Re: Different size Cam Journals.... 55mm 60mm ect
[Re: ragingram]
#659084
04/02/10 04:58 PM
04/02/10 04:58 PM
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Joined: Nov 2006
Posts: 637
Kokomo,IN
StripeHOG
mopar
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mopar
Joined: Nov 2006
Posts: 637
Kokomo,IN
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i think the purpose is for less flex
Andrew Brough D372
1969 Dodge Dart GTS
1.43 60'best
6.82 1/8 98mph
"the light came on and I ran out of talent"
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Re: Different size Cam Journals.... 55mm 60mm ect
[Re: StripeHOG]
#659085
04/02/10 05:33 PM
04/02/10 05:33 PM
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Joined: Jan 2003
Posts: 6,151
Melbourne , Australia
LA360
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master
Joined: Jan 2003
Posts: 6,151
Melbourne , Australia
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The cam core is larger and allows for more aggressive lobe profiles due to the larger base circle.
From memory there is a durabond coated Babbitt bearing that allows the use of a 55mm camshaft in a tunnel for a roller 50mm tunnel. If you are having to bore the tunnel, speak with your machinist.
AL...
Alan Jones
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Re: Different size Cam Journals.... 55mm 60mm ect
[Re: ragingram]
#659088
04/02/10 09:10 PM
04/02/10 09:10 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
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Master
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Romeo MI
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Its both... lift and flex... I have the 50mm roller bearings in my SB.... the cam bores are straight through (all the same size)... other than boring the cam tunnel its fairly easy to put the bearings in... I made a alum plug that the bearing fits over with a shoulder on it and used a threaded rod through the plug with a plate at the end of the engine... they all pulled in nicely. You might be able to go 60mm but check what cam blanks are out there for you 
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Post deleted by Defbob
[Re: ragingram]
#659089
04/02/10 09:22 PM
04/02/10 09:22 PM
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Anonymous
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Post deleted by Defbob
[Re: ragingram]
#659091
04/02/10 11:36 PM
04/02/10 11:36 PM
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Re: Different size Cam Journals.... 55mm 60mm ect
[Re: LSP]
#659094
04/04/10 08:38 AM
04/04/10 08:38 AM
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Joined: Jun 2009
Posts: 705
Michigan
Hemiroid
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super stock
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Michigan
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Quote:
The Davis Bros. used to run IHRA PS way back with a 426 based Hemi, they had a 4.800" bore space KB raised cam solid block 704" motor that was a 4.600" x 5.300" combo, with a Ti or steel you get some room for more stroke.
I'd use the largest flat cam bearing (60mm?) I could fit in the block and find cam cores for. The roller baring allows you to take some oil away from the cam bearing area, but other than that, I don't see any advantage, I'd rather have the larger cam core with that bulky valvetrain and the pressure necessary to contol it.
I'm sure the roller bearing in a PS engine takes the tension from 1500+ lbs of open spring load and 10,000 RPMs better than the slider does as well.
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Re: Different size Cam Journals.... 55mm 60mm ect
[Re: Hemiroid]
#659096
04/04/10 10:03 AM
04/04/10 10:03 AM
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Joined: Oct 2007
Posts: 4,213
New York
polyspheric
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New York
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A roller has far less load-bearing area than a plain bearing for the same OD, but doesn't require pressure to float the cam. The starter drag on a plain cam is higher until you have pressure at the journals.
Boffin Emeritus
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Re: Different size Cam Journals.... 55mm 60mm ect
[Re: polyspheric]
#659097
04/04/10 10:44 AM
04/04/10 10:44 AM
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Joined: Apr 2005
Posts: 1,107
Quebec, Canada
Diablo
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super stock
Joined: Apr 2005
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Quebec, Canada
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It said in DTHEMI article that it had a 55mm cam. And with the lobe size he gave and the rocker ratio he gave the cam lifts in the mid .900's
So what is the max cam journal size you can go with a KB raised cam block? I've got a 5 inch Bryant crank with GRP alum rods.
My 636ci right now only has a standard size and i'll be looking at going 55mm next year but if i could go 60mm i might as well. Unless there is something i'm missing.
I think Ragingram and I have nearly the same bottom end except mine is a 4.840 block
Last edited by Diablo; 04/04/10 10:47 AM.
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Re: Different size Cam Journals.... 55mm 60mm ect
[Re: Diablo]
#659098
04/04/10 06:10 PM
04/04/10 06:10 PM
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Joined: Oct 2004
Posts: 3,097
back in Georgia
dthemi
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The cam in my 654 is 55MM, and bigger would be more stable, and better. It didn't limit lift really, it just meant it would have to come from more rocker ratio and I didn't want to murder the springs with more lift. Also the valve pocket gets really close to the top ring land even with a back cut top ring in a hemi. Having a 5" stroke I wanted as long a rod as possible so more lift would mean sacrifices elsewhere in the motor including a worse rod angle than it already has, and the ring package is already jammed up as high as possible. 2:1 rocker ratios are common in other motors, and much easier to deal with with a wedge. Also the 5" with a 55MM means notching the rods to clear the cam. Another problem is there isn't much meat in a BBM for a huge dia cam. the front bearing gets thin and weak. even though most of the force is directed down where there is meat, it's hard to keep enough press for the bearing without supporting it by adding material. The oiling path in some blocks, and depending on whether you oil through the pushrod or not are also factors. A KB block looses its oil path in the last journal when you go to big journal, and you have to cut a path behind where the bearing goes. World and indy require their own mods to make it work. If you oil up through the head you'll need to cut a path there as well.
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Post deleted by Defbob
[Re: LSP]
#659100
04/05/10 09:51 AM
04/05/10 09:51 AM
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Re: Different size Cam Journals.... 55mm 60mm ect
#659102
04/05/10 06:04 PM
04/05/10 06:04 PM
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Joined: Aug 2003
Posts: 1,314
Charlotte, NC
LSP
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pro stock
Joined: Aug 2003
Posts: 1,314
Charlotte, NC
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Quote:
Quote:
The Davis Bros. used to run IHRA PS way back with a 426 based Hemi, they had a 4.800" bore space KB raised cam solid block 704" motor that was a 4.600" x 5.300" combo, with a Ti or steel you get some room for more stroke.
I'd use the largest flat cam bearing (60mm?) I could fit in the block and find cam cores for. The roller bearing allows you to take some oil away from the cam bearing area, but other than that, I don't see any advantage, I'd rather have the larger cam core with that bulky valvetrain and the pressure necessary to contol it.
Not with 10.725 deck, or 4.8 bore space. Think about it, 4.6 bore on 4.8 center, .1 between cylinders,,,,I don't think so. 5.3 stroke?? do they have little men pushing the rings back in place when they come out the bottom
there's a guy that ran a 695 inch motor .
I kept these notes on what it took in deck height to do it. he made spacers to add the height
Quote:
Regarding deck ht., I ran 11.225" & 11.800" (with aluminum spacer plates on the block). The 11.800 ht. was likely overkill once the pistons were finally light enough, but it did allow me to get a 7.800"+ rod in it - which again probably isn't needed if the piston is light enough. I initially had a lot of skirt wear (specifically piston rock at the bottom of the stroke) and the longer the rod, the better they lived
Your calculator is broken, a 4.600" bore on a 4.800" bore space block = .200" between cylinder bores. They had issues with the aluminum between the cylinders always cracking but that's what it was. I said it was a 426 based motor, I didn't say what the deck height was. And a 5.300" stroke isn't as hard as you think, if you don't build a fuel motor to go bracket racing with, then there are a lot of possibilities - steel rods, smaller rod journals, these all help make room.
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