The specs call for between .003 and .0045 piston to wall with the Lunati pistons. My engine builder says .003 is too tight and he wants to have it at .004 minimun. I told him I want a fairly tight motor since I plan on putting a lot of miles on it. He still insists on .004? Any opinions on this?

 

Steve, I have been running 4.5 skirt to wall and works well, there is just a little Forged piston sound when it's first started in cold weather, it goes away by 140F.

Good luck
Joe.

 

.004 is fine lunati will grow .001 hot

 

My builder is talking about using a clearance of .0015" on mine. That seems too small. Can you run them less then .003"? He would use a ring gap of .018 top and .024 on the 2nd.

Any thoughts?

George

 

my guy went .005 and it seems to let a lot of blow by through , but the rings havent seated

 

friggin moly rings , i dont think id let him do that again , i hear they take forever to seat , i have 4000 + miles and they still arent close,, she uses oil like a pig,, gettin a little better with each oil change , but very slow <img border="0" alt="[bang head]" title="" src="graemlins/gr_banghead.gif" />

 

I'm looking for a tight engine but I don't want it too tight.

This doesn't only apply to the Lunati kit. What do you guys use for clearance when installing forged pistons in an LS1?

George

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by ibjamin:
<strong> My builder is talking about using a clearance of .0015" on mine. That seems too small. Can you run them less then .003"? He would use a ring gap of .018 top and .024 on the 2nd.

Any thoughts?

George </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The guy who assembled mine (everthing but the cam,etc and covers which I did) builds tons of boat motors and race car motors.I told him I wanted it tight and he told me .0025 to.003 was too tight. He said with the Lunati pistons, .0025 to.003 would scuff. He said .004 was tight so I went with his advise and went .004 It all depends on the aluminum used by the piston manufacturer.

 

TTT. Any other thoughts?

 

George,
What piston are you using? Find out what the manufacturer recomends for clearance and go with that. .0015 sounds way too tight for most forged pistons but might be fine for a cast hypereutectic alloy. It's all about what alloy the piston is made from and its rate of thermal expansion.

 

It's the forged Lunati piston that comes with the 383CI stroker kit from Lunati. They specify .002-.0025 in the little blub describing the kit here:

http://www.holley.com/HiOctn/ProdLin...KA/Chevy1.html

"Ring lands are 1.5mm, 1.5mm and 3mm and piston-to-wall clearance is .0025". Rings are from GM."

But in the sheet with the kit they say a generic amount based on bore size, such as 3.5" to 4" bore, .0035 to .004" .

George

 

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by ibjamin:
<strong> It's the forged Lunati piston that comes with the 383CI stroker kit from Lunati. They specify .002-.0025 in the little blub describing the kit here:

http://www.holley.com/HiOctn/ProdLin...KA/Chevy1.html

"Ring lands are 1.5mm, 1.5mm and 3mm and piston-to-wall clearance is .0025". Rings are from GM."

But in the sheet with the kit they say a generic amount based on bore size, such as 3.5" to 4" bore, .0035 to .004" .

George </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">It actulally says .003 to .0045 and my builder said .003 was to tight.