Re: Offset gring a cast 360 crank??
[Re: all spooled up]
#869131
12/02/10 11:34 AM
12/02/10 11:34 AM
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Joined: Feb 2005
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Menomonee Falls
DemonDust
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Menomonee Falls
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Sounds like you went thru alot of work to put a 360 crank in a 340..... Kasey, My buddy has ground quite a few cast cranks with no issues. Not sure what the owners are putting them thru though 
Last edited by R5P7Duster; 12/02/10 11:39 AM.
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Re: Offset gring a cast 360 crank??
[Re: Moparnut426]
#869132
12/02/10 11:51 AM
12/02/10 11:51 AM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
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Romeo MI
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Quote:
A buddy of mine wants to built a circle track engine on a tight budget. He has a nice NOS 72 360 crankshaft, and has a sweet set of w2 heads, and he is only limited on a cam, has to be a flat tappet, and ci limited to 400. Has anyone ever offset ground a cast 360 crank with any success?
Thanks
Kasey
Since 400ci is the limit he would be better off getting
a 3.79 forged crank(I dont think they make it in
cast) but that would put him alot closer to the
400ci... he could even have it off ground to put
him right there but I dont think that part is worth it
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Re: Offset gring a cast 360 crank??
[Re: Moparnut426]
#869135
12/02/10 12:34 PM
12/02/10 12:34 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
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Quote:
He doesnt want exactly 400, but the figure of 385" is good. He told me 389 ci, but might have the block bored already.
Kasey
offset grinding to a 2" (327 chev) journal will get you to about 3.7" stroke, which will be 378 CID on a 30 over 360...
now, offset grinding a 4" crank to de-stroke, using a 2" journal would get you down to about 3.88" stroke, and would yield 396 CID.
other thoughts....use a 318 block.
smaller main bearings=less friction. easy to find, later ones seem to be much more consistent as far as core shift...poly blocks allegedly are thicker, some can be bored .090 over....
.030 over with a 4" crank=390 CID, .060 over with a 4" crank=396 CID. at that point it's bore is only .030 under a 360's
Diamond and Icon (KB forged) make shelf flat top pistons for this combo, which should yield ~10.5-11.5:1 depending on your W2's comb. chamber...
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Offset gring a cast 360 crank??
[Re: patrick]
#869136
12/02/10 01:03 PM
12/02/10 01:03 PM
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Moparnut426
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His problem is parts, he has the crank, has the heads, has access to many blocks, has a set of rods. He dosnt have a ton of cash to spend on a crank. His dad is a machinist i guess, so machining is not an issue.
I have tried the polly block theory, but for some reason the main webs on a poly 318 are not solid, they have holes cast into the webbing. Dont know how stron the bottom end would be. I know they will go to a 4.00 bore pretty easily, but strength is an issue.
Kasey
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Re: Offset gring a cast 360 crank??
[Re: Moparnut426]
#869138
12/02/10 03:12 PM
12/02/10 03:12 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
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Quote:
His problem is parts, he has the crank, has the heads, has access to many blocks, has a set of rods. He dosnt have a ton of cash to spend on a crank. His dad is a machinist i guess, so machining is not an issue.
I have tried the polly block theory, but for some reason the main webs on a poly 318 are not solid, they have holes cast into the webbing. Dont know how stron the bottom end would be. I know they will go to a 4.00 bore pretty easily, but strength is an issue.
Kasey
I wasn't talking about the poly to maximize bore, but to maximize wall thickness--some say LA318's get a little thin when going .060 over....
a cast SCAT 4" crank is ~$350 or so. a nice K1 forged 4" crank can be had for ~$700-800 IIRC.
what kind of rods does he have? to offset grind a crank, unless you weld up the journals to re-grind, the rods have to be smaller journals than the starting crank....if he has chrysler rods (2.125" journals) or large SBC (2.1" journals), he's not going to realistically get any meaningful displacement increase by offset grinding.
also, when offset grinding, you'll have oddball compression heights, which means custom pistons, which could get spendy....saving $400 on a crank and spending $500 additional on custom pistons is penny wise and pound foolish.
cheapest way to get close to 400 cubes without going over is going to be a 318, 4" crank, and these pistons
if you plan on staying under 600 hp and 7500 RPM, I'd use this crank
that's $800 for a 4" crank and forged flat top pistons for a 318 block...how much are you going to spend getting custom compression height pistons for a 3.7" stroke 360?
Last edited by patrick; 12/02/10 03:17 PM.
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Offset gring a cast 360 crank??
[Re: patrick]
#869139
12/02/10 03:42 PM
12/02/10 03:42 PM
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Moparnut426
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Quote:
Quote:
His problem is parts, he has the crank, has the heads, has access to many blocks, has a set of rods. He dosnt have a ton of cash to spend on a crank. His dad is a machinist i guess, so machining is not an issue.
