What are the cons of Aluminum heads on a street car?

kidglok said:
I forgot about that Paul. When you buy a set of "8 bolt" aluminums they are set up for stock style rocker shafts. I personally don't trust this setup with higher spring pressures since I have seen the rocker stands break off on aluminum heads. I think tom charged me $120 to mill the stands off and drill them for jessel rockers.

8 bolt Gn1's still have the outter bolt holes like the 14 bolt does, but the inner head bolts are not drilled and they have stock style rocker stands


The 14 bolt GN1's are set up for all 14 bolts drilled and the Jessel style rocker setup.


David to answer your question I don't think it's the rockers themselves that break, but more so the stands they are bolted to. Also running the taller valves opens up the spring choice which is the main reason for doing it. I think the valves are about $35-40 a piece, and Tom had to cut them down because they don't make the proper height "off the shelf".


Posted from the TurboBuick.Com mobile app
Click to expand...
I have longer threaded studs and was able to get below the cylinder head horizontal plane. Folks that broke had shorter studs that were too high up in the pedestals
 
I've been using Champion GN1 aluminum heads with T&D roller rockers on my street car since 2001 without any problems. I did have to buy different bolts for the rockers because the ones supplied were to short.

I guess the only con would be the price between the iron and aluminum heads.
 
Talked to someone (woman) at TA and was told that the my currently installed HS roller rockers on my STOCK iron heads will fit and work on the TA SI heads.
I read somewhere that aluminum heads could not use roller rockers that were for an iron head.
Can any one confirm this?
 
TURBOPOWERED68 said:
Talked to someone (woman) at TA and was told that the my currently installed HS roller rockers on my STOCK iron heads will fit and work on the TA SI heads.
I read somewhere that aluminum heads could not use roller rockers that were for an iron head.
Can any one confirm this?
Click to expand...
The towers on my GN1's are cast narrow so the roller rocker fulcrum does not have a hard interference. I see no reason why your HS's should not work. The towers in your new heads are probably narrowed to clear the fulcrum bearing housing of the rocker. The most important thing is that your rocker down force on the valve pushes straight down so that you are not side loading or running off the valve center line through the rocker arc of motion.
 
TURBOPOWERED68 said:
Talked to someone (woman) at TA and was told that the my currently installed HS roller rockers on my STOCK iron heads will fit and work on the TA SI heads.
I read somewhere that aluminum heads could not use roller rockers that were for an iron head.
Can any one confirm this?
Click to expand...

Not sure on TA heads, but the valve spacing on gn1 aluminums are different.


Posted from the TurboBuick.Com mobile app
 
The TA SI heads (only) have a rocker stand that will accept the iron head RR. You will most likely have to shim the rocker spacers to get the proper rocker to valve stem alignment.
 
For serious valve spring pressures I would only run the Jessel style


Posted from the TurboBuick.Com mobile app
 
kidglok said:
Not sure on TA heads, but the valve spacing on gn1 aluminums are different.


Posted from the TurboBuick.Com mobile app
Click to expand...
I thought the TA's had the same rocker offset ~ 0.050" do to valve re-positioning. Sorry I stand corrected.
 
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