Does anyone take the time to “massage” pistons anymore before installing them? I grew up watching my dad build engines for the race car and then I started myself at 15 years old racing. But every engine that I have built and even when I worked at an old school race engine shop in my late 20’s early 30’s we would take every piston and break all the sharp corners and contour the domes. I know out of the box, pistons look so pretty with their machining but they don’t work their best that way. Sharp points cause hot spots and on big domes there’s lot a sharp corners. Just like you wouldn’t want sharp corners and turns in a cylinder head port, why would you want them for flame travel. Maybe it’s just too time consuming for engine builders today and it adds too much to assembly cost I don’t know, here is the pistons that went in my 565, hopefully they show up as correct order but you can see out of the box and how they went in.
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Piston work before installation
bracketchev1221
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Does anyone take the time to “massage” pistons anymore before installing them? I grew up watching my dad build engines for the race car and then I started myself at 15 years old racing. But every engine that I have built and even when I worked at an old school race engine shop in my late 20’s early 30’s we would take every piston and break all the sharp corners and contour the domes. I know out of the box, pistons look so pretty with their machining but they don’t work their best that way. Sharp points cause hot spots and on big domes there’s lot a sharp corners. Just like you wouldn’t want sharp corners and turns in a cylinder head port, why would you want them for flame travel. Maybe it’s just too time consuming for engine builders today and it adds too much to assembly cost I don’t know, here is the pistons that went in my 565, hopefully they show up as correct order but you can see out of the box and how they went in.
![Image]()
![Image]()
I do the same thing. I also slightly bevel the edges and bottom of the skirt to make sure there are no high spots there.
On engines that have enough stroke to pull some of the skirt out of the bottom of the cylinder the bottom edges of the cylinder need to be rolled/beveled with a very smooth finish to keep from destroying the skirts.
I read an interview that Allan Patterson gave years ago. Back in the old days of modified production it was very difficult to get compression in the small engines (283-302). Patterson had always smoothed the dome but put an engine together with the sharp edges on the piston, dynoed, then took it apart and smoothed the dome trying not to lose compression, dynoed again. It made the same power. Working the dome falls into the category that it doesn't hurt.
On engines that have enough stroke to pull some of the skirt out of the bottom of the cylinder the bottom edges of the cylinder need to be rolled/beveled with a very smooth finish to keep from destroying the skirts.
I read an interview that Allan Patterson gave years ago. Back in the old days of modified production it was very difficult to get compression in the small engines (283-302). Patterson had always smoothed the dome but put an engine together with the sharp edges on the piston, dynoed, then took it apart and smoothed the dome trying not to lose compression, dynoed again. It made the same power. Working the dome falls into the category that it doesn't hurt.
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My dad ran Modified Production in the early 70’s with a .060 over 283. 292 inches with a tunnel ram and 2 550’s. The shop I worked at built motors in the 70’s for Richie Zul’s pro stocker and Dennis Ferrara’s Comp cars so I guess it’s all old school stuff carrying on.
Sweet! Little things can matter, passion for engine building
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I am not a professional engine builder,although I have rebuild mine three times now.
Every set of pistons got all the sharp edges smoothed like you did in the above pictures.
Does it help ?? I cant answer that.
Did it make me feel better ?? Sure did !!!
LOL
Guy
Every set of pistons got all the sharp edges smoothed like you did in the above pictures.
Does it help ?? I cant answer that.
Did it make me feel better ?? Sure did !!!
LOL
Guy
Nothing wrong with old school. We can take a pile of parts discarded by the younger internet generation because they're not new or shiny enough and make them run.
Nothing sounds as good as a 292 modified engine about 9k. Nothing. The shop you worked at exposed you to a lot of knowledge.
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I do admit to old school knowledge. I may be out of date on LS motors and fuel injection and power adder motors but I did have fun building and running what I ran and the stuff I was involved in at the engine shop.
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I’m guessing that’s a external balance engine or are you removing the exact same weight of the piston face? But smooth edges seem like it help prevent hot spots like you were saying. I know my chambers are smoothed over, pistons are coated though.
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This motor was internal. But I do it to all engines. Each piston comes out the same when done.
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Yes and I’d do some more work to that dome.
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For the last 15+ years I've been going with coated pistons.
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Don't forget to check pin bore clearance
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I just used fine sand paper, but I don’t remember what grade.
Guy
Guy
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I use an angle die grinder with red scuff pads.
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I massage the pistons and chambers to remove all sharp edges and have for decades.
Daily driver and tow stuff and I run a lot of compression compared to many here.
11.9 with 224@ .050 cam gen 1 small blocks.
Daily driver and tow stuff and I run a lot of compression compared to many here.
11.9 with 224@ .050 cam gen 1 small blocks.
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I touch 'em all. Found a good flap wheel and use it on my Milwaukee Fuel die grinder. It may not help but it makes me feel better.
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