which 318

-
S

sorewrist1

FABO Gold Member
FABO Gold Member
Joined
Mar 18, 2012
Messages
352
Reaction score
71
Location
Sac Cal
Hi all you's numbers guy's I have a 318 # 400675-318 4. It has flat top pistons and a nylon timing gear. Don't know what year it is. Was wondering if this was a block that could take a 4.040 overbore No way I could be that lucky. Thanks Jim
 
Quite frankly I don't believe any LA 318 will take a .130 over bore, and be useable.
 
no way to know without having it checked

but yes is is done, and they are quite usable,
as long as the walls are thick enough, you can bore a 318 out to a 340, and it will run just as good as a factory 340, for a lot less money
 
Did you mean bore it .040 or are you trying to put a 340 piston in it with a 4.04 bore?
 
so which blocks can be bored to take standard 340 pistons , just curious as I
have a 68 - 318 also a 69 - 318 and a 77-4 speed truck with a 318 in it.

that would be 0.13 boreing job guess if the walls are thick enough
why not.
 
I think my block is a 78 I think a 84 or 86 can be bored with no prob just can't remember
 
Before ,you think of a 4.040 bore,A question. What do you want it(this build/block to do? 318's can run hard,as well 360's.
 
SGBARRACUDA said:
There isn't a certain year block that you can bore .130 without having it sonic tested.
Click to expand...

This quote 100x over. The block year don't mean a thing. If anything, the later year engines would have a higher chance due to less core shift from refined casting processes. You have to get it sonic checked to know if the engine can go that far over safely. It's been done plenty of times thanks to sonic checking. No engine is a deadset guarantee it will go that far over unless sonic checked.

Abodybomber said:
Before ,you think of a 4.040 bore,A question. What do you want it(this build/block to do? 318's can run hard,as well 360's.
Click to expand...
And this. Why go so far overbore? 318s can rev like hell and make power. They may be an underdog, but think about this. Can you go out right now to a junkyard and even have a chance of finding a forged crank for one? Hell yeah ya do. Best of luck on your build. I honestly would like to know what your goals are for this build
 
Only overbore what you need to do to clean up clean up the cylinders. Very little is gained for over boring the block.
 
Well I have a 318 now with one rusty cylinder so it needs to be bored anyway . Just thought it would be a cheap way to get a 340 depending on the sonic testing. It's going in a 71 swinger 727 8 1/4 suregrip no gears yet. I just want to burn rubber Jim
 
Well, my understanding is that all LA small blocks have the same external casting as per their generation and the differences came in the internal casting, giving different cyclinder bores. and cubic inch measurement becomes based on the bore in relation to the stroke from the crank.

So my point is any small block can be bored out, but the more you bore the more likely you are to hit a weak spot in the block.
So if you can have a qualitly sonic test done prior to any major machine work you can find out if the block and any internal stress cracks so you can be sure you start with a good block.

Or depending on the availability in your area you may just want to buy a used 340 emply block, and save the sonic test and save the machine work, and possibly alot of money.

And if you can afford it, the safest thing is to have cyclinder sleeves installed in the bore to prevent wall cracking and high heat.

So this is just my 2 cents, Im sure I don't make sense to most people, but I think this is the theory.

Good luck,,
I hope I may have been some kind of help
 
You must log in or register to reply here.
-

Back
Top