0C_Williams@RPM

Completed the measurements -

Comments:

• more stem-to-guide clearance than we run with bronze guides
• more taper than we like to see
• several seat TIR's over .0020

lebvette

FNBADAZ06

Wow

CGZO6

Help a dumb$ss out here, what would be "good". Are they out of GM spec?

And thanks again for posting this info!

0C_Williams@RPM

1 - The guides are in spec - just looser than we typically run them.
2 - Again, surprised at the taper - but in spec
3 - Thought they would have a little tighter control on the TIR

forg0tmypen

What is TIR? And Taper?

carnutsx2

I wounder if the seat runout is from the poor job on the guides. Sounds like GMs sub contractor has either a room full of worn out tools or worn out operators??

track junkie

Would a head ever leave your shop with over .002 total indicated runout for the valve guide to seat?

kenw

Thank you for posting this information. Please keep weighing in on this n-e-v-e-r ending discussion on our LS-7's.

0C_Williams@RPM

The seat TIR is not by any means horrible on these - it's just that I've seen many, many GM heads under this and was surprised.

Please bear in mind that TIR on the seat has several components that make the reading all the more difficult to repeat the measurements

(1) pilot guide condition -(a) how tight to the gage (b) how square to to indicator
(2) gage needle condition
(3) operator

For me, I like to have no more than .002 and typically measure .0015 - but in some cases we can also exceed .002.

0C_Williams@RPM

Total Indicated Runout

Taper = cone shape

0C_Williams@RPM

I don't think the measured TIR is an issue.

TIR on the seat has several components that make the reading all the more difficult to repeat the measurements

(1) pilot guide condition -(a) how tight to the gage (b) how square to to indicator
(2) gage needle condition
(3) operator

NORTY

Thanks for posting actual measurement numbers instead of some lame *** " not too much" or "a whole lot" or "a little bit" phrases that don't mean a damn thing.

Thanks for taking the time to do it right, Charlie.

mistermog

So what I'm taking from this is while they arent perfect they arent bad either. definitely not out of spec as new.

WhiteDiamond

What is the build date on these heads?

Edit: Never mind. Saw the other thread. 2 yr old heads with basically no use.

0C_Williams@RPM

yes

ByByBMW

What I see is the even number heads/valves have worse numbers across the board for the most part. Worse than the odd number heads/valve yet isn't it the #5 exhaust valve that seems to be the worst performer?

Random84

Well, that's something. Thanks for taking the time to post.

SteveDoten

Interesting data.

ChevyCobb

Cool, this is the kind of information I was hoping to eventually see. Thank you for taking the time to do this!