To switch or to not switch?

[bcjjones]

I see a lot of articles about switching a 6 bolt into a 2g, but none about a 1g with a 7 bolt. Im either going to switch a 6 bolt from a 1990 eclipse GST into my 1993 GS or just keep the 1990 and put the head from my 93 onto the 1990.

Basically the 1993 has a ton of new parts, rebuilt head, starter, alternator, rebuilt a/c compressor, new c/v axles, new clutch and couple other odds and ends. BUT just spun a rod bearing.

The 1990 GST has a rebuilt motor 30k miles ago and thats about it as far as i know. The guy im buying it from, a Level 4 ASE mechanic, had the motor rebuilt built but just had the a/c belt break and cause the timing to job resulting in some bent valves. He's wanting to sell it as it for 600 with a clean title. Says everything else on it works fine but the body is a little beat up and is in much worse condition then my 1993.

So basically trying to decide if i should switch the motor out for the 6 bolt or keep it in and just swap the rebuilt head and other components over? Not sure what all parts are interchangeable and I know I would have to customize something to make the 7 bolt head work on the 6 bolt correct?

Just trying to gets yalls opinion on what yall would do, and if anyone has any links to any tech articles on switching the motor in a 1g 7 bolt to a 1g 6 bolt and also putting a 7 bolt head on a 6 bolt motor as i cant find any.

Sorry to be so lengthy

 

[greanbeans]

to make a 7 bolt head work on a 6 bolt you have to machine the head stud holes out to 12mm over 11mm that they are and thats about it

 

[bryanwheat]

to make a 7 bolt head work on a 6 bolt you have to machine the head stud holes out to 12mm over 11mm that they are and thats about it

The 1g 7 bolt head doesn't have the smaller holes like the 2g head. ALSO if you are using stock bolts than the 1g bolts will fit right thru the holes.

If the 93 is alot cleaner than swap the turbo 6 bolt into the 93 and put the non turbo into the 90. For electronics i would go with the 91+ electronics with the 93 car if you use the 90 engine in it.

 

[greanbeans]

The 1g 7 bolt head doesn't have the smaller holes like the 2g head. ALSO if you are using stock bolts than the 1g bolts will fit right thru the holes.

If the 93 is alot cleaner than swap the turbo 6 bolt into the 93 and put the non turbo into the 90. For electronics i would go with the 91+ electronics with the 93 car if you use the 90 engine in it.

didnt know that i just thought that they all were 11mm

 

[bcjjones]

Okay cool, so basically there is no mods needed to make the head fit because it came off a 1g 7 bolt as opposed to the 11mm on the 2g? If im using the stock bolts, which I am.

I have read that the heads on turbos and none turbos are exactly the same, correct?

Only other question is, will the 6 bolt bolt directly up the trans in my 93 n/t? Even though its a 7 bolt because its still a 1g?

 

[bryanwheat]

Okay cool, so basically there is no mods needed to make the head fit because it came off a 1g 7 bolt as opposed to the 11mm on the 2g? If im using the stock bolts, which I am.

I have read that the heads on turbos and none turbos are exactly the same, correct?

Only other question is, will the 6 bolt bolt directly up the trans in my 93 n/t? Even though its a 7 bolt because its still a 1g?

The head is the same and will bolt right on. The cams will work, but the lift and duration is different. The 6 bolt engine will bolt to the transmission, but you would have to but the non turbo 6 bolt flywheel to get it to work. Your stock non turbo clutch will likely not hold the power from the turbo engine also.

 

[phantom_19]

The 1G turbo guys use the 1Gn/t tranny in their cars,because of the shorter ratios. Based on this information i would say yes on the question. The clutch and flywheel parts cannot be interchanged between the two

 

[bcjjones]

Yea thats what i figured, at very least the flywheel would be different, and you answered another question i had about the clutch handling the extra strain. Seems like i wouldnt run as well if the lift/duration is different? I guess i could just switch the cams from the 6 bolt head onto the rebuilt one that i have on my 93?

If i do end up switching, then ill probably just switch the clutch also. Or install a new one

Cannot be interchanged or can be interchanged?

 

[bryanwheat]

The clutches are different and not interchangeable between turbo and non turbo.

 

[bcjjones]

Got it, so i'd have to switch the clutch also then.

What about putting the turbo cams from the 1990 on the rebuilt none turbo head? Would it just be a straight cam swap or would the lifters have to be changed also?

Thanks for all the help fellas. Idk what id without you guys

 

[Nosroxs]

IMO, i would try to sell the heads you have seeing as one is freshly rebuilt and im sure there is someone on here or on the net looking for a fresh head then go buy the right head that you need or have the one with bent valves rebuilt. but like i said that just my 2 cents.. i would keep the 6bolt to be shure of no crank walk, get a freshly rebuilt head and pull as many parts from the 90 as ya can .. good luck..

 

[bryanwheat]

Got it, so i'd have to switch the clutch also then.

What about putting the turbo cams from the 1990 on the rebuilt none turbo head? Would it just be a straight cam swap or would the lifters have to be changed also?

Thanks for all the help fellas. Idk what id without you guys

You can just swap the cams over, the valves, springs, lifters and rockers are the same.

 

[bcjjones]

Yea ill probably just switch the cams over since everything else is exactly the same.

Yet another question is the engine isn't running obviously due to the bent valves. He has paperwork on the rebuild nut is there any pointers y'all would give me when checkin the motor out?

Also could I get away with only replacing the head gasket? Would hate to buy an entire set, and once its together find out I have to tear it apart for some reason to. I mean it would only have 30k on the gaskets if the rebuild was done.

Replace head bolts or not necessary if they we're replaced at time of rebuild?

I think that's all I got . Thanks again so much for yalls time

 

[architechnik]

I swapped a '91 block into my '94. There are no immediate gains from this other than the support for the 6-bolt exceeds the support for the 1g 7-bolt. If you're looking to do a complete build, then go with the 6-bolt, while a stock engine should probably stick with the 7-bolt. It's just hard to find front cases, oil pans, and other miscellaneous things for the 1g-7.

 

[bcjjones]

Keeping the 7 bolt was never part of the question. It has a spun rod bearing