Smaller mains sbc

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Little Mouse
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Smaller mains sbc

Post by Little Mouse »

So can a 2.45 main 4340 crank be ground down to the 2.30 size, assume doing the journal 2.00 not a problem.
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Re: Smaller mains sbc

Post by Walter R. Malik »

Little Mouse wrote: Tue Oct 29, 2019 12:19 pm So can a 2.45 main 4340 crank be ground down to the 2.30 size, assume doing the journal 2.00 not a problem.
Yes
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Re: Smaller mains sbc

Post by Little Mouse »

Walter R. Malik wrote: Tue Oct 29, 2019 5:11 pm
Little Mouse wrote: Tue Oct 29, 2019 12:19 pm So can a 2.45 main 4340 crank be ground down to the 2.30 size, assume doing the journal 2.00 not a problem.
Yes
So ok how did the 2.30 main 327 blocks main webs compare in strength to the later 2.45 main blocks.
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Re: Smaller mains sbc

Post by mag2555 »

What's your reason for looking at going to a main size this small besides friction?
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Re: Smaller mains sbc

Post by tenxal »

I'm using a 2.450 crank cut down to 2.300 in a Dart SHP block with no issues. Make note of the oil holes being centered, as mentioned by BLOCKMAN.
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Re: Smaller mains sbc

Post by Little Mouse »

The two blocks I already have and have had them in a garage since the mid 70s never used them one is a 68 one a 70 both have the 3482 nodular caps. While back I took both to a known good machine shop just had him clean them up, check them for cracks and my thought then if I used one was to bore it .030. So when I picked them up he said the mains were in spec could be used as is or I could line hone it my choice ( had already mentioned line honing to him ) one block he said needed .030 the other .060. He said something about the 68 block being worth a bit of money to someone running in a stock class. He did mention he had a 327 block but I asked no questions about it was not interested in it. I did build a 327 back mid seventies using a large journal 327 steel crank in a 350 4 bolt block .030 over. But I was thinking even these new Chinese steel 4340 cranks should be considerable stronger then any of the old factory cranks. Maybe cut one down to the smaller size and milodon still makes there nodular center main caps with splayed outer bolts for the 2.30 blocks. So I was wondering if the 327 blocks main webs were at least as good as the later blocks. Eagle is the only one I know of makes a reasonable priced 4340 crank in .3.25 stroke but uses the 2.45, 2.10 sizing. Will have to use this crank no matter what block I use.
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Re: Smaller mains sbc

Post by Little Mouse »

tenxal wrote: Thu Oct 31, 2019 8:41 am I'm using a 2.450 crank cut down to 2.300 in a Dart SHP block with no issues. Make note of the oil holes being centered, as mentioned by BLOCKMAN.
Shp block has 2.45 mains how did you accomplish this ?
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Re: Smaller mains sbc

Post by tenxal »

Little Mouse wrote: Fri Nov 01, 2019 10:07 am Shp block has 2.45 mains how did you accomplish this ?
A spacer between the main bores and the bearings.
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Re: Smaller mains sbc

Post by Little Mouse »

Who makes the spacers ? Me and a friend built a 348 cu. For his car putting 2.45 crank in 400 block with trw stuff. But that was mid 1970s.
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Re: Smaller mains sbc

Post by tenxal »

Little Mouse wrote: Fri Nov 01, 2019 2:55 pmWho makes the spacers ?
These are 2.450 main bearings line honed to fit the 2.300 bearings.
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Re: Smaller mains sbc

Post by Little Mouse »

How does that work the 2.45 bearings are already bigger dia. I would probably be better off just keeping the 2.45 main and cutting the rod journals to at least 2.00 size or maybe the 1.8 something size they call a honda size bearing.
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Re: Smaller mains sbc

Post by leahymtsps »

Little Mouse wrote: Fri Nov 01, 2019 10:07 am
tenxal wrote: Thu Oct 31, 2019 8:41 am I'm using a 2.450 crank cut down to 2.300 in a Dart SHP block with no issues. Make note of the oil holes being centered, as mentioned by BLOCKMAN.
Shp block has 2.45 mains how did you accomplish this ?
Clevite MS-1110H bearings

Tom
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Re: Smaller mains sbc

Post by Little Mouse »

leahymtsps wrote: Fri Nov 01, 2019 7:06 pm
Little Mouse wrote: Fri Nov 01, 2019 10:07 am
tenxal wrote: Thu Oct 31, 2019 8:41 am I'm using a 2.450 crank cut down to 2.300 in a Dart SHP block with no issues. Make note of the oil holes being centered, as mentioned by BLOCKMAN.
Shp block has 2.45 mains how did you accomplish this ?
Clevite MS-1110H bearings

Tom
Thanks will look them up at summit.
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Re: Smaller mains sbc

Post by Little Mouse »

Ya that would work there even chamfered. Will call a machine shop here in hell, or some prefer dfw tx. See what the cost to do it. Everytime I read about E-85 flex fuel the compression it would allow me to use on a 90/10 street car and its cooler intake air, think I'm going to use it.
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