350/255HP Help please - Page 5

V M Kauffman · 06-05-2016, 09:27 AM

Quote:

Originally Posted by GTOMayhem

What would the fix be after you tore it down? I know, probably a novice question. Also how would a supercharged engine change what you would be looking for as far as ring seal and blowby?

Rick Thomason
GTOMayhem

Tear it down are bores straight? Not enough top ring radial wall tension? Bores or piston scuffed? Bottom line is its not sealed up and you do what ever it takes to get it to seal!

Allen Sherman · 06-09-2016, 01:13 AM

Chipper sounds like the guys have given you a lot of places to look and are all pretty spot on. 5-6% leak down isn't terrible but most of the stuff we do leaks 3% or less at 100*, the cam isnt the best of the bunch, the block at .065" over is a boat anchor unless it's filled, and even then it's not primo, we hone with diamond stones rather then vitrified stones which is the best option out there especially with the small ring packages, and we have most of our stock/super stock engines below 5cfm of blow by on the Dwyer gauge and we have a VERY fast 255/350 engine that was built at my shop and on our dyno which everyone says is exceptionally stingy it makes 442hp@6500rpm peak...this engine has been 10.90's in H/SA...just some info for u

Alan Nyhus · 06-13-2016, 09:30 PM

As a point of reference, here's the sectioned cylinder wall from the block mentioned earlier. It measures about .120-.125 thick.

HP HUNTER · 06-14-2016, 11:47 PM

Quote:

Originally Posted by Alan Nyhus

This is a non filled '72 vintage block +.070 from my Nova Stocker that split the #4 cylinder. Will section the cylinder wall this week just to see how thin it really is. At high rpms, the walls in a block like this gotta' be shakin' like a female intern in the Clinton White House.......

What were your rings gapped at?

06-09-2016, 01:13 AM	#42
Allen Sherman Member Join Date: Dec 2001 Posts: 147 Likes: 0 Liked 5 Times in 3 Posts	Re: 350/255HP Help please Chipper sounds like the guys have given you a lot of places to look and are all pretty spot on. 5-6% leak down isn't terrible but most of the stuff we do leaks 3% or less at 100*, the cam isnt the best of the bunch, the block at .065" over is a boat anchor unless it's filled, and even then it's not primo, we hone with diamond stones rather then vitrified stones which is the best option out there especially with the small ring packages, and we have most of our stock/super stock engines below 5cfm of blow by on the Dwyer gauge and we have a VERY fast 255/350 engine that was built at my shop and on our dyno which everyone says is exceptionally stingy it makes 442hp@6500rpm peak...this engine has been 10.90's in H/SA...just some info for u

06-13-2016, 09:30 PM	#43
Alan Nyhus VIP Member Join Date: Dec 2002 Location: Lower Dakota territory Posts: 1,166 Likes: 1,018 Liked 762 Times in 226 Posts	Re: 350/255HP Help please As a point of reference, here's the sectioned cylinder wall from the block mentioned earlier. It measures about .120-.125 thick. __________________ "That'll never work....."