706 heads
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Teching In
Joined: Feb 2016
Posts: 27
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From: New Hampshire
706 heads I asked about some 317 heads a few weeks ago and was advised to stay away given my N/A plans for my 2000 t/a. I have a chance to pick a set of 706 heads from a 2006 5.3 and a intake from a 2002 for $200. Comes with coil packs. The motor it came from had 80k on it before a lifter went bad. Would these be worth picking up and having them ported/polished and bigger valves installed given what I can buy the heads for? Wasn't planning on using the intake and could sell that to make up for the cost of the package. Any thoughts, suggestions or advice will, again, be greatly appreciated.
Thread Starter
Teching In
Joined: Feb 2016
Posts: 27
Likes: 0
From: New Hampshire
Stock ls1. No aftermarket cam yet but will be a 228r. 1 7/8 headerso, ory, slp loudmouth are all that is done to the car so far. Have been on the hunt for a ls6 intake and 243's but came across these today. Won't be using the intake that is being sold with the 706'same, still looking for a ls6.
Well don't know who advised you not run 317s they are probably the most overlooked of all LS heads and best bang for the buck imo. But as for the 706 , some concerns are the castech casting and I would stay away from notched heads also. If these are the original heads off a 2006 5.3 most likely you be ok on both counts. But I would always advise having them checked before install. As for the bigger valves there is a recent thread on this subject just a couple weeks ago.
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Joined: Mar 2014
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From: Ohio
$200 for 706 heads?
I'll ship you some for $125, you'll have to reuse your coil packs/valve covers.
706 heads flow slightly less on the exhaust side than your stock heads, but they raise compression.
317 heads flow slightly more, but drop compression a good bit.
Having your stock heads milled will you get the compression of 706 heads without the loss of flow.
I'll ship you some for $125, you'll have to reuse your coil packs/valve covers.
706 heads flow slightly less on the exhaust side than your stock heads, but they raise compression.
317 heads flow slightly more, but drop compression a good bit.
Having your stock heads milled will you get the compression of 706 heads without the loss of flow.
True , many guys dismiss these due the issues I mentioned earlier but they offer a lot potential once worked over. the 706 is not a bad head , but should be checked, in one aspect , in stock form it is a better casting than the 862.
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$200 for 706 heads?
I'll ship you some for $125, you'll have to reuse your coil packs/valve covers.
706 heads flow slightly less on the exhaust side than your stock heads, but they raise compression.
317 heads flow slightly more, but drop compression a good bit.
Having your stock heads milled will you get the compression of 706 heads without the loss of flow.
I'll ship you some for $125, you'll have to reuse your coil packs/valve covers.
706 heads flow slightly less on the exhaust side than your stock heads, but they raise compression.
317 heads flow slightly more, but drop compression a good bit.
Having your stock heads milled will you get the compression of 706 heads without the loss of flow.
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To the op. The 5.3 706 heads have a lot of great potential! I would have them ported or at the very least have your local shop do a valve job and put your LS1 valves in them. If you're planning on running the TSP cam I'd talk to them about porting your heads too. If you send them the heads it's actually not that expensive.
They do flow more, just like the LS6 but they also have around a 72cc combustion chamber. What you lose in compression will overshadow any gains from the added flow. Btw, just to clarify this, I've seen this internet myth over and over that bolting on stock ls6 heads will gain a ton of power. That is simply not true. You gain some flow and you gain a little compression. But on your standard LS1 it's about 10rwhp. That's a lot of work and $ into swapping heads for 10hp. Don't believe the hype. Do not read too much into flow numbers. There's much more to a head than just that.
To the op. The 5.3 706 heads have a lot of great potential! I would have them ported or at the very least have your local shop do a valve job and put your LS1 valves in them. If you're planning on running the TSP cam I'd talk to them about porting your heads too. If you send them the heads it's actually not that expensive.
To the op. The 5.3 706 heads have a lot of great potential! I would have them ported or at the very least have your local shop do a valve job and put your LS1 valves in them. If you're planning on running the TSP cam I'd talk to them about porting your heads too. If you send them the heads it's actually not that expensive.
Agreed the 706 needs to be touched up , to see any gains over LS1 stuff. As for a 2" valve I would not recommend it without chamber work . I would not go larger than say 1.95 . This was discussed just last month here in another thread .
Milling a head that far DRASTICALLY reduces the cam that can be run due to piston to valve clearance. Not recommended for someone wishing to run a cam his size. Also are you telling me everyone that runs over a 2" valve in their 5.3 heads (tea, tsp, ai, etc) are wrong?? 
Milling a head that far DRASTICALLY reduces the cam that can be run due to piston to valve clearance. Not recommended for someone wishing to run a cam his size. Also are you telling me everyone that runs over a 2" valve in their 5.3 heads (tea, tsp, ai, etc) are wrong??