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1995 mitsubishi 3000gt SL
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Discussion Starter · #1 ·
So I'm relatively new to the 3000gt platform and havent really done a whole lot v6 rebuilds, but as of recent my 95 has started a knock bad enough for me to park it out front of my appartment and not drive it. Plan is to pull the motor and send the block and heads to have the heads rebuilt and machined, and the block machined possibly bored out and honed. I've got the general knowledge that boring out kn a rebuild is usually a better way to prevent the quick demise of a rebuild, and most websites including 3sx only have .50mm over bore pistons which I don't know much about boring engines but should I just get the block bored out to .50 off the get go? Also what other parts besides new pistons and rings and bearings, and the 60 service parts would I need for a full rebuild top and bottom?
 

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If I am understanding your question correctly, then no, the machine shop will need the pistons first before boring. You are getting way ahead of yourself without a teardown and assessment first unless adamant on spending money unnecessarily already.

-sent from my Galaxy Note 9
 
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Discussion Starter · #3 ·
I've heard a lot of different ways of going about doing this but what your saying is take the new oversized pistons to the shop before you get it bored out so they can accurately machine the block? And I'm not buying anything until that motor is nothing but a bare block and I know for sure what I need. More so just gathering information and putting a parts list together prioritized to what I need to buy first.
 

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I've heard a lot of different ways of going about doing this but what your saying is take the new oversized pistons to the shop before you get it bored out so they can accurately machine the block? And I'm not buying anything until that motor is nothing but a bare block and I know for sure what I need. More so just gathering information and putting a parts list together prioritized to what I need to buy first.
Just curious to know if you are going to do the rebuild yourself or have everything done by a shop?
 

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Discussion Starter · #5 ·
I'm going to be doing the rebuild myself. Mitsubishi in town quoted me 4k so I said he'll no lol. It's about half that to get parts and pull it to build myself. That and I trust myself building it more than I would a shop.
 

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I'm going to be doing the rebuild myself. Mitsubishi in town quoted me 4k so I said he'll no lol. It's about half that to get parts and pull it to build myself. That and I trust myself building it more than I would a shop.
Thats good to know and more power to you!(y) I did mine and I can say that these engines run a very tight clearance and if the build is done right and well maintained you will have a daily driver that will last another few decades!!. There are tons of measurements that need to be taken to make sure all components are with in factory specs...the only thing i did was to get ride of my first gen cast iron crank but i can live with the two bolt not really in for serious and ridiculous HP gains:alien: just keeping everything stock and it is more of a restoration and preservation project...taken me a while about a year or two but she is all done now and i could say that this stock build with a few minor mods just may turn a few heads.
 

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1995 mitsubishi 3000gt SL
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Discussion Starter · #7 ·
Right on, my 95 was actually my daily driver up until it got the knock, and does the manual have everything thag needs to be measured in it? Or is that something you need to find elsewhere?
 

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The shop manuals have everything that is important such as crank run -out, journal specs, even the block height when it is machined ( cant really trust machine shops they dont tell you how much material has been removed, just to cause serious issues such as valve clearance, higher compression resulting in pre-detonation and loss of power or worse, complete component failure. With that being said yes you will have to take measurements yourself to make sure all is good and within specs, same goes with the heads if machined. Seems to me that the knock you are hearing probably is a messed up main or rod bearing, and hope that the journals are not messed up or it will be more $$ out of your pocket to get it turned if it is salvageable or a new crank...or a refurbished one like i got and fairly cheap..and that too a forged....then if you are considering rebuilding the heads after you get it cleaned hot tanked, pressure checked for cracks, you can proceed in getting a complete set of valve train components like i did, however, the valve seats were in great condition ( I know that for a fact when I hydro tested the new valves and achieved a perfect seal in all 24) valve guides and rollers were fine including all 4 cam shafts after doing a run out check. I just got new 100 pound BC springs with titanium retainers and new valves from Mahle ( stock size )..maybe my next build shall be all performance on a 4 bolt..lucky you!! :D . you can port and polish the runners like i did, not that easy but very tedious delicate work...i watched too many youtube vids and i think i got it done right, I hope:unsure:...hard to measure the flow of air volume through each runner intake and exhaust after it is ported out ( I am sure there is a way to find out ) but the amount of material removed by the carbide burr and using a head magnifier to see if all the runners look a like, well then, that should do it...not an easy job but you will get the hang of it, but if too much material is removed just to shape out the sides then you messed up that runner for good...that means you will have issues somewhere in the combustion process, I think:unsure:...a 3 stage port and polish job costs big bucks from a shop!!! even though i am not going down in the direction of creating enormous power , i have actually set up my build to handle 700 to 900 HP's if necessary by simply altering the air and fuel ratios with a fine tune. I would like to say this about the 6G72, perhaps i may be the last one to discover the amount of design flaws that the Jap engineers forgot to correct or just didnt care because of fast production, but there are very fine details that need to be fixed just to bring out its full potential. For example minimizing air flow restrictions in the exhaust manifold if using stock, minimizing oil flow restrictions in the block and heads and obviously porting out the runners.
Just a few pics of the block, tell me what is that red stuff inside the crankcase? and what is that stuff on the piston heads? and why are the main bearings that color?:cool: this is just my block, you should see the heads!!!:geek:
SAM
 

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Discussion Starter · #9 ·
I'm seriously hoping my journals aren't messed up or that I am going to mess them up in its final move to the location I'll be pulling the motor, what precision tools should I get my hands on to measure tolerances and such after I have it torn down, and what information should I give my machinist when it comes time to take my heads and block in? Of course I'll be uploading progress photos to also ask for more assistance as I go:unsure:
 

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I'm seriously hoping my journals aren't messed up or that I am going to mess them up in its final move to the location I'll be pulling the motor, what precision tools should I get my hands on to measure tolerances and such after I have it torn down, and what information should I give my machinist when it comes time to take my heads and block in? Of course I'll be uploading progress photos to also ask for more assistance as I go:unsure:
I can give you a list of what tools you need and where to get the shop manual, its better to have the entire manual on hand instead of bits and pieces, also when you take the block in and heads for machining, tell them you have the factory specs and limits of service and that you will check it immediately after they are done, I know there is a standard amount of material that is removed.
 
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