brown stain

[got6spd?]

no pun intended

So I took apart my engine the other day and noticed that the intake as well as the intake runners in the head were stained a transparent brown color. Its not sticky and it won't even come off with brakeleen.

Anybody have any ideas what might be the cause? I don't recall the engine ever running really rich but I pulled the plugs and they were pretty dark so I guess it must have. It's been a while but I remember pulling the carb a couple of times and the intake was dry, not pulling oil by the pcv.

383
pro topline 200cc
comp xs290 252/260 duration
10:1
Air gap manifold
MSD ignition locked out vacuum advance
Holley four corner 750 dp(w/whatever jets came in it stock)

Thanks for any replies,
Chris

[got6spd?]

any similar experiences?

[Carver67]

Not sure how long the car sat in its current form (or if ,like the rest of us, it sits between new parts installs) but I've had similar staining from varnish build up in the fuel when I don't use a good fuel stabilizer. Just a random thought.
-mike

[Vegas69]

Would say it's just pooling or a needle and seat not sealing correctly. I wouldn't lose sleep over it.

[megaladon6]

it's pretty common. some of the fuel in the charge attaches to the wall and dries on there. as long as it's a film you're ok, if it starts getting gunky then you need to clean it.