I've been thinking about putting together a 331 stroker for my '90 box, and I've got some questions about my block and overall project. My goals for this car/project would be a nice street/sleeper with 425hp/450tq (or less), carbureted, and with an auto tranny cause where I live there are hills everywhere.

I've been looking at the SCAT 331 stroker rotating assembly on summit racing, could I still use my factory block with the kit or would I be better off looking at an older/different block?

If I could use my block, what type of heads should I use along with the flat top pistons from the kit?

I'd also like to mention here that I'd prefer going over to carb on this engine because it would be my first project with a carb on it and I would like to tinker around with it and have fun with the car as well.

The key to making this work is going to be cam selection. The temptation to go big is strong, and it will absolutely ruin the car. Yes, you get the RUMP RUMP idle, but you lose the power brakes and cruise control, not to mention the HVAC. All that stuff needs vacuum and lots of it. To get the vacuum, you'll need an RV-type cam, and those run out of breath pretty early, like below 5000 rpm. And that limits the HP you can expect.

Head selection (chamber size) depends on what fuel you're willing to put in it. You can get a lot more power if you're willing to feed it Rockett or CAM2 at eight bucks a gallon.

425 HP is a pretty lofty goal for a small-block Ford unless you're gonna supercharge it. 425 HP with an RV cam and streetable compression ain't gonna happen.

If it was me, I'd drop a 460 in there. Easy to get a lot of mild-mannered power out of one of those, and it'll live forever doing it.

Keep in mind the gear ratio. You likely have a 2.73 open in there. Need at least a 3.55 for good performance, maybe a 4.10 with a cam upgrade. Might be able to get away with a 3.27 with a 460. Trak-loc is mandatory.

Al

And you'll have to feed it. Box EFI fuel lines are only 1/4 or 5/16, not nearly big enough to fuel any kind of HP.

Just re-gearing it will give you the illusion of a lot more power, at the expense of fuel economy. What fuel economy?

If you mod the engine to HO spec, use the GT40 heads and intake off a late Mountaineer, and give it some gearing you'll have a good cruiser that will move out better than stock and have enough vacuum that everything will work.

I'm yet to see any modern V8 car with only a 1/4" and mostly 5/16" was history by the '70s. It's cheaper to fit one size to all vehicles than to use different sizes. Regardless of size, fuel system should be re-plumbed when switching to carb.

I have a Blue Print 415Hp 347 earmarked to go into my '69 Fairlane. Plan is to remove the slightly rumpy cam & install a Extreme Energy Comp 35-349-8. Probably kill 25 HP but be friendlier on street.

https://www.summitracing.com/parts/cca-3...ZgaAj-_EALw_wcB

https://www.summitracing.com/parts/mll-b...OQaAn5dEALw_wcB

The cruise control and HVAC are gone on my car, so the only worry is the power brakes. I knew deep down that the 425hp goal was a very high goal, I just wanted something with a little more punch than the stock motor and could fit in my car without any hacking and fabbing of motor mounts. The car would be driven in spring/summer months but I wouldn't really drive it day to day, so MPG doesn't really shake me all that much. If the 460 is a viable replacement that would satisfy my needs, I guess I'll look into it more.

With a 351W 400 Hp would be fairly easy. Plus it'll fit without a lot of mods.

With AFR 195 heads, Engine Masters Produced 484 Hp out of a 410 stroker and that motor had a very tame cam.

What about staying stock and doing a tune? Has anyone done this? Any gains?

Stock, you're severely limited by the size of the throttle body. Yes, it's got a great big hose going in, but inside is a throttle plate smaller than on a Harley.

It's cammed accordingly. Gobs of torque, peaking at 2,000 rpm. But it can't move enough air to go above 4,000.

You might get a HP bump by changing the intake and adding dual exhaust, but it wouldn't be a real big one because of the cam.

that and sock valve springs will float at like 4500rpm even if you ran a better cam.

So from the way it sounds, the options are between a 351 stroker or a mild 460 build

The 351 will go in a hell of a lot easier, and it's a lot lighter.

Yep. They put a 351w in the boxes at the factory so it would be a drop in. There have been at least a couple 460 swapped boxes, but for your goals a think a 351 would be a better starting point.

That said, you can make impressive power out of a 302, and your '90 block is set up for a roller cam so its a good foundation for a good build. With some good heads, cam, intake, exhaust, all matched properly, you could make a pretty streetable combination that motivates the car really well. It is not uncharted territory, there have been thousands of well built 302s put together thanks to it being such a common engine in its day.

With the 351 being a police/tow package motor, what are parts like trying to find them, specifically the stock motor mounts? I know the 351w is a extremely common motor found in trucks, but that's not really helpful when I'm trying to build one with high output.

Blocks, cranks, rods are basically all same.

IF you're going to build one for HIGH output, stock parts ain't the way to do it. Scrap the asthmatic heads, intake etc and go with aftermarket pieces. The 351 HO CVPI was pathetic, rated at something like 185Hp.