Valve Clearance
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From: Worcester
Car: 1984 Firebird T/A
Engine: 406sbc
Transmission: TH400
Axle/Gears: Moser 9"
Valve Clearance
I just Bought AFR 210cc's with 66cc and it says max lift is .670. I also bought a Lunati Voodoo Mechanical Roller Camshaft with.585''/.600'' ,Adv. Duration is 278°/285°, Duration @.050 is249°/255°. But with my stroker engine and such a big cam am I going to have to worry about valve clearance. i dont want to mess up my engine. Theres been a lot of money put into this and I dont want to break anything because of too big of a cam. Oh yeah and I have 5.7 rods.
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From: Worcester
Car: 1984 Firebird T/A
Engine: 406sbc
Transmission: TH400
Axle/Gears: Moser 9"
I was hoping to find out without putting the cam in so then If it is too big of a cam I could just sell it brand new unopened for about what I paid.
other than checking all you can do is guess. i'll guess it'll be ok, then again if it isn't i'm not going to be out anything. another option if there is too little clearance is to increase the clearance and keep the cam.
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From: Ontario, Canada
Car: 1988 Firebird S/E
Engine: 406Ci Vortec SBC
Transmission: TH-350/3500stall
Axle/Gears: 7.5" Auburn 4.10 Posi-Traction
Come on. Throw the cam in and fire it up. I want to see all those expensive valves bend....Then you'll be asking if you can straighten them out with a hammer .
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From: Mims, Florida
Car: '87 IROCZ
Engine: 395 ZZ4
Transmission: ProBuilt 700R4
Axle/Gears: 9 bolt 3.70s
Do it right, buy a valve clearance checking tool. You can loosely bolt down the new head, leave in the old cam, and check the valve clearance with that special tool, or use modelling clay. I recently used modelling clay because I had not yet permanently bolted down my new heads.
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Joined: Sep 2001
Posts: 6,111
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From: Ontario, Canada
Car: 1988 Firebird S/E
Engine: 406Ci Vortec SBC
Transmission: TH-350/3500stall
Axle/Gears: 7.5" Auburn 4.10 Posi-Traction
Do you have a dial indicator and magnetic stand?
Same as used to degree in a new camshaft.
Same as used to degree in a new camshaft.
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Thread Starter
Senior Member
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From: Worcester
Car: 1984 Firebird T/A
Engine: 406sbc
Transmission: TH400
Axle/Gears: Moser 9"
No I don't have a dial indicator or anything. I guess I'm going to have to put everything in and hop for the best.
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Joined: Sep 2001
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From: Ontario, Canada
Car: 1988 Firebird S/E
Engine: 406Ci Vortec SBC
Transmission: TH-350/3500stall
Axle/Gears: 7.5" Auburn 4.10 Posi-Traction
Why? Dial indicators are not expensive.
What you want to do is mock up the motor as it will run except without the head gasket installed.
Then adjust the valve lash of say #1 cylinder to exactly Zero Lash on both the intake and exhaust.
Then set up the dial indicator on the valve retainer and turn the rocker nut further from 0 lash until the valve opens .060". Then do the same for the exhaust.
Then do the same thing to a cylinder on the other bank. Say #6. Now that one cylinder's from each side of the motor has its valves cranked open .060" past the 0 lash point you can rotate the crank shaft over SLOWLY BY HAND twice. If there is no interference, You are good to go.
You have at last .060" clearance between the retainer and seal at full lift and at least .060" further spring travel before coil bind at full lift. You also have at least .060" +The valve lash (.016 to .030") + the gasket thickness (.040") of net total valve to piston clearance. Don;t forget the go back and properly re adjust the valve lash before fireing it.
You must set the vlave lash at 0 lash with that cam lobe on the back side (base circle) of the lobe.
use the intake closing, exhaust opening method to position the crank for this adjustment.
