Valve to piston clearance
Discussion
ClassiChimi said:
You boys rock.
So won't the piston be weakened by cutting the groove out or is it negligible?
Will it effect the engines balance or will you be doing it to all the valves ?
Alun
I am still undecided on the course of action.So won't the piston be weakened by cutting the groove out or is it negligible?
Will it effect the engines balance or will you be doing it to all the valves ?
Alun
I know people have used this cutter to good effect but it does make me nervous.
All 16 cut outs would be done as identical as possible in order to keep balance.
My other options are to fit a set of 4.6 pistons with new rings. The CR would come down but would still be accpetable.
Ultra thick gaskets could make life easier but lead times mean i wouldnt have them in time.
db484bhpv8 said:
ClassiChimi said:
You boys rock.
So won't the piston be weakened by cutting the groove out or is it negligible?
Will it effect the engines balance or will you be doing it to all the valves ?
Alun
I am still undecided on the course of action.So won't the piston be weakened by cutting the groove out or is it negligible?
Will it effect the engines balance or will you be doing it to all the valves ?
Alun
I know people have used this cutter to good effect but it does make me nervous.
All 16 cut outs would be done as identical as possible in order to keep balance.
My other options are to fit a set of 4.6 pistons with new rings. The CR would come down but would still be accpetable.
Ultra thick gaskets could make life easier but lead times mean i wouldnt have them in time.
Changing the cam profile will necessitate a re-mapping as well as upping the workload considerably to physically dial it in etc. Unless the existing one is thought to be worn, I'd be inclined to leave well alone and at least have the baseline of a known tune to work from if you're intending to run hard from the off. Got to be the better approach to pull the slugs and have them done rather than try to cut them in-situ.
Not really familiar with any of the cams you list, are they more top-end focused than your existing one? Again, the exhaust clearances can get very close indeed with longer durations (don't ask me how I know)
Not really familiar with any of the cams you list, are they more top-end focused than your existing one? Again, the exhaust clearances can get very close indeed with longer durations (don't ask me how I know)
Pupp said:
Changing the cam profile will necessitate a re-mapping as well as upping the workload considerably to physically dial it in etc. Unless the existing one is thought to be worn, I'd be inclined to leave well alone and at least have the baseline of a known tune to work from if you're intending to run hard from the off. Got to be the better approach to pull the slugs and have them done rather than try to cut them in-situ.
Not really familiar with any of the cams you list, are they more top-end focused than your existing one? Again, the exhaust clearances can get very close indeed with longer durations (don't ask me how I know)
In my case its the Inlets that are currently the worst for clearance. I guess it all comes down to specific cam profiles, valve sizes, set up etc. Not really familiar with any of the cams you list, are they more top-end focused than your existing one? Again, the exhaust clearances can get very close indeed with longer durations (don't ask me how I know)
Theses cams are higher lift and longer duration but still hydraulic. I have the heads to accept them and my CR will still be in the 10's despite the valve reliefs. I would check the tune through the megasquirt but as soon as its up and running would be making a visit to Dale Bladen for a full RR checkover.
If i do get a bigger cam banged in i will also use adjustable pushrods this time.
db484bhpv8 said:
I guess it all comes down to specific cam profiles, valve sizes, set up etc.
It's actually more to do with which way pistons and valves are travelling relative to each other, an inlet kissing a piston will intrinsically be at less risk of damage than an exhaust... actually not uncommon on four and five valve race bike engines with pent-roof chambers for the inlet reliefs to be completely clean of deposits and even have witness marks from contact at high rpms when clearances are absorbed through inertial loads etc Pupp said:
It's actually more to do with which way pistons and valves are travelling relative to each other, an inlet kissing a piston will intrinsically be at less risk of damage than an exhaust... actually not uncommon on four and five valve race bike engines with pent-roof chambers for the inlet reliefs to be completely clean of deposits and even have witness marks from contact at high rpms when clearances are absorbed through inertial loads etc
I guess thats why more clearance is given to the exhausts then.Gassing Station | Chimaera | Top of Page | What's New | My Stuff