C1AE head porting

[chilly460]

I posted this topic on the Network54 site as well, but it's tough to find and recall the topic using that format.  I appreciate several folks chiming in and didn't want to lose the info.   I found several topics on porting the early low riser heads but they had Photobucket attachments which are now broken links, so figured I'd post this. 

I'm by no means an expert, or even a novice so this isn't a "how to" guide.  Just figured I'd take a stab at porting a set, get some advice from knowledgeable folks along the way, and see how it goes.  I gathered some flow numbers from various sources and old posts, I'd feel very lucky to pull 280cfm @ .600" or so with these.  I have a set of BBMs flowed locally that I can compare, as well as some Edelbrocks that are currently on a car and will be put on the bench, so I'll have numbers for reference. 

Anyway, copied from other site:

1) Will 2.15 intake valve flow appreciably better than a 2.09?  Undecided between a 4.08 or 4.16 bore at this point, most likely 4.08 though. I'd like to try a solid flat tappet, old school combo with these, so lift would not be over .600" 

2) The "knobs" at the top of the intake ports on the right half of the head, can they be taken out? Seems odd as the two left ports do not have them, not sure what purpose they serve but they're obviously right on the roof where velocity is high and if possible I'd like to take them out.  If they need to be retained, can they be shaved down a bit, and radiused into the corners of the roof? 

3) The intake ports have a 45* or so chamfer on the roof at the entry.  I'm planning to basically raise the roof enough to flatten that chamfer to the roof and blend it back into the port, any issue there?  It's abrupt enough, seems that it'd cause turbulence at the intake junction.

4) The vertical short turn of each port, can I lay that back a bit?  The inside wall of each intake port seems a bit "hooked" and seems it would bounce flow out towards the outside wall.  Looks fairly simple to straighten that out and blend it into the runner as I'm doing a light gasket match?

[chilly460]

To summarize the answers I got, the knobs in the roof don't necessarily impede flow enough to bother with.  If they are taken out, it will likely expose the rocker stud hole, and will require sealer.  The 45* chamfered opening can be laid back, especially on the roof.  The short vertical inside short turn can be laid back right at the opening too. 

Unfortunately, I got antsy and took the rocker bosses out of the roof.  Many aftermarket heads break through when ported, as they don't have any boss, so don't think it's a huge deal to seal it. 

[chilly460]

Followup post:

Unfortunately, I'd taken the bumps down in one head by the time I read this.  Oh well, it was about an hour of effort to remove them and hopefully it's no detriment.  The rocker bolt hole was exposed on both of the oil fed bolts so I'll do a little extra work to seal them up. 

Been a good experience, learning where to use different bits and finding quite a difference in the air grinder vs my electric die grinder.  Just a roughed in port that I need to straighten out but looking better so far.  Learning how tough it is to not make "troughs" in the corners.  Still need to flatten the roof a bit, and then I can start blending the floors.  The vertical short turns are all roughed in as well. 

Regarding the valve job, should I have them roughed in and bowl hogged, then do my blending?  I don't really want to work on it with a completed valve job, but not sure if there is an intermediate step where they can cut to size and bowl hog it, then I can blend before the final valve job is done?

That divot on the upper right (actually left side of floor) is not nearly as bad as it looks, bit of an optical illusion.  I do need to flatten it a bit more, and further back in the port is flat, the rust in the port makes it look like a huge trough back there but it's just a nice radius to the wall. 

[chilly460]

Another followup:

I finished up the intake entry and runner and started working a bit on the bowl area.  I'm wondering should I get the seats cut for 2.15" and bowl hogged so I can just blend it?  Seems useless to do any blending work as-is with bigger valves going in. 

I just barely started on the valve guide, a little 3/8" double cut burr chatters like hell if you go anywhere on that right side so it gnawed on the guide boss in a hurry.  Finally got it to blend in that area a bit by playing with cutter speed, going very slowly, and throwing some ATF down there. 

The large "pinch" on the right, shown in the red oval, can that be laid back all the way to blend with the runner?  I assume there's water behind it, but can it be blended back to be even with the seat?

