Re: cutting Ross piston for valve clearance
[Re: Plymouth340]
#1334108
11/12/12 01:20 AM
11/12/12 01:20 AM
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Joined: Aug 2003
Posts: 43,173
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,173
Bend,OR USA
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Quote:
Got a small block with a 630 roller cam and .090 piston to valve clearance on intake and exhaust and would like to go bigger cam. like maybe 700 lift. can these piston be cut for valve clearance that much or do i need new pistons? has a 3.79 stroker crank and ross pistons..6.123 rods 
Get the new cam and installed it by the cam makers specs and then check the piston to valve clearances  Roller cam lobes are designed to work well, I have had roller cams fit in motors that a similar solid lifter cam wouldn't fit in do to piston to valve clearances.  I do use .050 intake valve to piston and .080 exhaust valve to piston clearances as my goal when using light checking springs  Cam grinders recommend what they think will keep you from blaming them for the valves hitting the pistons  I use 240 to 325 lbs on the seats and from 600 lbs to 850 lbs open also, with really good valves, pushrods, keepers, lash caps rocker arms, and retainers
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: cutting Ross piston for valve clearance
[Re: Cab_Burge]
#1334109
11/12/12 01:34 AM
11/12/12 01:34 AM
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Joined: Feb 2006
Posts: 501
CEDAR RAPIDS
Plymouth340
OP
mopar
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OP
mopar
Joined: Feb 2006
Posts: 501
CEDAR RAPIDS
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Quote:
Quote:
Got a small block with a 630 roller cam and .090 piston to valve clearance on intake and exhaust and would like to go bigger cam. like maybe 700 lift. can these piston be cut for valve clearance that much or do i need new pistons? has a 3.79 stroker crank and ross pistons..6.123 rods
Get the new cam and installed it by the cam makers specs and then check the piston to valve clearances Roller cam lobes are designed to work well, I have had roller cams fit in motors that a similar solid lifter cam wouldn't fit in do to piston to valve clearances. I do use .050 intake valve to piston and .080 exhaust valve to piston clearances as my goal when using light checking springs Cam grinders recommend what they think will keep you from blaming them for the valves hitting the pistons I use 240 to 325 lbs on the seats and from 600 lbs to 850 lbs open also, with really good valves, pushrods, keepers, lash caps rocker arms, and retainers
thanks..its a running motor and dont really want to go to all that work if it aint going to fit..but it would be nice if it did..hows them rocker stands i sent you work out?
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Re: cutting Ross piston for valve clearance
[Re: Plymouth340]
#1334110
11/12/12 02:09 AM
11/12/12 02:09 AM
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Joined: Aug 2003
Posts: 43,173
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,173
Bend,OR USA
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There in my cabinet waiting for the next project that may need them Probally a set of aluminum heads with M.W. ports with a broken rocker shaft pedestal  Thanks again, Cab
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: cutting Ross piston for valve clearance
[Re: LaRoy Engines]
#1334113
11/12/12 02:52 PM
11/12/12 02:52 PM
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Joined: Feb 2006
Posts: 501
CEDAR RAPIDS
Plymouth340
OP
mopar
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OP
mopar
Joined: Feb 2006
Posts: 501
CEDAR RAPIDS
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Quote:
Remember also that just because you go another .070" lift, it doesn't mean your piston to valve clearance will change .070". I don't remember for sure but it seems like it may be more like .010-.020"
i talked to ross pistons and they said i cant cut much off the pistons i have now but talking to other people if i get the right cam with a widened lobe seperation i could probaly get a bigger roller to work. may call comp cams and see what they say,,,,
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Re: cutting Ross piston for valve clearance
[Re: Plymouth340]
#1334114
11/12/12 04:51 PM
11/12/12 04:51 PM
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Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
Guitar Jones
Paddle faster! I hear banjo music!
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Paddle faster! I hear banjo music!
Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
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You did the right thing by calling Ross. Most light weight pistons don't have much room to cut anything deeper. If you need deeper reliefs you need to order them with the pistons.
"Follow me the wise man said, but he walked behind"
'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost coming soon!
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
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Re: cutting Ross piston for valve clearance
[Re: Plymouth340]
#1334115
11/12/12 05:55 PM
11/12/12 05:55 PM
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Joined: Oct 2007
Posts: 4,206
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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I'd ask Ross for a dimensioned drawing of the piston dome in both plan and elevation. You want to know where the bosses are, and the contour of the underside of the dome.
The maximum depth of a notch is not absolute, but varies greatly between the center of the piston and directly over a pin boss, as well as the local temperature etc. The same depth of intake notch to the boss is far safer then an exhaust notch to the ring land.
Boffin Emeritus
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Re: cutting Ross piston for valve clearance
[Re: polyspheric]
#1334116
11/12/12 06:49 PM
11/12/12 06:49 PM
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Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
Guitar Jones
Paddle faster! I hear banjo music!
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Paddle faster! I hear banjo music!
Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
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It's going to be the intake notch to the top ring land that's the problem.
"Follow me the wise man said, but he walked behind"
'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost coming soon!
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
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Re: cutting Ross piston for valve clearance
[Re: Plymouth340]
#1334117
11/12/12 09:25 PM
11/12/12 09:25 PM
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Joined: Aug 2011
Posts: 2,859
Pattison Texas
CSK
master
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master
Joined: Aug 2011
Posts: 2,859
Pattison Texas
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when you advance the cam the intake valve gets closer & ex gets further,you can retard the cam to get more clearance ,but may lose some lower rpm hp
1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392 Stock 11.79 @ 114.5
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Re: cutting Ross piston for valve clearance
[Re: CSK]
#1334118
11/12/12 09:30 PM
11/12/12 09:30 PM
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Joined: Oct 2003
Posts: 3,698
NE Oklahoma
Von
master
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master
Joined: Oct 2003
Posts: 3,698
NE Oklahoma
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Call Eric at RebCo machine in Wichita KS. You can find his website on google.
He cut a set of Ross BB pistons for me. I needed the valve pockets increased to lower comp for pump fuel. The valve pockets started out at 7cc, he cut them to 14cc.
He sonic checks all parts of the piston and tells you what he can and cant do. He made mine a little thin for nitrous use. I wasnt terribly upset, cause the block will split anyway...if it melts a piston first, oh well....
72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72.
Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.
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