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Re: Cylinder wall thickness??
[Re: Madness]
#1306566
09/18/12 09:59 PM
09/18/12 09:59 PM
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Joined: May 2005
Posts: 6,446
NJ-USA
HPMike
master
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master
Joined: May 2005
Posts: 6,446
NJ-USA
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Quote:
What is considered minimum for cylinder wall thickness on a 470 low deck stroker, no nitrious,
7.1" rod? I have a block that's betwen .133" & .153" on the minor thrust on #8 cycl. .157" on #2 minor thrust. .169" On #1 major thrust.
Rest of block is .188" to .259"
If you plan on making more than around 600 horse and its a dedicated race engine, id fill that block. You'll make more power too!
MB
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Re: Cylinder wall thickness??
[Re: Jwilli500]
#1306572
09/19/12 11:39 AM
09/19/12 11:39 AM
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Joined: Jan 2003
Posts: 75,418
A gulag near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,418
A gulag near you.
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Quote:
 Sounds ta bit long huh. I dont guess I've seen a .92 CH Piston before...
Quote:
7.1 rod in a low deck? 
Exactly , I don't think one could even get a piston made with that short a CH , the pin will be into the second ring land , ???
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Re: Cylinder wall thickness??
[Re: Thumperdart]
#1306574
09/19/12 01:03 PM
09/19/12 01:03 PM
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Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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Quote:
I remember reading that one of the bigger builders out there shot for no less than .100 on major thrust side up to around 600 hp. Been there done that and have been fine........... 
Everything I've seen says a major thrust surface needs to be .200" at a minimum.
I don't recall what "acceptable" thicknesses for minor thrust or non-thrust surfaces are, but .100" doesn't sound right for those, either.
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Re: Cylinder wall thickness??
[Re: Madness]
#1306575
09/19/12 01:06 PM
09/19/12 01:06 PM
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Joined: Aug 2003
Posts: 8,716
Baltimore/Denver
64Post
master
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master
Joined: Aug 2003
Posts: 8,716
Baltimore/Denver
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Quote:
It appears you guys are correct & I am wrong on the 7.1" rod. I just called Diamond & Randy said they couldn't fit the ring stack in that C.H. I was getting my info from an old High Performance Mopar magazine article (July 2000, P.53) written by Frank Licari. He goes on about the 7.1 rod (#CRS7100C3D) & a dished Diamond 2618 piston w/ .990" pin. Said it gave a rod angle of 1.82 on the 3.90" stroke.
Years ago I was ordering a set of pistons from Diamond for my 470. I mentioned I intended to add a small nitrous kit, & they talked me into using a 6.7 rod so they could move the ring stack down out of the heat. My pins are into the oil ring grooves using bridges.
Now I'm really confused. May be one of those articles where the motor was never really put together. I know there have been several articles written by a local machinist & our local GM parts dept. about wild Chevy combinations, complete with pictures, that never were assembled. Sold lots of parts, though.
May have been a simple typo. Several guys, myself included, are running the 6.7 Chevy rod in a low deck. It's a fairly common and well running combo.
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Re: Cylinder wall thickness??
[Re: BradH]
#1306577
09/19/12 01:23 PM
09/19/12 01:23 PM
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Joined: Nov 2003
Posts: 7,348
Mt.Vernon ,Ohio
VernMotor
master
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master
Joined: Nov 2003
Posts: 7,348
Mt.Vernon ,Ohio
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Quote:
Quote:
I remember reading that one of the bigger builders out there shot for no less than .100 on major thrust side up to around 600 hp. Been there done that and have been fine...........
Everything I've seen says a major thrust surface needs to be .200" at a minimum.
I don't recall what "acceptable" thicknesses for minor thrust or non-thrust surfaces are, but .100" doesn't sound right for those, either.
Do not think you ever find a block that is .200"
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Re: Cylinder wall thickness??
[Re: 64Post]
#1306578
09/19/12 01:57 PM
09/19/12 01:57 PM
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Joined: Jan 2003
Posts: 75,418
A gulag near you.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 75,418
A gulag near you.
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Quote:
Quote:
It appears you guys are correct & I am wrong on the 7.1" rod. I just called Diamond & Randy said they couldn't fit the ring stack in that C.H. I was getting my info from an old High Performance Mopar magazine article (July 2000, P.53) written by Frank Licari. He goes on about the 7.1 rod (#CRS7100C3D) & a dished Diamond 2618 piston w/ .990" pin. Said it gave a rod angle of 1.82 on the 3.90" stroke.
Years ago I was ordering a set of pistons from Diamond for my 470. I mentioned I intended to add a small nitrous kit, & they talked me into using a 6.7 rod so they could move the ring stack down out of the heat. My pins are into the oil ring grooves using bridges.
Now I'm really confused. May be one of those articles where the motor was never really put together. I know there have been several articles written by a local machinist & our local GM parts dept. about wild Chevy combinations, complete with pictures, that never were assembled. Sold lots of parts, though.
May have been a simple typo. Several guys, myself included, are running the 6.7 Chevy rod in a low deck. It's a fairly common and well running combo.
The article might have been talking about an RB block ? That is the rod of choice for some RB combos , but no way, no how in a low deck.
