318 Poly Stroker Crank & Rods

-

66 Sat

Well-Known Member
Joined
Jun 20, 2020
Messages
86
Reaction score
227
Location
Australia
Hi all,
I've got a fully rebuilt 318 poly in my Satellite which I want to stroke. I had originally planned to go this route with the help of Gary Pavlovich but in the end stayed with a stock stroke. I would like the extra torque of the stroker plus I can paint my engine bay body color when I pull the engine.

I'm planning on using a 3.58" crank rather than the 4", as this will work with my existing camshaft (264/.450” (222@.050”) 110LC Solid Camshaft) and will be less stress on the engine. I also understand I can use 318 LA pistons with this crank with fly-cutting one intake valve relief, rather than custom pistons with the 4" crank.

Two questions:
1. Scat Cast Crank Series 9000 Cast Stroker Lightweight Crankshaft or Scat Forged Crankshaft? It's only a street cruiser with less than 400 hp goal so I'm thinking cast would be sufficient (it's half the price of the forged)?

2. Scat Rods - 2-ICR6123-2124 Pro Comp I Beam - would these be a good choice?

Any advice from anyone that's done this previously would be appreciated. I'm in Australia and although 318 LA engines are fairly common here not many people are familiar with the poly and I can't afford to make the wrong parts choices.

Thanks
20210121_183348 (003).jpg
 
the scat 9000 cast crank is a good piece member and engine builder RAMM has run 697 hp with one and i have been running one since 2009 at 530 hp both in LA engines .
 
Hi all,
I've got a fully rebuilt 318 poly in my Satellite which I want to stroke. I had originally planned to go this route with the help of Gary Pavlovich but in the end stayed with a stock stroke. I would like the extra torque of the stroker plus I can paint my engine bay body color when I pull the engine.

I'm planning on using a 3.58" crank rather than the 4", as this will work with my existing camshaft (264/.450” (222@.050”) 110LC Solid Camshaft) and will be less stress on the engine. I also understand I can use 318 LA pistons with this crank with fly-cutting one intake valve relief, rather than custom pistons with the 4" crank.

Two questions:
1. Scat Cast Crank Series 9000 Cast Stroker Lightweight Crankshaft or Scat Forged Crankshaft? It's only a street cruiser with less than 400 hp goal so I'm thinking cast would be sufficient (it's half the price of the forged)?

2. Scat Rods - 2-ICR6123-2124 Pro Comp I Beam - would these be a good choice?

Any advice from anyone that's done this previously would be appreciated. I'm in Australia and although 318 LA engines are fairly common here not many people are familiar with the poly and I can't afford to make the wrong parts choices.

Thanks
View attachment 1715752149

What 318 LA piston are you thinking of using???? What compression ratio are you thinking you will end up with?? Years ago I thought about doing something like this with an LA 318; 360 crank in a 318; I had a set of Badger cast, pin height 1.74 inches, doing the math, the piston stuck out of the bore .055, fly cut them to zero deck, then figure valve reliefs, I was getting the notion that the crown might be getting a little thin, I scraped the idea. Maybe you'll have better luck.
 
I'm not sure on the pistons, the "use the LA pistons with the 3.58" crank" was a comment from Gary Pavlovich in some of the previous email correspondence I have. Compression ration is 10:1 in the current set-up, and it already has .060" pistons. The rebuild was only 3 years ago so the bores would be fine I'd hope.
I'm really not an expert at any of this - I wanted to slowly start gathering parts (crank and rods) - the pistons would be bought later, once everything was torn down, and on the advice of my engine builder.
The reason I wanted to buy the crank and rods now is then I'm committed to doing it, instead of just thinking about doing it, plus it obviously spreads some of the cost over a longer time.
 
I don't know why anyone is mentioning LA pistons for the Poly. Uh,, the valve relief is different, maybe?!!!!
 
So ur gonna have a 3.97 bore, 3.58 stroke, the pistons Compression Height (CH) will be 1.69 assuming ur Deck Height (DH) is 9.6

Is this correct?
 
So ur gonna have a 3.97 bore, 3.58 stroke, the pistons Compression Height (CH) will be 1.69 assuming ur Deck Height (DH) is 9.6

Is this correct?
Not sure on the compression height, but the bore sounds right if this is what .060" yields.

For now I'm really looking for advice on the crank and the rods, in terms of quality, strength, weight etc.
 
For now I'm really looking for advice on the crank and the rods, in terms of quality, strength, weight etc.

For your intended power level a cast crank will be fine, rods are no worries eather. A stock Poly rod is around 726 grams, not real sure how that compares to the scat rod, a catalog look up will tell you that
 
For your intended power level a cast crank will be fine, rods are no worries eather. A stock Poly rod is around 726 grams, not real sure how that compares to the scat rod, a catalog look up will tell you that

The Scat rods are 595 grams.
 
I wonder if the 351 Cleveland piston would work? 4" bore and staggered valve reliefs with a 3.5" stroke. I don't know rod length and compression distance off the top of my head.
 
Buy a box of these, mod up some 440 valves to act as fly cutter notching devise, the crank and rod idea you chose is good. The UEM 1278 piston with a compression distance of 1.658 and the notches you create yourself in a Poly will give you more working room than what I did to this LA. Also you'll buy a crank instead of having the mains turned down and counterweights clearanced (blue inked area).
100_1767.JPG

100_3480.JPG
100_3484.JPG
100_3489.JPG
100_3184.JPG
100_1980.JPG
 
Last edited:
-
Back
Top