Newbie w. New GN

[bryes]

Hello everyone,

A couple weeks ago I  bought an '87 GN project (it turned out to be more of one then I was hoping for!), and now I a few questions. Any replies or reading suggestions would be much appreciated. I have begun reading Steve Wood's excellent tech section, but it looks like it will take a few reads through before it really sinks in. In the meantime I would like to ask a few questions about my particular situation if someone wouldn't mind  answering some newbie questions.

The GN that I bought had been setting for the last decade. To get the car running again, the previous owner said that he changed plugs and wires, and I think the fuel pump. However, whoever did the work hooked up the plug wires in the wrong order. Thinking the problem was a "dirty" injector he proceeded to "clean out the injectors" , by driving the car. During this "cleaning", the car started smoking what I am judging to be blue oil smoke. 

When I started working on the motor I discovered that the middle PS cylinder had 0 compression. I also noticed that the spark plug electrode was burnt maybe halfway off. Since then, I have started to remove the head to repair what I am hoping is a burnt Ex. valve. Additionally, I think the turbo might have a  blown seal. I noticed that it was weeping oil right above the oil return line and there is oil residue in the intake Manifold (Before pcv inlet, so I think it could only be from the turbo).

When I get it fixed I intend to use the car just to cruise with. I am open to some performance upgrades that wont hurt driveability / reliability if anyone has suggestions.

My questions are as follows:

1: Any ideas, suggestions, similar experiences, etc..??
2. Now that I will soon have the heads off, what other components should I look into replacing and suggestions on where and what to buy?


As it stands right now I will also be replacing the  timing chain and water pump.

Any additional pointers are greatly appreciated.

Thanks in advance,
Bryes








'87 GN, 51k miles (not verified)

[Steve Wood]

would not be surprised to find a blown head gasket after reading your plug description... but, that will usually leave some compression.

Check to see if all the valves are closed properly. 

Check each lifter base to make sure one is not scrubbed indicating that it lost a cam lobe as well.

I prefer the Victor Reinz hgs over the Feldpros we normally suggest.  VR 3797  Be sure to buy new bolts, or use studs.  Factory bolts cannot be reused.

Look in the up pipe to the throttlebody for oil from the turbo which is usually the case if the seal is gone.  Smoke might be a result of a blown hg.

Before you go too far after getting it going again, be sure to check the fuel pressure to see if the pump is performing properly under boost.

It's no fun getting a car from someone that did not know what he was doing,but, if you are patient, you can get it right and learn a lot doing it.  I know it seems like a lot to learn, but, it will come thru osmosis and experience. 

[earlbrown]

If you still have the stock vent tube that runs between the PS valve cover and the turbo inlet....   you found your oil.
That little jewel will coat the hell out of the intercooler, uppipe, throttle body and intake(ESP with a chitload of blowby).

[Guess]

http://www.gnttype.org/maint/basics.html  I followed this guide when I first got my GN.  Check that out if you haven't already.

Get a Scanmaster  I found my tps settings were really whacked out.

I don't have the experience to tell you about the bad plug and compression.  However, maybe consider a port job and stronger springs for the heads if they are going to be off anyway.

I agree going ahead with a new timing chain and sprocket.  I've heard people saying good things about the TAperformance chain.

http://www.taperformance.com/
http://www.nos4gn.com
http://www.gbodyparts.com
http://hrpartsandstuff.com/
http://www.cottonsperformance.com/

I've bought from all but one of the vendors above and have never had a problem.

You can also keep an eye on the parts wanted/for sale section to pick up some good pieces for cheaper.

I think the basic starting upgrades are hotwire kit for the fuel pump, maybe a high volume fuel pump, ajustable fuel pressure regulator, fuel pressure gauge and a chip.

Oh yeah, http://www.turbotweak.com/

[SuperSix]

Great post. A scan tool is required. Minimum Scan Master, best - Powerlogger.

And what he said ^.

[Charlief1]

Welcome aboard.   Now that you're here where are you located? One of us may be near you and can help you out.

[bryes]

Wow, thanks to everyone for their replies. This is some very helpful information. I'll be working on it more this weekend so we should know a lot more then. I've been taking pictures all along so I'll try and post some when I get a chance. Hopefully it'll be a chronicle for a successful repair, and maybe someone can keep me from doing something stupid. 
 
 Thanks to Guess and everyone for the information on the vendors and needed upgrades. A timing chain, (ARP?) head studs and water pump are definitely in my future.  I'll be sure to order a VR 3797 head gasket too. Right now I'm about 80% power-logger and 20% scanmaster, I'll have to research it more to decide.
 
  As far as the fuel system goes, I'll definitely be buying a gauge and adjustable regulator. I think I'll take the advice and upgrade the injectors while I have the intake off. I have been reading that a 40 psi injector should be fine for a mild street car. 
 
 I'd like to ask why a valve spring upgrade is needed, are the stock springs too light? After all I'm not planning on running 10's any time soon!
 
 ...

Check to see if all the valves are closed properly. 
...
Check each lifter base to make sure one is not scrubbed indicating that it lost a cam lobe as well.
...
Look in the up pipe to the throttlebody for oil from the turbo which is usually the case if the seal is gone.  Smoke might be a result of a blown hg.
...

