Clear material for steam chest cover timing

[Benjamin Maggi]

I am getting ready to time my Sweet William engine. I have read on these forums (though for the life of me can't find the threads) where people used clear steam chest covers to aid is setting the valve gear. I was going to purchase some 3/8" polycarbonate to make covers but wanted to see if others had a better recommendation for material and perhaps thickness.

Thanks.

[squandt]

as someone who has worked with polycarb,it can be cut with HHS ,drilled and tapped ,etc, you can heat polish it with a propane torch.As to the thickness,are you going to make your clear cover the same as the one used to close the steam chest? if so 3/8 will work. The only thing about polycarb is it scratches very easy, 3/8 thickness will stop a 357 mag round from 10 feet,but will scratch .

[cbrew]

I did this, i just stopped by the local glass shop and asked if they has any 1/4 plexiglass in the scrap pile, he handed me a piece large enough to make a couple lids. it worked well, but they will not hold up to steam (dont ask)

[squandt]

plex dose no have the crosslink that polycarb dose,the parts that the company I worked for made from polycarb were used in the medical testing area,it had to stand up the being autoclaved,pressure up to 500 psi and acid .I don't know if you can put it under steam or not,butair will not hurt it,have fun.

[cbrew]

well the .25 plex had not issue with air and the price is right.

[Benjamin Maggi]

Thanks guys. I think 1/4" thick poly. will be fine. I found some on Ebay inexpensively.

[Rwilliams]

Years ago I saw a Briggs & Stratton gas engine with head removed and replaced with some 1/2 inch thick Plexiglass. The compression had been lowered a bit to reduce the firing pressures. The clear plastic allowed one to see the rapid flame front propagation from the spark plug. It only took a few minutes of run time to reduce the clear plastic head to a well fogged, slightly toasted and useless mess. Each demonstration required a new head the guy told us.

[Greg_Lewis]

Years ago I saw a Briggs & Stratton gas engine with head removed and replaced with some 1/2 inch thick Plexiglass. The compression had been lowered a bit to reduce the firing pressures. The clear plastic allowed one to see the rapid flame front propagation from the spark plug. It only took a few minutes of run time to reduce the clear plastic head to a well fogged, slightly toasted and useless mess. Each demonstration required a new head the guy told us.

But I'll bet it was fun while it lasted!