516 heads , good or bad

[3175375]

Not that I’m going to be doing this anytime soon, if you did break through, is the oopsie repairable?

 

[Henrique]

I have also found two different castings in the exhaust area above the valve.
Some of the later 65/66 heads have a collapsed roof section.

I guess as the castings got near the end of the run they become worse.
If you try and raise the port roof around the exhaust guide, it breaks through.

Thanks a lot John for the help and information. I am going slowly and listening to the sound of the wall as I remove material particularly in the erea you pointed out. When you tap it with a metal bar or screwdriver you can hear the sound charging as it gets thinner. This is how far I am going. (pictures) the exhaust, as you mentioned has this collapsed (picture) roof that I removed as much material as I felt brave enough to do it. Most of the reshaping and increase in area was done on the sides and bottom. It is significantly larger than stock.i will probably cc the volume after I am done just to see the numbers.

 

[John Hatchard]

My pleasure to help where I can.
I have ported many Mopar heads and the 516 is very tricky to do.

There are deep exhaust port earlier castings and the less desirable 65/66 ones.
When you see them next too each other its very obvious indeed.

This cutaway is a low roof 66 head it broke through in several places.
if you cut the roof too deep it will go into water, same as between the valve pockets...

 

[John Hatchard]

This one may explain better, with the ruler lined up with the port exit

The circle shows where you break through between the valve pockets
(Exhaust pocket shown, cut between the ports)

 

[Henrique]

This one may explain better, with the ruler lined up with the port exit

The circle shows where you break through between the valve pockets
(Exhaust pocket shown, cut between the ports)

View attachment 751943

View attachment 751944

Thanks John! That really helps! I will just polish the exhaust and not going any further. It should flow much better than before. On the intake side, I got the wall towards the pushrod hole to be about almost 1/8 larger which should help make power above 5k rpm. I am installing a 239/249@.050 cam with 106 lobe separation and a tunnel ram with 2 Carter afb 500s. The 66 polara ran 13.8s with a 430 lift cam shifting at 5k rpm. Hopping to go faster next summer.

 

[John Hatchard]

We cheated with our Polara...

512ci with Edelbrock heads and a 550 Crower roller camshaft.

13.20 in Drive, if you run a 12.99 or faster you need a rollcage and other safety stuff

 

[Henrique]

We cheated with our Polara...

512ci with Edelbrock heads and a 550 Crower roller camshaft.

13.20 in Drive, if you run a 12.99 or faster you need a rollcage and other safety stuff

View attachment 752084

View attachment 752085

Wow! Nice! Beautiful! That's a badass sleeper! Here you need a rollcage if you go 11.99, I believe. That's my polara atbthe track when it ran 13.8.