4 hours...and my ports are shiny...


Today...day 2 of the Cobra Six build up (in earnest) I ported and polished my exhaust and got it ready to send to the machine shop for milling and new valves.

Yesterday I CC'ed my head and ground down the numbers on the head for the Offy adaptor. I also started sanding my exhaust.

Porting and polishing wasn't too bad. The first one took about 1 hour...the other 5 only took about 2.5 hours. Gotta love the learning curve. Also gotta love a dremel. i hope to have pictures up tomorrow...I'm tired now.

Have a good evening.


Looking forward to seeing the pics. So, is this a first time port and polish for you?

I will need to go back today with a finer grit sanding wheel to smooth it out one more time...but it is 90% complete after looking at it again.

I love this stuff.

And people thought I was crazy when I said I spent 20 or 25 hours on my "portin & polishin job"

Now the fun really begins...."the bowls and intake ports" ;) :LOL: :LOL:

Be sure to take some pics!!



I couldn't have done it without your site. It is a good thing I got the respirator...my mask was black by the end of it.

I'm not sure how much of the bowl and intake I'll be doing.

The intake runners are'nt all that critical (IMO) because you cant do that much to them (because of the the intake log) But I would definitely spend some time in the bowl area under the valves.

Mine were all messed up and had a lot of wierd angles and casting flash all over the place.

I think it would be time well spent ;)

Unshrouding the valves would also be worth the effort!!

Glad my site helped some :D :D



When I get home, I'll post a picture of my bowls. They are different slightly from yours. It is a 67 head and There is not a whole lot to unshroud. I'm thinking of popping the freeze plugs and porting the intake log a little bit. I do have some flash, but nothing major in the bowls. I intend to go big tonight with rough sanding wheel to smooth it out a little.

Also...I do have one question. In all of my exhaust ports, there was a raise 'plateau' (for lack of a better term) on one side of the exhaust port about 1/3 of the way from the valve to the header. I did not want to grind that down because I wasn't sure it it was needed. It did not seem to be a valve cover bolt...but I'll double check when I get home. Do you know what I'm talking about? THanks.

I left those "lumps" in mine also. Just smoothed them out a little bit because I dont know what they do.

I would like to get a head sometime and disect it with a bandsaw just to look at the inside of one.....I am kinda wierd though... :roll: ;) :LOL: :LOL:

if you can take some pics of the bowls...i want to compare them to my 66 and 80 heads.


They look like your 66 head...but I'll post you some just for comparison.

I was about to smooth out the bump...but then I realized that every one had it in there so I ended up wondering if it is something structural so all I did was polish it up.

If you look right next to the lump, the roof is raised at that point. Feel the front of the lump and it seems like it has a little lip on it. I would have to guess that it helps control the exhaust turbulance somehow. I ground a couple of them down flat and didn't break through anything.



What if a person was to drill holes in the side of the intake manifold in line with the intake ports. Would this aid in porting the intake runners?
Then block the holes off (obviously) afterwards.

Question #2: Generally how much iron can ported off the walls of the runners. I know castings vary, but what's typical?

:LOL: what head has the "lumps'? when i did my '70 170 head it didn't have no stinking lumps :LOL: :LOL: . glad i didn't have to make that decission. i had about 30hrs. in mine as it was.
like cobrasix, i would keep going back and see something else i wanted to take off. i was still rubbing the bowls with my finger as they were putting the valves in. when the last valve went in then i was finished...frank..
:LOL: i have pics. but i don't know how to post them. could someone 'splain it so i might understand how to do this pic. thing :roll: ?..frank..
Are you talking about the intake log? You can actually pull the freeze plugs on the end and port and polish the intake log.

I'm less concerned with the intake since I'm going with an offy set up.

I just wanted to clean up the exhaust a little. I'm not looking for perfect...I only plan a few more hours of polishing.

Well...I gotta go. Doug...I'll post those pictures tomorrow...long day today and tomorrow is going to come early so I'm outta here.

Lookin good!!! ;)

Now look at the bottom of the bowls in these 2 pics,



See the ridge that runs around the bowl??

Make that go away, and smooth it all up :D :D

One other thing....Have you gave any thoughts about installing the later 1.75" intake valves?? Your machinist can cut the seats bigger so they fit. Mine did that as part of the 3 angle valve job. Just order valves for a 1980 head. I think mine cost $30.00 for all 6 valves.


Will it make a difference since I'm going with a higher lift cam?

I haven't really thought it would help that much...but if you know otherwise...let me know.

I'm not sure which ridge you are talking about. Are you talking about the ridge on the exhaust side of the bowl? I'm just unclear on which one you are talking about.