L32 3.4L Intake and Exhaust Valve Margin

[shwgidy]

Hi all,

R&Ring the top end in my 95 camaro because of water in the oil and vice versa... Also installing new valve seals while Im in there due to burning oil on startup after it has sat for a few days... In checking my haynes manual I noticed they omitted the specification for the valve margins for my engine...
What is the min. intake/exhaust valve margins for an L32 3.4L v6?

I ask this because all of my intake valve margins are about 0.061" except it looks like one is 0.055" with some burring going on (I think I will replace that one just because it looks different.) The one with the "burring" is the driver's side and nearest to the driver (RWD camaro, cylinder #5)

All of my exhaust valve margins are 0.095" to 0.100". All of the driver's side exhaust valves have some minor pitting on the seats. (Should I replace these?) The pits are almost as deep as the Lincoln memorial on a penny. (What a reference right?)

In the technical specification section I noticed that the specifications for the valve margin is most likely wrong... http://60degreev6.com/content/34L_GE...Specifications

After converting the mm to inches I get:
Intake: 0.067" to 0.079"
Exhaust: 0.061" to 0.073"

I reckon for one that they should be at least switched...(I found this site looking for valve margin specifications for which my lovely Haynes manual omitted)

Thanks for any and all help.

-Brian

[shwgidy]

After reading about exhaust valves in general on other websites I think I am going to buy (1) new intake valve and lap all of the valves tomorrow and call it a day.

Any thoughts/ideas would still be appreciated.... I'll reply with the new intake valves margin.

[60dgrzbelow0]

http://cgi.ebay.com/ebaymotors/93-95-Camaro-Firebird-3-4-V6-Cylinder-Heads_W0QQcmdZViewItemQQhashZitem53df6275a3QQitemZ360230057379QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

http://cgi.ebay.com/ebaymotors/Chevy-173-189-3-1L-2-8L-Camaro-Firebird-V6-Head-Bolts_W0QQcmdZViewItemQQhashZitem35a7a3668bQQitemZ230445770379QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

[shwgidy]

Carquest guy sold me a lapping tool and grinding paste. He also said the "burring" around the face of the intake valve was a manufacturing defect on this one of six intake valves put into my engine (no real need to worry).

He also recommended that I get new keepers... So it looks like summitracing will be finding an order from me on Monday.

-Brian

[60dgrzbelow0]

After reading about exhaust valves in general on other websites I think I am going to buy (1) new intake valve and lap all of the valves tomorrow and call it a day. Any thoughts/ideas would still be appreciated.... I'll reply with the new intake valves margin.

From HP-Books, "Engine Builder's HandBook" ISBN 978-1-55788-245-5 Page 93

"...the Gray Band on the Valve(s) should be Full Circle, indicating Full Contact between the Valve and the Valve Seat. If it's NOT Full Circle on the Valve Seat...the Seat is NOT concentric with the stem... If it's NOT Full Circle on the Seat... the Seat is NOT concentric with the Guide."

Get two small shoe boxes to use via poking holes in the lid and marking the means to recognize that how you stack your finished valves in the holes in the box cover matches their respective positions in the engine heads when it comes down to re-assembly time. The reason this step is necessary is because you will need to thoroughly clean and remove all of the lapping paste from inside each head before assembly, lest the residue wear out anything that it comes in friction contact with later. Likewise, carefully clean the stuff off of each valve...from "stem" to stern before applying your valve tools to compress the springs and install them back in the right positions in the heads.

[shwgidy]

Update...

Bought a set of keepers and (1) intake valve from RockAuto... Summitt didnt have the keepers in their "standard" line-up.

The new intake valve has:
0.060" margin
4.711" long
0.042" dia. stem
marked V2291, federal mogul

The keepers are VK-115, Sealed Power, Federal Mogul

Hopefully this weekend I can finish up the heads, install'em and get'er back on the road.

10-4 60dgrz, I put them in labeled baggies after identifying them on a "plan".

The head bolts got jammed into a piece of 4" styrofoam after labeling it front, passenger, driver... Haynes told me to do that, not necessary since I am replacing them anyways, just more for the placement of the single stud.

-Brian

[geoffinbc]

The 3400 specs will work.
Valve Margin - Minimum Intake
2.10 mm
0.083 in
Valve Margin - Minimum Exhaust
2.70 mm
0.106 in

I must have copied them wrong back when I did it.

It is better practice to have the seats and valves machined together. Lapping the valves does not produce the proper interference fit that is requires to create the best seal.

[shwgidy]

Alright,

After lapping for a long time on the exhaust valves (with the time it took it probably would have been better to just replace them) and the intake valves (a rather quick 1 or 2 lappings) I took a look at my 89 eldorado's factory service manual and it defines "valve margin" differently then what my Haynes manual. The Haynes manual shows it as the flat part after the seat which is parallel to the stem... The factory service manual defines it as the horizontal measurement (perpendicular to the stem) from the last part of the valve which contacts the head to the outside edge of the valve face, I believe this is (or would be) defined as "overlap".

Which is correct? (google images agree with Haynes)

Either way there is still a margin left for my exhaust and intake valves, which the Haynes manual says its still good to go...

[geoffinbc]

Margin is the very edge of the valve face parallel with the valve stem. The margin on the intake valve is not as critical as the margin on the exhaust valve. If it is too thin on the exhaust valve it will get too hot and can lead to detonation.



The chevy manual I have does not list margin for the iron head stuff. But my online manual does list it.