Is there anything you do not under stand?
it will cost you far more to rebuidl this motor if there is valvetrain inteference than the cost of the dial indicator. it won't be pretty. You'll find lots of other uses for the dial indiator.
What you want to do is mock up the motor as it will run except without the head gasket installed.
Then adjust the valve lash of say #1 cylinder to exactly Zero Lash on both the intake and exhaust.
Then set up the dial indicator on the valve retainer and turn the rocker nut further from 0 lash until the valve opens .060". Then do the same for the exhaust.
Then do the same thing to a cylinder on the other bank. Say #6. Now that one cylinder's from each side of the motor has its valves cranked open .060" past the 0 lash point you can rotate the crank shaft over SLOWLY BY HAND twice. If there is no interference, You are good to go.
You have at last .060" clearance between the retainer and seal at full lift and at least .060" further spring travel before coil bind at full lift. You also have at least .060" +The valve lash (.016 to .030") + the gasket thickness (.040") of net total valve to piston clearance. Don;t forget the go back and properly re adjust the valve lash before fireing it.
You must set the vlave lash at 0 lash with that cam lobe on the back side (base circle) of the lobe.
use the intake closing, exhaust opening method to position the crank for this adjustment.
Is there anything you do not under stand?
it will cost you far more to rebuidl this motor if there is valvetrain inteference than the cost of the dial indicator. it won't be pretty. You'll find lots of other uses for the dial indiator.
Last edited by F-BIRD'88; Mar 2, 2007 at 03:38 PM.
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From: Worcester
Car: 1984 Firebird T/A
Engine: 406sbc
Transmission: TH400
Axle/Gears: Moser 9"
None of that seems too hard, I'm just 18 so I don't know too much about doing valve lash and things with my car. I'll have to get someone more technical and knowledgeable to help me.
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Joined: Sep 2001
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From: Ontario, Canada
Car: 1988 Firebird S/E
Engine: 406Ci Vortec SBC
Transmission: TH-350/3500stall
Axle/Gears: 7.5" Auburn 4.10 Posi-Traction
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From: Maui, Hawaii
Car: 1984 Trans Am
Engine: broken 385sbc
Transmission: G-Force rebuilt T-5
Axle/Gears: Currie 9" Ford 4.30:1
well to give you a rough idea, i have a .592" lift, 260* @ .050" solid flat tappet cam(with 1.6's).. from piston to head, its .040".. .025" deck and .015" gasket.. plus heads are milled .020".. i run fine with .020" lash.. no problems whatsoever..
is your block Zero-decked?? what head gasket thickness?? you should be fine with that cam.. i would only be worried with over .600" lift WITH valve lash..
is your block Zero-decked?? what head gasket thickness?? you should be fine with that cam.. i would only be worried with over .600" lift WITH valve lash..
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Joined: Sep 2001
Posts: 6,111
Likes: 53
From: Ontario, Canada
Car: 1988 Firebird S/E
Engine: 406Ci Vortec SBC
Transmission: TH-350/3500stall
Axle/Gears: 7.5" Auburn 4.10 Posi-Traction
Te fact that your flat tappet cam clears is no indication that a particular roller cam will clear in someone elses motor.
The lift curve action when the piston is nearTDC is a lot different on a roller profile.
many Harbor Freight type stores Summit, Jegs, sell dial indicators and the magnetic stand for very reasonable prices. threr is no excuse the not check and verify valve to piston clearance on this one.
You'll find a ton of other uses for the dial indiator, or just sell it when you're done.
The camshaft is worth just as much money wether The box has been opened or not.....
The lift curve action when the piston is nearTDC is a lot different on a roller profile.
many Harbor Freight type stores Summit, Jegs, sell dial indicators and the magnetic stand for very reasonable prices. threr is no excuse the not check and verify valve to piston clearance on this one.
You'll find a ton of other uses for the dial indiator, or just sell it when you're done.
The camshaft is worth just as much money wether The box has been opened or not.....
Last edited by F-BIRD'88; Mar 8, 2007 at 10:06 AM.
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