bracketracer

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.

PREDATOR-Z

You should use 6.0 head gaskets. 4.100 bore will be too large.

_GTO_

Will there be any losses in power if you use 4 bore chamber on 3.9 bore block ?

PREDATOR-Z

Why would you want to do that?

_GTO_

I don't want to do that but bracketracer did , so I thought it's a strange thing and want to know if this effects the performance .

bracketracer

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.

Pocket

iTrader: (22)

LS1's use pop-up pistons so chamfering the cyls probably isnt a good idea

ChucksZ06

iTrader: (9)

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.

Fastdriver1992

iTrader: (1)

use the 6.0l gasket. i did on my stock ls6 and it worked fine

bracketracer

Thanks for the info. I'll check out the 6.0 head gaskets.

bucketlist1957

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.

bracketracer

Thanks bucketlist1957! That's what I needed to hear.