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  #1  
Old 06-26-2000, 01:08 AM
mopardude mopardude is offline
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Does anyone know what the absulute min.piston the head clearance i can run on a 360?This engine has forged wiseco flat tops with steel rods and x heads?? I keep hearing different stories what do you think?
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  #2  
Old 06-26-2000, 01:39 AM
DusterDave DusterDave is offline
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Cool

As a general rule, with steel rods, .040". I am in the process of building a 440, and that is the number I am using. I'm no smallblock expert, but are the X head chambers open style? If so, you have nothing to worry about.

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  #3  
Old 06-26-2000, 03:36 AM
Gene Gene is offline
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Dont know myself but I am putting 340xheads on a new chrysler performance 360 shortblock with 10.1 pistons. The pistons are flattops with deep valve recesses and my cam has a 5.09 lift at valve. I contacted Chryslers tech advisors where I purchased the shortblock and they told me I needed a min. of 32 thous. piston to head clearance and not to use a thin head gasket. They advised me to use gasket P-4529454. Now I havent gotten all my valve train done so I havent turned my engine yet to see if they were right. Dont know if this helps, Gene
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  #4  
Old 06-26-2000, 07:23 PM
sanborn sanborn is offline
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We have always used .035" clearance with the stock type rods and had good success. Use a sandwich type gasket which is .036-.040" thick.
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  #5  
Old 06-26-2000, 07:57 PM
Maxwedge Maxwedge is offline
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I just saw a really kinda cool way to check this clearance..stack a feeler gauge to the tolerance number then place it inbetween the valve tip and the rocker arm then rotate the engine slowly, if it hits..then you know what you have to do..read this method in a hotrod mag. Havent had a chance to do it myself, but it looked good on paper..
Maxwedge
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  #6  
Old 06-26-2000, 09:10 PM
ChristianCuda ChristianCuda is offline
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MaxWedge that works real good with Piston to Valve clearance but need a different measurement for Piston To Head.

Christian

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68 'Cuda 383 Formula S recreation
Working on adding EFI
69 'Cuda Race Parts Car
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95 Neon 2.0 SOHC best of 16.96
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  #7  
Old 06-27-2000, 12:11 AM
Maxwedge Maxwedge is offline
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Misuderstood..my bad
maxwedge
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  #8  
Old 06-27-2000, 04:53 AM
JOHN SHERRED JOHN SHERRED is offline
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.035 thirtyfive thousandths is the magic number but you better be right on with your figures
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  #9  
Old 06-29-2000, 02:59 AM
440 demon 440 demon is offline
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Biggrin

Just picked my 440 short block up from engine
builder last night,.040 over eagle h-beam rods,10.0 to 1 comp. srp forged pistons ,we measured piston to deck height it was .010" they said not to use thin steel head gaskets use the thicker felpro.
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  #10  
Old 07-11-2000, 10:35 AM
PRO PRO is offline
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Im pushing the envelope at .032 with a 4 spd with no contact at 6800 rpms(steel rods) .035 has always been the rule of thumb...PRO..
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  #11  
Old 07-13-2000, 03:28 AM
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440 Jim 440 Jim is offline
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FYI,
For my 440, the Arias Pistons reccommend 0.040 for steel rods and 0.055 for aluminum rods. 360 should be similar, maybe 0.005 less.
One technique if you plan to use compositon head gaskets (0.039-0.042) is too put a head on without the gasket, and slowly rotate the engine. If the head bolts are loose, you need to check for the slightest (dial indiacator?) movement of the head. If tight bolts, be very careful, aluminum dings easily.

Confucious says, "Assembly should take 4 times longer than disassembly"
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[This message has been edited by 440 Jim (edited July 12, 2000).]
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  #12  
Old 07-13-2000, 04:49 AM
340king 340king is offline
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I assume that your compression ratio is about 10.5:1. This can make a difference. The clearance is most critical when an engine is wound up without a load on it. Like at the end of the quarter or end of the straight away. Typically, the cylinder pressure drops and allows the rod/piston to extend slightly, not to mention the associated thermal loading(expansion) after a full throttle thrash.

Higher compression engines retain more cylinder pressure than low compression engines in this scenario and may offer a little bit of margin. Also the stroke has an effect on the piston speed(momentum) prior to stopping at tdc.

My recommendation is to go with .040" and stay a little on the safe side.
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  #13  
Old 07-13-2000, 06:02 AM
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23T-Wedge 23T-Wedge is offline
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In line with 340-Kings thoughts about piston speed and momentum is the weight of the piston. i.e. more weight, more rod stretch, hence the need for more piston to head clearance. An alloy rod has more elasticity than a steel rod, that's why they usually recommend more clearance, although GRP says their aluminum rods can go .040 p to h on a low deck 482 I'm building. They are great looking rods and I've heard nothing but good things about GRP but I'm still skittish about running them that tight. Anyway, back to the original question, on a small block short stroke motor .035 is probably safe,especially if Sanborn recommended it. He's forgotten more about small-blocks than I'll ever know and their Mopar dirt car flies. Just remember the longer the stroke the more piston speed per rpm, static piston weight and reciprocating piston weight being two different animals. In other words, the reciprocating piston weight of a 4 inch stroke engine is more than that of a 3.5 stroke with the same static piston weight so the rod is going to stretch more, thus the need for more clearance. Hope I'm making sense. They say your memory is the second thing to go.........I forget what the first is.
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  #14  
Old 07-20-2000, 05:29 PM
Fly Boy Fly Boy is offline
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I am building a 440 with KB quench doam pistons and the magic number is .040 like the other guy's said.
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  #15  
Old 07-21-2000, 01:57 AM
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Brian_wo Brian_wo is offline
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Quote:
Originally posted by Fly Boy:
I am building a 440 with KB quench doam pistons and the magic number is .040 like the other guy's said.
That is what KB says but other brands like Ross say .055,I think thats a bit much and they use it to save their own butt.
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