connecting rod side clearance
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New User
Joined: Mar 2018
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From: Pahrump, NV
connecting rod side clearance
I'm building a bored & stroked 460 (504 cuin) to replace the 351W in my F250. The 359W and the E4OD are on their "last legs".
I installed a Lunati forged steel crank and a set of 6.8" Chevy rods.(also from Lunati)
Upon checking my clearances I found the connecting rod side clearance to be 0.026". the Ford OEM spec is 0.0100 - 0.0200.
So I'm 0.006" on the "loose" side. Is this a serious problem ???
I installed a Lunati forged steel crank and a set of 6.8" Chevy rods.(also from Lunati)
Upon checking my clearances I found the connecting rod side clearance to be 0.026". the Ford OEM spec is 0.0100 - 0.0200.
So I'm 0.006" on the "loose" side. Is this a serious problem ???
Posting Guru
Joined: May 2010
Posts: 1,146
Likes: 17
From: Central Indiana
I'm building a bored & stroked 460 (504 cuin) to replace the 351W in my F250. The 359W and the E4OD are on their "last legs".
I installed a Lunati forged steel crank and a set of 6.8" Chevy rods.(also from Lunati)
Upon checking my clearances I found the connecting rod side clearance to be 0.026". the Ford OEM spec is 0.0100 - 0.0200.
So I'm 0.006" on the "loose" side. Is this a serious problem ???
I installed a Lunati forged steel crank and a set of 6.8" Chevy rods.(also from Lunati)
Upon checking my clearances I found the connecting rod side clearance to be 0.026". the Ford OEM spec is 0.0100 - 0.0200.
So I'm 0.006" on the "loose" side. Is this a serious problem ???
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New User
Joined: Mar 2018
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From: Pahrump, NV
connecting rod side clearance
Thanks for your honest but painful reply. I'll contact Lunati, who like Scat & Eagle get their forging from communist china.
Why can't we make forgings here in the U.S. They may cost more, but it would be a lot cheaper than billet.
Why can't we make forgings here in the U.S. They may cost more, but it would be a lot cheaper than billet.
Cargo Master
Joined: Mar 2010
Posts: 3,328
Likes: 292
From: Laramie, WY
I found this discussion interesting:
http://www.fordmuscleforums.com/all-ford-techboard/419651-connecting-rod-side-clearance-how-much-too-much.html#/topics/419651?page=1
edit: realized you (Ray) said nothing of pressure, my mistake. More precisely, what do you mean by oiling?
Posting Guru
Joined: May 2010
Posts: 1,146
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From: Central Indiana
I don't follow how a 0.010" vs 0.026" opening will change oil pressure, when oil flows through a 0.0025" bearing to get there.
I found this discussion interesting:
Connecting rod side clearance... How much is too much? - Ford Muscle Forums : Ford Muscle Cars Tech Forum
edit: realized you (Ray) said nothing of pressure, my mistake. More precisely, what do you mean by oiling?
I found this discussion interesting:
Connecting rod side clearance... How much is too much? - Ford Muscle Forums : Ford Muscle Cars Tech Forum
edit: realized you (Ray) said nothing of pressure, my mistake. More precisely, what do you mean by oiling?
And yes, that wider rod side clearance can influence oil pressure. The wider the side clearances, the wider the gap that oil can escape past. The faster the oil can escape, the lower the overall oil pressure in the engine will be. Those gaps/clearances were determined by engineers to allow a prescribed volume of oil to leak past bearings, etc. to provide enough oil flow for cooling/lubrication but not be so wide the pressure is too low for longevity.
I hope that explanation wasn't as clear as mud. Been a while since I've taught automotive theory..
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New User
Joined: Mar 2018
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From: Pahrump, NV
connecting rod side clearance
Thank you all for your replies. I called Lunati Cams and the tech support person said not to worry the extra .006"
is need to allow for rod expansion as the engine heats up.
I also called my machinist who did the initial work on the block and he also said that much clearance is "normal" for
non-stock high performance rods. His shop specializes in high performance and all out racing engines.
So I'm satisfied. I also have a Jon Kaase BBF heavy duty oil pump that should provide adequate oil pressure.
is need to allow for rod expansion as the engine heats up.
I also called my machinist who did the initial work on the block and he also said that much clearance is "normal" for
non-stock high performance rods. His shop specializes in high performance and all out racing engines.
So I'm satisfied. I also have a Jon Kaase BBF heavy duty oil pump that should provide adequate oil pressure.
