No announcement yet.


  • Filter
  • Time
  • Show
Clear All
new posts

  • Cranky

    Ok I saw some chatter about forged steel vs. cast iron cranks.Heres what I know, helped my boss out by doing some detective work on a blown engine, the engine in question was a Chevy 350 1984 model in a one ton pickup.He had a local engine rebuilder do a major upper and lower, after about 6,000 miles oil pressure fell of radically.I tore the motor down and behold the center mains were whipped out bearings all down to alum.First thing I did was to check the shaft for straight and it was,the next was to talk to the rebuilder he says not his fault and what we need is a steel crank.That didn't sound right so to call his bluff I got on the phone with G.M.and talked it over with their eng. dept.and they said that for the app.the cast crank was recomended as it had greater capacity to absorb torsinal vibration,also he said that the app. they used steel cranks on was certain muscle cars and 400+cid heavy truck motors.Long story short the failure was traced back to a warped block(boat anchor)new block and presto 60,000 mles later still running strong. The main difference between the Ford cast cranks and the Chevy's is the mains are bigger on the Fords along with the rods.Most hotroders I know lean towards Chevy because they are lighter,I suspect that the forged crank was more a selling point than a requirement although a fewer number of main bearings on certain models could have also had influence.
    I just need one more tool,just one!

  • #2
    Ford is retarded. I had a 1971 429SCJ Ram Air Fastback Rustank...I mean mustang 57cc heads, flat top pistons, 12.5:1 compression, CAST pistons. Morons. But I am not bitter, not me.

    Even Chev is smarter than that.

    MoPar would not get caught dead without forged slugs - long live the hemi!


    • #3
      Adding to the conflagration Ford Vs Chev Vs Mopar

      For many years a friend of mine had a small fleet of 1/2 ton vans for his furnace and sheet metal business. It was always a mix of Fords and Chevs and Dodges whatever was on the two year old used market at the time. He didn't care. He just wanted to fill out his fleet.

      I recall sitting in his office as he browsed 40 years of excellent paper maintenence records. The subject came up of which engine provided the best service for the buck. This led to a spread sheet that he built as I called the figures to him.

      Remember this is a guy who takes care of things like regular oil changes and rune ups. Most of his service people are older guys hand picked to, among other things, drive conservatively. He never disposed of a van unless if was shot for some reason or another.

      I don't recall the details but I do recall the scheduled service costs were a bit higher for the Fords and Dodges maybe because of the price of the parts. There were no blown engines or catastrophic failures, 90% of the engines went for more then 150,000 miles, and theres was only one lemon.

      This leads me to think that while people have their preferences there's little evidence in one small diversified fleet operation of 20 or so vans to justify statements alleging superiority of one make over another.

      Racing is another matter. You have to expect a few grenades unther the hood.

      99.9999% of all driving is on public roads. If people blow up engines on the streets I suggest is most likely due to one or more of the following: premature failure (lemon vehicle),lack of maintenace, botched modification, illegal operation, or concealed damage emerging as a result of an earlier accident.

      I live in Chev country (Western Washington). My bro' in law come from Ford country (east Texas) He's an intelligent and sophisticated man but I've heard his blurt out the most improbable nonsense relating to Ford supiority.

      There really isn't much difference between onemaake and another. It's mostly a case of chose a favorite and bicker the rest of your life with people who chose something else.

      I used to favor Pentax camera equipment. In the '70's and '80's this was good reliable stuff capable of taking excellent photographs under most any conditions. I recognized that Nikon of the era was more rugged but also more expensive.

      I was shooting a wedding minding my own business and almost got in a fight with a guy who, cold sober, was mortally insulted that I showed up at his sister's wedding with a bag full of Pentax stuff. He followed me aroungfor two hours and told me so.

      So there's the usual kind of bigots who prate about race and national origin. Then there's camera bigots, car bigots, political bigots, etc. I'm a machinery and manufacturing bigot, I guess, but I'm glad there's a few farmers and doctors and road builders and politicians, and the rest to link the machinery together.

      Takes all kinds to make our country great. Even different brands of car and trucks.

      [This message has been edited by Forrest Addy (edited 02-14-2003).]


      • #4
        Sounds like they screwed the machining of the block or crank up. Chevy or the shop. I got one of them old 350's that has been in 7 different vehicles now. One you could see the sky up the hood in 1st and second. (77 monza spyder with Iroc 5 speed) IT HAS A CAST CRANK, but I try to limit the rpm to 5500, try, try, try. In a light car with a low gear there ain't much time for shifting.
        I saw a video on a cast crank at 6000 it looked like rubber flexing.
        Funny thing about blowed engines, they never hardly come apart until they miss. I suppose they transfer the stress to the weak side of the rod, and rock the cylinder with unusual stressful explosions? Or.. a dropped valve that starts a chain reaction.
        Anything out of tolerance can do it's own machining, whether you want it to or not. I did see some horsepower increase on angle boring once, I didn't understand it tho.


