magnum head porting / pushrod pinch area / etc

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I have a set of Magnums, off my "need to be rebuilt" 5.2 that I am going to put on my new "used" 360.

I am also removing the center divider in the kegger manifold, and porting the runners to match gaskets.

My question is on the heads. Supposedly Magnum heads outflow traditional LA heads, but I can scarcely see how. The intake runner is as wide as my thumb, and I do not have Megan Fox's thumb.
  • How much material is there in the pushrod pinch area for porting?
  • Does anyone have any pictures of home ported heads
  • how much benefit (HP and TQ) do basic ported heads offer?
My plans are to gasket match the kegger and heads to intake gasket, streamline the pushrod pinch area, basics bowl blend up to the valve seat, smooth out the valve guide, and open up the exhaust ports ALMOST to the gasket, while leaving a small ridge to minimize reversion.

I am pulling the heads apart tonight, to get started. This will not be an aggressive port, but rather remove obvious obstructions, and streamline the airflow path.

Thoughts?
 
I will be following your post as I also have a 360 magnum that I would like to clean up the heads on.
 
The general concensus is that stock heads are thin, and crack prone. The high powers of the world want you to buy aftermarket castings, but that is not possible. Too much $$ for a commuter truck.
The truck made good power with a 318, and good exhaust system. The 360 with cleaned up heads, and tweaked kegger intake manifold should run even better. I have the engine apart, I might as well spend a few hours in the name of efficiency....
 
I havent ported a set of Magnums... so take this for what it's worth... What I know of them is they are a high speed port. Small but fast. The issue I see is if you simply enlarge the pinch you may speed up the port more, causing it to go turbulent earlier (at a lower lift). What I would suggest is fit them with 2.02 intake valves and have a 5-angle valve job done. Then blend the throat cut into the bowl, streamline the guide, very slightly lay back the short turn, then gasket match and address the pinch area, working only the roof and shared wall and simply smoothing the radius of the pushrod area. Beyond that, seriously... replace the heads. Also bear in mind the valve job and valves will cost within $200 of what a set of EQ Magnums that will flow better out of the box does. The engine doesnt know what it's in, and a truck can be harder on an engine than in a car. Especially in regard to cracking between the seats.
 
I might have one of the last un used magnum porting template kits,lol! O.K for magnums the bowl is actually quite good. The pinch is the really big restriction. I dont recall how much material is there at the pinch,but it's not a whole bunch.I'll go look at my notes and see if I can find the best gains for you. The cam choice has to be made with the magnums fantastic exhaust ports in mind.A single pattern cam is a much better choice,as is one with fast ramps. If you can find a roller like this your set. Also,there is a set of chevy beehive springs for sale here which you will need.That is the expensive part of upgrading magnums! Springs from Mopar will run you $120-130,but the chev ones are easily $40 less.
 
Due to core shift in any casting, magnum or non-magnum, a Helgeson E-Tool is really the only way to know how much meat you have on a given port. Unfortnately, you gotta pay one way or the other. Speed 'ain't cheap.
 
I think it was the Engine Masters magazine (I will check and see if I still have it) did an article on porting magnum heads. They took it through steps and flow checked it after it step.

They did the simple stuff; multi angle valve job, bowl blend, streamlined the guide, gasket matched the ports and cleaned up the short turn radius. Don't recall the exact numbers but they made about a 30% improvement in the peak flow and made improvements across the lift range. As I recall none of the improvements had a significant change above .5" lift.
 
I saw that article too. It was pretty informative.

It is in HodRodding Engine Masters Fall 2009 edition. "Head Porting Basics - Simple Modes boost head Flow 15 Percent" (page 46-54).


