89 Carrera - do I need to replace head studs
 

My engine's apart for a valve job. It had done 80000 miles but had excessive guide wear. Should I be replacing the head studs on reassembly?

I would, it's relatively cheap insurance against future problems. Whilw your in there, chain wheels, chains, clutch/pp and all the other wear items should be closely looked at.

Nathan, you only need to replace the 12 exhaust side (lower) head studs. They are the dilavar ones. The upper studs are steel and do not have the corrosion problems the dilavar ones do.

I would recommend replacing the lower exhaust studs, as Kurt mentioned...

If it were my engine, I would also replace the rod bolts too...

-Wayne

I went with the ARP racing rod bolts. Considered it not so cheap insurance.

I always replace all 24 studs in cases like these,...... :)

The steel ones and the latest 993 dilivar ones do expand at different rates and using the 993 studs keeps even torque on the heads from cold to hot.

ARP rods bolts are indeed, a no-brainer,....:)

So Steve, you recommend the 993 ones over the early steel ones? Interesting...

-Wayne

993 Dilavar studs? I've been trained to consider the "D" word a profanity around these parts.

My dilavar head studs are not showing any corrosion. I take it this is no guarantee they are OK? Which studs should I replace them with?

With regards to rod bolts, if I go with ARP ones can I safely have the rev limit increased when I have my chip (custom) remapped?

Thanks,
Nathan

Theoretically, yes. However, most people don't like to push their engines further than they were originally designed to go. It's up to you though...

-Wayne

Hi Wayne:

The latest 993 TT dilavars have been very good and I use them in everything. Steel studs are OK too for early (non-mag) engines that do not get hot,.....:) They are quite strong and reliable of course, but they cannot accomodate the engine's expansion very well and in the big-bore motors, I see some leakage from the head-to-cylinder surfaces due to bending when hot.

I don't use Raceware or ARP studs any longer due to head loosening issues.

Nathan:

You can turn the engine up to 7100 if you have the ARP bolts but unless you make some cam changes, its rather pointless.

Well I just bought 12 steel head studs to replace the dilavar. Should I send these back and get the 993's? This is on my '86 3.2 engine. Should I buy 24 of the 993's or just the 12 on the exhaust side?

bump for an answer to my question.

Thanks Steve. I was considering a change to 964 cams. Would this be a worthwhile move and would I it also be worth the extra expense to move to Euro pistons?

I'm still confused as to which head studs to buy, as per Kurts question above. Are the 993 ones all the same material then?