tortron Posted April 29, 2014 Share Posted April 29, 2014 Short of CC'ing the head, how can i figure this out Lets assume everything is standard 4 cylinder bore :2.244in / 57mm stroke :3.543in / 90mm capacity : 56.04 cu.in / 918.636cc compression ratio : 6.7:1 Headgasket: 0.0433in/1.1mm will have to pop a vernier gauge down the spark plug hole to figure out piston heights aiming for 7.5ish as the new ratio Obviously the issue is the volume of the area above the valves, the area above the piston is mostly flat Quote Link to comment Share on other sites More sharing options...
Guypie Posted April 30, 2014 Share Posted April 30, 2014 On my briggs and stratton i skimmed as much as i could without the valves hitting the head. Doesnt detonate on 91, but i had planned on moving to methanol so that was never going to be the problem. Not really relavant but theres my 10c Quote Link to comment Share on other sites More sharing options...
Guypie Posted April 30, 2014 Share Posted April 30, 2014 Also i have a few syringes you can borrow if you do want to cc the head Quote Link to comment Share on other sites More sharing options...
tortron Posted April 30, 2014 Author Share Posted April 30, 2014 yea can grab some syringes/disposable burete's easily enough. Probably its the best/only way to get a good idea Quote Link to comment Share on other sites More sharing options...
JoKer Posted April 30, 2014 Share Posted April 30, 2014 [ling] whip as much off as you dare then make metal head gaskets/space it out with gaskets till it doesn't go bang? [/ling] 1 Quote Link to comment Share on other sites More sharing options...
tortron Posted April 30, 2014 Author Share Posted April 30, 2014 so here is an image of the offending item note the plug position over exhaust valve, this head is the result of 30 years of development! Trying to get a compromise between compression and flow. Quote Link to comment Share on other sites More sharing options...
SOHC Posted April 30, 2014 Share Posted April 30, 2014 Ricardo combustion chamber I have tried putting the plug over the piston on a side valve motor that had a bung for seting the timing, it ran like a bag of shit. Quote Link to comment Share on other sites More sharing options...
tortron Posted April 30, 2014 Author Share Posted April 30, 2014 Ricardo combustion chamber I have tried putting the plug over the piston on a side valve motor that had a bung for seting the timing, it ran like a bag of shit. sounds about right. Should put some Singh grooves in there too for max turbulence 1 Quote Link to comment Share on other sites More sharing options...
tortron Posted April 30, 2014 Author Share Posted April 30, 2014 ok gents, no one on here will want to know, but the head combustion chamber is 32cc per cylinder also approx volume given by the headgasket is 5.4cc deck height is 0.05in/1.27mm all these measurements give me a compression ratio of 6.65 which is pretty spot on Turns out i want to lose about 5cc per cylinder chamber (throw out the headgasket i hear you say) now to figure out what that means in terms of my oddly shaped sidevalve head volume Quote Link to comment Share on other sites More sharing options...
tortron Posted April 30, 2014 Author Share Posted April 30, 2014 lets assume the area is another rectangle approx 52*62mm depth is around 10mm (deeper as you get towards the piston, and then slants up ) this gives 32cc so in order to get 27cc i want to mill off 1.5mm, or about 0.06" which doesnt sound to crazy does it Quote Link to comment Share on other sites More sharing options...
Rookie Posted April 30, 2014 Share Posted April 30, 2014 Just mill it until the valves touch with no head gasket and then you will be good to go. Maths has no place in a side valve. 1 Quote Link to comment Share on other sites More sharing options...
tortron Posted April 30, 2014 Author Share Posted April 30, 2014 wont matter once i bung a blower on it anyway have about 4.5mm valve clearance on a std cam (pretty sure il run into water jacket issues at that point), The area above the valves can of course be milled too. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.