[RESOLVED] Are all 1g 4g63 heads the same?

[mhuffman]

I'm putting in new pistons and my cylinder head's already messed up so im going to go pull one from the junkyard. But they only one they have is non-turbo 1g 4g63. Does this head bolt right up? Same valve springs, ect?

Also, my intake manifold is full of nasty crud; what's a good way to clean it (other than having it hot tanked?)

 

[peypey's ride]

The non-turbo heads are the same except for the cams. Reuse your turbo cams from you other head and your good to go. Also, please do a search first. There are many threads asking the same question.
Hot Tank it, nothing better.

 

[cruisintalonawd]

and the intake ports are smaller

 

[92awddsm]

and the intake ports are smaller

The intake ports are identical on 1g 6 bolt heads between the turbo and n/t. The heads are identical except for the cams.

 

[Rex2342]

The heads are exactly the same except for the cams. You'll also have to remove the plug for the oil feed to the turbo in the front left corner of the n/t head.

 

[Talesin]

Be warned, 90-92 have six-bolt engines, 92.5-94 had seven-bolt engines. The 1G seven-bolts do not suffer from the 2G crankwalk problem, but the headstuds are smaller in diameter, so it won't bolt up to a six-bolt. I believe they can be machined out larger to fit on a six-bolt, at which point they bolt up without any problems.

Aside from that, the 1G head cores are all the same (2G heads had smaller intake ports, 1Gs all had the 'large' ports), but the factory turbo head came with much better cams... higher lift, longer duration. Springs are identical, but it's always a good idea to replace hard-to-get-to parts with performance pieces when you get the chance. And the springs *definitely* count as hard-to-get-to. I'd recommend a set of Crowers, just in case you do decide to go with larger cams down the road. Won't have to pull your head and re-do your HG just to replace the springs to run the bigger cams safely. As an added benefit, you don't need to worry as much about running around/at 7Krpm for extended periods, if you like to autocross.

 

[mhuffman]

Be warned, 90-92 have six-bolt engines, 92.5-94 had seven-bolt engines. The 1G seven-bolts do not suffer from the 2G crankwalk problem, but the headstuds are smaller in diameter, so it won't bolt up to a six-bolt. I believe they can be machined out larger to fit on a six-bolt, at which point they bolt up without any problems.

Are you sure the heads are different in this respect? Is it possible to remove the headstuds?

 

[MountainDew]

Are you sure the heads are different in this respect? Is it possible to remove the headstuds?

WTF I'd hope so.

Basically in order for a 7bolt head to fit, you'd need to machine the headbolt holes on the head. It'd be easier to just find a 6bolt N/T head and swap the cams. Also someone mentioned something about an oil line as well.

If you can, try to get a blacktop CAS as well. I'm not sure if your car has the older style harness with the really long wires though.

 

[cruisintalonawd]

well then what is it just the intake manifold ports different because my friend has a n/t intake manifold and its ports are way smaller then mine were

 

[Talesin]

His is the '91, the blacktop 93-94 Hall effect CAS is a straight bolt-on and plug-in to his harness. Only the '90 used the 'long-harness' olive-top optical CAS. 91-92 used an optical CAS as well, but with the same wiring harness the 93-94 used.
Only down side is that the 93-94 CAS is in high demand, so they're a little hard to find, and not cheap. :b

Yes, your car came stock with head bolts (not studs). You have to replace the headbolts every time you take off the head, or switch to ARP headstuds which are good for something like 12-15 removal/torquings before replacement is recommended. They thread into the block, get torqued down, then you slide the head down over them and put nuts on the top.
If you have a 1G 7-bolt (or 2G head for that matter, but that's a whole different can of worms), you can get the 'head bolt' holes machined out to fit six-bolt head bolts, and just use the six-bolt ARP headstuds at that point.

No, the intake ports are the same on all 1G head cores, aside from the 1.8L. Or if you swap on a 2G head, sacrificing a lot of top end power for midrange drivability. All 1G six-bolt head cores are IDENTICAL, as are all 1G seven-bolt head cores. The only difference between turbo and NA versions of each is the cams installed at the factory, and the only difference between the six and seven is the size of the head bolt holes.

