516 heads-porting/unshrouding valves

[Mark Barnes]

If you pull some valves out and post some pictures it would be easier to tell you how to proceed porting. Also...I don't know if you've bought a torque converter yet, but I'd recommend a 9 1/2. They are tight and you can cruise on the street just fine, Imo your 383 combo is going to respond to more stall then 2900. Ptc or dynamic...good choices.
Porting my concern would be going straight in the bowl deep with 2.14s. It likely will get thin as you approach the radius. The short side I don't think you will have any trouble just blending it. But, I believe the exhaust are where guys tend to grind to much on 516s and hit a water jacket, they seem to lack cfm on the exhaust even after port work (compared to the later heads).

Ok, heres a couple pictures of heads/valves. The layout dye is because I asked the shop to just touch the previous angles that sat on the shelf for 15 years unused.

 

[Dodge Bros]

A good place to start would be transitioning the valve angle cut into the bowl on the intake and the exhaust. Remove the casting flashing in the roof. Then narrow up the valve guide boss.

Next step for finding some more (intake) flow would probably be widen the intake port window some above the short side radius on the sides walls and the roof and transition that into the bowl. To blend that makes the bowl area a bigger diameter, will end up deeper with a little longer radius. Then straighten the port at the push rod pinch point on the intake.

Some leave the short side alone, we blend the short side radius into the bowl by making it look like a water fall.

 

[Mark Barnes]

A good place to start would be transitioning the valve angle cut into the bowl on the intake and the exhaust. Remove the casting flashing in the roof. Then narrow up the valve guide boss.

Next step for finding some more (intake) flow would probably be widen the intake port window some above the short side radius on the sides walls and the roof and transition that into the bowl. To blend that makes the bowl area a bigger diameter, will end up deeper with a little longer radius. Then straighten the port at the push rod pinch point on the intake.

Some leave the short side alone, we blend the short side radius into the bowl by making it look like a water fall.

Thank you sir. Very informative info, and exactly what I need. Any specific areas that I need to lay off because of thin walls/water? Is there any benefit to a polish in these areas, rather than hogging material out, or is it better to leave the walls rough like some people say? Thanks for the great info.

 

[IQ52]

Some leave the short side alone, we blend the short side radius into the bowl by making it look like a water fall.

Waterfall? Yosemite, Niagara, Sentinel, Horsetail, Multnomah, Shoshone, Cumberland, Palouse, Burgess? I'm so confused!

 

[4406bbl]

I did not read everything here, and this may have been posted but the best way to unshroud is bolt the heads to the block, scribe the cylinder on the head, mark them left and right and do not go past that line. If you go all the way to the gasket you may need a slight bore notch.

 

[Mark Barnes]

Waterfall? Yosemite, Niagara, Sentinel, Horsetail, Multnomah, Shoshone, Cumberland, Palouse, Burgess? I'm so confused!

My only concern is making it look like a watering HOLE....

 

[Dodge Bros]

Lol. No holes. Widen the floor, wide and flat, gentle radius on the floor. I have seen others head porters call it like a “waterfall”. LOL. Maybe it is to someone..

If you listen to every little do this or do that you would be to terrified to touch the inside of a port. Do not let it worry you though. One of the first heads we ported when we started using a flow bench was already worked over by a big Mopar guru. We started grinding and right off the bat lost flow everywhere and thought we just ruined our fancy heads! We kept working on it and took the flow from 265-270 cfm to about 325-330 cfm, we gained very close to 100 hp with a small cam change and the head work. You have to start somewhere. There are guys out there that can flow your heads for you to see how you are doing. Only one way to learn is to dive in and DIY. Plenty of expert here to guide or provide info for you. Pics and flow numbers are worth a thousand words.

 

[Curiousyellow71]

The advice to not get carried away with removing material on the bumps in the exhaust port on 516s is very sound. The later heads don't have them and I think guys get in trouble thinking they can get the 516 ports to look and flow like later heads.. It's pretty obvious to start grinding in the bowls where the machining stopped when they installed the new seats. It's also far enough from the seats to give you a little confidence. Once that is done work around the stem area and blend. Then come back up and blend leave some of the 70 degree. Pictures posted in your thread are a great reference. Many heads respond to making the port taller. But 516s don't have much meat on the short side radius so taller seems to reward minimal rewards for the effort.....and probably a waste of time. The short radius is going to need blending and grinding with your bigger valves, and the pinch point that PR heads took a picture is a good place to find flow. The exhaust... Probably do the bowl again first and then use a sharpy with a exhaust gasket to port match. The exhaust ports aren't real long so once you have the bowl area done and the gasket area done, you can try to open it up in between. But be careful here. A 516 needs careful work in the exhaust. You can really hog out a later head...516 aren't thin by any means but you really can't reshape the port and turn into a different shape without finding a water jacket. Also mopar used some hard cast iron, cheap carbides wear fast, and now is the time to buy a good die grinder....nothing is more frustrating that having a tired grinder and a dull carbide. If it were brand x made of butter you could be done quickly. But porting on mopar heads is a different deal...its not easy work. There is a reason why aftermarket aluminum is so popular.

 

[qkcuda]

I am about to do my 516 heads. In the third picture you can see a huge machined step in the exhaust port. My question is can you continue that cut straight down without getting into water?

Ok, heres a couple pictures of heads/valves. The layout dye is because I asked the shop to just touch the previous angles that sat on the shelf for 15 years unused.

View attachment 937158 View attachment 937159 View attachment 937160

 

[Mark Barnes]

I am about to do my 516 heads. In the third picture you can see a huge machined step in the exhaust port. My question is can you continue that cut straight down without getting into water?

I just ground the hump down so it wasn't so "severe". Kinda blended the edges in...too much time and money in them to get brave and find water now.

 

[Mark Barnes]

I just ground the hump down so it wasn't so "severe". Kinda blended the edges in...too much time and money in them to get brave and find water now.

AND...blended that "step" in also. There are a lot of guys with a lot more experience than I have, and they do fantastic work. There are endless threads on the subject.