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12-13-2023, 06:37 AM | #101 |
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Re: Shoud I relieve my block
Pete>>>You give up a LOT of intake port area with those old raised surface blocks.>>>
A LOT? How much? Not much of a ridge. What was it's purpose anyway? Easier to re-surface if needed? |
12-13-2023, 08:13 AM | #102 |
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Re: Shoud I relieve my block
Now I'm curious. From what I gather, it's not so much higher, but the surface below it is lower. I have a few in the garage and now I feel the need to do some measuring.
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12-13-2023, 08:58 AM | #103 |
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Re: Shoud I relieve my block
I think Pete's point is that when doing extremely large full-competition porting (like bigger 'D' ports toward the cylinders), you'll run out of material toward the outside edge of the raised intake area. On later 59x or 8BA blocks the whole surface is flat, so you can be more aggressive and not have a sealing issue.
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12-13-2023, 10:28 AM | #104 |
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Re: Shoud I relieve my block
TA>>>it's not so much higher, but the surface below it is lower>>>
B&S>>> On later 59x or 8BA blocks the whole surface is flat, so you can be more aggressive and not have a sealing issue.>> OK, Makes sense. But why do you suppose the surface was ever milled down that way to make a ridge in the first place? My '38 21-studder doesn't have a ridge either. |
12-13-2023, 11:33 AM | #105 | |
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Re: Shoud I relieve my block
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My guess is that they made their patterns a few different ways and later decided to go back to a "flat top". Who knows the truth . . . |
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12-13-2023, 02:12 PM | #106 |
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Re: Shoud I relieve my block
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The only disadvantage I can see is the difficulty in making the top intake port the D shape other than that they are a cool looking block. Ronnieroadster
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I use the F word a lot no not that word these words Flathead , Focus and Finish. "Life Member of the Bonneville 200 MPH Club using a Ford Flathead block" Owner , Builder, Driver of the First Ford Flathead bodied roadster to run 200 MPH Record July 13, 2018 LTA timing association 200.921 in one and a half miles burning gasoline. First ever gas burning Ford flathead powered roadster to run 200 MPH at Bonneville Salt Flats setting the record August 7th 2021 at 205.744 MPH |
12-13-2023, 03:53 PM | #107 |
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Re: Shoud I relieve my block
Ronnie is correct, they made the raised intake surface blocks in both 221 cubic inch Ford sizes as well as the 239 cubic inch Merc, Truck and WWII production versions.
Another term for them was the 'Keystone" block -- with many tall tales about how they were thicker, had more nickel content, made hair grow on bald heads, that all the "chicks dig them" . . . you get the point . . . lots of urban myths! I've done quite a bit of analysis; I've managed to corroborate none of the myths - especially the last one mentioned above. |
12-13-2023, 04:04 PM | #108 |
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Re: Shoud I relieve my block
I guess if the blocks were actually cast --- instead of milled --- that way, you might save a few milling pennies too?.
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12-13-2023, 04:08 PM | #109 |
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Re: Shoud I relieve my block
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12-13-2023, 06:31 PM | #110 |
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Re: Shoud I relieve my block
Here is a size comparison of a rough finish port to a stock one.. There is about .030 more to finish size.
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12-13-2023, 06:43 PM | #111 | |
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Re: Shoud I relieve my block
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12-13-2023, 07:19 PM | #112 | ||
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Re: Shoud I relieve my block
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Quote:
I understand what you mean now. Issues with the a large D port not sealing on raised intake block due to the lack of material would be the "lowered" section in the direction towards the deck surface. Never thought of it that way, but I guess you are right. Regarding D shaped ports, do you guys do this on a mill or freehand? If freehand, any useful tips or tricks? |
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12-13-2023, 07:29 PM | #113 | |
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Re: Shoud I relieve my block
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We researched doing it with CNC but what with only doing one every few years, it was not worth the effort. |
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12-13-2023, 07:39 PM | #114 |
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Re: Shoud I relieve my block
B&S>>They were not milled - this was all due to the casting patterns they used. Why? Who knows>>>
What I meant was only the raised area would need to be milled for a good seal, not the whole top. So less milling costs. |
12-13-2023, 07:58 PM | #115 |
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Re: Shoud I relieve my block
Pete >>>We do it by hand with a air die grinder and carbide burrs.>>>
If the cylindrical area defined by an open valve and its seat is probably always gonna considerably smaller than the port area, then how much do you really gain by further enlarging the port area? |
12-13-2023, 08:28 PM | #116 | |
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Re: Shoud I relieve my block
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The valve seat is the dam, the port behind it is the lake. The more surface area in the lake the higher the pressure at the outflow due to atmospheric effect and dead weight of the water. (fuel charge dead weight plus inertia) How much gain?? If we get to the finish line 1 inch ahead of the next car, we win. |
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12-13-2023, 08:58 PM | #117 |
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Re: Shoud I relieve my block
I guess I looked at it more like two funnels or cones having the same minor exit orifice surface areas, same column lengths or heads, but different major entrance orifice surface areas. Flow rates should be about the same due to the same heads at the same minor diameter orifices despite the volume differences
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12-13-2023, 09:03 PM | #118 |
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Re: Shoud I relieve my block
I think the way to look at it is the amount of stacked up intake charge (fuel, air and pressure) that the bigger port has on the flow equation.
It is like having your finger over the end of a hose, the more pressure in the hose when you first let your finger off, the bigger the initial "burst" out of the hose end. That is about the best analogy I can come up with . . . after a good bourbon cocktail! LOL |
12-13-2023, 09:21 PM | #119 |
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Re: Shoud I relieve my block
Lotsa variables & combinations thereof!
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12-13-2023, 11:52 PM | #120 |
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Re: Shoud I relieve my block
The biggest problem with FLOW is turbulence. My new port will be Linier very little curvs. Like the wings of an airplane. skin friction causes turbulence.
Everybody has their ideas. What somebody did last year, just improves what somebody does this year, Graps |
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