Curious 400 block vs. 350?

Imo Apita

Imo Apita

Well-known member
Joined
Feb 28, 2009
Messages
244
Needs some help with some basic questions here.
Can't use the 350 block for a 383 build because of a chunk of cylinder wall missing.
Found a 400 4 bolt block on my local craigslist. Block only, nothing else, asking $250.
I understand that a 400 is a bolt in for a 350 so no issues there. However for the 350 I intended to use a 383 stroker kit with a 3.750 crank.

Can I use this crank in a 400?
From Hotrod forums:
350 and 400 blocks use different main journal diameters: 2.45 inches for the 350; 2.65 inches for the 400. However, the rod journal diameters are the same at 2.100 inches.

A 350 crank will fit in a 400 block with bearing spacers (available from speed equipment suppliers etc. for about $50). With a 4.125-inch bore and 3.75-inch stroke, this will produce 372 cubic inches, or 377 ci with a .030 overbore
Click to expand...

So a 030 overbore on a 400 block with a 3.75 crank will give you 377 ci?
I sit necessary for steam holes to be drilled when using aluminum heads?

Bottom line is am I better of with a 377 (of 400) or a 383 (of a 350)?
If I can buy a 4 bolt 400 for the same $$ as a 350 with which one am I better of?
This is supposed to be a low budget build to replace my ailing L48.
 
I am happy with the engine I got 12 years ago....a all roller 355 factory 4 bolt '89 truck block forged flat slugs TRW, being factory rollers they use the better dawg bone retainers....best heads I have had on there are the old L98 stock heads...aluminum #113 casting....for some odd reason the headers don't even come loose on them, go figger....

I would rather have a torquey roller cam than just raw CI....

:goodnight:
 
Imo Apita said:
Needs some help with some basic questions here.
Can't use the 350 block for a 383 build because of a chunk of cylinder wall missing.
Found a 400 4 bolt block on my local craigslist. Block only, nothing else, asking $250.
I understand that a 400 is a bolt in for a 350 so no issues there. However for the 350 I intended to use a 383 stroker kit with a 3.750 crank.

Can I use this crank in a 400?
From Hotrod forums:
350 and 400 blocks use different main journal diameters: 2.45 inches for the 350; 2.65 inches for the 400. However, the rod journal diameters are the same at 2.100 inches.

A 350 crank will fit in a 400 block with bearing spacers (available from speed equipment suppliers etc. for about $50). With a 4.125-inch bore and 3.75-inch stroke, this will produce 372 cubic inches, or 377 ci with a .030 overbore
Click to expand...

So a 030 overbore on a 400 block with a 3.75 crank will give you 377 ci?
I sit necessary for steam holes to be drilled when using aluminum heads?

Bottom line is am I better of with a 377 (of 400) or a 383 (of a 350)?
If I can buy a 4 bolt 400 for the same $$ as a 350 with which one am I better of?
This is supposed to be a low budget build to replace my ailing L48.
Click to expand...

if you have the 400 block why not build it with the long stroke of the 383/400 and build a 406? why de-stroke the 400? cubes are king. hell i wish i could start over and build a 496..... or better yet something 540+
 
A 350 crank will fit in a 400 block with bearing spacers (available from speed equipment suppliers etc. for about $50). With a 4.125-inch bore and 3.75-inch stroke, this will produce 372 cubic inches, or 377 ci with a .030 overbore
Click to expand...

I think that's a typo in your quote.

Guess where that 3.75" crank for the 383 came from originally. Yep, a 400SB. 3.75" is the original crank stroke for a 400SB.

A 400 crank in a 350 yields a 383, a 350 crank in a 400 yields a 377 (with .030 overbores). A 400 crank in a 400 yields a 400 (or 406 with a .030 overbore) :)

No reason to destroke it. 400's run very well when the bottlenecks are removed.
 
No reason to destroke it. 400's run very well when the bottlenecks are removed
Click to expand...
Good point.
Question is are the bearing sizes the same on a 3.750 stroker kit crank the same as the 400?
Before I get myself (and everybody here) confused;
I planned on getting a 383 stroker kit for my 350.
Can I use that 3.75 crank, 5.7 rods and pistons in the 400?
Being Sunday night I can't call them just yet, this is the kit:
http://cgi.ebay.com/ebaymotors/SBC-...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

Question is how different are the 400 from the 350 blocks?
Just different bore and stroke?
Can I use a 350 intake on a 400? 350 headers on a 400?
 
For 250.00 you can buy a roller cammed 350 short block, then buy a ZZ-383 cola crank and notch the block for clearance. Then the longer throw of the ZZ383 crank with standard 350 bore & rods makes 383CI
 
My friend took a 1989 L-98 block that I had and had it drilled for splayed 4 bolts, notched for the zz-383 crank, carrillo 6" rods, bored .030 over, AFR 215 heads, 8.0:1 compression then he is putting some ATI procharger on it and some TPIS bigmouth intake, Tpis full exhaust, SLP runners.

