New Magnum heads for 347 with Flow data

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Past experience has taught me to consider the chamber when flow stability is problematic. I put a spare valve in the guide and carefully blended and tried to remove anything abrupt around the perimeter of the valve seat--especially the sparkplug boss. You can see that it was worth some flow but 'nill in stability. J.Rob

.1 63
.2 126.5
.3 191
.4 223
.45 215
.5 215
.6 215
 

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Considering how the port is acting and has acted all along-there is only 1 or 2 things to look at. The pinch or the S.S. I know the S.S. is tall and nice and I also know that laying it down or shortening it can unlock some flow. Usually though you trade low lift flow for high when dealing with the S.S. I went in and used a smooth carbide to just lay it back .020-.030" and finished it with a sand roll. It flowed quite a bit better and the stalling point moved up to exactly .435". I will wait until I have the manifold on it to do any further testing. A manifold will usually calm things down which allows the flow to hang on better. J.Rob

.1 64
.2 128
.3 191.5
.4 228.5 *233 @ .435"
.45 224
.5 219
.6 219

p.s. Make no mistake-I have quite a few hours in these heads and would have to charge a decent buck to do this. However I would move to a set of EQ's and never look back.
 

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Ramm, dont mess with the chamber side blend too much, it will speed it up and you end up with the turbulence you have. whats the plan to slow it down?
 
RAMM said:
Considering how the port is acting and has acted all along-there is only 1 or 2 things to look at. The pinch or the S.S. I know the S.S. is tall and nice and I also know that laying it down or shortening it can unlock some flow. Usually though you trade low lift flow for high when dealing with the S.S. I went in and used a smooth carbide to just lay it back .020-.030" and finished it with a sand roll. It flowed quite a bit better and the stalling point moved up to exactly .435". I will wait until I have the manifold on it to do any further testing. A manifold will usually calm things down which allows the flow to hang on better. J.Rob

.1 64
.2 128
.3 191.5
.4 228.5 *233 @ .435"
.45 224
.5 219
.6 219

p.s. Make no mistake-I have quite a few hours in these heads and would have to charge a decent buck to do this. However I would move to a set of EQ's and never look back.
Click to expand...


its true that the intake will slow it down, but it will kill the flow quiet a bit as well. Ive tested heads at 298cfm and after putting a victor on ...they flowed 265-270's cfm. before working the manifold it can eat up 30 something cfm.
The rpm and ld340 intake for instance only flowed in the 220'scfm per runner as cast.
You may find yourself in that case with only about 215-220cfm after the intake gos on.

How about skipping on the sand rolls and leaving the port rough, and if you attack the short turn more...make it longer, lay it back from the half way point just a lil past the floors as cast peak. Also sometimes a basic 3 angle is all you need, in other words too many angles can work against you in the fps depot.
 
Hebrews10:26 said:
its true that the intake will slow it down, but it will kill the flow quiet a bit as well. Ive tested heads at 298cfm and after putting a victor on ...they flowed 265-270's cfm. before working the manifold it can eat up 30 something cfm.
The rpm and ld340 intake for instance only flowed in the 220'scfm per runner as cast.
You may find yourself in that case with only about 215-220cfm after the intake gos on.

How about skipping on the sand rolls and leaving the port rough, also...sometimes a basic 3 angle is all you need, in other words too many angles can work against you in the fps depot.
Click to expand...

The sand rolling of the S.S. helps the air turn a little better. These ports are too small and a rough carbide finish only makes them act smaller. I have tried it both ways--smoother is better on these heads. The valve job will get changed when I finalize with the stones. J.Rob
 
Ok, thats ok if your experience leads you to this conclusion. Just offering advice from evey head ive done from 240z inlines, toyota TC, slant six, sb/bb mopar, sb ford and bb chevy etc...has always help to leave it rough. smooth and glassy is for a BIG *** port with no speed issues and or and BIG rpms.
 
Hebrews10:26 said:
Ok, thats ok if your experience leads you to this conclusion. Just offering advice from evey head ive done from 240z inlines, toyota TC, slant six, sb/bb mopar, sb ford and bb chevy etc...has always help to leave it rough. smooth and glassy is for a BIG *** port with no speed issues and or and BIG rpms.
Click to expand...

I appreciate that. I normally leave them as carbided. This time it helped the air stay attached a little longer. J.Rob
 
I have a question I'm sure either or both of you can help with: I've heard the term "lay back" in reference to short side radius numerous times and I'm at a loss for what that term actually defines. If you could describe it with a pictorial or a cross section as a reference, how would you explain it?

I'm typically a visual/tactile learner, so please understand the ignorance.

EDIT: I'd like to perform some light port work on a couple different sets of heads I have, and knowing the terminology would greatly assist.
 
This is a very crud scribble of a mopar'sih int port.

the dots represent ''laying it back''

up from the seat a bit , then lay it back with a slight plain to it yet not completely flat and blend it to the floor a air. if you think about a funnel, the turn is just directing suction, to be crud some more. the taller the port, the more air it will flow on its own.
 

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ah ha-got it. Kinda what I figured, but I wanted to make sure I understood correctly, and was more often led to believe that messing with the SS other than some flash removal was all but forbidden to amateurs.
 
I have decided on the camshaft to be tried first in this engine-A Comp High Energy 268 single pattern. I like to machine the spring seats to accommodate a 1.25" Chev style spring. I modified an everyday tool to machine the guideboss/spring seat on Mag heads. These Manley springs are inexpensive and my goto choice on mild builds such as this. They fit nice and snug and are completely compatible with the stock Mag retainers. Installed height is currently 1.68"J.Rob
 

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RAMM said:
I have decided on the camshaft to be tried first in this engine-A Comp High Energy 268 single pattern. I like to machine the spring seats to accommodate a 1.25" Chev style spring. I modified an everyday tool to machine the guideboss/spring seat on Mag heads. These Manley springs are inexpensive and my goto choice on mild builds such as this. They fit nice and snug and are completely compatible with the stock Mag retainers. Installed height is currently 1.68"J.Rob
Click to expand...

Good choice, i hold a lot of stock in manley products and as it turns out many vendors sell manley but in their own packaging. cool on the home made tooling, thats what its all about.
 
I like the Comp Cams 268h,a versatile grind. Lines up nicely,with the airflow numbers.
 
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