Grinding header internal weld.

[battlecry]

Just pulled the header off the horiz head and noticed the weld holding the flange to the inside of the header pipe.  Has anybody ground it down or smoothed it?  How much did you grind down?

I've seen worse welds, but it may be nice to grind it and expand the diameter somewhat.

Also, looking into the exhaust port, the back of the  valve is whitish.  Is this normal?  I was expecting it to be darker.

[Rock Store]

whites & or light tan ,means shes running correclty,its burned ash deposits & normal.You will find the entire exhaust valve from face to stem is this color,any darker would indicate a fueling issue from rich to pinging. The weld ,unless its protruding enough to disturb the flow of the exhaust ,I would leave it alone.with all the thermal dynamics of cooling & heating up ,grinding to much off can jeapordize the integrity of the weld .
later..RS

[Popeye the Sailor]

It's not broke.....

[battlecry]

True enough Mr. I., but the weld drops the cross sectional area 15%  I think I'll grind the weld down to 1mm or so.  That will reduce the cross sectional area only 5%  May make a slight difference in the longer distance the gases have to travel from the horizontal cylinder.

Back to watching the Canadians grind the Russkies into the ice.  SIX TO ONE NOW.   GO CANADA!

[scott_araujo]

Just wondering, is the diameter even with the weld larger than the actual exhaust port?  If so, no point in grinding.

Scott

[Strafer]

Increasing the exhaust port diameter tends to increase gas flow volume at higher RPM but it will also decrease gas flow velocity at lower-RPM which usually has an adverse effect upon low-to-mid range throttle response.

[Bizzarrini]

I've never actually seen the inside of the first part of the header pipe, but I can imagine that large welds could cause turbulence in the header which increase resistance (much like the clogging of an artery and subsequent flow problems). Could this have an effect on the output?

[brad black]

i've ground a lot of 4v ones out, don't think it makes any difference.

[battlecry]

Thanks for the advice, guys.  I ended up leaving 1mm all around.  Open dia went from 33.7mm to 35.7mm and was quick work.  Further grinding would have taken longer, as more material is involved.