vg30 heads - gurus, help me out!

[bartZ32tt]

I'm looking into buying a set of heads from someone to fix a misfire. I have a 1990 tt, I read 90's had a TSB out for soft valve seats. I am wondering what I need to look for with these heads before buying them to ensure they wont fail me like my current ones did. Here are some details:

-The heads have around 20K on them and had a p/p done.-It has stock tt valves-I asked him to have a machine shop pressure test the valves and provide paperwork of the results before I purchase

What else should I look for?And if I were to end up getting these heads, I would have them disassembled and cleaned before installation. Anything else I can/should do to them to make it bullet-proof?

Thanks.

[Zwicked]

If they are used heads they will also need to be resurfaced before using them ( as well as new head bolts).As far as I remember, only the NA heads had the valve issue as they were made from a softer material.The issue with some of the real early 1990 heads was the cam/CAS mount was slightly misaligned causing premature CAS failure.

[bartZ32tt]

Thanks for clearing that up zwicked.

In that case, he's asking too much for his heads (500 + shipping) since they need to be cleaned as well as resurfaced. I think I'd rather buy from ipp or z1 than d!ck around with getting these heads usable..

[Zwicked]

Agreed. Installing heads, gaskets and the bolt set as well as it would be a good idea to install new cam seals etc it adds up, and it would suck to not have perfect heads after the expense and time invested.

[bartZ32tt]

Just ordered a leakdown tester. I've searched and watched brief videos about it, but need clarification. Since the z's firing order is 1, 2, 3, 4, 5, 6 - i should test companion cylinders (1+4, 2+5, 3+6) at tdc, correct? Or will I only be able to do 1 cyl at a time? Been awhile since I did an overhead valve adjustment; can't remember valve positions in relation to firing order.

[Zwicked]

You can only do one cylinder at a time, and may as well do them in firing order as each needs to be at TDC on the compression stroke so the valves are closed. Take each to TDC but don't go past and back it up as the rings need to be at the bottom of the lands on the piston just like they would be when it's running. You will need a decent output air compressor to do this to generate about 100 psi. Some normal leakage will occur. I think around 90% of what's put in is normal. Record the readings and see how close each cylinder is to the others. Remove the rad cap when doing each cylinder to check if there is a head gasket leak into the coolant circuit.*Remember when charging the engine it's like it's firing so the crank will want to turn. Put it in 4th gear with the park brake engaged so the engine can't turn.
Modified by Zwicked at 9:08 AM 1/24/2010

[bartZ32tt]

Awesome tips, thanks once again zwicked!

I'll report back once my tester arrives and The weather subsides for me to test it.

[Chase300]

buy my heads! 500$+shipping! resurfaced ported reseated. have matching lower plenum to match for free! (1990NA heads> compared them to TT and they have much better airflow but basically same port runner diameters)

sprry for posting in genral