there and I was only trying to state an issue that has bit people in the past. Maybe I'm a dumbass, I dont know. But I never intended for it to be a major debate,
Sorry for any a$$hattery on my part, I hope you get the boat up and flying across the water soon

 

[K85 Octane]

ok ladies

In the next couple of days (hopefully tomorrow) he will have it out of his boat and started pulling some things apart. I wants to check it over before anyone buys it, since it's been sitting in his stored boat for a while. No, I don't remember what the time frame was He will make out a build sheet for it and invoice. Once it's partly apart, I'll be going over to take a look at it. He will be swapping the tall intake with some kind of corvette intake with brass inserts in the front, or whatever. I wish I understood more of this stuff. He said it would kick ass and fit my Holley better, not having to use a squarebore adapter.

The guy I talked to, who said my distributor might not work, is not the owner. The owner said my Dizzy will work and is a nice unit for the engine. He also likes my carb, since the guy I bought it from did a lot of work/ modifications to it....so he would mount mine up and dyno it with the dizzy as well. Of course, that's after I say yes. He has invited me to watch the dyno runs and tuning.

Looking to take the boat out the week of Aug 22nd, we'll see. I also plan to beat on it till it's too cold to go out. I've missed so much of this summer.

 

[ryoken]

well, I'll tell ya right now.... if that's a non marinized vacuum advance dizzy that is a "nice unit" for a boat, I wouldn't let the dude change my spark plugs...

 

[DEMON44]

well I don't know nothin about nothin in a boat........ 'cept the top end of the 454 thats in my z-28 came off a built 454 jetboat engine. 990 squareport heads and all.

 

[K85 Octane]

well, I'll tell ya right now.... if that's a non marinized vacuum advance dizzy that is a "nice unit" for a boat, I wouldn't let the dude change my spark plugs...

Hey Bud. I guess I should clear this one part up. He only owns jet boats with engines sticking half way out of the back. The 427 is no different. I can see the spark plugs at eye level So maybe its not proper for my covered engine bay, but he hasn't seen what I have.

 

[K85 Octane]

Update
Ending up going with the guys motor.
Pulled it apart today and it looks great. It has a solid lifter cam and lifters, but I've got him changing it to hydrolic. I believe he said he'd like to go with a 280 grind for my boat. The tall manifold will be changed to a factory GM marine aluminum intake with brass inserts. The motor looks really nice, has big rectangle intake ports, SS valves, 3/8 pushrods, and TRW forged pistons. It was built a couple years ago and sat. The owner forgot about some of these things, since it's been a while and he builds engines all day long. He will break in the new cam, time dizzy, and tune it with my carb before I get it. It should be sent out to the boat place by Wednesday.

Here is his 1200hp 21' race boat.

Here is a video as to why he doesn't race anymore. He fell out of the boat, then it landed on him, scooped him up into the engine area as it rolled back into proper position, then proceeded to sink as his life vest was caught on something. Nothing broken, just stupid sore, and bad dreams. Few months ago and the boat is totalled. He still has the engine in good shape, so that may work it's way into another toy. He was 2nd in the race and 3rd in points. Out of all the lakes to crash at, Lake PuddingStone is the worst, simply cause it's such an ugly, dirty water, small lake.
[youtube]wBmyhhlXgVU&feature=related[/youtube]

 

[imiceman44]

Hey Bud. I guess I should clear this one part up. He only owns jet boats with engines sticking half way out of the back. The 427 is no different. I can see the spark plugs at eye level So maybe its not proper for my covered engine bay, but he hasn't seen what I have.

I don't think you got his point, if he thinks the wrong dizzy is good for your boat means he's not competent enough to even change spark plugs.
But I am going to go on a limb and assume that the dizzy you have IS a MARINE dizzy?

 

[K85 Octane]

no, I understood Iceman, but the guy only runs open engine boats, so he understands the problem with marine parts and fume fires, but has never been worried personally. He doesn't always remember mine is covered. His dizzy is just a regular Accel HEI.

 

[imiceman44]

no, I understood Iceman, but the guy only runs open engine boats, so he understands the problem with marine parts and fume fires, but has never been worried personally. He doesn't always remember mine is covered. His dizzy is just a regular Accel HEI.

Oh gotcha.
Now that you are going thru these issues, I want to check mine out, it's been sitting for 3 years, it's time to get it out and see what is wrong, I could still enjoy some of this summer.

 

[K85 Octane]

Oh, and before I look like an aszhole that doesn't listen to my bros....I will be changing the dizzy. I don't have the funds AT THIS MOMENT, I just bought a carb, dizzy and now new motor dammit. I will be running the HEI with extreme caution. The blower works and I'll make damn sure it's cleared out. I guess if I don't ever post anything after the ~25th, something happened to me

 

[Fordum]

I guess if I don't ever post anything after the ~25th, something happened to me

Understood. Make sure the widow has your password, and knows we want pics...............

 

[wasted wages]

and don't try to race Jesus.....

and don't try to race Jesus.....