Small Block & Big Block Chevy Specific Mouse & Rat Motor Discussion & Conversions

377 build

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Old Oct 18, 2012 | 01:16 PM
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Ok so I am wanting to do a 377 build that will be going into my 93 formula, and I know I might get ear full on why I want to do this but I was wanting to do it to, so I can do something different, now my question is, will anything from my lt1 be compatable? Also which would be the easiest way to do it, using a 350 block or a 400 small block becuase I have both already, but already have rods for the 400 block. Just wanting to get some people's opinions, thanks.
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Old Oct 18, 2012 | 05:25 PM
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I believe all factory smallblock 400's are two piece mains, so not even your crank from the LT1 will work because it is a one piece rear main seal. Mains on the 400 are bigger so you will have two options. One is a spacer setup that is staked in place with a bearing that rides on the spacer or a oversized single bearing. I used the spacers from Jegs with a .010 Clevette 350 bearing. I had no problems. Motor rev'ed well over 7000 with the short stroke and pushed my Nova to low 10's on a 100 shot. 11 o's N/A with a B&M superholeshot and 12 bolt 4.11's.
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Old Oct 18, 2012 | 06:19 PM
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Ok so I can't use anything from an lt1
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Old Oct 18, 2012 | 06:39 PM
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A 400 block .030 over with a 3.48 stroke crank, rods 5.7 or longer with 4.155 bore pistons with the proper compression height is how you make a 377. This is a big bore short stroke combo.

If you start with a 350 block then you will have a small bore long stroke motor. (383)
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Old Oct 18, 2012 | 08:08 PM
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Right. But will I still be able to use my lt1 intake??
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Old Oct 18, 2012 | 08:17 PM
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I dont know why you would want to but if you run your current heads, drill steam holes and run a reverse flow water pump I suppose it would work.
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Old Oct 19, 2012 | 06:54 AM
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LT1 blocks are different where the water pump bolts up. Don't think anything from a LT1 will fit an earlier SBC except the tranny and motor mounts.
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Old Oct 19, 2012 | 12:34 PM
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I built one years ago using a 4 bolt 400 block, and a 350 crank. I used the spacers and 5.7 rods with wisesco pistons. CR came in around 10.5:1 with 64 cc heads. Not a lot of low end, but it would really pull from 3K to almost 8K. I used and old Crane fireball cam and an original Torquer single plane intake (showing my age) Nothing from your LT1 will fit.
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Old Oct 19, 2012 | 05:13 PM
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Originally Posted by zboy2012
Right. But will I still be able to use my lt1 intake??
The intake has no hole for the distributor provision and the LT1 intake is not a direct bolt on to 86 or older Gen I head. Some people have managed to do it with an assload of machining but a good Victor Jr. or Weiand Team G would be half as cheap and make more horsepower.
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Old Oct 19, 2012 | 05:23 PM
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Originally Posted by beach cruiser
I built one years ago using a 4 bolt 400 block, and a 350 crank. I used the spacers and 5.7 rods with wisesco pistons. CR came in around 10.5:1 with 64 cc heads. Not a lot of low end, but it would really pull from 3K to almost 8K. I used and old Crane fireball cam and an original Torquer single plane intake (showing my age) Nothing from your LT1 will fit.
Nothing wrong with the Crane Cam or the Torquer intake. Back in the early 80's the combo you ran would smash just about anything on the streets minus an occasional built big block. I built a large journal 327 with a 350 4 bolt block in shop class. I was very proud of that cam, my Edelbrock Torquer, a 650 Holley doublepumper and 1.94 fuelie heads. It was pretty quick when backed up by good gears and a TH350 in a 64 Chevy II.
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Old Oct 23, 2012 | 06:51 AM
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Yeah, It smashed just about everything in the late 80's too! I ran it in front of a super T10 and a 3:55 rear in my 67 Camaro (now getting an LS1 Swap) I used 441 heads that I had 2.02/1.94 valves installed, then I worked over all the bowls and port matched everything. I also used a 650 mech secondary carb. I found a 750 was just a bit sluggish even though the 650 was a little small for the top end. I built it as a pro touring car with 255 dunlops on current year z28 rims. It had lots of suspension mods and would really carve the corners. I'd like to say I started the pro touring movement, but I built it after Big Red which I think may have been the first.

Here's a video before I pulled it out last fall to prove that it still runs!
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Old Oct 25, 2012 | 02:58 PM
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Originally Posted by cambirdracing
LT1 blocks are different where the water pump bolts up. Don't think anything from a LT1 will fit an earlier SBC except the tranny and motor mounts.
Misinformed. The bottom ends are interchangeable but not the top end. If you have an LT1 then do a LT1 build.
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Old Oct 26, 2012 | 10:43 AM
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Originally Posted by 93Euphoria
Misinformed. The bottom ends are interchangeable but not the top end. If you have an LT1 then do a LT1 build.
I should have stated just what you have. Block and heads are propietory to each other.
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Old Oct 26, 2012 | 11:31 PM
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Who sells a 377 kit?
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Old Oct 27, 2012 | 06:42 PM
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Originally Posted by f body lover
Who sells a 377 kit?
It's basically a 350 stock bore block and 400 stock stroke crank.
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Old Oct 28, 2012 | 11:14 AM
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Originally Posted by cambirdracing
It's basically a 350 stock bore block and 400 stock stroke crank.
Or the other way around. but just 30 over the 400 block
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Old Nov 1, 2012 | 07:30 PM
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Originally Posted by cambirdracing
It's basically a 350 stock bore block and 400 stock stroke crank.
What I meant was a 377ci destroked kit
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Old Nov 2, 2012 | 08:25 AM
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That would be a .030 over 400 block (4.155 bore) with a 350 (3.48 stroke) crank.

bore x bore x stroke x number of cylinders x .7854 = cubic inches
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