6 bolt head on a n/a 7 bolt block

[camas90gsx]

Alright, i threw a rod on my 1g gsx and the block has a hole in it so obviously it's destroyed.Now i found a 7 bolt n/a 4g63 with 2g block,2g pistons,1g big rods,.50 bore over,new turbo pistons,new water pump,new seals etc.. for a really good price.I would get the complete longblock but there might be 2 bent valves and needs new hydraulic lifters.So i was thinking i could salvage my 6 bolt head from my gsx and use it on the new shortblock.But the problem is i dont know if it would match up as far as the cam position sensor,and crank position sensor etc..And this longblock is 3 hours away and if so i want to drive to pick it up tomorrow.But if there might be issues with every thing matching then i might look elsewhere.Its just that with this shortblock being rebuilt 2,500 miles ago with reciepts to show everything like crank machining,seals, etc,i hate to pass this up.So what do y'all think i should do?PLEASE HELP Y'ALL!!

 

[herms99gst]

I would say if this is a dd I would stay away from this block. Why they went .50 i dont know, but thats stretching it for a dd, you might run into some over heeating issues. As for the head fitment yes it will work with some modifications, you would be better off just picking up a good used 6 bolt short block.

 

[g4ebguy90]

How would the seller have a N/A 4g63? They were offered in the 1g's. But then you say it is a 2g NA block. As far as I know, Mitsubishi never made a 2g non-turbo 4g63 powered car.

The engine sounds like a complete oddball frankenstein. The 7 bolt engine with 1g big rods. The 50 over bore. Then you wanting to put the 6 bolt 1g head on it, just sounds like a big mess.

I would just find a 6 bolt short block, put your head on it, and call it a day.

 

[camas90gsx]

Yeah im not sure why he went that far,maybe he had big plans? I guess before i was running probably around 300whp and probably would have kept going to about 360-375 so i dont know if boreing that much would be a good or bad thing in my case.I guess the main reason that i was interested in this motor was the new pistons,new water pump new seals and the machined crank and all reciepts to prove it.Not to mention the price.If i do go this direction i'm still wondering if the cam and crank position sensors will line up and if there would be any other sort of fitment issues? If i do happen to stumble upon a better deal i'm all for it but for now i'm just wondering if this would be possible.Also what timing belt would i go with,sounds stupid but when you are putting a 6 bolt head on a 7 bolt block what belt do you get? i have alot of questions obviously,sorry.

 

[RvlutionMtrsprt]

50 over is retarded. The block should have been thrown in the scrap pile. Second, if the crank has been undercut, it too needed to be tossed in the scrap pile. Do yourself a HUGE favor and look for a different engine.

 

[g4ebguy90]

To answer the head timing belt question. You don't need a special belt. The problem is the head bolt size.

I want to say, 7 bolt's use a 11mm x 1.25 bolt. 6 bolts use a 12mm x 1.25.

Putting a 6 bolt head, with the 12mm bolts will not fit in the 7 bolt blocks threads unless you make them bigger. One thing I have heard is that you can simply use the smaller 7 bolt bolts. But I would expect there to be some play and some movement when tightening the bolts if you went that route.

Best thing again for you. Is a 6 bolt short block.

ONE thing, I would like to mention. 50 over does not make it a junk engine. It just can't handle a HUGE amount of power. The more you bore the engine, you decrease it's strength. But 50-60 over is fine for a stock to mild setup. Yeh I wouldn't run 20+ psi on it. But you could maybe get away with it.

As for the cut crank, cranks get cut alot, and it's so little metal, again this is mainly a issue with high horsepower cars. A stock to mild performance build would be just fine with a cut crank, with correct bearings.

 

[camas90gsx]

I guess also i didnt think .50 bore was that conciderable but im still learning these cars.I was hoping that it would work because i was under the assumption that most of the 4g63 parts were interchangeable throughout 90-99 and n/a to turbo.I dont know if i was clear about this either,its just a n/a block casing with all turbo internals.He is actually giving me the longblock but he has 2 bent valves,so thats why i was thinking about putting my 6 bolt head if its all good on or maybe exchanging my valves from my 6 bolt to the 7 bolt head.Basically i just need a shortblock and it is a turbo short block with a n/t casing.But i dont know if it will match up

 

[bryanwheat]

50 over is retarded. The block should have been thrown in the scrap pile. Second, if the crank has been undercut, it too needed to be tossed in the scrap pile. Do yourself a HUGE favor and look for a different engine.

