Did other vehicles in the GM line up use the same block as the L-98 that I have in my 85? If so how do I find out which ones? Is if covered in a parts interchange manual? Ok, so it is more than one question.

 

I believe the block was the same 1957-1986 excluding a very few years, then 1987-1991 in Vette's, probably more, the LT-1 uses a different cooling passageway, and obviously the LS1 is completely different. Cheby trucks probably used the same block, excluding the LS variants, all the way from 1987 to present.

 

L98 is just the configuration of the entire engine... really has nothing to do with the block. Go get the casting number off the back drivers side of the block... directly behind the drivers cylinder head. Then go here to look up your casting number: http://www.mortec.com/location.htm My "L98" block was made from 80-85 in 2 and 4 bolt main configurations.


[Modified by billreid1@***.net, 1:33 AM 2/25/2002]

 

The reason that I am looking for one is that I am going to build another engine, and was going to try to get a block from a junk yard.

 

Then the site I just posted will give you all the info you'll need to select a good block. It also has head casting numbers further down the page. Good info. I'm looking for a 400 4 bolt main block to build a budget monster motor so 3951509 or 3951511 is what I'm looking for. I'm patient though... they are out there.

 

OrangeC4,
Are you more concerned with a compatable block, or an engine to build up?
Any fully complete gen I small block will bolt in place of your engine. The
question then becomes one of cubic inches and component compatability. As
an assembly, an '88 up with a roller cam and one piece rear seal, bolts in (with
the flywheel or flexplate). As a block purchase, those differences will have to
be dealt with. If you buy a used or core engine, everything works together,
as is. You just build what is there. To build a 350, you can start with any 4"
bore block starting from a 1962 327 through about, a 1991 350, including the
302's. The main bearing size changed in 1968, so anything earlier would
require a special crankshaft. In 1980, the dipstick was moved from the left
side to the right. It is a minor fitment problem, but some people don't want
to deviate from the origional look. Dipstick situation aside, I would just look
for any 350 long block core. If 4 bolt mains are desired, the truck engines
had a much higher percentage of (all?) 4 bolt usage. When you can tell me
exactly what and how you want to do this, I (and others) can help you sort
out the details. I have a similar, albeit protracted project of my own.

billreid1
I stand to be corrected, here, but I don't think 400, 2 and 4 bolt blocks share
casting numbers, like the 4" bore engines can. Only in the 4.125" block
family, the 4 bolt block is the weaker of the two. The main bearing webs and
bulkheads are thinner and weaker in the 4 bolt block. Because this is a basic
difference in the main casting, I can't imagine that they share casting
numbers. I have a 3159509 block. It is 2 bolt mains. I really don't believe
that CHEVY made a 4 bolt with that casting number. If you are looking for a
good strong block, stay away from the 400, 4 bolt. If you feel that you need
more strength than the 2 bolt block can provide, you can install Chevy 4 bolt
caps on your 2 bolt block. The next step up is the billet steel after market
caps. Beyond that, it's an after market racing block. I KNOW I'm right about
the block strengths, we'll see about the casting numbers. Good luck.


[Modified by CFI-EFI, 1:55 PM 2/25/2002]

 

I am looking for a compatible block that I can do a switch with, and swap the heads over to the new one aswell as most of the parts that I currently have on my engine right now. I am trying to this without buying too many things right now and change the other things out later.

 

Accessory, wise I can't think of any differences, off hand. Accessories depend mostly on long or short water pump and head castings. The main things to watch out for are the previously mentioned dipstick location, rear main seal type, and roller lifters. Then your present crank, heads, cam, etc will fit without modification. I have to admit, I still don't really get what you're up to, but I think I've answered your question, in any case. I hope is helps. Have fun.

 

CFI-EFI,
Check the Mortec website I posted earlier in the thread... it states:

"3951511....400...70-73...4...Some replacement blocks had 2-bolt main caps"

Where Mortec got this info is beyond me... and would agree with you that standard castings did not come in both 2 and 4 bolt configuration for the 400 block. I also agree with you that the standard 2 bolt blocks (converted to 4 bolt) are actually stronger than as cast 4 bolt blocks. I had heard this on several occasions but also have been rebuffed on the same subject. I will continue to look for 2 and 4 bolt blocks. The odds of me finding a 4 bolt 400 are not nearly as good as me finding a 2 bolt block. I have a complete 80 Corvette 350 sitting in the shed thanks to one of my fellow forum buddies. I haven't checked the casting number on it yet but would assume it to be 2 bolt. My goal is to build at least a 406. If I don't find a 400 block for the right price I'll probably build a 396 out this 350 I already have... converting it to a 4 bolt splayed cap. Any other advice would be much appreciated :yesnod:

 

Instead of doing an engine swap, I just want to swap the block and the internals. I don't want to pull my engine take out the internals then put the new parts in, because it will take too long, so I am going to build the block how I want and swap the other parts on to it. That way all I have to do is pull the engine that I have now and swap the necessary parts that I need from it to the new block.

 

Actually there are very many differences in blocks from 57-86. One a 57 has a different bore size, an 86 has a one piece rear main seal (all of them). Also the L-98 block was used on the corvette maybe first in 82'. They have pass side oil dipsticks and the 80-81's did not. If you want a good block to build on find you either a two bolt or 4 bolt 0010 block. This is what they used in the Corvettes from 69-76. Unlike the L-98 blocks it is not a mexican cast block, and the 0010 has a thicker casting around the cylinders. You will have to change your pan to use a driver side oil tube but is only a small change for the extra dependability you get out of the earlier block.