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| andycap73 |
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Hiya, looking to get some advice on a 393c stroker, I need to know if anyone can tell me if I can successfully machine the chambers in my 2v closed chamber heads to get about 80cc, I need to lower the compression ratio a bit to be able to run it on pump gas, I am aware I will need to run a fairly radical cam to get what I want, It is currently at 10.5:1, I want to achieve as close to 10 as possible. If I machine the chambers will this upset my quench? and if so can I get rid of the resulting knock with a better timing curve? I currently have a zero deck height..
Regards Andy |
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| xafalcon |
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2V open chambers were 72-78cc so that gives you an idea.....
10.5:1 on closed 2V's is fine with even a moderate cam around 224 @ 050 running on ultimate fuel. This requires no compromise on spark advance curve. If your piston is dished rather than d-cup design, you may need to pull back on compression a tad
_________________ XA Faimont 351C, AU2 XR8 Manual 5.0, DA LTD 5.0, Mk1 Capri 5.0, 1995 Mustang 5.0, EF2 XR8 Manual, EF2 Fairmont Ghia 5.0, AU3 XR8 Auto, AU2 XR8 Auto, AU2 XR8 Manual Ute, TE Cortina 5.0 Manual, DU LTD 5.0 soon to be manual |
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| andycap73 |
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xafalcon wrote: 2V open chambers were 72-78cc so that gives you an idea..... 10.5:1 on closed 2V's is fine with even a moderate cam around 224 @ 050 running on ultimate fuel. This requires no compromise on spark advance curve. If your piston is dished rather than d-cup design, you may need to pull back on compression a tad It has flat tops with no valve relief etc, will it still be fine to use the 2v open heads? someone has suggested a cam with 235ish @50deg, what are your thoughts? Cheers Andy |
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| 66 coupe |
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no valve releif - make sure you check piston to valve clearance!
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| andycap73 |
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66 coupe wrote: no valve releif - make sure you check piston to valve clearance! Miles of room in that respect, just a bit concerned that when I crunch the numbers if I run with the 2v closed chamber heads, it works out at about 12.5:1, not exactly street friendly. But if I run with open heads at 77-78cc still around 10.5, I really want about 10:1 for some safety, I just want to know if anyone has machined a few cc's out of closed heads and what results they got. |
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| xafalcon |
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You said it was currently 10.5:1 with closed 2V's......
Open chamber cleveland heads will ping anywhere from 9.5:1 upwards, and really aren't a good combustion chamber design except for emissions. I don't use them, ever I would use a D-cup piston & closed chamber 2V heads opened up to about 66cc's to unshroud the valves.
_________________ XA Faimont 351C, AU2 XR8 Manual 5.0, DA LTD 5.0, Mk1 Capri 5.0, 1995 Mustang 5.0, EF2 XR8 Manual, EF2 Fairmont Ghia 5.0, AU3 XR8 Auto, AU2 XR8 Auto, AU2 XR8 Manual Ute, TE Cortina 5.0 Manual, DU LTD 5.0 soon to be manual |
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| andycap73 |
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Does it ping due to the lack of quench with the open heads?
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| XR9UTE |
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Do you specifically want to stay with Iron heads Andycap?
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| andycap73 |
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Yeah I would like too if I can make it work.
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| XR9UTE |
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Anything else you already have that you want to keep?
Personally I'd run a dished piston if I was to stay with CC iron heads but then, I wouldn't stay with iron heads. If you already have a flat top stroker kit and don't want to change that I'd use OC heads but then I'd just buy CHI alloy heads. It sounds like you already have a built set of CC's that you just want to open up a bit? I've only heard of small amounts of 5-6cc being removed but that's not to say more couldn't be? Are you able to machine a chamber shape dish into the pistons? This would be more desirable. Of course they need to be able to take it. |
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| andycap73 |
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Yeah you are right, I already have a set of closed 2v heads that are already built, I have access to an NC machine and a top operator for nix, I might have to talk to him and see if he look at maybe splitting the difference over the heads and pistons.
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| andycap73 |
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Yeah you are right, I already have a set of closed 2v heads that are already built, I have access to an NC machine and a top operator for nix, I might have to talk to him and see if he look at maybe splitting the difference over the heads and pistons.
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| xafalcon |
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A dish-top piston design is old-school. When you dish the piston top you loose quench, and effective quench is especially important when you're getting close to a detonation limit. The D-cup design is the way to go as it leaves the quench area untouched and fully effective.
_________________ XA Faimont 351C, AU2 XR8 Manual 5.0, DA LTD 5.0, Mk1 Capri 5.0, 1995 Mustang 5.0, EF2 XR8 Manual, EF2 Fairmont Ghia 5.0, AU3 XR8 Auto, AU2 XR8 Auto, AU2 XR8 Manual Ute, TE Cortina 5.0 Manual, DU LTD 5.0 soon to be manual |
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| XR9UTE |
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That'd be the way to go I think Andycap, You could do your chamber first and mirror that shape into the piston.
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