4stroker Posted August 20, 2008 Report Share Posted August 20, 2008 at a quick glance it looks like 50 thou off them domes is gonna reduce your dome size by about 2.2cc!! unless you take some material outa the hemisphere i think itll be too high on compression. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted August 20, 2008 Report Share Posted August 20, 2008 (edited) at a quick glance it looks like 50 thou off them domes is gonna reduce your dome size by about 2.2cc!! unless you take some material outa the hemisphere i think itll be too high on compression. that's what i too was thinking about the .050" situation. i know that taking like .005 off a stock head (on head gasket surface i mean), can reduce the head cc volume by like .4 something. so taking .050" off (i know we are talking the squish band here), might get you into high comp trouble quickly, without taking a little more out of the hemisphere part of the dome, like 4stroker said. you also have pm. Edited August 20, 2008 by mopar1rules Quote Link to comment Share on other sites More sharing options...
dlnoss Posted August 20, 2008 Report Share Posted August 20, 2008 Modifying an existing, stock stroke dome to work with the stroker is difficult if you want to maintain a decent combustion chamber. The exception might be if you started with, say, a 24cc stock stroke dome and wanted to end up with maybe a 18cc stroker dome. You can carve out the squish area to accomodate the 2mm extra deck height but there won't be much 'bowl' left. You can machine the bowl to add the necessary volume back into the dome but now the spark plug will be hanging down into the combustion chamber. I know people do modify domes to work but they usually start out with a large volume dome. It's certainly easier (for me anyway) to just make it the way you want it from the start. Just my opinion, -David Quote Link to comment Share on other sites More sharing options...
4stroker Posted August 21, 2008 Report Share Posted August 21, 2008 You can machine the bowl to add the necessary volume back into the dome but now the spark plug will be hanging down into the combustion chamber. i forgot about that! depending on how much you remove you might be able to get away with using a thicker washer on the spark plug to space it back up. but yeah like you said Dave its gonna be a whole nicer to start from scratch! could you make domes for this guys trinity head? Quote Link to comment Share on other sites More sharing options...
dlnoss Posted August 21, 2008 Report Share Posted August 21, 2008 i forgot about that! depending on how much you remove you might be able to get away with using a thicker washer on the spark plug to space it back up. but yeah like you said Dave its gonna be a whole nicer to start from scratch! could you make domes for this guys trinity head? I don't make domes that fit the Trinity head, sorry. I am broadening my dome inventory though. Besides domes for the stock heads, I do Puma, Cougar, Super Cub, DMX, some sled domes, and Cheetah PV domes in the next week or two. -David Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted August 21, 2008 Report Share Posted August 21, 2008 (edited) You can carve out the squish area to accomodate the 2mm extra deck height but there won't be much 'bowl' left. You can machine the bowl to add the necessary volume back into the dome but now the spark plug will be hanging down into the combustion chamber. i see what you are saying, but you wouldn't have to necessarily make the dome "deeper"....would you? couldn't you just keep the same dome depth, but then just widen/open up the diameter, where it meets the squish band? you know, the squish band width would get skinnier. that way the spark plug wouldn't stick into the dome any further. yeah, so i guess the radius of the hemisphere would be greater. Edited August 21, 2008 by mopar1rules Quote Link to comment Share on other sites More sharing options...
dlnoss Posted August 21, 2008 Report Share Posted August 21, 2008 Yes you could gain the volume back by widening the bowl and narrowing the squish area. I don't know if you could gain the needed volume without making the squish area too narrow. Might end up pretty pipey. -David Quote Link to comment Share on other sites More sharing options...
lunatic Posted August 21, 2008 Author Report Share Posted August 21, 2008 Yes you could gain the volume back by widening the bowl and narrowing the squish area. I don't know if you could gain the needed volume without making the squish area too narrow. Might end up pretty pipey. -David How do I check dome volume? Can i grease the rings and put piston on tdc and fill the chamber to the bottom of the plug hole? Quote Link to comment Share on other sites More sharing options...
dlnoss Posted August 21, 2008 Report Share Posted August 21, 2008 I put a plug in it and clamp a piece of lexan with a hole in it to the bottom of dome. I fill it (upside down) with a burett. A cattle syringe would work if you don't have a burett. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted August 21, 2008 Report Share Posted August 21, 2008 I put a plug in it and clamp a piece of lexan with a hole in it to the bottom of dome. I fill it (upside down) with a burett. A cattle syringe would work if you don't have a burett. So when you cc' a dome you dont figure in the space that the piston crown takes up. Your just measure the total volume of the dome correct? Quote Link to comment Share on other sites More sharing options...
dlnoss Posted August 21, 2008 Report Share Posted August 21, 2008 So when you cc' a dome you dont figure in the space that the piston crown takes up. Your just measure the total volume of the dome correct? Flat plate volume is usually what is referred to when domes are ordered since that is how they are checked when not installed. Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted August 21, 2008 Report Share Posted August 21, 2008 Yes you could gain the volume back by widening the bowl and narrowing the squish area. I don't know if you could gain the needed volume without making the squish area too narrow. Might end up pretty pipey. -David so, skinny squish band widths make an engine more "peaky/pipey" and a wide squish band will make an engine's powerband more broad? also, how does a guy know what radius to put on, or make his hemisphere on the dome too? is there some common norms, or what? Quote Link to comment Share on other sites More sharing options...
lunatic Posted August 21, 2008 Author Report Share Posted August 21, 2008 Flat plate volume is usually what is referred to when domes are ordered since that is how they are checked when not installed. That dont sound right my 7mm domes would measure like 30cc because of the .130" step thats added for the stroke. Or is your plate round that fits up into the step and rests up against the squish band? I guess i will have to junk both my heads cause i still havent got a answer of what degree to cut my bands.lol ...thanks good reading guys Quote Link to comment Share on other sites More sharing options...
mopar1rules Posted August 21, 2008 Report Share Posted August 21, 2008 lunatic, you will need to know the piston crown angle and then i would assume go anywhere from 1 to 2 deg greater with the squish angle versus what your piston crown angle is. Quote Link to comment Share on other sites More sharing options...
badassbanshee479 Posted August 21, 2008 Report Share Posted August 21, 2008 you have to remember also that there is a squish clearance between the dome and the pistion so using a flat plate to cc the head is the correct way. Just remember.... "you can go broke trying to save money!!" I would sell the domes you have and just have noss cut ya the correct ones. Trust me on this, I tried to modify a set of domes I had and it cost me a couple pistons because I could not stop the detonation!!!! Had a new set cut, problem solved!! Quote Link to comment Share on other sites More sharing options...
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