Someone´s been carving in my head!

fiatfan · May 29, 2016

Removed the inner parts of my 850 head the other day, and found this. Obviously someone has been at it, and I guess it´s not easy to see how much material that´s been removed by looking at pictures. But I know there´s quite a few of you who is doing this kind of work. Maybe someone can tell me if I should keep it or bin it? Thoughts?
Tommy

guest76 · May 29, 2016

I'll be honest with you - I have seen a LOT worse than this!!!

It's a little bit scratchy, and would benefit from some smoothing, but I definitely wouldn't scrap it!!!

Danno · May 29, 2016

Appears someone did a crude job of scraping off some carbon buildup. As long as you have it apart, you can smooth it out with some emery cloth. The port surface doesn't have to be polished to function properly. In recent years, conventional wisdom has changed to make a semi-rough port surface desirable for good mixture atomization. So as long as it runs ok, no harm done.

pommie john · May 29, 2016

When I had some new valve guide fitted, the new guides were perfectly round ( of course) but the ports weren't and there was a mis match that was fixed by a bit of grinding like what we see in those photos.

EDIT : I meant valve SEAT not valve guide.

acotrel · May 29, 2016

A bit of porting and polishing around the back of the valve seat won't change the torque characteristics of the motor. However if the port has been enlarged from start to finish - not good.

Rohan · May 29, 2016

Have you tried it yet to see how it goes ?

Definitely wouldn't bin it without trying it first.
The proof of the pudding is in the eating, as they say.

Who knows, someone who knew what they were doing may have been there...

fiatfan · May 30, 2016

Thanks everyone for the encouraging and, for me, hopeful answers! I have had it running, but not enough to determine if this has any effect on how it runs. Hope to be able to put it together during this summer, there is some restoration going on....
Tommy

JimC · May 30, 2016

Since I don't know a damn thing about head porting, despite than having the privilege of watching C.R. Axtell port one, if it were me I would need dyno comparison runs. One with a stock head and one with the head in question.

Brooking 850 · May 31, 2016

While it is off the motor, get the head flowed and you will know if has been improved or not by the porting guy.
The head flow guy will know what to do. There is plenty of info around this site to compare to see if it has been made better or worse.
Just a thought
Regards Mike

Someone´s been carving in my head!

fiatfan

guest76

Guest

Danno

pommie john

acotrel

Rohan

fiatfan

JimC

Brooking 850

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