Home porting a set of 516 heads ?

[1967coronet]

Last summer I stuck a motor home 440 prob 7.5.1 comp in my old 67. put a comp cam & lifters XE262 in it along with crane springs & eddy performer intake and 750 carb on it.
The engine runs great, still dealing with a ticking lifter that comes and goes but will track it down this winter.
Now since this 440 is running just fine with the 452 heads. I am thinking what the heck,
I have 2 pair of 516s, I would like to take a pair and get the exhaust valve seat cut for 1.74 , then try a home porting job on them, nothing wild, just clean them up and try them on the 440. question is will the switch to the closed chamber and the half azz home port job I will do add much HP ?
Would a 15 to 20 hp gain be out of the question if I don't butcher the job ?

 

[Ironbuilt]

Port them to match the intake and exhaust/header ports then polish the exhaust side to help the gases escape quicker. That should easily gain you 20-25 HP. Don't overdo it, as going beyond the intake/exhaust port sizes actually restricts flow. Good luck.

 

[Garys1969RR]

I have a 77 440 RV motor in my 70 Dart. Runs good, but we always want more, right? So I'll build a 451 with zero deck and closed chamber alum heads, that should do it. The 516s can be made to flow well with the right port work. A head porter on here has posted some impressive power gains with a low comp RV motor and 516 heads. Check out his thread. I would put in the 1.74 ex valves, and pocket port the area under the valve. Get some porting templates to help with port shape. Areas near the valve seat can see big improvements, with the proper shape.

 

[PRHeads]

IMO, you’d be way ahead to do what you’re thinking to the 452 heads.
They flow more ootb, and respond with bigger gains to that initial bowl work than 516’s do.

You’re still not going to have any quench with closed chamber heads on that short block, and the difference in chamber volume is only a few cc’s.

For a nice little bump in Cr, just mill the 452’s .030 or so and use thin gaskets.

 

[1967coronet]

IMO, you’d be way ahead to do what you’re thinking to the 452 heads.
They flow more ootb, and respond with bigger gains to that initial bowl work than 516’s do.

You’re still not going to have any quench with closed chamber heads on that short block, and the difference in chamber volume is only a few cc’s.

For a nice little bump in Cr, just mill the 452’s .030 or so and use thin gaskets.

Thanks for the flow info.
That seems like a good idea, Can I still use my oem rockers if I shim the shaft that 0.30 plus the diff in the gaskets or will 0.30 plus have everything out of line on the valve stem and rocker tip ?
Thanks all for the replies, I prob will still use the 516s to practice on

 

[PRHeads]

Milling the heads has no impact on the rocker to valve relationship on a motor with a fixed rocker mount.

It will affect the required/desired pushrod length though.

 

[Garys1969RR]

I have ported a few sets of 915s, as well as some 906s. The 915s I had milled .020", which put the lifter plunger near the bottom of it's travel. So I made some .020 shims from an old head gasket, and doubled them up on each rocker stand. Total shim height of .040. Then the plunger was at the top of it's travel. It ran great! 509 cam.

 

[Garys1969RR]

I bought a used die grinder at a pawn shop for $30, and a nice set of burrs/rotary files for $30 at Harbor frieght. Works great! And a dremel tool works good for detail work. Put some old valves in the head when doing chamber work, to protect the seats. I like to blend the area where the top cut meets the chamber. Helps with low lift flow.

 

[Cranky]

Doing port match helps but a decent amount of gain is also in the pockets....the area just under the valves. They suck in stock form on ALL stock heads and the only real way to clean up the pockets is with the valve out of the way. Closed chamber heads will help but with pistons so far in the hole, you still won't benefit from any quench to be had imo. Practice on a set of junk heads before doing a set that you care about.

 

[1968rt]

Make sure you cut the throats when you install a larger valve

 

[69a100]

I have a set of 516's that I had pocket ported, cleaned up and had the 1.74 exhaust installed. I had a shop do the porting, they could've done a better job, but still. Noticeable improvement all around.

 

[PRHeads]

From 15 or so years ago......

http://www.moparts.org/Tech/Archive/bb/62.html

http://www.moparts.org/Tech/Archive/bb/40.html

 

[1968rt]

Take a look at this article. A 1972 low compression motor. On the last pull they switched to 516 heads and wow!!!
https://www.forabodiesonly.com/mopar/threads/dyno-testing-a-stock-1972-440.249866/page-2

 

[Ghostrider 67]

346 heads on a '73 440 @ .030 over. Ported and polished with gasket match. Valves lapped, material removed under the valves.

 

[Ghostrider 67]

I bought a porting kit from Eastwood. Worked great along with a Dremel and some different shaped bits.

 

[1967coronet]

I bought a porting kit from Eastwood. Worked great along with a Dremel and some different shaped bits.

I just ordered a few carbide bits, I have the straight die grinder and a couple sets of 516s.
Im going to give it a try.
I have got a lot of info from all you guys { Thanks } and have read more and seen examples on U tube ect. Just going to clean the bowls up and gasket match to start.
Need to add that I will practice on a scrap head 1st LOL

 

[Ghostrider 67]

I just ordered a few carbide bits, I have the straight die grinder and a couple sets of 516s.
Im going to give it a try.
I have got a lot of info from all you guys { Thanks } and have read more and seen examples on U tube ect. Just going to clean the bowls up and gasket match to start.
Need to add that I will practice on a scrap head 1st LOL

One easy thing is to get rid of the overhang between bowls. Take the straight edge out between cylinders on each bowl.

 

[PRHeads]

Supposedly, a picture is worth a thousand words........

346 head:
A- stock head, OE valve job
B- grind seat
C- before porting
D- bowl roughed in, bullet nose guide

 

[Ghostrider 67]

It's really basic removing material along any ridges and directing air flow to smooth the way...you just have to be careful and go slowly.

 

[PRHeads]

E- quick sanding roll job
F- stock port opening & pushrod pinch(.975”)
G- gasket match, open pinch to 1.060”
H- testing the work

The stock head will flow about 220.

These tests were done with a back cut OE 2.08 valve.
Test A is with the valve job and blended bowl, test B adds the gasket match and widening of the pinch area.
4.375 bore, 28” test pressure:

Lift——A/B
.100– 69.8/69.8
.200–142.8/142.8
.300–202.0/206.8
.350–221.4/222.5
.400–231.8/236.6
.450–237.1/241.9
.500–243.8/251.3
.550–249.4/258.0
.600–252.4/259.9