Copyright © Dave Propst. All rights reserved.
If you have arrived at this article by clicking a link at davepropst.com:
If you have arrived at this article by clicking a link from an outside source such as another website, a discussion forum or an email message:
When reading this article, this browser window can be resized with the mouse to adjust text width to individual reading preference. As the window is resized, text line width will dynamically adjust to the new window size. When reading text, this eliminates the need for left-right scrolling with the browser horizontal scroll bar, assuming browser zoom is set to 100%. For those articles containing photos, the browser window can be resized with the mouse to display the entire width of the photo. The text will again dynamically adjust. A video display of at least 1024x768 is preferred. If viewing this article with video settings lower than 1024x768, use full-screen browser mode to see the full height of each picture without the need for vertical scrolling. Full-screen mode can be cycled on and off in many browsers by repeatedly pressing the F11 key. Additionally it may be necessary to close the browser 'Explorer Bar' depending on which version of Internet Explorer is in use. It is important that the video resolution setting in use provides the correct aspect ratio for the computer monitor being used. That is, a round circle (Circle.jpg) should appear perfectly round instead of oval-shaped on the monitor. Display quality of photos is best if browser zoom is left at 'Normal' or '100%'. Article photos are edited for viewing at a computer monitor gamma setting of 2.2. If any photo fails to load, simply right-click on the red 'X' or anywhere inside the box outline and select the 'Show Picture' option. For more information about these viewing details, see the Site Help page listed on the main website menu.
New articles are published on an irregular schedule. Check the Updates page on the main website for notification of new articles.
Please direct any inquiries to: email@example.com
Port Flow Test Tools
Copyright © 2002 Dave Propst. All rights reserved.
This article contains pictures of a few cylinder head port flow testing tools. These are fabricated/machined items that can be built with lathe and milling machine.
The cylinder head in the photos is an Edelbrock RPM series Ford FE head. (The head in these pictures is 'as-delivered' from Edelbrock, including the rough-in 'port matching' machine work. Meaning... don't take the port machine work as anything to be pondered or critiqued.)
Cylinder Head Flow Test Adapter
This first set of photos display an adapter box which very precisely replicates the size and position of an engine's cylinder bore against the cylinder head's combustion chamber. It can be used with either flow bench or FlowQuik. Cylinder bores can be swapped out to replicate different bore sizes. This was originally designed for the purpose of investigating the effect changes in cylinder bore size has on airflow in Ford FE motors. From the 352 all the way up to the 427, these motors cover quite a wide range in bore size while potentially using the same cylinder head.
The box structure has a rubber seal in the ID of the hole in the end plate for sealing the cylinder OD. This permits rapidly swapping cylinders of differing sizes of ID's for testing.
I've so far made six different cylinder bores accurate to +/- 0.002 ID for an FE project.
Dial Indicator Fixture
The next photos are of a dial indicator fixture built for use in analyzing camshafts. It is shown next to a standard duty dial indicator and base to illustrate it's rather massive design.
The heavy duty design provides the rigidity needed for measuring camshaft lobe lift on opening and closing to 0.0001 inch or even to +/- 0.00005 inch (or at least to detect motion of such small amount when needed) with the Starrett gauge. That high degree of accuracy is extremely helpful in distinguishing closing ramp from actual cam lift when analyzing a camshaft. This precision in determining valve motion is necessary in order to come up with a real-world seat-to-seat duration figure in degrees rotation of the camshaft lobe. The combination of a standard dial indicator's 0.001 accuracy/resolution and it's less-than-stable (in terms of four decimal places) base is hard-pressed to quantify a valve event to even 10 degrees of rotation on the closing ramp of extremely gentle OEM cams like the one in the Cad motor in the picture below. One degree, or at the very most two degrees, of resolution is desirable in seat-to-seat duration data for entry in the software in question.
A visual size reference for the gauge and fixture is that the engine it is mounted to has a bore size of 4.36.
Valve Opening Fixture
The following pictures illustrate a valve opening fixture. Using a precisely machined step gauge to open the valve provides speed and repeatability. I prefer this over the typical threaded adjuster/dial indicator combination. After a dozen or so consecutive tests, cranking a threaded stop becomes very tedious. The step gauge is particularly a time-saver when the need to jump to a non-adjacent lift point arises. For example, if for whatever reason one wants to go back to 0.100 inch lift from say 0.500 inch lift, the process is immediate and instinctive. The device is also very quickly moved from one valve to the next.
This method would not be all that practical for lifting to specific computed L/D ratios since one would need to build a number of custom step gauges. For generic 0.100, 0.200, 0.300..... lift values (or 0.025, 0.050, 0.075, 0.100, 0.150, 0.200...), it is a very fast and accurate method with outstanding repeatability particularly when used with the FlowQuik.
End of Article