I have tried the polly block theory, but for some reason the main webs on a poly 318 are not solid, they have holes cast into the webbing. Dont know how stron the bottom end would be. I know they will go to a 4.00 bore pretty easily, but strength is an issue.
Kasey
I wasn't talking about the poly to maximize bore, but to maximize wall thickness--some say LA318's get a little thin when going .060 over....
a cast SCAT 4" crank is ~$350 or so. a nice K1 forged 4" crank can be had for ~$700-800 IIRC.
what kind of rods does he have? to offset grind a crank, unless you weld up the journals to re-grind, the rods have to be smaller journals than the starting crank....if he has chrysler rods (2.125" journals) or large SBC (2.1" journals), he's not going to realistically get any meaningful displacement increase by offset grinding.
also, when offset grinding, you'll have oddball compression heights, which means custom pistons, which could get spendy....saving $400 on a crank and spending $500 additional on custom pistons is penny wise and pound foolish.
cheapest way to get close to 400 cubes without going over is going to be a 318, 4" crank, and these pistons
if you plan on staying under 600 hp and 7500 RPM, I'd use this crank
that's $800 for a 4" crank and forged flat top pistons for a 318 block...how much are you going to spend getting custom compression height pistons for a 3.7" stroke 360?
I was told he has a set of king 6.3" rods with small chevy pin size, so that might be an issue.
And the Poly 318 I looked at was out of a 65 dodge coronet.
Kasey
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Re: Offset gring a cast 360 crank??
[Re: Moparnut426]
#869140
12/02/10 04:55 PM
12/02/10 04:55 PM
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Joined: Jan 2003
Posts: 16,123
Grand Haven, MI
patrick
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I Live Here
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Grand Haven, MI
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Quote:
Quote:
Quote:
His problem is parts, he has the crank, has the heads, has access to many blocks, has a set of rods. He dosnt have a ton of cash to spend on a crank. His dad is a machinist i guess, so machining is not an issue.
I have tried the polly block theory, but for some reason the main webs on a poly 318 are not solid, they have holes cast into the webbing. Dont know how stron the bottom end would be. I know they will go to a 4.00 bore pretty easily, but strength is an issue.
Kasey
I wasn't talking about the poly to maximize bore, but to maximize wall thickness--some say LA318's get a little thin when going .060 over....
a cast SCAT 4" crank is ~$350 or so. a nice K1 forged 4" crank can be had for ~$700-800 IIRC.
what kind of rods does he have? to offset grind a crank, unless you weld up the journals to re-grind, the rods have to be smaller journals than the starting crank....if he has chrysler rods (2.125" journals) or large SBC (2.1" journals), he's not going to realistically get any meaningful displacement increase by offset grinding.
also, when offset grinding, you'll have oddball compression heights, which means custom pistons, which could get spendy....saving $400 on a crank and spending $500 additional on custom pistons is penny wise and pound foolish.
cheapest way to get close to 400 cubes without going over is going to be a 318, 4" crank, and these pistons
if you plan on staying under 600 hp and 7500 RPM, I'd use this crank
that's $800 for a 4" crank and forged flat top pistons for a 318 block...how much are you going to spend getting custom compression height pistons for a 3.7" stroke 360?
I was told he has a set of king 6.3" rods with small chevy pin size, so that might be an issue.
And the Poly 318 I looked at was out of a 65 dodge coronet.
Kasey
he might luck out then...6.3" rods, 3.7" stroke yields a compression height of 1.45" for a 9.6" deck.
Diamond makes a shelf piston with a chevy pin that would be .007" out of the hole:
http://www.campbellenterprises.com/parts.php?type=search&query=dia51027
1976 Spinnaker White Plymouth Duster, /6 A833OD
1986 Silver/Twilight Blue Chrysler 5th Ave HotRod **SOLD!***
2011 Toxic Orange Dodge Charger R/T
2017 Grand Cherokee Overland
2014 Jeep Cherokee Latitude (holy crap, my daughter is driving)
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Re: Offset gring a cast 360 crank??
[Re: all spooled up]
#869142
12/02/10 07:30 PM
12/02/10 07:30 PM
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Joined: Nov 2004
Posts: 4,330
Lynchburg, VA
Leon441
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master
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Lynchburg, VA
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If blocks are not a problem just bore a good 360 block to 4.100" and stay with a stock stroke. That makes a 378. I ran one for years. Or bore to 4.100" and and offset grind the rods to gain a little more. Chrysler rod bears are not available with a lot of undersize. I think .020" is the smallest so 2.100" chevie peices may be the choice.
Career best 8.02 @ 169 at 3050# and 10" tires small block power.
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