I've ran more cut 4g63 cranks than not and have yet to have an issue with them. The hardened surface goes at least .020-.030, so cutting it .010 will be fine. As for the .050 on the block. It would probably be ok if you weren't making big power. Also you CAN run 6 bolt rods in a 7 bolt, you just have to narrow the big end. It's been done quite a few times by many people. If it is a 2g block than it won't work in a 1g anyways because it doesn't have the bolt holes in the block for the front roll stop. If it is a non turbo 7 bolt block than it has to be from a 1g, there was never a 2g 7 bolt non turbo engine, other than the 2.4 spyder engine.

 

[g4ebguy90]

Yea that guy P.M'd me saying that you can't use cut cranks, and can't use a 60 over engine. He don't know anything about engine building. Again your right, this is a stock setup not a 10 second car. Some people need to wake up. Some how he mentioned 60 over engine would cause a rod knock after 3000 miles. People these days.

 

[jimbob_843]

So a 1g n/a 7 bolt block? No oil squirters with i assume cast pistons, especially with the 50 overbore? No no no, all kinds of wrong here. Not saying it wont work, but how long will it work? Dont waste your money on this. Maybe its super cheap for a reason.

 

[bryanwheat]

Yea that guy P.M'd me saying that you can't use cut cranks, and can't use a 60 over engine. He don't know anything about engine building. Again your right, this is a stock setup not a 10 second car. Some people need to wake up. Some how he mentioned 60 over engine would cause a rod knock after 3000 miles. People these days.

It doesn't have anything to do with the bearings. It's all about the integrity and strength of the cylinder walls. It would be perfectly fine for a stock turbo application. Also i have ran plenty of cast pistons with no oil squirters.

 

[g4ebguy90]

No oil squirters really isn't as big deal as you think. Yea it helps for sure with some temps. But, you take them out, or use a N/A block, you got higher oil pressure, no risk of one falling in your pan.

The 50 over is a oddball.

As for the cast pistons...Almost all stock-mild performance pistons are just cast aluminum. Not many people unless there making alot of power run forged.

 

[camas90gsx]

The pistons are supposed to be 2g turbo pistons.I guess he built this motor by the book but thats what he says not what i know.it is supposed to be 2g turbo pistons,1g big rods that were brought to a machinist,new water pump and he swapped out the oil pump for a tsi front casing for better oil pressure for the bore.

The main thing is if there will be a cam and crank sensor issue between 7 bolt and 6 bolt.Because it is a 7 bolt set-up that im putting my 6 bolt block on.Will it match or not,thats what i am wondering.I dont even know if i want to do this i am just wondering more now because i just am curious.

 

[bryanwheat]

The cam angle sensor goes in the head on a 1g. No need to worry about anything on the block. So the guy said he used a tsi oil pump huh. The pumps are the same from turbo to non turbo, there is no difference. Sounds like this guy has no idea what he has. But as i said, if it is a 2g 7 bolt block you will not have a front motor mount because there is no where to mount it. I'd be willing to bet that he bored it to make more power also? You don't need more oil pressure for a larger bore engine. There is no oil pressure that goes anywhere in the cylinders.

 

[delta448]

As far as I know, Mitsubishi never made a 2g non-turbo 4g63 powered car.

The European 2G models had a N/T 4G63, but I'd imagine he has a 1G 7 bolt and someone in the chain is just confused that 7 bolt doesn't also have to mean a 2G.

Putting a 6 bolt head, with the 12mm bolts will not fit in the 7 bolt blocks threads unless you make them bigger. One thing I have heard is that you can simply use the smaller 7 bolt bolts. But I would expect there to be some play and some movement when tightening the bolts if you went that route.

The 7 bolt head fasteners thread into the 7 bolt block and will work just fine for securing a 6 bolt head. The head will not move as long as you didn't also pull the head locating dowels out of the new block's deck.

ONE thing, I would like to mention. 50 over does not make it a junk engine. It just can't handle a HUGE amount of power. The more you bore the engine, you decrease it's strength. But 50-60 over is fine for a stock to mild setup. Yeh I wouldn't run 20+ psi on it. But you could maybe get away with it.

Maybe you should tell Andrew Brilliant that. His 4G64 bottom end has the same cylinder wall thickness as a 4G63 block that's been bored 0.060" over. This is of course assuming that the 0.50 written above was a typo and the block wasn't actually bored one half inch oversize.

