Block diffrences?

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Nov 15, 2002 | 07:55 PM

'79ProwlerOrange

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From: Seattle WA

Block diffrences?

Is there any diffrence between the blocks of a 283-400? i know the bore/stroke are diffrent so i dont mean that, but a friend of a friend is telling him that a 305 cant be made into a 350 :confused: i was positive it was the same block. the only diffrences in blocks ive heard of is the LS1, and siameased(sp?) cylinders, and ive never heard of that for SBCs.

to make a 305 a 350 dont you just have to increase bore ro 4.000 and put a 350 crank in it? i think its 3.750 stroke, but i dont remember that for sure. :confused: :cheers:

Nov 15, 2002 | 07:59 PM

joeveto

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Re: Block diffrences? ('79ProwlerOrange)

Your friend is wrong, in that they all use the same block. A small block is a small block. A big block is a big block. On either, displacement is determined by the bore and the stroke.

Nov 15, 2002 | 08:03 PM

Corey_68

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Re: Block diffrences? ('79ProwlerOrange)

The only differences between the SBC's is the bore and stroke. This applies to the 283, 305, 327, 350.

The 400ci SBC has simeasedcylinder bores, and you are limited to the overbore. You can drill a set of 350 heads(steam holes) to work on a 400ci.

[Modified by Corey 68, 7:04 PM 11/15/2002]

Nov 15, 2002 | 08:38 PM

'79ProwlerOrange

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Re: Block diffrences? (Corey 68)

thats what i thought. i didnt know about the 400 being simeased though... good info :cheers:

Nov 15, 2002 | 09:03 PM

Flareside

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Re: Block diffrences? ('79ProwlerOrange)

The 400 also uses a larger main bearing size, so the block and crank are different from a 350, and they are not interchangable without work. There are actually 3 different main journal small blocks, so they are not all the same.

Nov 15, 2002 | 09:19 PM

Corey_68

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Re: Block diffrences? (Flareside)

Quote:

The 400 also uses a larger main bearing size, so the block and crank are different from a 350, and they are not interchangable without work.

True, the 400 is somewhat of an bastard engine. The cranks can be swaped amongst small blacks excluding the 400ci without trouble. 305/327/350, all swap, no problem. :cheers:

Nov 15, 2002 | 10:08 PM

fauxrs

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Re: Block diffrences? ('79ProwlerOrange)

I dont believe that a 305 can be bored out to match a 350 bore that would mean that the cylinder walls are at least 3/8" to 1/2" thick - which I guarantee they are not - most 305 blocks are considered a lightweight casting. and I dont think you could cool an engine very well with such a thick cylinder wall.

A 305 has a 3.74 bore - so you would need to bore at least 1/4" thats 250 thou compared to 30 to 60 thou the general max bore most people accept.

Yes the blocks are physically the same external dimensions, but the thickness of the castings vary. In the same vein a 350 cannot be bored to match a 400.

I think the definition of "the same block" needs to be better defined. All small blocks are not created equal. the 305 has the same stroke as a 350 but a much smaller bore - in fact it can be very difficult to tell the two cranks apart

Nov 16, 2002 | 08:46 AM

Flareside

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Re: Block diffrences? (Corey 68)

Quote:

True, the 400 is somewhat of an bastard engine. The cranks can be swaped amongst small blacks excluding the 400ci without trouble. 305/327/350, all swap, no problem. :cheers:

Corey, there are a few more things that you should be aware of. The 305 and 350 use the same main journals, but do not use the same balancing scheme, so the 305 crank would have to be rebalanced to run with 350 components. This doesn't seem like a big deal until you realize that this particular balance, when using hi performance rods, etc., will require "heavy metal", and will cost more than a Scat, Eagle, etc. brand new unit. IMO, stay away from 305 parts. Also, all 327s are not created equal. Some have small journals, and some have medium journals, so you really have to know what you've got.

Realistically, everything except for your everyday 350 is a "bastard" :lol:

[Modified by Flareside, 8:48 AM 11/16/2002]