302 vs 351

Discussion in '1974 - 1978 Mustang II Talk & Tech' started by frigidmonkey, Jun 10, 2003.

  1. ok, new development, I have the 77 LTD with 302 2bbl in it that I bought for 100 bucks, not much of an investment... I was just offered an early 70's (not sure the exact year) 351 4bbl with tranny for $150 , should I stick with the 302, or should I go for the 351????
  2. It depends on how much work you're willing to go through just for some extra torque. The 351W does not fit near as easy as a 302 and a 302 can be just as quick as the 351W, just the 351W can be pushed a bit further and will always give you a bit more torque than the 302.

    I actually would prefer the 302 if it weren't for the fact my original goal from my high school days was to build a car/engine that could get sideways on demand...the 351W fit that bill...guaranteed sideways in 1st or 2nd below 35mph, and sometimes it'll come loose in 3rd just from rolling the throttle.

  3. Seth,

    Does the 351 run?

    If it does, get it and worry about what to do later (sound familiar?).

    Unless it's a 351M. If it's an M stay away, their wider and taller than the other 351s and the bell housing won't bolt up to the SBF, W or C. Ms are also dogs.

    But if it's a W or C, scarf it up. If only to have it.

    Installing it in a II will be a PITA, but, hey, it's only time, money and your nerves.
  4. Yeah, what they said. Buy it to have it like Wart said. I have a couple sitting in the garage right now. But if you wish to install it it can be a pain in the ass. Fun to drive, but a pain to get it to that point.

  5. Instructions for installing a 351w can be found on Mustang II .net,biggest problems are-oil pan,exhaust manifolds,and front components.since the 351 is wider than the 302,the alternator and power steering mounting brakets will have to be from the 302,as well as the original 302 exhaust manifolds.the pass side manifold will have to be shaved by grinder.
  6. unfortuantely I can't just buy it for the sake of having it around, I wish I could afford to do it, if I buy it, it will come out of the money for putting the v8 in the mustang. oh, and its a 351W it turns out

  7. Why not just take a sledge hammer and beat the frame out of the way, both are classless installations.
  8. Hey Wart,just TRY to find headers that fit a 351w swap! I have been toying with the idea of making my own,but i've never attempted it before. the companies that used to make them don't anymore,and they try to sell you shorties that also won't fit. so it looks like i'll have to be "classless' for a little while longer,and STILL be able to blow more than a few ricers and chevys outa the water!:spot:
  9. I think you can massage the Headmans around enough to make 'em clear. Never had a set of hookers to tell you there. The Dynomaxes are not gonna work either. :shrug:
  10. I'm going to have some custom made by a race car shop. That's probably going to cost some moola.
  11. The dynomax's will fit the 351 and an auto. They will fit better with the II bell I bet. But they will fit with a a standard 157 tooth bell too. The heddmans can be made to fit the 351 (I did it) but I had to cut every tube and and a small piece of pipe to each one. And I also had to put a "dogleg" in the #1 tube to clear the frame rail because of the 351's extra width.
  12. It depends what you plan on doing with the motor.
    I'd rather have a stroked 302 than a stock stroke 351W. The recipricating mass of a 351W is FAR greater than that of a 302. Also, the stock 351W main bearings have too much surface area for reliable high revs. For this reason, it takes more cubes in a 351W to surpass the power potential of a stroked 302.
    It also costs more money to build a 351W than it does to build a 302.(not including the extra investment of the 351W swap into your car)

    Unless I was planning on building a serious stroker motor from a 351W,(which I currently am) I would stick with building up the 302. Smaller package, easier installation and maintenance, higher efficiency, quicker and higher revs and cheaper parts.
    If you plan on running either motor in mostly stock form, obviously the 351W will be the more powerful choice.
  13. Really? I'm planning on doing the same thing!
  14. I though about a W but decided that I am going to do a 331 with a little extra air ;)

  15. Gee thats funny Aren't you the same person except one of you is banned :owned:
  16. I have been looking into it and I think a 302 stroker (347) is the way to go! It used to be that the 347 was a race only piece, but one company (forget the name) is offering a 347 where the ring does not go thought the wrist pin area. The 302 based engine came factory and it could be installed with all off the shelf stock and aftermarket parts. It would fit better and you would not need to get your fabricator hat on. :D
  17. I'd have to agree with you and also 77sleeper. I love my 393, but I could've saved a LOT of time and effort and headache and just gone with a stroked 302.

  18. If the ring doesnt go through the pin area, then the rod must be very short, which means it will have a terrible rod/stroke ratio. 302s don't have a seriously high ratio to begin with, so I wouldnt want to lower it. A low rod ratio means more side load on the piston skirts, causing greater parasitic losses and increased cylinder/piston wear.

    A higher rod ratio allows the piston to dwell at top and bottom dead centers longer, allowing greater cylinder filling and better exhaust evacuation. (It also doesnt require as much timing advance, which avoids several other related issues)

    I have a set of JE pistons in my stroker, and they came with special machined billet plugs that install into the wrist-pin holes after the spiral locks.(they're free floating pins) So those grooved plugs fully support the rings.
    I run 5.5"(stock 302 is 5.09") H-beam rods in my motor, with a 3.25" stroke crankshaft, giving it a same as factory 1.69:1 rod/stroke ratio. I would have liked to weasle an even longer rod in there, but its just tough to do with that tiny deck height.

    My motor has about 4 thousand hard(!!) miles on it now, and it's not using any oil at all. Engines that have been built using similar JE slugs seem to be holding up very well, with much higher mileage on them. It seems to be a very solid, reliable system.