If your talking the guide boss that extends into the port on the roof, I grind it out. If you look at a the area right in front of the spring seat on the outside roof, under the valve cover, there is a dimple in the roof, I guess that's what you call it. When maxing these out, I almost always burn thru right there. A little spray weld, or good epoxy, to fill that void, and your good.
I have been mia for awhile. I have been beyond, or still am really, beyond swamped. I have been a lurker lately. Wow, is all I can say, what a drama fest. I have just stayed off, and have bit my tounge. It seems the drama has calmed down now, so, "Lets make Speedtalk Great Again" lol.
915 mopar flow test
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mag2555
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Re: 915 mopar flow test
At 330 cfm I am surprised that just 14 psi of coolant pressure that the port walls did not blow out, good Gawd!!
You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
Re: 915 mopar flow test
Did a few sets for customers back in the day (906 and later 452's) into the 280's to 290. That's about as thin as I wanted to do. Was doing a set of the late low short-turn/hard exhaust seat heads for our bracket car. We had a old super stock roller laying around. approx .720 net lift. Got the test hole to 308 at .750" with 2.14 valve.We also took that bump out. Hardest iron I've ever carved on.If you look at a port mold of the late heads you'll see a reasonable short-side can be done. Not good. Just more than you'd expect to see.
Had the other holes roughed out when Indy came out with the SR head. So, they never got finished.
Had the other holes roughed out when Indy came out with the SR head. So, they never got finished.
Re: 915 mopar flow test
So what is the average wall thickness of the port walls, assuming no significant rust in the water jackets?
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mag2555
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Re: 915 mopar flow test
Many times it's the core shift not any rust that makes for thin areas!
The thinnest area is at the back of the bowl where the guide joins the roof.
I tend to look at the push rod wall thickness as a gauge for what I have to work with in regards to Mother Mopars iron heads, that is if the casting seams show little signs of core shift.
As in this photo, doing your starting Throat increase with a cutter made for installing seats will tell you right quick what you have for core shift!
And on the common wall when your kicking that out watch out for that oil passage up to rocker stand!
The thinnest area is at the back of the bowl where the guide joins the roof.
I tend to look at the push rod wall thickness as a gauge for what I have to work with in regards to Mother Mopars iron heads, that is if the casting seams show little signs of core shift.
As in this photo, doing your starting Throat increase with a cutter made for installing seats will tell you right quick what you have for core shift!
And on the common wall when your kicking that out watch out for that oil passage up to rocker stand!
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You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
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Walter R. Malik
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Re: 915 mopar flow test
And, just why is there a photo of a Pontiac head posted ...?mag2555 wrote: ↑Wed May 02, 2018 6:17 am Many times it's the core shift not any rust that makes for thin areas!
The thinnest area is at the back of the bowl where the guide joins the roof.
I tend to look at the push rod wall thickness as a gauge for what I have to work with in regards to Mother Mopars iron heads, that is if the casting seams show little signs of core shift.
As in this photo, doing your starting Throat increase with a cutter made for installing seats will tell you right quick what you have for core shift!
And on the common wall when your kicking that out watch out for that oil passage up to rocker stand!
People who don't know any different will certainly be confused.
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mag2555
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Re: 915 mopar flow test
This picture shows that the core is centered very well as both sides of the valve bowl are showing the same lip after maching.
I thought I had a saved shot of one that's got core shift but I do not.
I thought I had a saved shot of one that's got core shift but I do not.
You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
Re: 915 mopar flow test
My experiences with the 906/915 heads is that the flow goes turbulent over the SSR as soon as you blend away the ridge where the factory bowl cut meets the as cast surface.
The 915's I've worked on had their own ex port.
They have less of a radius on the short turn as it comes off the seat.
I don't feel the ex port is as good as the later heads.
I find that much of the difference between the typical 240-260cfm "home port" type job that crashes at about .450-.500 lift(2.14 valve) and something that will go 265-285, and hang on pretty well to .700 or so....... Ends up being how well the SSR is reworked.
It's much much less work to get the 346/902/452 type intake port to go 275+.
The 915's I've worked on had their own ex port.
They have less of a radius on the short turn as it comes off the seat.
I don't feel the ex port is as good as the later heads.
I find that much of the difference between the typical 240-260cfm "home port" type job that crashes at about .450-.500 lift(2.14 valve) and something that will go 265-285, and hang on pretty well to .700 or so....... Ends up being how well the SSR is reworked.
It's much much less work to get the 346/902/452 type intake port to go 275+.
Somewhat handy with a die grinder.
Re: 915 mopar flow test
The 915 exhaust port is about 1/8th" lower at the header flange. And, you're exactly right. They are not as good on the exhaust side as the later heads. I prefer the 452 style head on the intake side for porting also. The finished short turn isn't as ugly as you might think. I believe the 452 style head benefits a lot from a larger "window" over the crown.