Starting to port my new 0630 head

[Desertjr]

Ok guys since my last one turned out great, minus the 6th chamber being about .08 outside the head gasket I'm starting a new head.

Start by gasket matching. Then following john(nosigma's) advice on how to do the runners & chambers. I will also be trying to clean up the oil & water passages in the head some to help promote drain back and flow. Pictures to follow.


Just wanted to ask any advice? And tips? Thing you wish you would or could have done? Obviously go slow and such but other than that?

[Desertjr]

I started with "drain back" type stuff. Started polishing the top porting of the head where the valve train goes with 180 grit stones. Cleaning up any big rough spots and knocking off most ridges and such, making the curves and bends slightly better to help keep wool flowing back to the pan and not sticking to any 1 surface too much. It's something ill probably never notice but its getting ready to really get into it, helping me steady my hand and such ill have pics in a few hours. It's a ssslllloooowwwwwww process

[SilverXJ]

Don't change the shape of the port too much. I would smooth out all the sharp edges and clean up the casting grain. Polish the combustion chamber and exhaust port, leave the intake port slightly rough, 120 grit or a flap wheel. Cleaning up the oil surfaces is definitely a good idea. Unshourd the valves if possible, but on mine there wasn't much to remove. It takes a shole, especially since its cast iron.

Wear a dust mask, eye protection and ear protection.

Oh yeah.. make sure you don't enlarge the combustion chamber past the head gasket. lol

[IH 392]

A "bump" in a port is ok, a "dip" or "hole" in the port will cause WAY! more turbulence than the bump will, if the depression is less than an inch in any direction its counter productive!, smooth relatively flat surfaces with nice radius's, sharp edges are also turbulent causes, don't take to much off of the guide boss (reduce it's height), you want to blend it to the valve in a "tear drop" fashion, round side on the inflow and the tail on the out flow, guys will grind the boss right out and when the air hits the valve stem it introduces turbulence.

Yep, take your time, you're not going to get it done in one evening after work!

[Desertjr]

Thanks chris ill be sure to take it slow this go around. Whole head and I messed up on the 6th chamber at th e back side by the darn freeze plug..litterally the very last bit of the port work

Thanks for the info guy. I wasn't to thrilled with my guides last time although I have seen way worse, I knocked out runner 1 & 2 today, just roughed them in. Will clean them up tomorrow when I'm fresh.
I was actually VERY surprised by this head. The chambers didn't need much gasket matching at all. I mean, not even 1mm difference on the intake ports. Same gasket I used for the 7120 and those were easily an 1/16-1/8th off. It's a 94 just like my last head was, this is a 97 head & ill be using the same gasket for it. I was very happy to see that...wonder if heads got better as the year progessed


And not to start controversy but I believe 1bolt either mixed up his words or was wrong in a few cases, or maybe he found another way to pick up the flow, opposite of john. I spoke to John (nosigma) for advice this go around. 1bolt states to open the roof more than the floor. Seen in this quote here, "Eventually this was raised to 246 cfm with added flow at all lift values by widening the port with most of it occurring at the roof and then tapering down to the floor."
John stated the opposite. He said he pulled the ramp back and shallowed it a bit vs being so steep. He said that picked up quite a bit low lift flow. He also had wider floors than the roof, and his runner shape was almost a trapezoid shape. He said he opened up the floor and wall on the cylinder side more than the anything and picked up a great deal of flow doing so & that it promoted swirl.
So his ports looked something like this, except favored a bit more to the wall closet the exhaust port.


I'm kinda copying that but not so extreme. I pulled the ramp back a bit & opened up the floor & wall on that side slightly more, also most of the grinding down towards the floor vs the roof. John also said a very slight trench was added in his head, also on that side...about a 1/16 of an inch deep. I have yet and probably won't do that. But I figured I'd post this info for everyone to ponder on and give their opinion or thoughts.

Fwiw last time I stuck to 1bolts advice on my 7120 cast, and kept the same basic port shape. And it was flowed, I'm getting those numbers shortly & will post them up. This go around I'm doing the opposite and working more the floor and exhaust side wall & pulling the ramp into the chamber back some to, back further & less steep of an entry. Hoping to flow this head as well and will post them to. I'm very curious to see the difference.

I'm actually curious about flowing the head with the stock bivalve size, then cutting it again to my bigger valve size and flowing it after. We will see if I have the funds. It will get flowed 1 way or another though.

[Desertjr]

Ok so I was wrong.. 1bolt said he had opened up the roof of the exhaust tapering to the floor. The intake being opposite, which is open floor tapering to the roof.
So for any misinformation.