Valve to piston clearance

Valve to piston clearance

Author
Discussion

phazed

21,844 posts

203 months

Sunday 1st March 2015
quotequote all
Speaking as a builder, is it wise to fly cut by hand?

I have a vision of cutting right through!

db484bhpv8

Original Poster:

8,655 posts

219 months

Sunday 1st March 2015
quotequote all
phazed said:
Speaking as a builder, is it wise to fly cut by hand?

I have a vision of cutting right through!
You use an old head and set the cutter stop. This method works.

phazed

21,844 posts

203 months

Sunday 1st March 2015
quotequote all
db484bhpv8 said:
phazed said:
Speaking as a builder, is it wise to fly cut by hand?

I have a vision of cutting right through!
You use an old head and set the cutter stop. This method works.
Ah, makes sense.

OleVix

1,438 posts

147 months

Sunday 1st March 2015
quotequote all
you cold also regrind a bigger valve and use it as the cutter

ClassiChimi

12,424 posts

148 months

Sunday 1st March 2015
quotequote all
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

db484bhpv8

Original Poster:

8,655 posts

219 months

Monday 2nd March 2015
quotequote all
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.
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.

phazed

21,844 posts

203 months

Monday 2nd March 2015
quotequote all
YHM

neal1980

2,574 posts

238 months

Monday 2nd March 2015
quotequote all
or get some forged pistons to your spec and go BIG smile

db484bhpv8

Original Poster:

8,655 posts

219 months

Monday 2nd March 2015
quotequote all
neal1980 said:
or get some forged pistons to your spec and go BIG smile
Need to decide on a solution that i can impliment asap.
Racing at Easter!

SILICONEKID345HP

14,997 posts

230 months

Monday 2nd March 2015
quotequote all
db484bhpv8 said:
Need to decide on a solution that i can impliment asap.
Racing at Easter!
s to

Crate lS engine ,would only take you a few weeks for you to complete .

db484bhpv8

Original Poster:

8,655 posts

219 months

Monday 2nd March 2015
quotequote all
SILICONEKID345HP said:
to

Crate lS engine ,would only take you a few weeks for you to complete .
thats just silly

SILICONEKID345HP

14,997 posts

230 months

Monday 2nd March 2015
quotequote all
db484bhpv8 said:
thats just silly
Well i am a bit silly cool

macdeb

8,492 posts

254 months

Monday 2nd March 2015
quotequote all
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.
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.
I'd take them out mate, get them weighted at same time.

db484bhpv8

Original Poster:

8,655 posts

219 months

Monday 2nd March 2015
quotequote all
macdeb said:
I'd take them out mate, get them weighted at same time.
The decision has been made.
They are coming out on Friday to be shipped to Chesmans for reliefs.

Now.... do i replace the Typhoon cam with a Crower 50233, 50234 or a real steel RS234?

Pupp

12,205 posts

271 months

Monday 2nd March 2015
quotequote all
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)

Alexdaredevils

5,697 posts

178 months

Monday 2nd March 2015
quotequote all
db484bhpv8 said:
Now.... do i replace the Typhoon cam with a Crower 50233, 50234 or a real steel RS234?
Kent M238 IMO

db484bhpv8

Original Poster:

8,655 posts

219 months

Tuesday 3rd March 2015
quotequote all
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.
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

Original Poster:

8,655 posts

219 months

Tuesday 3rd March 2015
quotequote all
Alexdaredevils said:
Kent M238 IMO
A good rule of thumb... whatever you choose - 2 smile

Pupp

12,205 posts

271 months

Tuesday 3rd March 2015
quotequote all
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

db484bhpv8

Original Poster:

8,655 posts

219 months

Tuesday 3rd March 2015
quotequote all
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.