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Piston to Valve Clearance

 
busterrm2013
V-6 Camaros rule!
Posts: 46
Joined: 07/13
Posted: 07/15/13 05:50 PM

I am going to check the piston to valve clearance on my Dart SHP 400 and from all the literature I have read the clearances need to be .08 intake and .10 for exhaust. Does anybody care to give me a yes or no on those values? I have read so many different articles and books, from what I have read it ranges from .055 - .08 on intake, .075 - .10 on exhaust. Are these safe ranges?  

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Dave632
I mow my lawn and find Chevys
Posts: 2253
Joined: 07/08
Posted: 07/15/13 06:35 PM

I always tried to get at least .05 on the intake side as the intake does not expand as much as the exhaust. On the exhaust I would go with about twice  as much. There is no harm in going with more clearance, just don't go a lot less.
I have read where some builders go as close to .01 to .015 on the intake side.
Now if you have aluminum rods I would triple those numbers.  
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busterrm2013
V-6 Camaros rule!
Posts: 46
Joined: 07/13
Posted: 07/15/13 06:41 PM

No, the rods are forged steel rods!  

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Pontiacman2
Moderator
Posts: 8956
Joined: 09/08
Posted: 07/16/13 07:35 AM

Minimum piston to valve clearance is .080” on the intake and .100” on the exhaust valves. If aluminum connecting rods are being used, add a minimum of .030” to these suggested clearance figures. Aluminum rods will stretch and expand more than steel rods.

Note: Be sure to check piston to valve clearance after the cam has been degreed. The positioning of the cam in the engine will greatly affect the piston to valve clearance.  
Pontiacman2
Pontiacman2

Professional Hi-performance engine builder

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skyeking
I mow my lawn and find Chevys
Posts: 2738
Joined: 08/09
Posted: 07/16/13 03:45 PM

Hi Poncho Man,
Long time no see.
All the best to you and the gang And RustyNutts.
 Are you busy turning over a rare Dollar??..
 See you when the Mud dries Pal...MeinOz..  
skyeking

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busterrm2013
V-6 Camaros rule!
Posts: 46
Joined: 07/13
Posted: 07/16/13 04:27 PM

Yes the cam has already degreed and rephased!  The cam specs are 525 lift(modified to 563 with 1.6 rockers), 224 dur @  050, LSA is 110, intake center is 106, intake closing angle is 66 but will be retarded 4 degs. The degreeing process found that the duration is 1 degree short @ 223 degrees both valves, Lift is exact on intake and .001 short on exhaust and the intake closing is 65, so retarded 4 degs it will be 69.  

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busterrm2013
V-6 Camaros rule!
Posts: 46
Joined: 07/13
Posted: 07/16/13 04:27 PM

Yes the cam has already degreed and rephased!  The cam specs are 525 lift(modified to 563 with 1.6 rockers), 224 dur @  050, LSA is 110, intake center is 106, intake closing angle is 66 but will be retarded 4 degs. The degreeing process found that the duration is 1 degree short @ 223 degrees both valves, Lift is exact on intake and .001 short on exhaust and the intake closing is 65, so retarded 4 degs it will be 69.  

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