7.4 454 Repower opinions needed.

[sparky774]

OKAY, so this is my first post and i really need some help and advice here.


I have a cigarette style boat that i need to repower. Trans and outdrive are freshly rebuilt. The boat is originally a Mercruiser 330 TRS with merc trans 2.


I blew the motor out about 3 weeks ago, originally i thought it was a rod but after inspection i found that ALL of the cylinder walls are scored horribly. (Looks like someone ran a grinder vertically up and down the cylinder walls.) Blew out a few sets of rings. This motor was fresh off rebuild from the P.O. but the machine shop was obviously incompetent.


ANYWAYS i am considering options here. Rebuild, get a new shortblock, or get a new longblock???


My concern with rebuilding again is that this scoring is beyond excessive and i really do not want to mess around here, i want this to be a one shot deal.


WHAT do you guys think about getting a michiganmotorz REMANUFACTURED GEN IV Longblock??? http://www.michiganmotorz.com/marine-engine-1990earlier-p-191.html


If i go for the longblock where is the best place to buy one?


If i go for the shortblock where is the best place to buy one?

 

[Fishermark]

Re: 7.4 454 Repower opinions needed.

Welcome aboard! I am always amazed at how much more expensive a big block is than a comparably equipped small block. Anyway - several have expressed having a good experience with rapido marine. I just did a quick search - their web page mentions the big blocks being sold out... but that may change on a daily basis. It may be worth your while to give them a call or email. Here's where the prices are mentioned for the big block.

 

[sparky774]

Re: 7.4 454 Repower opinions needed.

For the time being i would like to stay away from rapido unless someone can really vouch for their work.

I am not in a position to be able to get on the water next year if i receive a bad motor and end up eating the cost.

I would rather put the money down and get something with a real warranty and that will be 100% there.

 

[Bondo]

Re: 7.4 454 Repower opinions needed.

My concern with rebuilding again is that this scoring is beyond excessive and i really do not want to mess around here, i want this to be a one shot deal.

Ayuh,... Welcome Aboard,....

You definitely want a rebuilt crate long block motor,....

I've never bought 1, so I can't say where to find 1...

 

[sparky774]

Re: 7.4 454 Repower opinions needed.

I guess im really wondering where the hell to buy a new longblock or shortblock that isnt going to screw me over.

Budget is about 4000 bucks but i would rather keep it closer to 3000.

 

[joewithaboat]

Re: 7.4 454 Repower opinions needed.

I dont mess with big blocks much but i think you might be unrealistic with your funds $$$
They are getting fewer and farther between but you might look for local cusom machine shops that can work with what you have to start if you want to go on the cheap.
Good luck! keep us posted

 

[sparky774]

Re: 7.4 454 Repower opinions needed.

Honestly i dont think 3-4k for any shortblock is unrealistic especially considering a 502 shortblock can be had for under 2k remanufactured...

Now for a quality longblock i think that may be pushing it but thats why im looking for advice on where to purchase from

Is there any reason to be weary of that reman 454 longblock from michiganmotorz? Seems like a reasonable price and like they are more legitimate than say rapido or 1800runsnew.com

I mean if it comes down to it i will find a new block use my old heads after they have been gone through and build a motor locally with a new rotating assembly. Im not talking forged internals here this is not a MAG motor it is cast rotating assembly built for 330 horsepower.

 

[Silverbullet555]

Re: 7.4 454 Repower opinions needed.

Big Blocks are definitely pricey. A new Merc crate long block will be around $15K. Good reminder for me to take care of my big block.

 

[sparky774]

Re: 7.4 454 Repower opinions needed.

I dont need a completely new powerplant here i have almost new stainless marine exhaust, intake, holley 850, new oil lines, new oil cooler, all acc are good, etc etc.

 

[picklenjim]

Re: 7.4 454 Repower opinions needed.

It really depends on how mechanically inclined you are. Can you do this kind of work yourself? You say the engine was just rebuilt. Well if true than what you really need to do is disassemble it and see exactly what is needed to repair it. You may be able to just take the short block in to a local shop as mentioned above and get it straightened out. If the cylinders are damaged to severly you can get a used block for $2-300 or less. That would be a mark IV 2 bolt main block. IF all it needs is pistons and reboring a local shop could do that for under $1000. Like I said though it really needs to be completely disassembled to see exactly what you need done. Keep in mind if you were to send it in for a core you are at their mercy.They will inspect it and deduct from your core charge (which I'm sure you pay up front)any unreuseable parts so you may not get your core charge back. Max overbore they would concider is probably .060". Shipping isn't cheap on an engine either which would be another reason to try to stay local with it.

 

[joewithaboat]

Re: 7.4 454 Repower opinions needed.

Reman can be good or bad, but if you look long enough for cheapest deal you will prob. find it. There are no doubt good and bad ones. I have a friend in the "big go fast boat buis." most of his customers buy name brand crate motors or go thru a local custom machine shop. Ill text him in the am and see what he says.
How far over has your block been bored to this point, as i recall some bigblock blocks can go all the way out to .125 over

 

[sparky774]

Re: 7.4 454 Repower opinions needed.

