I see this video of the 600HP 318 and hear the guy "say" it is a stock stroke with a 4" Piston. specifically a 4" piston for a LA360 top end is trick flow heads and .600something solid roller cam yada yada yada… I start think man that seems ez-pz and is said cant be done.

best I come up with is it would need a 6.250 rod maybe? chevy rod?

I just bored my 318 to a 3.970 bore =.060 overbore @ 328 C.I. piston CH 1.7 or 1.8

but I can not find any 4" pistons with a CH 1.7xx or 1.8xx only a 1.66 so I don't think it is adding up 360 piston @ 1.6xx CH would be way down the hole with a 3.31 stroke.

then you have the na sayers with you cant overbore a 318 block .090 overbore for a 4" bore safely?


I wager you can bore a 318 .090 overbore safely before you can make a 4"-1.6CH 360 piston work on a 3.31 stroke in a 318 block..... he has longer rods or a 4" stroke crank... so 4" bore x 4" stroke = what cubic inch? 401? 408?

now I did not research to see if you can have a custom ICON 4" pistons set made with the 1.8CH needed so I am still pondering this build of a 318.

but a 4" bore x 3.31 stroke for a 333 cubic inch 10.5-11.1 to 1 comp ratio would be awesome.

I am only .030 from that now.

3.970b x 3.31s = 328 cubic inch KB399-1.8CH pistons.


I guess you can not believe everything you see on the tube LOL!

And dyno #'s can be manipulated by the operator to give different results. Next question is why would somoen put that much $$ into getting that HP out of a 318 unless they are class racing and C.I. limited ?

Maybe they used a Poly block. .090 over is easy.

Kevin

Maybe it's the original motor to the car.

The bore to 4" can and has been done on a few of the older late 60's 318's. Some have bored then enough to put 340 pistons in. 600 hp? Maybe if it has nitrous or a blower.

Perfect timing Scratch!

Our engine build for a 66 Coronet with Poly 318ci.

We have now done the 402ci Poly build which in theory makes around 400hp?
That is tha 4.00 x 4.00 square set-up recommended by Gary P. of San D.

So his brother also with a 66 Coronet with the 318 LA wants to copy him...
Must bee iron headed and stock Eagle 6.123 rods @ 402ci direct comparison.

We have an LA block already at 4.00 and it’s ‘sound as a pound’ ( dollar ).

So I contacted DSS racing and they make the 4.00 piston for the ‘410’ range...

Just waiting to hear back about pricing?

They have flat-top, -18cc and -28cc for blown apps...

There is a 550hp 426ci Poly ‘out there’ but it’s a dyno mule!
How much it cost to build is anyone’s guess?

I contact them and Compcams for a Poly roller cam, and they clammed up lol...

The Hinckles 426ci Poly is very trick indeed.

They said the 318LA blocks have the same cores as the 340!
I believe the 360 blocks do have the same cylinder cores.
(You can quite clearly see that it’s a 318LA block in the pictures)

Hard to believe but they went 4.065 bore and 4.200 stroke.

6.400 inch roller cam and 12 . 1 compression Wow...

Me if I was going that big on such a special build would have used a 340 block.
Or a nice early 360 block at least...

good info.

I have always thought a 318 should be as good as a 340. it is just lacking 22 cubic inchs and cam/heads/intake/carb. with my 318 with a 3.970 bore 3.31 stroke @ 328 cubes I am only 12 cubes short of 340. so I can go to 4" bore 3.31 stroke for a 333 cubic inch. now I am only 7 cubes shy of 340.

IIRC a poly318 & LA318 share a lot of parts. (steel crank-float pin rods-pistons-timing gear/cover) so a .090over poly piston I looked at has a 1.8 CH and have a better comp ratio than a stock .060 OEM LA318 replacement piston @ 1.7CH and it is in the cheap OEM cast piston price.

so 4" x 3.31 = 333 cubic inches(steel crank/floating rods.4" poly pistons 1.8CH

bump my 1.88/1.60 J heads up to 2.02/1.60 valves with a little bowl work/clean up

then it would be about cam choice. it should buzz well past the 5500 mark with the right cam choice. I would be looking for 6200-6500 with a 4 speed.

is it worth the effort? I would think so.

The 4.00 bore pistons are for the 4.00 crank.

That’s a 402ci smallblock 318!

If you don’t have a steel crank, just get a 4.00 stroker ‘340’ crank off EBay for $400.

DSS has pistons in flat top, for iron head use.

Got to be 400 plus in my book!
Do it once and do it right...

This 340 on Ebay at the moment is 600+hp, who needs a stroker anyways?

Its cheap at $19,000...

If you 'miss a shift' at 7000, you is AOK till 7600 and more probably...

WHAT'S THAT ROD BEARING DOING ON THE LIFTER TRAY?

Rod bearing? Are you talking about the dipstick handle?

good eye spy!

I bet that wont idle around town in traffic without over heating during the dogdays of summer here in the swamps.

Why wouldn't it? Mine dynoed more than that and has never ran over 185° in five years, even at the drag strip.

That Ebay 340 has W9 heads, which is why it does what it does so well. You can make a 318 go plenty fast if you want to spend money on it as most all the 340/360 tricks of the trade would still apply. The smaller bore may limit the intake valve size though?

Hensley performance in Tennessee or selling crate motor 4 inch bore
For a while come in the entrance was there. They were all Sonic testing.
Jim F