862 head help
09-11-2015, 03:40 AM
#1
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862 head help I bought a set of heads off a 5.3 and didn't realize until after the fact that they were 862 and not 853. Now my question is are these going to be good heads? I plan on having them ported and polished...do I really need to upgrade to 2.0 valves? I am going to be using them with a tick performance sns stage 2 cam 227/235 .61x/.62x....everything I read keeps saying get 243/799 heads... I know these are better heads but I now have these 862 and I am going to use them and just curious what my options are and possible results....
Thanks in advance!
Thanks in advance!
09-12-2015, 08:32 AM
#2
Try a search, there's plenty of info on these heads. There are certain castings to avoid because they crack. There are some that need a specific head gasket or you will have a coolant leak.
They are capable of making good power. If you're going to replace the valves, you may as well go up to 2.02" and 1.60" valves, like from Ferrea or Manley. The smaller chambers will give you an advantage if you have a smaller engine and want to get the compression ratio up.
They are capable of making good power. If you're going to replace the valves, you may as well go up to 2.02" and 1.60" valves, like from Ferrea or Manley. The smaller chambers will give you an advantage if you have a smaller engine and want to get the compression ratio up.
09-12-2015, 08:39 AM
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I'm running PRC 5.3 heads. They are the 862 castings as well. Great head for the money IMO. Realistically 243/799 heads are only going to make about 10 hp more if the same 2ork has been done to them
09-12-2015, 02:37 PM
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FWIW, the 862 and 853 heads flow the same. The 706's are the ones I try to avoid. The 862 will have better compression. The compression will work will with that cam. If you really want to wake them up, do like HCI did and call PRC. Their head has a good reputation
09-17-2015, 11:05 PM
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The 862 is a good casting , not all 706s are bad , but you should have a 706 checked to be safe . But what I would try to stay away from , is the early notched 5.3/4.8 heads. With the notched heads you will need to run the proper corresponding gasket which will limit selection choices. As far as valves are concerned I would go with 1.94 intake and 1.57 exhaust. I believe the 2" is just a little too big for the small chamber, while it will fit and many have done it . Shroud becomes a problem once you go past 1.95 , if your on a budget you maybe able to have a 2" turned down to say 1.97 . But I would go with a aftermarket 1.94/1.95