[scott foxwell]

I don't know if this will help, but this is a 2.05 x 11/32 valve in a C6AE R head with basically the same chamber. The port opening is physically much bigger but you could fill the floor with 1/2" of epoxy and lose nothing. I did with clay...no change. Lot of wasted space. This intake port flows 260 for all intents and purposes with nothing more than a valve job and bowl blend. The port and guide boss was untouched. I did get rid of the bumps in the roof of the port but that's not the high velocity part of the port.

[Heo]

The Guy that Did My heads Said that what
They needed was a better shortside radius
And some cleanup work in the bowl C4-G
Heads

[scott foxwell]

The Guy that Did My heads Said that what
They needed was a better shortside radius
And some cleanup work in the bowl C4-G
Heads

90% of your gains are going to be within 2" either side of the valve job. Since there's really nothing to gain in these chambers, then it's all in the bowls and valve job. Maybe a little s/t work.

[Heo]

Yes thats what he told me. The port in it self is big enough
He worked on the shortside radius,cleaned up some casting
Flash in the ports, Did some work in the bowls,was a bit narrow
Around the valveguide he said , the nubs in the port roof dont
matter acording to him.He Said filling the port floor may give some
Gains in Fuel milage

[chilly460]

Scott and Heo, thank you for the insights.  I have a set of BBMs sitting on the bench and it's obvious how much smaller the medium riser ports are, with basically the floor filled as you've described.  I just knocked the casting flash off the floor, knowing that there would be very little flow there.  I'll work on the bowl now that temps are back to "normal" here in VA. 

I don't know that I'm experienced enough to mess with the short side radius, could do more harm than good there, especially without a bench to help me understand what's working.  I'll clean up any obvious ridges with a sanding roll so I can go slow, but not looking to reshape anything.

[cammerfe]

Back when I was playing with heads, I took an old valve and chucked it in a drill. Bracing the drill on a belt-sander table enabled me to create a 'gauge' to help me open the throat just below the seat. Drop it in place and you can easily see where a bit more needs to come off the head to keep things neat. It's only of value for a short distance, but it helped me 'eye' things.

KS

[scott foxwell]

Back when I was playing with heads, I took an old valve and chucked it in a drill. Bracing the drill on a belt-sander table enabled me to create a 'gauge' to help me open the throat just below the seat. Drop it in place and you can easily see where a bit more needs to come off the head to keep things neat. It's only of value for a short distance, but it helped me 'eye' things.

KS

I drop a smaller valve inside the bowl quite often. Gives a good visual especially from one port to the next...helps keep things consistent.

[KMcCullah]

Hey Chilly.. Your work looks pretty good so far. Here's a couple pics of some port work I did on some C1-A heads. If forgot to get a pic of the bowls after pocket porting  before I blended everything back in. But a lot of iron had to be worked out. Valves were 427LR imports from Alex's parts. I turned them to 2.15/1.65 and gave them a new 3 angle grind. I didn't mess with the valve guide bosses. The exhaust side of the combustion chamber got a little unshrouding though.

[chilly460]

Thanks for the additional pics, that does help to visualize.  I saw another post where you'd mentioned the valves from Alex's parts, appreciate that tip.  This is an experiment so I didn't want to spend too much on the valves and other hardware. 

[chilly460]

Spent about an hour working the bowl and guide on a port last night, I feel like I got the dogleg pretty well laid back and blended, and smoothed the transition to the runner where I'd come in from the other entry.  Also, worked the blend from the seat, and opened up the bowl a bit as it approaches the seat as it felt like it was constricted there.  Some other subtle work on the long radius where the wall felt "flat" and would shoot the air towards the middle of the valve.  I will say, I chowdered the hell out of the valve seat just with a sanding roll, just a little bump and it tagged it pretty good, definitely would be touchy trying to do this after a valve job. 

The first pic, I used a piece of solder formed over the short turn.  It seems fairly "vertical" off the seat, but since the air is running almost exclusively along the top of the port in these heads, didn't know if it made any sense to lay it back.  For now I just lightly knocked off a square edge that is right at the apex, talking 30seconds with a sanding roll to knock it down.