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Re: Cylinder wall thickness??
[Re: JohnRR]
#1306579
09/19/12 02:26 PM
09/19/12 02:26 PM
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Joined: Aug 2003
Posts: 44,208
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 44,208
Bend,OR USA
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Quote:
Quote:
Quote:
It appears you guys are correct & I am wrong on the 7.1" rod. I just called Diamond & Randy said they couldn't fit the ring stack in that C.H. I was getting my info from an old High Performance Mopar magazine article (July 2000, P.53) written by Frank Licari. He goes on about the 7.1 rod (#CRS7100C3D) & a dished Diamond 2618 piston w/ .990" pin. Said it gave a rod angle of 1.82 on the 3.90" stroke.
Years ago I was ordering a set of pistons from Diamond for my 470. I mentioned I intended to add a small nitrous kit, & they talked me into using a 6.7 rod so they could move the ring stack down out of the heat. My pins are into the oil ring grooves using bridges.
Now I'm really confused. May be one of those articles where the motor was never really put together. I know there have been several articles written by a local machinist & our local GM parts dept. about wild Chevy combinations, complete with pictures, that never were assembled. Sold lots of parts, though.
May have been a simple typo. Several guys, myself included, are running the 6.7 Chevy rod in a low deck. It's a fairly common and well running combo.
The article might have been talking about an RB block ? That is the rod of choice for some RB combos , but no way, no how in a low deck.
My 512 has 6.8 long BB Chevy type rods in it with the 4.300 long stroke crank I would love to build and dyno test a low deck with a 3.91 long stroke with a 7.100 long rod  Can you say super lightweight pistons 
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Cylinder wall thickness??
[Re: Cab_Burge]
#1306580
09/19/12 03:12 PM
09/19/12 03:12 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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9.980 - 7.100" = 2.880" for 1/2 of stroke plus compression height.
The smallest compression height with which I am familiar is 1.000" in some smallblock engines, pushing the envelope, like a 4" crank and 6" rod in a chevy 350.
So you take your 2.880 and subtract 1" = 1.880"
2 x 1.880 = 3.76" stroke.
This is an undoable package unless you are going to use 0.927" or smaller diameter pins. Anyway, there's no need to because you don't need that long a rod in a B engine.
Spend the few bucks it takes to buy Streetwize's engine book. I believe he likes the 6.535 bigblock chevy + 0.400" rod in a B engine.
I have really backed off my "long rods are best" ideas after seeing short rod engines with really big heads taking the Enginemasters competitions. I know Smokey is dead and unable to defend his theory, but I think that late engines are showing us that shorter rod ratios are practically better, to the point that the B rod 451 looks better than the RB rod 451 for everyday use. John Kaase would be the leader on this rethink.
As for cylinder wall thickness, if you have a new World block you may see 0.300" walls, but on an OEM Mopar bigblock you'll be lucky to see 0.200" on all 8 holes, anywhere.
If you can keep the major thrust to 0.170" and never go below 0.100" on any portion of any hole, it should be OK. A few years ago a major builder looked at a number of 400 blocks and found that most of them had 7 good holes and one that needed sleeving. I have read accounts here of a "cold weather" 400 block that had a cylinder with less than 0.090" on one bore, with the bore standard sized.
It was traditional to think that Mopar blocks were hell for stout and cylinder walls were no problem, but that was before sonic checking became affordable. Now we can see how bad the castings really were!
That's analagous to the new thinking about heads that has come from having flowbenches on every streetcorner. Now we know how bad those B/RB heads really were.
Also about 10 years ago it surprised everyone to see that a mostly stock 440 really did make about 325 hp. Before there was a dyno in every garage, it was easy to imagine much more.......
The good old days are now!
R.
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Re: Cylinder wall thickness??
[Re: dogdays]
#1306581
09/20/12 04:14 PM
09/20/12 04:14 PM
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Joined: Jan 2003
Posts: 426
Ransom Canyon, Texas
Madness
OP
mopar
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OP
mopar
Joined: Jan 2003
Posts: 426
Ransom Canyon, Texas
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I was after the longest rod possible without getting into the oil ring groove. I hoped to lessen the side loading on the thrust side of the cylinder walls.
For kicks, here is a copy of a couple of pics & text from the article I mentioned.
Last edited by Madness; 09/20/12 04:15 PM.
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Re: Cylinder wall thickness??
[Re: Madness]
#1306582
09/20/12 05:29 PM
09/20/12 05:29 PM
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Joined: Aug 2003
Posts: 8,716
Baltimore/Denver
64Post
master
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master
Joined: Aug 2003
Posts: 8,716
Baltimore/Denver
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Quote:
I was after the longest rod possible without getting into the oil ring groove. I hoped to lessen the side loading on the thrust side of the cylinder walls.
For kicks, here is a copy of a couple of pics & text from the article I mentioned.
Since the article presumably makes no mention of turning the mains down to B block size, but does mention the offset grinding, I can only conclude the article is referring to a raised block.
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It tested like yours 
I would use yours with no fill in a hot second
It made 612 HP to start with on CA pump gas with ported big valve 906 iron heads 
