Blue Angel

I've replaced my valve seals already but was wondering about replacing my valve guides while I have the engine apart.

SDPC doesn't list an OEM replacement for the guides, so...

Where are the new valve guides coming from when heads get rebuilt? Are they the same as OEM guides? What's involved in pressing them out/in?

Blue Angel

Anyone?

toddk

In my research (sorry no real world experience), the stock valve guides are steel that wears much better than the various bronze alloy replacements that are installed during a rebuild.

The Service Manual discusses valve guide wear measurements before replacement or reaming them out to use new valves with oversize stems. Clearance more than 0.0037" must be repaired. Valves with stem diameters less than 0.313" should be replaced. It may be worth measuring to see if new guides are even needed.

Based on these two findings, I decided to buy low mileage non-rebuilt 243 heads instead of rebuilding cheaper higher mileage ones.

Hope this helps.

Todd

Blue Angel

Thanks Todd! I'll probably just leave the steel OEM guides in then since I drive the car a lot and I don't want to be into replacing valve guides every few years!

toddk

If you've still got the heads apart (and can get the seals off without destroying them), it may not hurt to try and measure the valve-to-guide clearance to see if new ones are even warranted. If you are running stock cam & heads I would expect them to run past 80k miles without needing attention (again from what I've read).

Todd

Blue Angel

Heads are completely apart right now and all the valve stems feel very good in the guides - very little freeplay. The surface of the valve stems looks good too, very little wear from what I can see. I will measure a few valve stems just for kicks but will likely just leave them as is.

Thanks for the information!

Georgies

Any update on this? Mine are measuring 0.311.

I will try a wiggle test.

SaberD

FWIW i had mine checked on my LS1 with 135k miles, and they were still well within spec.

Georgies

What did they measure?

SaberD

valve stem diameter and guide diameter.

Georgies

Ok do you have the measurements??

Georgies

Is the minimum of .313 also for the LS6?

SaberD

It was a few years back, so unfortunately no.

Georgies

Damn...there isnt much info on this...

Is it possible all valve stems wore down evenly to contribute to my .311 measurments??

Seems unlikely... i will try a micrometer instead of the vernier.

SaberD

The guides are made from a very hard sintered metal alloy, much harder than the valve stem itself. Likely the only time you will ever need to replace one is due to a bent valve. If the tolerance is on the high side, it's more likely the valve stem is worn than the guide.

Georgies

Hey thanks for the info.

What are my options in figuring out if i just need new valves or guides?

My valves are under spec from what ive read. I need to source some.

Should i buy just one new one and do the wiggle test to confirm the valves are the problem?

Should i get both intake and exhaust valves in stainless? I see manley makes them with stock height for around 150$ exhaust (8pcs) and 160$ intake (8pcs).

Thanks.

vettenuts

Use a micrometer and then check the numbers against the service manual.

Georgies

funny you say this. I'm almost done measuring each valve stem and guide on the passenger head. Almost doe will post result soon.

SO FAR SO GOOD!!!!

My mistake was using the vernier!!

Georgies

redzg

Them there be some classic measurement tools. Not exactly handy on the shelf at Harbor Freight...