3969854 engine block

[Kristoffer]

Hello

I friend of mine have a cbb Engine. It was assembled and it sopposed to be an 454. We took it apart, and found a 454 crank, 3/8 rods ect. But the casting is a 3969854, late 69 block, 4-bolt. I have looked all over the internet and in books, and the casting numbers tell it is a 396 (402) block, becasue it doesnt have the huge reliefs into the bottom of te cylinders as the 454 block has.
This block was also 0,30 bored, 4,280", how is this possible? Ive Heard of 396 bored out to 454 (4,250), but 454 + 0,30?

And this casting #854 with 4-bolt main, from what I can understand it is a L78 block? correct? The block it decked and there is no vin where the oilfilter is. It there any other way to tell what sort of block it is?

Thank You
Kristoffer

[69 Post Sedan]

854 blocks came in trucks too, so it could be a 4-bolt main truck block.

Do the pistons have any numbers on them? If so, do some research on them.

If not, I'm assuming someone had custom pistons made for the 454 crank. Very sneaky but very cool. <<GRAEMLIN_URL>>/naughty.gif

Kurt

[WILMASBOYL78]

309 [402] with a 454 crank is not an uncommon set-up...basically a &quot;stroked 396&quot;. If you go on the web and type in &quot;396 stroker BB&quot; you will see lots of info. A stock 454 cast crank is fine for most builds...if you have a forged one, use it. Depending on the over bore you can end up with a 434 or 440 CID engine. You will probably need to do some grinding on the lower part of the block for clearance...if you have a 4 bolt L78 block, then the reliefs should already be cut in the top of the bores for the bigger valves. This combo will make lots of torque with a &quot;sneaky&quot; presentation&quot;. Of course, most folks will argue that it is just as cheap to build a stroked 454..but, many of us have a soft spot for the little rat.

wilma <<GRAEMLIN_URL>>/3gears.gif

[Kristoffer]

Yes, but the bore is 4.280&quot;, how is it possible on a 396 block?

[Kristoffer]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 69 Post Sedan</div><div class="ubbcode-body">854 blocks came in trucks too, so it could be a 4-bolt main truck block.

Do the pistons have any numbers on them? If so, do some research on them.

If not, I'm assuming someone had custom pistons made for the 454 crank. Very sneaky but very cool. <<GRAEMLIN_URL>>/naughty.gif

Kurt </div></div>

Here is some pics on the pistons, I dont know what brand they are...

http://i115.photobucket.com/albums/n288/krillecheva/20140323_1347591_zps9c1b3277.jpg
http://i115.photobucket.com/albums/n288/krillecheva/20140323_1347271_zps9f4d4d09.jpg
http://i115.photobucket.com/albums/n288/krillecheva/20140323_1347131_zps88d0b45e.jpg

[WILMASBOYL78]

I'm sorry...guess I didn't understand your first post correctly. I know there are some #854 blocks that will go to 4.250...we have one. But, I've never seen one .30 over that....Could be somebody got carried away and didn't know what they were doing. <<GRAEMLIN_URL>>/hmmm.gif

I would suggest double checking the bore size and trying to find a part number on the pistons to confirm the specs...If it truly does have a 4.280 bore...I would have it sonic checked before using it...that thing must have awful thin walls after all that machining.

wilma

[Kristoffer]

I have measured the cylinders with a real bore indicator, I dont have the numbers here now, but the cylinders was about 4,278&quot;, and the pistons is marked 0,30.

I dont know if its Worth using this block on a hi perf 454 build

[WILMASBOYL78]

Well...if that's the size then the only thing left to do is have the block sonic checked for the wall thickness. Any competent machine shop can do this for you...along with having the block magged to check for cracks. If the walls are too thin, you will have constant overheating issues and eventually one of those cylinders will crack.

454 blocks are plentiful here in the states...not sure where you are, but it might be better to source another block to start with.

wilma

[Kristoffer]

Yes, Im going to try to find someone who can sonic test the block.

As you say, maybe it is better to build on a &quot;real&quot; 454 block.

[Kristoffer]

If the walls are to thinn, is it Worth saving the block? How rare is it when its 4-bolt? The block could go to a machine shop for sleevs....

[WILMASBOYL78]

Sleeving down for 396/402 application might be ok...what is the market for these motors where you are??..that will tell you the answer.