zeke2u

I like the Peterson springs (PAC 1518): they're nitrided (more resistance to metal fatigue/fracture) and made in the US. It's not a difficult job, but not one I'd want to do more than once - my time is more important to me.

Definitely replace the valve seals - don't mix-up the brown exhaust ones with the black intakes. The cover gaskets might not be necessary. If they look ok (not brittle, still intact and supple), I see no reason to change them. The oil that's sitting there is not under pressure and is not prone to leaking.

Larzmat

Also, how would I know if it has stock springs in it or not? Yellow seems to be the color if they are stock?

zeke2u

Yes, the stock ones are yellow. The replacement GM springs, made in Mexico, are now blue. My Peterson springs were bronze and a bit longer than the stock ones.

Larzmat

Thanks, I suppose I'll get the blue GM ones. Thanks!

GenerationX1

You might be able to remove the oil cap and shine a flash light down into it to see. I could and mine are definitely yellow but.... from a early build of 09/01.

SteveDoten@ARH

You got lucky on that one Don is the man to see for LSx installations and tuning. He has been doing this for over a decade.

laurent_zo6

I am leaning toward choosing the PAC 1518 for my 2002 Z. Can I re-use my stock valve seals since the car has very low mileage? Thanks.

zeke2u

Well, I was lucky on the valve spring issue, but not so lucky on the ARH's. When I got home with the headers, I noticed that the drivers' side header did not have the air fitting between the 2nd & 3rd cylinder. When I removed the cardboard padding that was on the front of the header, there was the air fitting, on the #1 cylinder tube. There's no way that this header would work on a C5 as it is too close to the alternator. I don't hold Don responsible for this mistake, but someone at ARH must have shipped a set of Corvette headers that were made for something other than a Corvette. I'm glad I noticed this before I started removing the stock exhaust.

zeke2u

First, "Very low mileage" is subjective and you might want to quantify that. Even if it were under 5k miles, I wouldn't take the chance because a set of new ones is only $44. If you reuse them and you notice a puff of smoke after every cold-start, it means you have to remove all the springs, again.

laurent_zo6

Which valve seals would you recommend I buy when installing PAC 1518?
Thanks.

zeke2u

Here you go - GM valve seals

laurent_zo6

Thanks for the answer. So it will be PAC 1518 with GM OEM valve seals.

Atok

Yes, you can see them looking in the filler cap. Later 2003 and 2004 Z06s did not have the yellow springs. The yellows do seem to be at much higher risk.

I always wondered why GM changed them mid-model year. Do you suppose they discovered a quality issue with the yellows? Maybe some 2002s started breaking while the 2003s were being manufactured? Hmm...

Larzmat

Sounds good, I will try and peek in through the oil fill. I figured if I have to go in and do the spring swap I might as well do the Harland Sharp rocker upgrade at the same time and be done with it.

I'm pretty sure it has to be done as there are no records of them ever getting replaced through the history of the car.

Is there an alternative way to hold the valve up in the head while replacing the springs? I have an air hose adapter for the spark plug but my air compressor is really small and I don't trust it to do a good enough job.


As far as GM replacing springs, they probably did a running revision considering the risk of failures to be low, or was it ever replaced under warranty or recalled somehow?

zeke2u

[QUOTE=Larzmat;1587387964]Is there an alternative way to hold the valve up in the head while replacing the springs? I have an air hose adapter for the spark plug but my air compressor is really small and I don't trust it to do a good enough job.[QUOTE=Larzmat;1587387964]

I had a hard time removing the collapsed spring, which was the exhaust on the #1 cylinder. My Emglo, which I've had since I was building houses 40 years ago, is also a small compressor (2-1 1/2 gallon tanks) which will put-out 105 psi, but I couldn't keep enough pressure in the cylinder while using the dual spring compressor tool. So, I brought the piston to TDC, using a 15/16" off-set box wrench on the crankshaft pulley - an easy matter with all the spark plugs out. On other springs, I did use the compressor - but I didn't feel that comfortable doing it. I felt more comfortable with the piston at the top.

NatB

I used the "rope" method, inserting a nylon rope into each cylinder and squishing it to the top by turning the crankshaft with a wrench to hold the valves. Time consuming but worked great. I have a good compressor and the hose attachment , but felt more secure with the rope holding the valves up securely.

racebum

and mileage really doesn't matter, it's age. rubber hardens as it ages

z06scentair

A.c.[QUOTE=zeke2u;1587388492][QUOTE=Larzmat;1587387964]Is there an alternative way to hold the valve up in the head while replacing the springs? I have an air hose adapter for the spark plug but my air compressor is really small and I don't trust it to do a good enough job.No problem with compressing
he cylinder with air. It doesn't require much air pressure to hold the valve up.

Even heard of people changing them with out doing anything. The valves are at such an angle they will not fall through.

If the valve does drop just grab the top of the stem and pull it back up as long as each cylinder is at the top.

Replace the seals when you change the springs, it's cheap.

Another thing to consider is the comp trunion upgrade. No sense in adding aftermarket rockers unless you are changing ratios.

The stock rockers are lighter weight than most aftermarket rockers and can cause excessive hammering on the valve train.

Keep in mind the exhaust valves are sodium filled stems and are hollow.

Freshbake

I just bought a 30k mile 2002 Z06 from a fellow forum member this past monday. Built in Feb 02, VIN 24000. I checked down the oil filler cap, and have got the yellow springs. I'm ordering new springs and getting them swapped out asap. So glad I stumbled on this thread!

apriliacati

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