I can do assembly myself. I prefer working from a longblock and just bolting on doing timing and tuning, but i have no problem working from a shortblock. I dont want to put a shortblock together though (crank rods pistons), that in my opinion is better left to the machine shop and engine builders.

I could reuse what i have but the issue here is that the previous owner had this block rebuilt 3 times bored each time so obviously there was a recurring problem or poor work was done.

You are correct in that i need to pinpoint the problem, thats why i will be going through exhaust and other critical components that can cause failures before installation onto a fresh motor. I will let you know when i pull the motor next week what exactly happened but for now i am content with the fact that i WANT a new block and rotating assembly at the very least.

I appreciate the input and i will check back as to what your friend says.

 

[Fishermark]

Re: 7.4 454 Repower opinions needed.

If you are concerned about the unknown quality of the rebuilts, then your only other option is to go new. You can buy a new crate engine (long block) straight from Chevy for under $3,800 then put your old marine externals back on. Here's one from Pace Chevy.

Here's what it is:

7.4L (L19-N) 1985-1993 Chevy/GMC Full Size Trucks "P" & "G" Van- Gen VI Engine- New

(Since it is from a truck, the cam should be good - you would want to check the core plugs to see if they are brass - many of the new crate engines already have brass core plugs. And the head gaskets are likely to be the new composite type that is fine with salt water).

Here's the pic:

 

[greg82255]

Re: 7.4 454 Repower opinions needed.

You can also buy a marine 454 long block from Michiganmotorz.com. They sell remanufactured 454 marine engines with the balancer installed, new oil pan, and new circulation pump for $3399 up to $5399.

http://www.michiganmotorz.com/marine-engines-remanufactured-marine-engines-c-31_51.html

 

[FreeBeeTony]

Re: 7.4 454 Repower opinions needed.

Just wondering why you are so hesitant to go with Rapido?

 

[joewithaboat]

Re: 7.4 454 Repower opinions needed.

Ok Sparky,
Friend said what I suspected he would. Either go with NAME brand NEW with warrantee or small local shop who regularly builds marine stuff. Most warrattee's will pay a quailfied mechanic's bill if engine goes bad. Reman in his eyes doesnt perform as well. Generally in business to make money by doing volumes of work. They machine and assemble as best as possible going as fast as possible. Now all that being said he works on any boat but specializes in expensive go fast, usually twin engine stuff. An in and out and swapping all the related components cost enough that it?s not worth the risk to the customer to save a couple grand. It looks like you are getting some response from people who have no problem with reman ??? I would shoot for local shop (from a refural)to assemble short block. Sorry if this doesn?t help
I once bought a reman small block that always burned oil. Ran but never ran well. A year later i pulled the heads and found seven .030 over pistons with one .060 over ,and several broken rings. Just sayin.... they are cheaper for a reason.
keep us posted

 

[FreeBeeTony]

Re: 7.4 454 Repower opinions needed.

I just pased 260 hrs on my Rapido 5.7l Vortec w/o any issues.....FWIW

 

[picklenjim]

Re: 7.4 454 Repower opinions needed.

If you are concerned about the unknown quality of the rebuilts, then your only other option is to go new. You can buy a new crate engine (long block) straight from Chevy for under $3,800 then put your old marine externals back on. Here's one from Pace Chevy.

They didn't even start making Gen VI motors until '96.

 

[sparky774]

Re: 7.4 454 Repower opinions needed.

Well, I'll vouch for their work, I've bought several blocks from them without any hassles at all and got exactlly what I wanted. They have a very good warranty to boot.

Just a side issue, you say this was a brand new rebult engine,,, how did you break it in? Kind of sounds like you didn't and if you are hot on the throttle with another new block you'll get the same results.

The motor was rebuilt by the previous owner, he told me it had approx 10 hours on it and had been broken in. Later on after i bought the boat i heard from a few people that he kept blowing motors and never got the boat to run right. I then blew the motor myself haha. Maybe he didnt break it in who knows i will find out when i yank this thing out

when i say it was rebuilt by the previous owner i mean he payed a machine shop to rebuild it. BTW.

 

[sparky774]

Re: 7.4 454 Repower opinions needed.

Ok Sparky,
Friend said what I suspected he would. Either go with NAME brand NEW with warrantee or small local shop who regularly builds marine stuff. Most warrattee's will pay a quailfied mechanic's bill if engine goes bad. Reman in his eyes doesnt perform as well. Generally in business to make money by doing volumes of work. They machine and assemble as best as possible going as fast as possible. Now all that being said he works on any boat but specializes in expensive go fast, usually twin engine stuff. An in and out and swapping all the related components cost enough that it?s not worth the risk to the customer to save a couple grand. It looks like you are getting some response from people who have no problem with reman ??? I would shoot for local shop (from a refural)to assemble short block. Sorry if this doesn?t help
I once bought a reman small block that always burned oil. Ran but never ran well. A year later i pulled the heads and found seven .030 over pistons with one .060 over ,and several broken rings. Just sayin.... they are cheaper for a reason.
keep us posted

Where did you buy that reman? i will make sure not to get one from there!