Measuring Valve Cover Rail

[1 Wild R/T]

So I'm slowly building an engine for my Coronet... As most of us have fought valve cover leaks this time I'm hoping to reduce the chances of a leak... Lotta guys have talked about the rails not being flat.... I currently have a head in my mill, leveled ( almost, might shim it slightly still) & squared... Tomorrow I might mill the rail but today I measured it.... Thought some of y'all might like to see the results...

First reading. -.012
Second reading .004
Third reading .025
Forth reading .026
Fifth reading -.005

So on the exhaust side of the head which is where they always leak about .040 variation... To be honest I expected more variation.... But I have the technology to make it better so I will...

 

[pnora]

Even at .040 that is a lot. Sheet metal covers with no reinforcement or backer plates made them leak a lot. No doubt leveling the playing field will make a difference.

 

[Runcharger]

Hmm: That really isn't that bad.

 

[Ironbuilt]

Looks like we need a bigger....gasket.

 

[eldubb440]

 

[PRHeads]

Ive seen several MP 518 MW replacement heads where the V/C rail varied by over .125”.
Not gradually from one end to the other either.......... several low and high areas along the length going from one end to another.
Horrible.

 

[WileERobby]

What I've done for 50 years: Apply Indian Head on both sides of the gasket, install gasket after about 30 seconds. Tighten bolts with an extension on a qtr inch socket using only your hands for a firm fit. DO NOT OVERTIGHTEN. After a while, tighten to torque spec, the uppers before the lowers. It's more important to have a flat, level rocker-arm cover. I never had a leak for myself or any customer back in the day.

 

[Don Frelier]

How about an O-ring setup? That would be pretty trick.

 

[1 Wild R/T]

Well I milled the first head (cut like butter) & set up the second head... Second head had over .125 variation... Started milling & discovered a couple really hard spots in the casting... Burned up a USA made Do-All HSS end mill.... tried a second USA made Viking carbide end mill & even going slow, using air to cool & taking little bites burned that end mill too.... Decided if I'm just gonna burn up tools I have a Chinese end mill a buddy gave me, he was saying how good they work... Figured I'll burn that up.... Nope... It cut right through the hard stuff.... WTH... A China tool that actually works??? I've heard it happens, never seen it happen before but I have now.... We're screwed...

 

[Fran Blacker]

Send cutters back to mfg with note about high quality chinese cutter finished the job.