The valves look like they are properly closed to me (I have the VC off). I didn't t get the lifter out yet but I took a peek in there and the cam lobes looked normal from what I could see through the lifter valley holes. I'll be sure to check lifter bottoms though this weekend. Oh yeah, I should mention that I looked for  head gasket damage in the lifter valley and couldn't see any. Hopefully it will be obvious once I get that last bolt out and take off the head.

I forgot to look at the up-pipe while I was out there, but I did look at the compressor side of the turbo. Both inlet and outlet and everything in between seemed completely oil free. The exhaust /turbine side was noticeably coated with oil though.  Maybe the oil I saw in the intake was, as sugested by earlbrown, coming through the stock pcv??

Welcome aboard.   Now that you're here where are you located? One of us may be near you and can help you out.

Thanks and I'm glad to be aboard!  I'm in Savannah, GA .

[Steve Wood]

Scanmaster first...and then when you can add PL, the scanmaster will connect to it and update about three times faster with more information for display.  The reason for the Scanmaster is that is connected all the time which gives you continual monitoring of timing retard so that you don't drive around with continued detonation if something is not right.  Also, being able to watch the O2s continually will let you know if something suddenly goes lean or rich.  It's not practical to drive around all the time with a laptop plugged in, and you cannot watch it while driving, texting, and recording, anyway. 

Be sure to not waste your money on a rail mounted gauge...they are inaccurate when you install them and they get worse with time.  Beyond this, you want to be able to see the fuel pressure under wide open throttle conditions and this will require a gauge that can reach the windshield.  When you get PL, you can add a transducer to the rail that will allow you to log fuel pressure.

Altho Earl is right about the line to the turbo inlet, that would not be your problem now.  I am hoping that it is something like a popped intake gasket, or head gasket that is cross firing rather than a holed piston, or such.  I guess you will know when the heads come off.  I would do both heads because if one side has been dinged, you can bet the other is not far behind.

The factory springs were fine for the stock cam as it is pretty much all in by 4800 rpm or so with regard to power.  Part of that is due to the size of the turbo and part is due to the duration of the stock cam.  The biggest problem is that they were not very good and were usually pretty much dead by 60,000 miles and the cars would often be reluctant to rev past 4500 rpm or so.  The 110# chevy springs were the first popular replacement.  I don't like them very much because I think they can cause an old cam to go bad faster.  Many have used the comp 980s, or one of the many equivalents with a single spring and a damper.  The factory splash shield cup is generally not used.  These will allow the factory cam to rev up to 5400 or so at the top end of the run in third gear.  This probably won't make much power but it does eliminate a shift into OD.  With a larger turbo to push more air, it will allow for a power band in the range of 5000-5200 and they seem to last longer.  The pressure will be closer to 85# depending upon the installed height.

Hopefully it will be apparent when you pull the head and not expensive.

[Guess]

Power Logger would be great.  I still need to get one myself.  Stronger springs seem to be what most people recommend as part of the first round of upgrades.  Not many miles but 25 years old now.     I suspect their a little weaker now.  New springs will keep it revving higher.  I'm having the crane double valve springs put in mine.

My upgrades were hotwire kit, scanmaster exhaust, intake, ls1 maf translator pro, high flow fuel pump, turbo tweak 93 octane chip with 42.5 injectors.  Just with that the car was surprising strong at only 15 psi.  However, I hear the fun doesn't really start until above 20 psi.

Mine is being rebuilt now with a little bit bigger cam, rough port heads, 3-angle valve job, forged pistons, TE-44 turbo, 3-inch downpipe and a 2800 stall 9.5 converter.  I can't wait until it's done.   After that, I'll probably just add a methanol kit and a better intercooler.  Supposedly good for being in the 11's somewhere with good tires and tuned right.  I think the 42.5 injectors I have will be fine.

Turbo Tweak sells chip and injector combos.  I would call Turbo Tweak and tell them what you have planned for the car.  He will recommend what injector size you should get.  Some say skip the 42's and get 60's so you don't have to upgrade later, depending on what you have planned.

I'm no expert.  I've had mine less than two years.  However, there are people on here that pretty much know just about anything about these cars and can steer you in the right direction.  The community has been a big help with me.

[Charlief1]

^^^ Don means the LT1 springs, not double. The LT1's have a dampner in the springs and aren't double.

[Guess]

Hey Charlie, these are the springs that are going on my heads.  Are they correct?

http://www.gbodyparts.com/product_info.php?cPath=46_21_51&products_id=876&osCsid=e6f0cda9fade3d841614c0e9e4c0730f

I don't want to do something dumb. 

[Charlief1]

Hey Charlie, these are the springs that are going on my heads.  Are they correct?

http://www.gbodyparts.com/product_info.php?cPath=46_21_51&products_id=876&osCsid=e6f0cda9fade3d841614c0e9e4c0730f

I don't want to do something dumb. 

Those are for a roller cam Don, not a flat tappet. You'll wipe the cam if you use them. Tell the machine shop you want a set of LT1 valve sprins with a seat pressure between 85 and 90 lbs. The springs have a coil on the outside and a flat looking coil on the inside which dampens the spring.

[Steve Wood]

those don't look roller springs to me?

[SuperSix]

Consider the pic source, I wouldn't trust it to be right.

[Steve Wood]

it might shine some light if the specs were looked up?