 

[camas90gsx]

I dont know much about this subject but he said the machinist told him that .50 over was not bad because most bore .40 over anyway.I am now thinking that fitment wont be that much of an issue after the last post.Does anyone really see any major problems with this situation other than the .50 bore issue.The mechanic that is going to be installing the motor didnt seem taken away by it when i asked him,but he is a japanese engine mechanic that specializes in all makes not just mitsubishi so maybe it is something he isnt aware of?I can buy just the short block for a little bit less,the only reason i was going to get the haed as well is because i dont know how mine is going to look when i pull it apart.Istill dont know about the cam and crank position sensors being an issue though?

 

[bryanwheat]

Id you would read what i am typing you would know. The cam sensor goes in the head, it will work on any engine. IF that engine is truly a 2g engine it will not properly work in the 1g because of the lack of front engine mount.

 

[camas90gsx]

The motor has 1g motor mounts,the motor was pulled out of a 1g so i dont think that would be an issue.Also the reason he yanked it is because it lost compression because the lifters were locked up so the valves could not seat,so basically 2 of the valves are bent.

 

[bryanwheat]

It is a 1g 7 bolt block then. If so than it will bolt in just fine. Kind of unlikely that a lifter locked up also. I'd suspect something different that caused it. If you do decide to buy it than make sure that the valves didn't damage the pistons at all. What kind of price if he giving you on it?

 

[camas90gsx]

He was saying that it is a 2g block just that it has 1g motor mount brackets so i dont know.One question though,the reason i wanted to get the head is because i threw a rod on my gsx and i didnt know if that would cause damage to the head as well.I just figured if i had the extra basically new head there i could pull parts from my 6 bolt or vice versa and just basically have my mechanic assemble 1 good head.Are the 6 and 7 bolt head interchangeable,or is that theory wrong?

 

[bryanwheat]

The 6 bolt head will go right on the 7 bolt block if it is in good condition still. They are fully interchangeable. You just want to keep the intake matched with the cylinder head. By the way it is a 1g block, i do know. I've got both sitting in my garage.


This is a 2g 7 bolt. Notice at the lower left corner by the bellhousing that there are no bolt holes.

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This is a 1g block, you see the 2 mount holes on the lower right left corner by the bellhousing

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[delta448]

I dont know much about this subject but he said the machinist told him that .050 over was not bad because most bore .040 over anyway.I am now thinking that fitment wont be that much of an issue after the last post.Does anyone really see any major problems with this situation other than the .050 bore issue.

You cannot bore a 4G63 0.4-0.5". What I wrote above must not have been clear enough. That extra zero makes a HUGE difference. The cylinder bores would overlap if you even came close to an 0.4" overbore. Do you understand that?

Every 0.020" is half of a millimeter.

You can bore the block up to an 88mm bore, which is 0.120" over for a 85mm bore stock 4G63. At that point your cylinder walls will be dangerously thin.

I still dont know about the cam and crank position sensors being an issue though?

You have a 1G. There is only a CAS, no CPS. The CAS mounts to the cylinder head on the intake cam opposite the timing belt. You're using the same head. You will not have to worry about anything. Just plug everything back in the same way it was.

 

[camas90gsx]

Thanks for the straight answer delta 488 i was really wondering about that.Im just wondering if the engine was infact over bored if that would have anything at all to do with low compression? he thinks it was because when you take the hydraulic lifters out you are supposed to bleed them because they adjust to where they need to go as it runs and refills with oil and he didnt do that? I dont know,what do y'all think.Sound like a possibility?

 

[bryanwheat]

There is nothing to adjust on the lifter, you put them in, install the rockers and cams and it is ready to go. If the lifters are primed up with oil than you will want to let it sit for a few hours before starting it for them to bleed out. But other than that there really isn't anything to mess up. What kind of price is this person selling the engine for?

 

[delta448]

Im just wondering if the engine was infact over bored if that would have anything at all to do with low compression?

No, that would indicate something is wrong. In fact, overboring might actually increase compression test results even with identical compression ratio pistons simply because you are now compressing more volume.

he thinks it was because when you take the hydraulic lifters out you are supposed to bleed them because they adjust to where they need to go as it runs and refills with oil and he didnt do that? I dont know,what do y'all think.Sound like a possibility?

Definitely. You MUST bleed the lifters. If you don't, the valves will still hang open even when the rocker is off the lobe and contacting the base circle of the cam. Pistons go up, valves get bent.