516 heads , good or bad

[Bryon Mason]

I'm pulling the engine next week on my 1966 300, has the 383, 727 trans and sure grip rear end. The heads are 516 and I've been doing as much online research as I can on them. Anyone still run these heads and what's your thoughts/experience with them? I see alot of pros and cons from what I read about them. I'm not looking to make a race car just gain a little power to help get the slab moving.

 

[stubs300]

My 66-300 is also runnin 516's on a stock motor. With mine, I've had them pocket ported and drilled out for the 1.76 exhaust valves. I noticed a big improvement in performance by helping get the bad air out. You will get answers all over the place on heads, that's a fact! Good Luck

 

[Bryon Mason]

My 66-300 is also runnin 516's on a stock motor. With mine, I've had them pocket ported and drilled out for the 1.76 exhaust valves. I noticed a big improvement in performance by helping get the bad air out. You will get answers all over the place on heads, that's a fact! Good Luck

How close to the water jacket are you with that port?

 

[cbarge]

I revived a 66 300 myself.
The original heads had burnt valves.
I replaced them with a set of rebuilt mid 70's 452's.
They already have hardened seats, better flow and the open combustion chamber the .5 drop in compression is more friendly on todays corn fed gas.
You will gain some torque and no loss in HP.
The cost of refreshing the 452's was a bit less than rebuilding the original heads but I take each case indiviually.
NO mods needed as they bolt right up.
Hope this helps.

 

[Newport 66]

Here's a list of R/RB cylinder heads. It provides info on valve sized etc. It gives the comparison of your 516 heads to all the others. Good luck with your project.

 

[413]

If you are keeping the stock cam and pistons then I love how they work, great with the small Exhaust valve 1.60 and closed combustion chamber. This provides great throttle response and low speed pep.

Does anybody just rebuild the stock heads with small exhaust valves and see how much better the engine runs? Any new valve job would have helped it.

Probably not. Just like how women who have curly hair need to straighten it. Straight hair, need to perm it. Dark hair goes blonde, others goes jet black.

Always gotta alter it to make it FEEL better to our minds.

If you are racing or want to maximize high speed power Above 3500-4000 RPM then there are gains to be made by bigger valves or other heads.

 

[detmatt]

I like the closed chamber heads and like Stubbs I put the bigger exhaust valves in and took a step up in the cam department.

 

[Bryon Mason]

I like the closed chamber heads and like Stubbs I put the bigger exhaust valves in and took a step up in the cam department.

What cam did you opt for? I was wanting to step it up but nothing agressive.

 

[detmatt]

I’m talking ‘67 440 and I just picked one with specs that were closer to the HP version which can be found in the factory service manual.

 

[Ripinator]

What cam did you opt for? I was wanting to step it up but nothing agressive.

In my '66 300 convertible, I'm running 516 heads and a Comp Cams 21-222-4 hydraulic flat-tappet cam. It is a "dual pattern" cam having a little more duration on the exhaust valve, which somewhat compensates for the smaller 1.60 exhaust valve size. The cam works well with my stock 3.23 diff and torque converter, and the engine has fantastic throttle response. Installed the cam when the engine was rebuilt. Also went with the entire kit: cam, lifters, springs and push rods, valve stem seals, etc. Here is a link to the cam specs: Xtreme Energy 218/224 Hydraulic Flat Cam for Chrysler 383-440

 

[stubs300]

I like the closed chamber heads and like Stubbs I put the bigger exhaust valves in and took a step up in the cam department.

I did too, I went with the Hughes 2330, what cam are you runnin?

How close to the water jacket are you with that port?

I don't know, I didn't grind the snot outta them if that's what you want to know? I just did enough to clean and smooth out the port, nothing more. No gasket matching, etc. just a simple clean up.

 

[detmatt]

I did too, I went with the Hughes 2330, what cam are you runnin?

I don't know, I didn't grind the snot outta them if that's what you want to know? I just did enough to clean and smooth out the port, nothing more. No gasket matching, etc. just a simple clean up.

I’ll have to look in my file, I don’t remember.

 

[furious70]

Moparts tech archives is the place to go do your research to understand what the oem heads do and what work on them is effective.
516's don't flow well and all the other heads do not have a drastically larger port volume such that 516's have any low rpm advantage.

 

[Mr onetwo]

by the guru.... Cylinder Heads Part I - Tech Articles - Mopar Muscle Magazine
https://www.hotrod.com/articles/cylinder-heads-ii/
https://www.hotrod.com/articles/cylinder-heads-iii/

 

[Gerald Morris]

I like the closed chamber high compression responses that the 516s give. They do nicely for 2 barrel engines built for lower revs, which is what I have and likely will continue to drive. There are said to be better closed chamber heads, the 915, then after market stuff made later, but 516s were VERY COMMON in the mid 1960s, and many a B/RB came with them then. For high rev motors the 516 isn't a good choice. You decide what you want and build for it.

 

[twostick]

One of those " it depends " questions.

Stockish short block with maybe a step above a 6pak cam, they will do just fine depending on what you plan to do with the car and the condition of the heads now

There are gains to be had with a proper rebuild which should include 16 valves, guides and hardened seats. Bigger valves are the same price as stock size so that's a free gain there.

The problem is the price of a "proper" rebuild is very close to the price of some aftermarket aluminum heads that flow as good OOTB as ported iron heads do plus the add bonus of not being as prone to detonation.

Kevin

 

[John Hatchard]

Good question indeed on 516 heads!

I've done a few 2bbl C-bod 383's, but their problem is 'dished pistons' for closed chamber heads.
If you fit a later head on then compression is gonna be real low!

The 1.60 small-block exhaust vale is the biggest issue here.
If you have seat recession them its a no brainer to fit a 1.74 and a mild 'pocket port'.

As the ancient mariner said '' water, water everywhere, waiting to break through''
So the area next to the valve, where there is a pronounced bulge, 'BE VERY CAREFUL'...

Broken through here on many occasions and all that work and time is LOST forever...

Nice article on 516 heads 'B-bods' site where they made good hp and super torque!