E-street vs Promaxx vs 440 Source

Which head ?

  • E-street

    Votes: 5 16.7%

  • Promaxx

    Votes: 9 30.0%

  • 440 Source

    Votes: 9 30.0%

  • Stick to your 452's, and do a little work

    Votes: 7 23.3%
  • Total voters
    30
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In the pic of the valve tips you can see the distance from the top of the lock to the top of the valve is longer on one valve(exhaust).
The “big” spring was the oddball one, and it was installed on the exhaust(the shorter installed height position).
It was installed short enough that it was at about 200lbs on the seat, and in coil bind at barely over .500” lift.
How can you miss that?
I saw it as soon as I put the head on my bench.

20FBF7FA-C4D3-4D8C-9F73-0663FDDD4AC8.png


You can also see the difference in the height of the retainers is quite a bit more different than the height of the valve tips.
 
318willrun said:
I agree. I had a set of hardened seats w/new guides/valves installed in a pair of 906's. One head, every exhaust valve would show light around the valve with a flashlight down the port (half moon sliver), and alcohol poured out of it like a fountain. Took me 4 hours to get the valves to seal with my lapper.
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This is the very story I was thinking of when I suggested you're likely not a machine shop customer for the heads...
 
j par said:
This is the very story I was thinking of when I suggested you're likely not a machine shop customer for the heads...
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well, I understand it happens to the best of them. I went to school with that guys son. His son had a Z28, and we raced (I had a 318 Demon). After I beat him, he looked under my hood hoping to find the "hidden secret" ... LOL. He went home and discussed with his Dad, who did the machining for my friend who had the Mirada that ran 9.20's @ 150 mph. The guy was a racer and machinist and he could build, but just like PHR stated, everyone can make mistakes and every head needs checked. "Wouldn't it be grand to go back to the 80's.... where rioting in streets happened in Lebanon and Covid meant what ?"
 
I saw this today on Facebook and figured I would post it. I think this is the cnc’d head but I didn’t watch it yet. I will later in the day.

 
whoever this guy is he didn't have very much good to say about these heads. i bought a set to put on a stock stroke 383 according to his flow numbers thats about were they should stay on a stock 383
 
Eric Weingartner racing, a pretty well known engine builder, specializes in chevies, won one of the engine master shootouts a couple times I think. Lots of good videos on you tube.
 
Lowcar said:
whoever this guy is he didn't have very much good to say about these heads. i bought a set to put on a stock stroke 383 according to his flow numbers thats about were they should stay on a stock 383
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It's too bad the numbers he claimed the CNC 440 source head made are identical to the non- CNC, even a little less.
 
They would be good for a street performance application, stock CID low deck engine. Even a 400. Like he said, not setting the house on fire. But a good bit better than stock OE castings.
 
rumblefish360 said:
They would be good for a street performance application, stock CID low deck engine. Even a 400. Like he said, not setting the house on fire. But a good bit better than stock OE castings.
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If they were unported, I think the numbers are ok. But the fact that they were supposed to be CNC ported, the numbers are skimpy at best. Just my opinion
 
318willrun said:
If they were unported, I think the numbers are ok. But the fact that they were supposed to be CNC ported, the numbers are skimpy at best. Just my opinion
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I don’t know what the stock flow numbers are.
Just looking at what Eric got out of them, I said what I said. Nothing more, nothing less.
 
Numbers are just numbers. Dynos and flow benches can be fudged enough to show anything you want. Numbers are no better than the man running the machine.
How does it run in the car? What does it run (mph) at the strip. That will tell if it makes power, or not.
 
Frankly, his numbers seem a bit low.

I know the “original” cnc ported version of those heads were done by Modern, but they aren’t anymore.

The numbers from Modern were a bit over 320.
I had one of the Modern ported heads here several years ago. I tested two cylinders and they were basically 315.

The chambers were cnc’d as well, and Jeff’s valve job produced excellent low/mid lift numbers.
They were also ported “a lot”...... to the tune of the finished volume being 252cc(12 bigger than a TF240).

I basically get 280 out of a Stealth head with a valve job and the bowls blended(15-20 better than ootb).

I’ll be interested in the numbers Eric gets from an unported rpm head(that he mentioned in the video).

I do think this is likely a situation where comparing numbers from different benches could show a pretty big swing in the results.

Here’s a screen shot of the numbers from the video-

4BA67199-BA38-4003-995D-3B74D6C03F25.png
 
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I know there were some big issues between modern and 440source. I wonder who is doing their cnc work now.
 
I’ll add this.......
“IF” they are having the heads CNC ported......... and leaving the valve job untouched......in other words, the same as the ootb heads....... then I can see the numbers not being too far off.

I know when I messed with some bowl blending on those...... the gains were pretty small until the seats were addressed.

“IF” they flowed similar numbers on my bench to the numbers in Eric’s video....... I’d say they probably need a little attention somewhere.
Any of the Ede originals or copies........ should all be a solid 300cfm+ to justify the cost of the CNC job.
 
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The seats are the first thing you notice needing to be addressed.
Even I noticed that. lol
 
I’m sure that at some point, one of the new version cnc Stealths will end up on my bench.
 
There was a thread pertaining to the Source/Modern situation over on Moparts.

In one of the more recent posts on it, Source mentioned they had another place doing the cnc work now.

Since the heads in the video didn’t have the chambers cnc’d, they should be from their new partner in CNC.
 
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