Making the GN Right

mtocrs1

Mtocrs1
Joined
Mar 16, 2007
I bought another GN and it’s a mystery. The original owner passed away in 2000, when the owner passed, the car was left to his sister and she kept it up until last year when she sold it to me. She was very sentimental over the car but she was retiring/moving and didn't want the hassle any longer. She took care of it to the best of her ability but it needs some TLC. Her brother was a GN lover and street racing it was his hobby. She told me some great stories about her brother racing the car etc. He spent a ton of money on the car but she had no records of what was done. I told her I would make her brothers car right once again. I plan to document everything here.

The car has 50k original miles but it’s been repainted. She said she didn’t really know why it was painted but I have some theories. When I picked up the car it would barely stay running. I eventually found the old ATR chip was programmed incorrectly so the throttle blade screw was turned in to compensate, therefore the IAC was ineffective. I replaced the chip with a SD2 and powerlogger. It ran good but some things bothered me and I want to know what has been done to the car so the engine is coming out.

It will be a fun little project…

This is what the car looked like when I picked it up.
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This is what under the hood is looked like up until a week ago
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Here it with the proper wheels
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And this is under the hood today
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So far I have discovered it has ported and polished heads, roller cam, roller rockets and ported intake manifold.
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It's nice to get a car with a some goodies and a built engine. Saves a ton time and money.

Now for the unveiling. Off with the pan..Lol
 
Nice find there!! Can't wait to hear the rest!!!


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Looks like a lot of the ATR catalog was in that car.

Dash, cold air box, 7th injector, wastegate and downpipe. Nice find.
 
Spent some more time pulling things apart tonight. The oil galleys in the block have been messaged. Has billet main caps and a good crank from what I can tell. Forged pistons and I'm not sure what to make of the rods. The oil pan is something else. Has a little trap door for the oil return....
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Looks like a guy named Doug T built the engine in October of 1995. Any ideas on who Doug T was from the east coast?
This engine was put into the car roughly a year later from the maintenance log. At the time the car only had 39xxx miles.
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1st thing that jumps out is the timing chain tensioner. It's not suppose to be there. It gets deleted when using a double roller chain. Lucky it's still intact. They usually get mangled when used on a double roller chain.

Looks like cam is a billet roller.

Crank looks stock. Kinda strange the balancer looked to be 0 balanced. Snap a couple more pics the balancer.

Rods look like some type of aftermarket.

Rick
 
1st thing that jumps out is the timing chain tensioner. It's not suppose to be there. It gets deleted when using a double roller chain. Lucky it's still intact. They usually get mangled when used on a double roller chain.

Looks like cam is a billet roller.

Crank looks stock. Kinda strange the balancer looked to be 0 balanced. Snap a couple more pics the balancer.

Rods look like some type of aftermarket.

Rick

All good observations. The crank is still a mystery to me. I don't know why someone would spend all this money with a stock crank. The balancer is a BHJ but is externally balanced. I'm not sure how to truly identify a "good" crank. I'll take some pics. It does have a billet cam and the lobes show some tracking but nothing to serious. Yes that tensioner needs to go along with the cast cam gear.


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One more thing. I can see it has felpro lock wire head gaskets. Not to thrilled about that....


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Didn't plan on removing the heads but it almost looks like the head gaskets are leaking externally just a touch.... not sure yet.


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The crank is a GM stocker. I found the stamping on it. At least it's still standard.
I'm opting not to pull the heads.
Just finished up porting the front cover and replacing the rear main seal. Not to exciting at this point.


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Been a while but I finally got a few hours out in the garage. The engine is now sealed up. Time to focus on the engine bay.
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Looks like a lot of the ATR catalog was in that car.

Dash, cold air box, 7th injector, wastegate and downpipe. Nice find.

My thoughts exactly. I would suspect ATR headers as well. A big neck intercooler, although I thought the cold air box/ ram air filter canister looks like a Kenne Bell along with the intercooler fan shroud.
Very nice starting point.
 
All good observations. The crank is still a mystery to me. I don't know why someone would spend all this money with a stock crank. The balancer is a BHJ but is externally balanced. I'm not sure how to truly identify a "good" crank. I'll take some pics. It does have a billet cam and the lobes show some tracking but nothing to serious. Yes that tensioner needs to go along with the cast cam gear.


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Maybe when the engine was rebuilt, sounds like 95, the forged cranks were still expensive. Hey Bison is running around 700rwhp with the stock crank, rods, pistons.
 
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