331 I'm lost..

SR86

Founding Member
Dec 4, 2001
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Alberta, canada
OK, never done much engine building, and from the searches, it seems everybody does somthing different. but - Do I have this right -

the 331 CAN use a stock bore, but usually uses a specialized piston?
There will be notching of the cylinder walls to allow the crank adequate room to rotate?
Stock crank journals, and rod journals?
Needs specialized 331 specific rods?

Ok, now my current Combo is Edelbrock Aluminum heads, 190 intake, approx 170cc intake runner, 64cc chambers,E-303 cam, 1.7 roller rockers, Typhoon upper and lower, and pro products 75mm TB, 1-5/8 long tubes..your basic bolt ons.

I'd like to use my exisiting heads, get a new cam, and buy a rotating assembly. this is all going into a t-5 backed Ford Ranger, 2 wheel drive. Shes currently in the low 14's, I'm hoping for quite a bit more...it is a street truck, but not a dailily driver, but streetability is important. Guide me Stangers!
 
I ran a 331 with a twin setup. to get a 331 from a 302 block you need a 3.25 stroke and a 4.030 bore so the bore needs to be .030 bigger than normal. I am pretty sure that without the .030 bore you get a 326 or 327, something like that.
You do need aftermarket pistons because of the bigger bore and as far as the rods I have always seen a 5.400" rod used. You might be able to use others but that is the most common I have seen. You are correct about the walls needing to be notched to allow that bigger crank to sling around. I don't see why you wouldn't be able to do what you want to do. Sounds pretty reasonable to me and would be pretty streetable. Here is a site that you can play around with the bore on. http://www.aacncclub.com/crucemotor/compressionratio.html
 
ok, so no special piston is required, opposed to the 347?

So, I can use some .040 over pistons that i bought before thinking of stroking, buy the aftermarket rods, and crank, have the needed machine work done, and bolt it back together? (it will be around a 333 when it's forty over though)

Any suggestions on who to buy from? is it easier to just buy a short block assembled?
 
When I got my 331 I bought the shortblock assembled from fox lake power products. The only thing about going .040 over is the weakness of the stock block if your using the stock block. I have always heard and thought myself that you don't want to go over a .030 overbore with the stock block. The webbings are already weak enough and you don't want to make it any weaker than they already are. I am sure you would be fine at .040 over but just something to think about. I really enjoyed my experience from fox lake power products and would recommend them if your going to go that route.
 
You have to use a 331 specific piston. You can't just use a 302 piston with a longer stroke crankshaft. It's a different crank, different rod and different piston. If you want a 331, buy a kit. I know where there are Scat stroker kits for $899 shipped. With a cast steel crank, forged I beam rods w/ ARP bolts, Probe forged pistons, rings and bearings, that's a great deal.
 
you could do a long rod stroker. Which basicly means your increasing the stroke. But I dont think you could do a 331 with stock bore...

Rod lenght has nothing to do with stroke the stroke is dertimed bu the distance from the center of the main journal to the center of the rod journal. changing rod lenght just moves the pistion up further at tdc and not as far down at bdc.
 
The 331 kits are for a .030 bore on stock or aftermarket 4.00" bore blocks. They use either a long rod 5.400" or short rod 5.315" They both use a 3.250" stroke. They both use different compression height pistons. the 5.400" rod uses a 1.175" compression height piston. The 5.315" rod uses a 1.250" compression height piston. The 5.400" rod had the wrist pins in the oil ring. The 5.315" rod does not. The Standard bore version 4.00" will be 326.7 cubes, .020 over will be 329.9 cubes, .030 over will be 331.6 cubes, .040 over will be 333.2 cubes, .060 over will be 336.6 cubes. The length of the rod has nothing to do with cubic inches. It is the Bore and Stroke that determine engine size.
 
Most of your newer style stroker kits for a 331 use the 1.175ch piston with the non intersecting wrist pin, the 347 kits are made both ways. The oil burning myth is just a myth, assembled properly it does not matter.

I build with the SCAT kit mentioned, it is a nice kit for the money