391 cubic inch small block? ? ?
Thread Starter
Drifting
Joined: Oct 2001
Posts: 1,439
Likes: 4
From: Kewaskum Wisconsin
391 cubic inch small block? ? ?
I came across an 87 vette for sale with a 391 cubic inch motor. What is the recipe to build a SBC and come out with 391 cubes?
Is the build a lot different vs a 383?
Thanks.
Is the build a lot different vs a 383?
Thanks.
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
Likes: 71
From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Actually it figues out closest to a 3.875 w/ a .010 overbore. A 3.80 w/ a .040" bore is under 390 and with a .060" bore close to a 394.
Drifting
Joined: Mar 2002
Posts: 1,251
Likes: 2
From: Thomson Georgia
Bore X Bore X Stroke X 0.7854 X # cyls = cu in displacement
4.001 X 4.001 X 3.875 X 0.7854 X 8 = 389.753203547 cu in
4.020 X 4.020 X 3.875 X 0.7854 X 8 = 393.46372296 cu in
4.030 X 4.030 X 3.875 X 0.7854 X 8 = 395.42368866 cu in
4.030 X 4.030 X 3.75 X 0.7854 X 8 = 382.6680858 cu in
4.030 X 4.030 X 3.80 X 0.7854 X 8 = 387.770326944 cu in
Whew! Too damn much math, especially on your fingers !!!
johnny
get em' chris
My new project
4.125 X 4.125 X 4.00 X .7854 X 8 = 427.6503 cu in
I rounded down cause 428 sounds like a ford.
4.001 X 4.001 X 3.875 X 0.7854 X 8 = 389.753203547 cu in
4.020 X 4.020 X 3.875 X 0.7854 X 8 = 393.46372296 cu in
4.030 X 4.030 X 3.875 X 0.7854 X 8 = 395.42368866 cu in
4.030 X 4.030 X 3.75 X 0.7854 X 8 = 382.6680858 cu in
4.030 X 4.030 X 3.80 X 0.7854 X 8 = 387.770326944 cu in
Whew! Too damn much math, especially on your fingers !!!
johnny
get em' chris
My new project
4.125 X 4.125 X 4.00 X .7854 X 8 = 427.6503 cu in
I rounded down cause 428 sounds like a ford.
Last edited by johnnyevans; Mar 22, 2006 at 01:03 AM.
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Le Mans Master
Joined: Jul 2001
Posts: 8,183
Likes: 3
From: Santa Maria, CA
I have one. Crank is 3.835 throw, with 6" H-beams, and pistons are .030 over.
It's for sale too
http://classifieds.nitromater.com/sh...2&cat=3&page=1
It's for sale too
http://classifieds.nitromater.com/sh...2&cat=3&page=1
Burning Brakes
Joined: Nov 2005
Posts: 848
Likes: 1
From: 1992 LT1 6 speed Cayman Islands
Originally Posted by 89 Paul in Cal
I have one. Crank is 3.835 throw, with 6" H-beams, and pistons are .030 over.
It's for sale too
http://classifieds.nitromater.com/sh...2&cat=3&page=1
It's for sale too
http://classifieds.nitromater.com/sh...2&cat=3&page=1
Now we know.
Racer
Joined: Oct 2003
Posts: 304
Likes: 0
From: Marlboro NY
Originally Posted by 89 Paul in Cal
I have one. Crank is 3.835 throw, with 6" H-beams, and pistons are .030 over.
It's for sale too
http://classifieds.nitromater.com/sh...2&cat=3&page=1
It's for sale too
http://classifieds.nitromater.com/sh...2&cat=3&page=1
Seems like an awful lot more trouble to gain only 8 more cubes.
More so than buying a Stroker kit like I did.
Drifting
Joined: Mar 2002
Posts: 1,251
Likes: 2
From: Thomson Georgia
Yep, went to small journal rods, slows bearing speed a wee bit.
If he'd stayed large journal, the crank would have had to be welded, which would have been a real waste, probably still had to go 0.040 under on the rod bearings. Expensive way to do it, unless the crank had a journal nicked and had to be cut anyways and you picked up the crank real reasonable.
If he'd stayed large journal, the crank would have had to be welded, which would have been a real waste, probably still had to go 0.040 under on the rod bearings. Expensive way to do it, unless the crank had a journal nicked and had to be cut anyways and you picked up the crank real reasonable.