 

[Rex2342]

well then what is it just the intake manifold ports different because my friend has a n/t intake manifold and its ports are way smaller then mine were

The intake manifolds should be the same too? I've never really compared the port sizes between n/t and turbo though. I do know that the n/t manifolds don't have the fitting for the bov lines.

 

[Bender]

Weren't the ports on a 92 head bigger? Maybe thats where people are getting confused on the size being bigger/smaller than N/A? Comparing a N/A against a 92 head the N/A would be smaller, comparing N/A to other year head they were the same.

 

[Talesin]

Yet again, NO. All the 1G DSM 4G63 head cores were the same, aside from smaller head bolt holes on the 7-bolt, on the 92.5-94 model years.
The 95+ (2G) 7-bolt head cores have smaller intake ports. NONE of the 1G DSM 4G63 heads had differently-sized intake ports compared to the other 1G model years.

 

[nc90awd]

yes all the 1g heads are the same except the bolt holes.. If you get a 1g 7bolt head you can enlargen the holes with a drill bit. It needs to be enlarged by 1mm(7bolts have 11mm holes and 6bolts have 12mm holes) We have done it several times. So yes any 1g head will work

 

[92awddsm]

yes all the 1g heads are the same except the bolt holes.. If you get a 1g 7bolt head you can enlargen the holes with a drill bit. It needs to be enlarged by 1mm(7bolts have 11mm holes and 6bolts have 12mm holes) We have done it several times. So yes any 1g head will work

I, personally, have seen 1g 7 bolt heads that had the 10mm outer exhaust manifold studs but the head bolt holes were already large enough for the 6 bolt 12mm head studs. What Im getting at is not all 1g 7 bolt heads nave to have the head bolt holes enlarged when installing on a 6 bolt block. As far as ports, they were the same from 90-94 model years.

 

[91WhiteGSX80]

Hey whats up guys i was wondering around ebay lastnight and i seen a rebuilt 4g head for 279.00 plus shipping .. now you think it would cost less to get all the parts one by one or should i go with this head... but i do have to pay the guy thats gonan come to my house to do the work for me..????

 

[Purevil]

Hey whats up guys i was wondering around ebay lastnight and i seen a rebuilt 4g head for 279.00 plus shipping .. now you think it would cost less to get all the parts one by one or should i go with this head... but i do have to pay the guy thats gonan come to my house to do the work for me..????

A 4g head is a completely different beast.

 

[Purevil]

well then what is it just the intake manifold ports different because my friend has a n/t intake manifold and its ports are way smaller then mine were

Your friend is most likely sportin a 1.8L, which would explain the tiny ports. All 6 bolt 4g63's both turbo and non-turbo use the same head, intake manifold, valvetrain (except cams).

 

[turboglenn]

91whitegsx80... by 4g do you mean 4th gen or 4g63?

I had my head rebuilt at a machine shop, nothing fancy just back to OEM specs and it was 450 bucks for magnaflux, pressure test, valve job and new springs and retainers. IF you trust the guy, that's probably not a bad deal unless shipping is a HUGE chunk. SHouldn't be anymore than 40 bucks to ship it though.

adn your last sentence says "but i do have to pay teh guy that's gonan come to my house and do teh work for me ????"

I'm confused on that one... Are you unsure if you are paying for labor? please explain.

 

[91WhiteGSX80]

Hey what's up... Sorry guys I ment to say a 4G63T head... I have oil in the ports and in the exhaust manifold.. so I guess its better to just get a rebuilt head.. u know so i dont have to worry, but yea then I have to pay this guy to put it on for me ... my car has 109.000 org miles so I hope the pistons and the rings are ok the car ran when I got it.. but smoked alot and a really ruff idle for the frist 20min till it wormed up... but hopefully I wont have to rip this thing apart he can do the head with out pulling the whole motor out of the car right??? sorry im new at the stuff im trying to learn... thanks guys

 

[MountainDew]

Hey what's up... Sorry guys I ment to say a 4G63T head... I have oil in the ports and in the exhaust manifold.. so I guess its better to just get a rebuilt head.. u know so i dont have to worry, but yea then I have to pay this guy to put it on for me ... my car has 109.000 org miles so I hope the pistons and the rings are ok the car ran when I got it.. but smoked alot and a really ruff idle for the frist 20min till it wormed up... but hopefully I wont have to rip this thing apart he can do the head with out pulling the whole motor out of the car right??? sorry im new at the stuff im trying to learn... thanks guys

I had no experience before, and I pulled my head off, dropped it off at the machine shop and got it back on in no more then two weeks. This was during the summer with many nights of partying inbetween.