Laughing Gas
Joined: Aug 2002
Posts: 1,069
Likes: 19
From: Central Wisconsin
Nothing to worry about... I have two sets of ex-NASCAR RO7 Pankl rods to use in a SBM race motor... I have about .030 side clearance. Won't be a problem. We used to worry about stuff like this but it's been proven not to matter much.
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Posting Guru
Joined: May 2010
Posts: 1,146
Likes: 17
From: Central Indiana
Thank you all for your replies. I called Lunati Cams and the tech support person said not to worry the extra .006"
is need to allow for rod expansion as the engine heats up.
I also called my machinist who did the initial work on the block and he also said that much clearance is "normal" for
non-stock high performance rods. His shop specializes in high performance and all out racing engines.
So I'm satisfied. I also have a Jon Kaase BBF heavy duty oil pump that should provide adequate oil pressure.
is need to allow for rod expansion as the engine heats up.
I also called my machinist who did the initial work on the block and he also said that much clearance is "normal" for
non-stock high performance rods. His shop specializes in high performance and all out racing engines.
So I'm satisfied. I also have a Jon Kaase BBF heavy duty oil pump that should provide adequate oil pressure.
Can't say I have any familiarity with Lunati, Scat or Eagle cranks; I always use Moldex Billet cranks for my stroker builds. My father started using them in 1965, I bought my first Moldex crank for a FE 427 Ford in 1973, stock stroke to run in the 7 Liter Hydroplane class. I think we ran something like .015" clearance on steel rods, Ford LeMans? Too long ago to remember everything. Forged aluminum rods were used the next year, I needed about .030" clearance to keep from binding at full temperature. This was also a dry sump application on a supercharged, alcohol & 'some' nitro engine that would turn upwards of 8,500 rpm. 60 pound relief spring in the pump, Kendall GT-1 straight 50w oil or on a hot day, half and half 50w and 70w.
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New User
Joined: Mar 2018
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From: Pahrump, NV
connecting rod side clearance
The main feature of his oil pumps is strength plus steady oil pressure
I haven't checked out Moldex cranks. All I know is billet cranks from Sonny Bryant, Calles, Crower, et al have all been out of my price range.
Besides I'm not running a full race machine so a billet crank is overkill for me.
But I'll check out Moldex just out of curiosity.
It's a shame this country has let the Chinese take over our forging industry. I'll write SEMA and suggest they form a coalition of maufacturers
such as Crower, Edlbrock, and others and find foundries here that can forge cranks.
I haven't checked out Moldex cranks. All I know is billet cranks from Sonny Bryant, Calles, Crower, et al have all been out of my price range.
Besides I'm not running a full race machine so a billet crank is overkill for me.
But I'll check out Moldex just out of curiosity.
It's a shame this country has let the Chinese take over our forging industry. I'll write SEMA and suggest they form a coalition of maufacturers
such as Crower, Edlbrock, and others and find foundries here that can forge cranks.
Posting Guru
Joined: May 2010
Posts: 1,146
Likes: 17
From: Central Indiana
The main feature of his oil pumps is strength plus steady oil pressure
I haven't checked out Moldex cranks. All I know is billet cranks from Sonny Bryant, Calles, Crower, et al have all been out of my price range.
Besides I'm not running a full race machine so a billet crank is overkill for me.
But I'll check out Moldex just out of curiosity.
It's a shame this country has let the Chinese take over our forging industry. I'll write SEMA and suggest they form a coalition of maufacturers
such as Crower, Edlbrock, and others and find foundries here that can forge cranks.
I haven't checked out Moldex cranks. All I know is billet cranks from Sonny Bryant, Calles, Crower, et al have all been out of my price range.
Besides I'm not running a full race machine so a billet crank is overkill for me.
But I'll check out Moldex just out of curiosity.
It's a shame this country has let the Chinese take over our forging industry. I'll write SEMA and suggest they form a coalition of maufacturers
such as Crower, Edlbrock, and others and find foundries here that can forge cranks.
More Turbo
Joined: Oct 2009
Posts: 596
Likes: 58
From: West Plains, MO
Side clearance doesn't matter at all (within reason of course), as long as it's big enough when at full operating temperature. Before the availability of Mopar width but Chevy journal diameter rods, many Mopar enthusiasts have run Chevy rods on turned down cranks, resulting in nearly .080" side clearance, and their oil pressure is the same. As someone already pointed out, the .002-.003" clearance in the bearing is what determines the amount of flow through it!
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