Porting and poilishing BB 516 heads...

[TheDartman]

My set of BB heads that I had previously thought were 915 heads are actually the 516 heads. My 440 is the 1966 variety and is rumored to have over 300,000 miles on the standard bore.

I am going to have one cylinder professionally ported, polished and flowed and then I will do the rest of the cyliders myself making them identical to the professionally done one. Once I have completed the work, he will flow the heads again and make sure that my work flows as well as his and make adjustments accordingly.

How much time, effort, and money should I put into these heads?

Should the heads be milled since they have seen so many miles?

Should the valves all be replaced? I may want to run stainless exhaust valves (or possibly both), but I have had to run race gas since the car was put toghter anyway.

Can these heads be cut for the 1.74 exhaust valve like in the 915?

Do the Mopar porting templates cover these heads?

I'm looking for performance in the low 11's in a 3000 pound car. I think that's about it.
Thanks! Dartman

[Chryco Psycho]

The 516 is a decent head & the closed cahmber is a big advantage , you can install the 1.74 or the 1.81 exhaust valve & I usually have the hard seats installed .The headsa should be milled to make sure they are flat , how much further you want to go depends on the end compression ratio & also what gasket you are using. the intake valves should be replaced if they are worn , too thin in the margin , or depending on the spring pressure you intend to use , the Mopar templates do work on these castings but be careful in the area between the intake & exhaust valve you can hit water there

[strokie451]

I ported 2 sets of 516 heads and they flow very good with 2.140 int. and 1.810 exh. and I use Mopar templates, you must unshrould the combustion chambers to the heads gaskets for best results. TEXT

[Chryco Psycho]

or twist the flow & use swirl to turn the flow away from the shrouded wall

[superb70]

I ported 2 sets of 516 heads and they flow very good with 2.140 int. and 1.810 exh. and I use Mopar templates, you must unshrould the combustion chambers to the heads gaskets for best results

I am also running a set of 516's with 2.14 int.-1.81exh. on my mild 440. What exactly do you mean by unshroulding the combustion chamber?

[Chryco Psycho]

unshrouding is moving the combustion chamber wall away from the valve to get more flow on that side of the valve

[superb70]

How far is enough? my chambers are 72cc but i don't want to add much more volume to them. I would like to keep my compression where it is now. Thanks!!

[Chryco Psycho]

I also like to keep the chambers tight , & prefer to swirl the flow to the open side of the valve instead

[strokie451]

IMHO it`s better to unshrould the valves to gain flow, I also unshrould cylinder walls to gaskets, you lost a little bit of cc`s but I think the flow is more important than compression... ;D

[blownzoom440]

victorylibrary.com/mopar/chamber-tech-c.htm maybe this will give you some insite.

[Don]

All good advice but.....What's the car used for?

If this is a Street Hot Rod why try and build a motor that will break a land speed record?

As you increase the air flow through the head you will need more compression, bigger cam, more manifold and more carb to feed it all. As you increase flow you move the tork band higher and higher as you remove metal. You start to slow velocity over the valve at low RPM creating clean idle and low end throttle response issues, that's why they make 5000 RPM convertors.

Here's what I would do.....Bowl hog and blend, work the short turn, don't over valve it, do the calculations based on air flow or have Jim at Racer Brown help you with your cam selection....ask an expert.

Jim will have his new 1.5/1.6 Rockers arms available in a few weeks and this combination will also add good bottom end tork and streetability to the combination.

75% of your gains will come from 20% of the work and money spent on the ports.

IMO all this excessive port work is a waste of good money for a street/ bracket racer, save your money for a set of Schubeck lifters and a good cam, a good ignition system, Demon Carb and fuel delivery system. A $695 Dynamic convertor will give you way more performance than $695 worth of port work over and above the basics. If your a novice then forget that $600 worth of finish porting and Flowbench charges and invest in a set of Schubeck lifters.

Your Motor has 300,000 miles on it, you start building too much tork and HP and the bottom end won't hold it, it's likely to scatter it's jewels the 1st time you nail it.

We look at probably 10 combinations a day and we see some horrid stuff being produced out there by machine shops that are more interested in your wallet than your Mopar. Over-building for the application and owners knowledge level is the biggest offence.

Nobody can advise you on how far you should go without knowing the rest of the combination, unless your building a motor around a port job?

As far as surfacing the heads goes....again how can anyone tell you what compression ratio to set it at without knowing all the other details...your trying to build a motor without a calculator and the end result will be mediocre at best.

Consult with a honest Mopar Builder who will advise you what to do based on the car, your ability, your goal in mind and help you achieve that goal.

11 second passes with a 440 in a A-Body are a piece of cake, we do it with an all Iron 318.

Bowl hog and Blend
2 hours Max on the short turn
Good Performance Valve Job
Racer Brown Cam
Racer Brown 1.5/1.6 combo rocker arms
Schubeck lifters
9.2 to 9.5 CR for pump gas ...add a little race gas for the track
Cometic Gaskets
Dynamic Dual Pattern 2800/3600 convertor
750 Speed Demon
BG 220RR pump
FBO Ignition and distributor
3.91 or 4.10 gear
Cal Tracks

Go drive it like you stole it...it'll run mid 11's easily