Porting a Chy 340/360 head.

[Flash]

[Malvin]

On the 596 casting the flow stopped at .515 lift so I just kept
working the ssr left to right & blending it to back down into
the bowl.

I am now working on set of 371587-8 castings the valve guide
bosses are not as big as they were on the 596 castings.

Malvin

[jfholm]

Gordon,
I am working with Dart Iron Eagle 180cc intake port heads. They are the version before the Platinum series. The Platinum series are supposed to be much better.

When I got them they were only 173cc not actually 180cc so they were 7cc short. The SSR was way too bulbous also. They may have been very good for a truck or something like that by I want power to 6000 or 6500 rpm. These gave me plenty to work with to get them to what I want. They are now 193.5 cc in the intake port.

I lowered the ssr and made the radius longer and flatter. That really picked up the airflow after .500 lift.

Here is what I did, the red represents the new port line:


Upper mold is new port and lower mold is stock port:

[200cfm]

John, on your port I notice the roof is fairly straight. Can you post a top view of your molds (looking down on the roof).

[jfholm]

Tom,
I could not find one from the top but I will take one and post it. But here is one from the bottom and one from the other side.

Once again the top mold is the ported port and bottom one is the stock port. You can tell that as the ported one is shiny:



from other side, once again the ported mold is on top:

[200cfm]

You did a great job straightening out that PRt wall. Wish mine looked that nice. That flat roof has given me an idea to try on my port. Remember I mentioned to you how dead the roof was in my port. I'm thinking of filling it for a flat roof test.
Thanks, (tom c)

[jfholm]

Here is a top view withe the ported port on left and stock port on right:

[jfholm]

Gordon,
I am not meaning to high jack you thread btw. This port from my head has a very good shape to it. I have to do a set of heads for a friend just like you are doing so I am learning a lot from this thread, thanks.

If I can study these SBC port molds maybe I can apply the shape some what to the Chrysler heads.

btw my port start at 1.910" tall and it is now 2.170" tall. So I have raised the ports about .260". Now be careful on the stock heads they may not have enough cast iron to do this.

Tom, this is where we get our sonic testers out.

John

[Flash]

John, is it a 188 or 2.02 head?

well wanted to do one mod at a time to see what the bench showed

Remove the bump on the roof of the port by cutting the guide boss out next to it, and rounding the bump upward toward the wall.

This gave a nice channel on this side of guide in the roof. look nice, and had high hopes.
didn't remove the bump completely.....still about .200 from the roof surface, but well rounded every were.

Cfm didn't change much, Probe showed ssr speed slowed. a little(i rounded and smoothed some casting flaws on the ssr) and just off the roof cfm speed up

ssr is now between 338 and 413. although cutting the bump in the roof help. i would hate to torque down this heads, and have it crack........so I'm done with the roof.
Tried to take a picture of it but my camera won't auto focus, close, to night:p

Going to straighten the wall on the slow side and blend onto the wall and bowl....and see what that does.

I real though that removing the bump and making a nice channel through it would really shift the are flow. I just don't thing the air want to go or will ever go that direction............I'm going to wait until every thing else is port before i grind on the bump in the next Intake port...............beginning to thing that, that big ugly guide boss is ment to be there for some reason........................

[jfholm]

Gordon,
Just to make sure I do not confuse anybody jumping back and forth, my Chevy heads are 2.05" intakes. The Chrysler heads I will be doing will be 2.02" intakes as we are doing them for a legal SS/JA car for NHRA. 1968 Barracuda. Beautiful car. I loved that year 'Cuda.

John

[Flash]

[Flash]

Well port session #3 is done and flow tested...................

this time i straightened the slow wall, removing the boldge just before the bowl smoothed and shortened the ssr were the wall meets.
Flattened the roof out a little bit more as well as the wall to roof bump, squaring up.................. well. cfm is identical to the last test, except at .500 lift and it gained 3 cfm
no change at 600 lift

all the air speed increased on the slow side, even at the ssr and slowed down slightly in the middle and other side or ssr

Also ground a slight venuri in the bottom of the bowl on the short speed side as well.

Here is a interesting tid bit of info!

After each port session, i wash the head with hot water, wipe dry and then spray the hole head with WD-40.
I wipe the port out before i flow test each time but there is always a thin layer that stays in the port.

What i have noticed !
Exactly 1/2 of the valve heads underside sureface is coated with oil......the other half is Dry!
My cylinder adapter is clear, and the oil is sprayed out on only one side of cylinder.
It is coming out, half of the ssr and the fast wall(prp side ) even after i straightened the slow wall and radious up the ssr at that wall.

If i had to do it over again i would not, remove the bump on the roof or straighten the bump on the slow wall.........It just help to send it over to the side it likes any ways :p

When i start on my next intake port, i will test these ideas..........as i will start backward from this port.

[Malvin]

Flash I always wash the head down then spray WD-40 in then take a paper towel spry it with carb & choke cleaner then wipe out the runners & the valve no more oil in there & it is clean ready to flow again.



Malvin

[Flash]

Well port session # 4 is done.

took some out of the prp area and straighted/open up the High speed wall(prp side)

Open up the botom of the bowl on that side and widend and rounded the ssr on that side.
still need to do more bowl work but was excited to see the resolt of this session.......

Well, the fps probe showed a nice drop in air speed on the ssr.
There is now no fps any where in the port at 400 or above.............even the localized hot spot that was way high, lowered from 439fps down to 403fps......is now at 386.

Flow tested my head, and gained 2cfm at .100 lift and 1cfm at .600 lift :angry:

I real thought i would get a BIG gain from this mod............still need to carve the bowl out proper............

Beginning to thing that, that 2.02 is shrouding some.............after all, the air is coming out the ssr and the prp wall.....which is not shrouded, as it travels over the exhaust valve....................

[Flash]

WOW! .......Yeah, I'm a dumb ARsss

Have known that you need a Radius plate.......or clay to make up a temporary one.

Tried two different brands of clay but the vac would just suck them in.
all the test up to now, were WITH OUT, a radius air entry plate :p

Re- tested this morning, with plate, and Wow! Gained all the way through the lift range and at .500 lift i had 33 more cfm.
At .600 lift the numbers when down, so that good at least.
Still need to shape the bowl better, and was going to lay back the ssr in the seat/bowl area, trying to get some more air......that was, until now.:p

My Goal was to get to 240 cfm.......I'm past that cfm now!

Sorry John, all the info given previously is kinda inaccurate now.
By the time i get to the next intake port, you will probably already have them Mopar head ported