Guess he wants to find out how fast he can grenade either his ZF 6 speed or his dana44 :trumpet::trumpet:
 
If that block still needs machining (I assume it does) then it's not THAT good deal....

You can buy a machined roller cam 1pc rms 350 block (,030" over) for $600-$700... maybe even less.... a new 350 block from Summit is $850 shipped...

Just food for thoughts, good machine work isn't cheap.. figure $400-$500 to hone and bore the block incl crack testing (now that doesn't sound right)... NDE or magnetic particle testing of course... that bumps your $250 block close to what you pay for a new 350 block :smash:

a cheap cast 383ci rotating assembly is usually $1000 at Summit, maybe $800 on Ebay - you can buy a assembled 383ci short block for $1400-$1500

IMO not worth the pain to build your own unless you do it for fun...
 
I decided to go with a 383 over a 400 because I don't like siamesed cylinder bores. And siamesed cylinder bores don't like boost.
 
To build a 383 you use the crank [mains turned to 350 size], rods and balancer from the 400 in a 350 block. Gotta buy special pistons with a higher pin placement. If you really have a [super rare] 4 bolt block I'd definately build the 400. I would build the 400 anyway. I like cubic inches. Just don't use the original heads, weak castings, hence the bad rep that 400's have. Drilling steam holes is no big deal.

I just re-read your orig post. I see your just looking at a bare block. I would still consider building a 400 for the displacement if you plan on spending a litlle extra money to build a nice engine. You''ll have to buy rods and pistons anyway, look at buying the longer rods. Not that I'm sold on the benifits of a long rod engine but the theory is there and you would be looking at about the same price. And nowdays splurge on a roller cam set too.
Frank
 
383/400?

a couple of years ago I bought a L98 block from a 98 chevy van,had 4 bolt mains(a hundred bucks @ a local yard),used a cheap stroker kit from Scat had the block bored .030,used a gm hi torque cam(hyd roller)ended @ 9.5 to 1 comp. ratio with Vortec heads.Runs very well,When I started the build I looked @ 400 blocks and was told that if I used one I should long rod it because the 400 used short rods and because of that if they saw high rpm use they scuffed the cyl. walls out,also they have more piston noise.I've never owned or operated a 400 so I have no experience with them.But my 383 is a nice mellow mannered torque monster,pulls hard from 2000 up to 5500,like a freight train.Hope that helps a bit.
$250 sounds pretty high for a bare block,unless its ready to go(cleaned,completely stripped,oiled down & ready to be machined).
Gimpy
 
2 bolt 400s are a better casting than the 4 bolt ones , not all, the 509 is a nice one, they are only stronger if you install spayed caps though
 
IMO, you're better off with the 400 simply because of the extra cubes...You'll never regret that extra power.

I've got aluminum heads and the engine builder opened up the steam holes.
 
Finally an email from the seller:
Its a 400 4Bolt Main I have the main caps No other parts This is a performance block and needs to be bored to 0.40 over..I have the water pump I will throw in.. its set up to cool the center cylinders.
Click to expand...

Something I don't like about this......

And I found two 350-ies on craigslist, $250 for both of 'em.
One 040 over the other one stock, decisions......:sweat:
 
It has been a while but there were at least two bearing manufacturers that made main bearings to use a 350 shaft in a 400 block. They came standard and plus 10 and 20.

I have a friend that used a 400 block and custom innards and came up with a 421 that produced well over 500 horse power on pump gas and a single four barrel carburetor.

Rich:thumbs:
 
Building that 400 is the expensive way to go. It would be fine if thats what you gotta have but it sounds to me like you would be just as happy if you went to a good engine shop and had them build you a mild to hot 350. Better heads if you want. That's generally the most economical way to go, or like MYBAD says check into some Summit engine kits.
 
00fxd said:
Building that 400 is the expensive way to go. It would be fine if thats what you gotta have but it sounds to me like you would be just as happy if you went to a good engine shop and had them build you a mild to hot 350. Better heads if you want. That's generally the most economical way to go, or like MYBAD says check into some Summit engine kits.
Click to expand...

I don't know about the cost being more. The first 400 I built was only $12.00. Using the same block with new aluminum heads I put about $1500 in it using Scat rods.

The difference between a 400 and a 350 (every thing else being the same) is quite surprising. Using the same cam, compression ration, intake, and carbs I was able to break into the 11s with the 400. The best I could do with the 350 was low 12s.

A 400 with good heads and good compression with either 5.7 or 6 inch rods-- I prefer 6 inch-- is the only engine I build for my Vette now. You have Big Block Power with Small Block Weight.:drink:
 
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