 

[mhuffman]

Hey what's up... Sorry guys I ment to say a 4G63T head... I have oil in the ports and in the exhaust manifold.. so I guess its better to just get a rebuilt head.. u know so i dont have to worry, but yea then I have to pay this guy to put it on for me ... my car has 109.000 org miles so I hope the pistons and the rings are ok the car ran when I got it.. but smoked alot and a really ruff idle for the frist 20min till it wormed up... but hopefully I wont have to rip this thing apart he can do the head with out pulling the whole motor out of the car right??? sorry im new at the stuff im trying to learn... thanks guys

It cost me $140 to rebuild my engine. You can get good pistons, rings, and bearings from an ebay vendor. I have 800+ miles on the rebuild, it pulls good vacuum, makes good compressor, and runs the best it ever has. The pistons are identical to oem(probably beck arnley) , and the rings are NPR Chrome. I also got rod bearings.

Do a compression check, and if your not 140+ across the board with less that 15psi variance, i'd rebuild.

 

[91WhiteGSX80]

No shit really... Yo thats like nothing... then again I bet u did alot of the work urself.. see Im not that good at this motor stuff im trying to learn as much as I can I been reading this haynes book everynight like its a bible... for real .. but it only tell you so mcuh.. but thank god for this site you guys help me out all the time... thanks for everything .. im gonne start looking round Ebay see what i can come up with now my turbo is ok no shaft play so i get a new one or should i stick with the stock and just get a stock 2G exhaust manifold and port it.. ???? not sure what to do on that part i have a Boost gauge and I just put on my MBC .. so not sure where to go from there I dont want a monster but i little better then stock u know???

 

[MountainDew]

No shit really... Yo thats like nothing... then again I bet u did alot of the work urself.. see Im not that good at this motor stuff im trying to learn as much as I can I been reading this haynes book everynight like its a bible... for real .. but it only tell you so mcuh.. but thank god for this site you guys help me out all the time... thanks for everything .. im gonne start looking round Ebay see what i can come up with now my turbo is ok no shaft play so i get a new one or should i stick with the stock and just get a stock 2G exhaust manifold and port it.. ???? not sure what to do on that part i have a Boost gauge and I just put on my MBC .. so not sure where to go from there I dont want a monster but i little better then stock u know???

Just do the rebuild yourself. It's really not that difficult. I didn't touch my bottom end, but you might not have to either. Leakdown test should help determine this.

 

[mhuffman]

No shit really... Yo thats like nothing... then again I bet u did alot of the work urself.. see Im not that good at this motor stuff im trying to learn as much as I can I been reading this haynes book everynight like its a bible... for real .. but it only tell you so mcuh.. but thank god for this site you guys help me out all the time... thanks for everything .. im gonne start looking round Ebay see what i can come up with now my turbo is ok no shaft play so i get a new one or should i stick with the stock and just get a stock 2G exhaust manifold and port it.. ???? not sure what to do on that part i have a Boost gauge and I just put on my MBC .. so not sure where to go from there I dont want a monster but i little better then stock u know???

I rode in a fast 1g and he was running the stock 1g ex. manifold, 300whp. i run a stock 2g ex. mani and its pretty good.

I have MBC @ 15psi, 2g ex manifold, 3" downpipe, 2.5" cat and catback, lower honeycomb removed and i like my power level, i dont plan on upgrading any more. I would say do these mods and if you really need more, there are plenty of options.

Yes, i did all of the rebuild myself. If you are methodical, have a decent understanding of what you are doing, and have access to a cylinder hone and a piston ring installer and compressor, you should be able to do the rebuild urself.

The rebuild might not be neccessary. But one of my pistons cracked at the track and i was way down on compression, so i did the rebuild.