Just bought a set of alum GN1s old style that was said to be new style

[G NASTY]

That good old saying when it's to good to be true it prob is. I bought a set of alum GN1s almost new. Seller stated they were new style and were only about a year old. When i got them I have been compairing pics and they are the old ones. Now iam deciding what to do with them. What is the differences between the two?

 

[antiquettype]

The newer castings have more material where the cracking was an issue. Also they use different plugs to leave more material in the critical area. The valves may be smaller too depending on which ones you would get and your application. In my opinion you need to make a lot of power for the older ones to be a real problem. I think the heads got pushed further than was anticipated way back when.

 

[wickedtt]

That good old saying when it's to good to be true it prob is. I bought a set of alum GN1s almost new. Seller stated they were new style and were only about a year old. When i got them I have been compairing pics and they are the old ones. Now iam deciding what to do with them. What is the differences between the two?

The older ones are more prone to crack easy period.

 

[G NASTY]

Looking to build a 10.50 car. Heads are mint though. What power are these heads failing at?

 

[wickedtt]

It's not a power level, its just over time after some many years the older set was just flawed by design that's why they came out with the newer version.
People have reached the high 9's with the ported irons..How old are they?

 

[thessman]

where do they crack???

 

[G NASTY]

Age wise I don't know? Prob only a few hundred miles on them

 

[Turbo1dr]

The newer ones have "GN1" logo on the ends of the heads....not between the exhaust ports.

 

[antiquettype]

I had a set crack between the intake valves and the spark plug hole years ago. Had them repaired by Tom at Champion. They ran fine cracked, never even knew until the motor was torn down for rebuild. I think they also had problems with rocker shafts pulling out? Use good rocker setups like T&D. In my opinion, if you don't feel like you were robbed with what you paid, you should put them on and enjoy them.

 

[wickedtt]

Age wise I don't know? Prob only a few hundred miles on them

Why were they removed after only a few hundred miles is the question.

 

[Grumpy]

Why were they removed after only a few hundred miles is the question.

I have bought cars after guys finished them and hated the car because it ran like crap and also had a few "divorce sale" cars to :biggrin:

 

[G NASTY]

They were on a low milage Gn that was going back to stock before going up for sale. The heads are truely new, seller was honest about that.

 

[G NASTY]

Thanks for the info. Is that the TA intake?

The newer ones have "GN1" logo on the ends of the heads....not between the exhaust ports.

 

[D's GN]

I purchased the latest castings from Tom a few months ago, the new heads have a significant amount of aluminum added below the outer bolt holes, the GN1 logo is on the side and front of the heads. A few other tweaks to the casting has been made to improve air flow as well.

Datar

 

[WarWagon]

Awesome! :biggrin:

 

[TurboTR]

They look pretty beefy now, kinda like the TA heads. Anybody have good flow numbers for a ported set? Can we see some pics of the chambers and intake ports?

I have a set of the older castings, GN1R. I think one thing that probably hurt them initially too, I don't recall them spec'ing a much lower torque value for the outer bolts either. Like the TA spec does.

TurboTR

 

[D's GN]

Here are a few more pics, I will take a couple of the chambers the evening.

Datar

 

[TurboTR]

Thanks! Did Tom give you some flow numbers too?

TurboTR

 

[D's GN]

They look pretty beefy now, kinda like the TA heads. Anybody have good flow numbers for a ported set? Can we see some pics of the chambers and intake ports?

I have a set of the older castings, GN1R. I think one thing that probably hurt them initially too, I don't recall them spec'ing a much lower torque value for the outer bolts either. Like the TA spec does.

TurboTR

I misplaced the spec sheet for these but recall the intake flowing at 260+cfm at a little over 500" lift, the exhaust was in the upper 190cfm range.

 

[Otto J]

The new ones still use the sme spark plugs. There is another version that uses smaller plugs but this is not the norm.
One thing i do believe HELPED crack the older version was the over torquing of the spark plugs.