A few tidbits from the article:


Here is the flow results after each step. See the legend

Flow Results
Production Mopar magnum head. Sperflow 600 Flowbench
Tested at 28 inches water depresssion

Intake
Lift Stock Bowl S.T P.M. V.J. G.B.
0.100 60 60 60 60 62 62
0.200 120 121 121 123 124 125
0.300 168 170 170 176 182 184
0.400 195 204 204 212 224 225
0.500 202 205 218 228 228 236
0.600 194 195 200 203 217 232

Exhaust - tested with pipe
Lift Stock Bowl S.T P.M. J.J. G.B.
0.100 59 59 59 58 58 59
0.200 113 111 111 112 121 122
0.300 142 145 155 159 168 175
0.400 148 165 171 173 177 199
0.500 150 168 176 183 185 208
0.600 151 165 180 189 199 213

Legend
Stock - Stock Magnum Port
Bowl - Simple bowl blend of factory machining
S.T. - Contour sort side turn to radiused form
P.M. - Port match to magnum intake gasket and enlarge runner in pushrod area
V.J. - Performance Serdi valve job, including chamber sweep
G.B. - Profile guide boss

Concerning the intake pinch point:

"Our our test heads, the pinch point at the pushrod clearance bulge is very tight, as the port becomes quite narrow here, measuring only about 0.800-inch wide, with a hight of 2.20". the gives a cross section area of 1.76 square inches, which is very limited."

"After reworking, the port window at the pushrod bulge measured 0.930 x 2.225 inches. That's a gain in cross-sectional area of over 17 percent. Intake flow responded with very large gains, showing that the restriction here was significantly impacting the head's flow capabilities."

Concerning gasket matching the exhaust:

"Port matching the exhaust consisted of opening the runner using a FelPro exhaust manifold gasket as a template. Although the gasket is much lower than the port floor, it is not always beneficial to match the gasket to the floor. We used the gasket as a template for the port width and height, but left the floor exit at the as-cast-height, just squaring the floor to the sides. The port match was worked deep into the runner."
 
Thanks for the info everyone.

I have 2 sets of OE heads. I valve job, etc is not in the budget. I am going to do some low buck gasket matching, bowl blend, and call it good. I am also going to "degunk" the valves, etc.

I will smooth the pushrod pinch area, but not much more. I guess if they have velocity in mind I will keep it that way.
 
When you open the pushrod pinch up it will slow the air down in that area which is a good thing because the air speed is WAY too high.
But you won't realize very much HP until you do a good valve job, and some slight bowl work with a back cut on the intake valve...that will not only speed up the air in the port but flow much more making more HP.
 
I suppose I should give a little background on use here.
This heads are going on a 360 into a 97 Ram 1/2 2wd 5 speed. It is a commuter, parts chaser, etc.
As such, velocity is probably the best direction for what the truck does and needs.
I am adding all new gaskets, new water pumps, and timing chain, plus some port and polish on the heads and intake manifold. (Timing set and water pump are new additions to previous motor).
Valve jobs, etc are not in the budget. After seeing the valves I figure I can gain power and TQ just by cleaning things up... several valves look like the TV commercials. All the exhaust valves have a layer of crust on them, so cleaning alone will have its benefits.
I have pictures of the heads that I wil try to post tonight....air path is terrible. Many of the intake ports, you can see where then ran a tool in to get the ports set enough for the for the valve seats, but there are angles, jumps and protrusions everywhere. Flow has to improve even if I only knock down the above imperfections.
 
I am going to use the 360. Since I am going to keep the truck for a while, I decided take the time to regasket the 360 and use the heads from the 318 that are good heads, plus port the intake.

Here are some head images:

The valve guide boss, is HUGE. Some definate improvements can be made here.

Also note the casting. They machined down in the bowl to install the valve seat but the rest is terrible. Monster angles, not a nice flow path.
Turbo292.jpg


Turbo295.jpg

Incredibly narrow intake runners
Turbo296.jpg


Turbo297.jpg


Turbo298.jpg

huge valve guide boss
Turbo299.jpg


Turbo300.jpg

step from valve guide to port
Turbo301.jpg

Valve stem seal not doing it's job....major flow restrictions.
Turbo304.jpg
 
Here is the tool I made & use to check amount of metal left in the pushrod pinch. I cut it out of 3/8" plate & the rod is 5/16" so there is .030" material left on each side. When a straight edge is flush with my plate there is .030".
I guess I need to get the cobwebs out of my heads.

Plate.jpg


pushrod pinch.jpg
 
Rcuda2, that is a clever gauge. For magnum heads the rod will need to be 8mm.
 
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