I may not go with the 331 stroker kit as planned. I may instead go with a 351W stroker (393 or 408). My questions: Has anyone here done a 351 swap? If so, what is required to get it to fit in a 1970 Maverick? Special headers required? If a shock tower mod is also required, how much material must be removed? How reliable are the 393 and 408 strokers? How long is the normal engine life? Thanks.
Getting it to fit is by far the most challenging part. Once you get it in there, you'll kick yourself for ever considering a 302....trust me!! Headers and towers are up to you. I build my headers, but that was me....it was the easiest solution at the time and I hadn't done that before, so that's the route I took. We also chopped the towers back slightly to make room for the 1 3/4" tubes. If I had to do it all over again, I'd do another Mustang II front suspension. Those stroker windsors are worlds ahead of most stroker 302 combinations...whether it be a 331, 347, 316, whatever. The 302 blocks are just too weak to start addind cubic inches. At about the 500 HP level, they get REALLY weak, and 500 HP is easy to attain with even a 302-inch engine (though RPM gets up there). That's where a 393 or 408 comes into play. They'll make the same power, even more, but at a lot fewer RPM than a 302 based engine, plus make a ton more bottom-end torque. How long it lives is dependent on the weight of your right foot and how well it's built. As with any engine, it's not if it'll let go, it's when and how bad. The 393 is simple to build....3.85" cast cranks are good to about 650 HP, you can use stock rods and off-the-shelf 302 pistons. Or you can go a little wild with rod/stroke combinations and SRP makes a piston that will allow you to use longer rods. The only problem I had was 1-the rods hit the lobes of the camshaft (cam has a nearly .700" lift on standard base circle) and 2-stock rods aren't as strong as everyone says they are, well, at least one of them wasn't. The bolts held fine but the rod itself broke at the bid end of the rod at about 7100 RPM which pretty well destroyed most of the engine. It was very torquey off idle, and very responsive (super-light pistons). The 408's are great engines, but require a dedicated "kit" to build (they don't use 351w-length rods). Every one I've seen is tough as nails and runs like a big-block but with the weight of a small block. VERY good engines, though they cost a bit more to build than a 393. That being said, When I grenaded my 10.8:1 393, I decided to build a stock-stroke 14.2:1 351w (cast crank/ESP 4340 rods). Guess what, it runs exactly the same as the 393 did, though the 393 had more bottom-end torque and left a little harder, the 1/8 mile times are the exact same. Well...maybe the 351 mph's a tad higher at 103.8 where the 393 was in the 101-102 range, so I guess the 351's got one or two more HP. I "could" have built a 408, but at the time I was already traction-limited and the extra torque would have been useless. Like I said, headers will be the biggest issue. It's challenging...though not impossible and not particularly hard to figure out. Do a search--there are TONS of posts concerning a windsor swap.
Same deal with the 331 I built, never ran any faster than the old 302. Used same heads cam and headers, only real improvement was the bottom end torque which in some cases , is more of a problem than a help because of limited tire size. Thought I would throw this in for laughs, the Eagle 331 kit and other different rod and crank combo's for the small block Ford's, use a Cheby rod bearing. In fact. that is exactly why my 331 exsploded, bearing failure. Damn GM parts anyway. he, he he.
So ...with all of the useful information you guys have given based on personal experience (the best kind of info). The things that stand out in my mind are that the strokers produced the same power as the stock cid engines ,BUT did it with LESS compression and fewer RPM`s also providing more low RPM torque. To me this means that a stroker would be the best thing to build for a street/strip car that you wanted to run pump (93 octane) gas in . BUT if you are doing a race only car then go with stock cid (cheaper) but with high compression requiring race gas. You could spend the money you saved on other components for the car.
Thats exactly what I did. Instead of spending thousands on the 408 I wanted to build, I just put together a mild 351w with the factory crank. The money I saved to put the 408 together went into a fund that eventually backhalfed the car, then installed the M2 front end. The car is no longer the same.
i was told the when building my 393W the 408-427 are best left to a sportsman blocks and they tend to run hot easy on the streets this is from guys that have them in mustangs.... that was why i went with the 393w ...and like mavman posted headers will be the biggest issue..... mine are not as big as i would like them to be but i wanted full exhaust...told this to the cam tech at comp cams they made the cam to work around it more lift and dur on the exh....i used the Hedman elite -500-88308 ......had 2 tubes cut off and remade to clear for steering but i am very happy with the power pulls hard to 6,800 rpm 393w AFR heads 11.25-1 comp http://home.columbus.rr.com/maverickgrabber/PB300004.JPG
