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Old 12-18-2011, 04:49 PM
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hey guys me again need advice on this 6x-4 head question...

so my friend at chastain engines called me an said he had a set of heads for me late model 6x-4 heads there going on my stock 400. The heads have fererra valves there not ported but had somthing like that done for flow and hardened exhaust seat ..


My question is how much $$$ is to much for the head ,,,,i always pay to much later

second he said i would have to run dish pistions because the heads have small chambers ,,,is that wrong ,,?

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Old 12-18-2011, 05:22 PM
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Google those heads. It's my understanding Pontiac made two versions of the 6x heads, those stamped "8" had 100 to 105 cc heads used on the 400 motors, the "4" stamp heads were 91 to 95 cc, used on 350's, but not religiously. There were also different size valves, depending on what year.

Hopefully one of our Pontiac guys will chime in, but I don't consider that small by any standard. I calculate a standard bore 400, with flat pistons, 6 cc valve reliefs, .041 gasket, .025 in the hole and 91cc heads at approximately 8.36:1 c.r.

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Old 12-18-2011, 05:33 PM
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X 2 with 68 nova said , the 6x-4 are about 93 CC. You will have to mill about .045 -.050 to get up to around 9.5 to 1 static. Zero decking the block will be almost a neccesity, as you want to get a decent quench in your build also.
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Old 12-18-2011, 05:48 PM
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ok

yeah i dont know why he wants me to run dished pistions i think he is mistaken he is supposed to be a pontiac guy ?? thats why im worrye if he dosnt know this then wtf!!!!!!!!!!!!!
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Old 12-18-2011, 05:56 PM
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Forget the dish pistons, and dont get pistons with the 8 valve relief either, they are BUNK.
look at some KB or at least some speedpro.
You will want forged, and forged rods too. Its cheap insurance. Stock rods are actually OK for up to a 450 horse build, but until you pay to size them and put in ARP fasteners, you can spend about 75 bucks more and get all new 5140 RPM forged rods with 7/16 bolts. Plenty tough enough for a healthy street build. LA Tech
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Old 12-18-2011, 05:58 PM
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um

um do most do yall usually have to tell the machinest exactly what yo want done ???/ or should this guy know this already...
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Old 12-18-2011, 06:00 PM
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cause im going to have to tell him i want the block zero decked and to shave .50 off the block and he was the one telling me that i would need dished pistions.....
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Old 12-18-2011, 06:13 PM
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Get another machine shop.
You will need to do some checking before you zero deck the block.
Be certain when you pick a piston you get one that has a 1.720 compression height. Read up on the specs for pistons. Once you understand it makes it easy.
The compression height is the distance from the center of the wrist pin to the top of the piston. Basic rebuilder pistons have a comp height of 1.714 .... a full .006 thou lower than the stock height. AND with the stock height and stock deck height the pistons are all ready down in the hole about .023. so use the ones with the comp height of 1.72.
Either the y guy you are using doesnt have a clue or he has an old box of **** pistons he wants to unload on you.
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Old 12-18-2011, 06:24 PM
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The first thing that you need to do is cc the heads, then deck the block to 0. Use a compression calculator http://www.wallaceracing.com/cr_test2.php to figure out what you need to have to give you 9.0-9.5:1, then have the heads milled to give you that number. (Approximatlly .005" for every cc to be removed) If you need to mill the heads .020" or more, mill the intake side of the head an equal amount, so that the intake will line up. It might be a good idea to have the intake and/or the heads gasket matched, also. By the way, you do NOT want dished pistons with 6X heads! I also agree with latech, find a better Pontiac builder.

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Old 12-18-2011, 06:36 PM
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damn ... i live in clayton county GA and everyone else says this guys the **** and he is a pontiac fanatic this sucks .......
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Old 12-18-2011, 06:37 PM
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Summit has KB ICON performance pistons
IC890-030 are for a .030 over 400 pontiac. They have a comp height of 1.720. They only have a 4.5 CC valve relief, making it a little easier to get to you target compression ratio.
Also note that they have only 1 set of valve reliefs, and that my friend is a good thing if you want to build real good quench in your motor.
Stick around here, and ask lots of questions, and do your homework. You dont want to just throw a bunch of parts at a motor and be dissapointed when it is together.which is real likely if you dont get your build figured out first.
Relax, get a cup of coffee, get in front of the computer and get busy.
There are a bunch of pontiac build questions in the engine section, just search for the posts. Also look in the knowledge base for other good info. If you cant find what you need to know or have aquestion, post it here. One of the many pontiac guys will be glad to help. I amusually around in the evenings.....so.......
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Old 12-18-2011, 09:50 PM
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those are 475. a pistion hell no lool

cant afford that
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Old 12-18-2011, 10:11 PM
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Quote:
Originally Posted by corybuice
cant afford that
What pistons are $475.0 per piston?? Nothing that was suggested here that's for sure! You may have found a full set of 8 quality pistons for $475...

You mentioned taking .5 off the block? Unless that's a huge typo, you need to brush up on decimals, that's half an inch!
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Old 12-19-2011, 07:58 AM
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You can get a kit from summit that has those Icon forged flattops, pins and rings for $580 for the set of 8...that's about $72 per complete piston...not bad at all for forged pistons...I'm looking at those too...I have smaller heads, but at my elevation and with the cam I'm going to run I'll have a dynamic compression ratio of 7.7:1, plently low enough to run pump gas...and my machinist recommended them over the dished version of that piston...

Those should work fine with 6X-4 heads...don't pay too much for those heads, they are a fairly common head, used on the 350 and the W72 400...not as common as 6x-8's, but still not too hard to find.
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Old 12-19-2011, 07:58 AM
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The machinist/Pontiac guru may know more than you do when it comes to those PARTICULAR heads. Or he may be less than experienced when it comes to Pontiac heads, or is living in the past, when ~72cc chambers were common.

You need to find out (or better yet measure yourself) exactly what the chamber volumes actually are. These heads could have been milled to hell and back and now need to use dished pistons on a 400 build to keep the CR reasonable, for all you know. And if that's the case, I'd pass on them and keep looking for an unmolested set of 6X-4's, if those are the heads you want to build your 400 with.
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