Bore diameter vs chamber diameter
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From: South Carolina
Bore diameter vs chamber diameter I'm in the process of building a LS6 383 and noticed the head chamber diameter (4.0) is larger than the bore (3.905). I planned on using a head gasket at least 4.100 bore to make sure the head seals properly against the block. Will this be a problem if the head gasket is much larger than the bore?
Second question is do people chamfer bores on these aluminum blocks to match the heads for better flow? Does it cause any problems? I used to do this on iron blocks all the time with great success in performance depending on how badly the valve was shrouded by the sharp edge of the block.
Second question is do people chamfer bores on these aluminum blocks to match the heads for better flow? Does it cause any problems? I used to do this on iron blocks all the time with great success in performance depending on how badly the valve was shrouded by the sharp edge of the block.
On The Tree
Joined: Jan 2010
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From: San diego , CA
Thread Starter
Registered User
Joined: Dec 2010
Posts: 19
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From: South Carolina
There seems to be a little confustion here. These are LS6 heads that have had the chamber polished and relieved a little near the edges of the valves. If you place a 4.0 diameter gasket over the head, the edge of the gasket protrudes into the chamber where it was relieved. This would make it a little difficult to seal. A larger gasket bore like 4.100 would cure that problem. That's what the first question was about.
With that in mind, because that part of the chamber is larger than the bore, the sharp edge of the bore disrupts airflow into and out of the cylinder. Hense, that why we used to relieve the edge of the cylinder. Question 2 was if that process was safe on these aluminum blocks.
With that in mind, because that part of the chamber is larger than the bore, the sharp edge of the bore disrupts airflow into and out of the cylinder. Hense, that why we used to relieve the edge of the cylinder. Question 2 was if that process was safe on these aluminum blocks.
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A little releaving of the bore edge will not hurt anything. I think the 4.1 gasket will work. A little closer to the 4.00 chamber width would not hurt. Hey pocket, Ls engines seldom use pop up pistons.
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Teching In
Joined: Oct 2010
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From: Topeka, Kansas
Head Gasket bore dia. I am getting ready to do a HC upgrade on my LS1. I am getting AFR 215 heads that require a larger gasket for the head chamber. I PM'd Tony at AFR and he said the larger gasket is what you want to run to take advantage of the air flow in the heads.
