Tractorsport Flowbench Forum Archive

Posted: **Wed Dec 14, 2005 9:15 pm**

Does anyone have a cheap source for 3/4" plexiglass for head fixtures? This stuff is d@mn expensive new from the plastic suppliers I've found.

I found a guy who makes aquariums from the stuff. He said he'd sell me enough of his scrap to make a fixture for $20 and it looks like about $20 shipping to get it to me. Is that a good deal? Anyone know of a better deal?

Posted: **Wed Dec 14, 2005 9:28 pm**

Posted: **Wed Dec 14, 2005 9:58 pm**

Local scrapyard around my parts sells plastic for $1 a lb. I picked up a 2'x4' peice 1" thk for making clear heads for my engines so I could watch the flow on the bench.

I know there were thinner peices there, didn't have enough cash in my pocket. This was last year, soon as it warms up a little I need to get back there and pickup some other stuff and I'll take a look. I keep an eye out for clear round stock but never run into that.

Sometimes you can find it on ebay also but its pricey there also

Posted: **Wed Dec 14, 2005 11:38 pm**

See if you can find a local company that uses plastic and see if they have some scrap pieces that fit your needs. I found one and they cut the material for me. Once I had it assembled I took it back to them with a plastic cylinder and had them cut the top and bottom and recess the cylinder into them. Turned out great. I believe I have around $90 in two stands but that includes a 6' piece of tubing.

Posted: **Thu Dec 15, 2005 1:01 am**

This cost me $40 15 was the clear tube in the middle. That stuff is $30 a foot where I bought it, but he let me buy just 6". I still don't have a boring head for my mill so I had to make this smaller than I wanted in the lathe. It's 8x8 3/4, the inside tube is 4.5" ID. I made a bore adapter out off plastic pipe that slides down into this. I still have to make supports for the head so it does not fall off when testing the end ports. The next stand I make will be about 24" long. I don't think you really even need machine tools to make this. The round tube is .020 out off round. A router and a circle cutting attachment should do fine. I'll try that next time.

Posted: **Thu Dec 15, 2005 6:50 pm**

This place had some good prices and a selection of materials.

Posted: **Fri Dec 16, 2005 12:28 am**

A good friend of mine owns a plastic company close by to me,I will get with him and see what he can do on pricing,I got 1/2" acrylic from him and made two stands,one for 600cc motorcycle bores and one for automotive.

Dean

Posted: **Fri Dec 16, 2005 12:55 am**

Ok I'm going to ask a few rather dumb questions here so don't shoot me and they are not meant as a "flame" or anything like that (you all should know me quite well by now, so I'm gonna ask) . . . why spend the money on clear plexi if you can't see anything? Why use clear if you are making a cylinder sleeve out of something else that you can't see through? Why use clear on the part that the head sits on? I can see using it for the bore but why for the head surface? And if you do use it to "see" something how are you "seeing" that something? (To answer this question I use thread on a wand or tape/glue tufts of thread on my part)

Again not to poke at anyone's ideas or start a war or anything just asking why? I agree they do look cool though

Posted: **Fri Dec 16, 2005 9:47 am**

Bruce when I first built my bench I built my fixtures out of plexi-glass so I could see the orifice disk. Since I have changed my setup I don't need to use plexi-glass but I probably will unless I find something better or cheaper.

Any ideas? If I use wood shouldn't it be coated or painted to protect it against the gas/oil that are on some cylinder heads?

Posted: **Fri Dec 16, 2005 11:30 am**

Bruce,The only reason I used clear is because it was free,but also easy to machine,I used a cylinder liner 4.030 bore and machined a counter bore in the plastic to hold and seal the liner and then bored the plastic to the bore ID,then plastic welded two spacers on each side to support head,the same thing could be done using hard wood,I will try and put a picture up later.

Dean

Posted: **Fri Dec 16, 2005 3:03 pm**

Bruce

I used Plexiglas's for 2 reasons. It is flat, and I figured it would be easy to seal to a head. And because it looked cool. The tube that is the bore adapter can be removed to see inside if I wanted to smoke test. I like the Idea of using a rubber sheet to seal the head to the adapter, so all this clear stuff is starting to look useless. I think I am going to make another one out of melinite wood and just use this one if I want to try smoke. If I do smoke I will hook a tube to the exhaust and run it out side!!

Nick

Posted: **Fri Dec 16, 2005 6:32 pm**

Here is something I have done in clear and has been quite a useful tool in my flowtesting on my flathead engines.

Curious on how the bore adaptors were machined in plexi? How'd they'd they clean up afterwards?

Posted: **Fri Dec 16, 2005 8:39 pm**

I use a Harley cylinder of the appropriate bore (within 0.030") for most of my tests.

For automotive tests, I use a Mondello slider set-up with interchangeable bores in the main bore and in the slide plate. It is a super slick unit that is very versatile and fast. It's probably too pricey for the hobby enthusiast, but when you're trying to make a living, it truly earns its keep!

I've always wanted to buy or make an acrylic test sleeve for watching flags, Dykem, or smoke. That is a beautifaul aspect of Bruce's flathead test rig. He is getting a look at what is happening on the combustion chamber side of the port. That is a very imortant part of flow tuning.

Bruce's rig reminds me that I need to mention another book in the other section. Bruce probably knows it since he is working on a Ricardo style head!

Posted: **Tue Jan 03, 2006 5:47 pm**

Anyone have a good source or know where I can get some 4.125" ID clear tubing? I have found several companies that carry 4" & 4.250" but not 4.125". I would like to get 6 feet of it. 1/8" or 1/4" thick.

Posted: **Tue Jan 03, 2006 10:58 pm**

You may want to look for metric sized tube to get you between what's available on the US size market. Just a thought.

Terry T.

Tractorsport Flowbench Forum Archive

Head fixture material