        • #5
          Hey, Forrest! What's your favorite side arm? Snicker, snicker!


          • #6
            When I wanted my 69 camaro to "go fast" I went and bought a 350 that had the forged crank and rods because it was going to spin to 7000 RPM +. Don't know if the forged pieces were necessary, but I feel better when the tach. reads 7000. Back in the 60's I believe companies were doing real R&D and if Chev. used forged cranks and rods in their hi-perf engines maybe they had a reason. Just my opinion, as I have no data to back it up, except this engine still runs fine. By the way, R&D today is devoted to making it cheap not making it good.


            P.S. Anyone interested in a 69 camaro with 42K original miles?


            • #7
              Speaking of flexed crankshafts: At Auburn uninversity, 1953, we had a dyno and strobe light and they made some pics of straight eight buicks, six cylinder flat head chryslers, engines with mains well supported and not so well. I was amazed at how crankshafts "wrapped up" under loads. the cars used heavy flywheels to smooth engines, but it seeemed they also wrapped the cranks. One professor speculated that part of proformance increase from lightened fly wheels, and short cranks was becasue the "timing" for the front and rear cylinders stayed the same when the crankshaft did not twist. I had doubts, but a few years back, I was told the fron damper on some Mopars was casueing cranks to break at normal service due to flex.

              Engines run more by witchcraft than engineering- engineering just explains what some shrewd person saw in their mind air obsereved and thought of.

              ANd I think american engines are all good for reliable service. And I shuld be struck down, but I think for long life an automatic transmisson beats manual- and used to be i refused to buy (willingly) any thing with auto xmission.


              • #8
                I got news for you guys it don't matter what the crank is made out of they all flex wobble and flutter.I have a Starrett crankshaft defection gauge that cost many bucks used it on several offshore platforms to get an idea of coupling runout.Thoose big diesil cranks that had 12.5-14.625"o.d.mains ran out under load .010-.018"on the flange face.If you think about it a crank is being deflected alternately between cylinders once on compression and once on detonation as well as torsionally.I suppose that the cast/forged steel cranks are needed when the compression goes above 8.5-1 i.e.180 p.s.i. Thrud:I to am a Hemmi fan seems like they had the best power to wieght ratio of them all,as far as the rustang I like Chevy but I drive Ford and Dodge because the Chevys have a tendecy to disolve in the rain.For those of you wondering about the 350 block that was warpped I later found that the rings were on the way out as well then my grandfather told me what the problem was,it seems that G.M. had some problems with the metalurgy on some 350's and 151 four cylinders where the castings were soft and they wore out and warpped he said it only happened to a few but they are still out there and once and a while you run across one.I also talked to the previous owner of the truck and he confirmed that it had been rebuilt twice before at low mileage.
                I just need one more tool,just one!


                • #9
                  I have to admit I have a place in my heart for ramblers, chev trucks, and mopars. Helped a friend hop a 292 six up in a one ton. That was a hell of a truck - had a stub welded on the rear axle hub to drive a ridgid pipe threader (vroom!) and could smoke those 16.5" tires all day (all four of them). My dad had a Biscayne that had a 327 police interceptor in it (4 bolt mains high nickle alloy nascar block). Had a friend with a LS-7 454 3/4 ton that would do 160+ mph (he was nuts). Another friend had a 64 coronet with 6 headlights and a dual quad cross ram 426 hemi - I was jealous. Another friend has a GTO with the original 389 Six pack and a holley six pack, and a 455SD currently in the car (the origanal motor kacked at 40 miles). Another has an Olds 442, King Corvette, 56, 57, 58 chevies.

                  The hemi was the neatest (small) engine ever built - other than the F-1 and Ducati engines! I would like to see the new Hemi.


                  • #10
                    Thrud, the local Dodge dealers are in a pinch to sell trucks I just heard an ad today that if you buy one this month you can get the Hemi at no extra cost!I do like the nash solution to exhuast connections smooth neck and a muffler clamp ain't it neat how simple stuff works?The 292,250,and 230 sixes were and still are dam dependable engines a friend of mine just converted his 292 to a t.b.i fuel injection setup more power and excellent fuel mileage also made an already smooth engine even better.

                    [This message has been edited by wierdscience (edited 02-15-2003).]
                    I just need one more tool,just one!


                    • #11
                      If 8.5 compression is 180 psi.- what is 10 to 1?
                      mark costello-Low speed steel


                      • #12
                        I should have said approx.180psi due to the different variables i.e.normally aspirated/turbo charged,head chamber/intake volume.180 is healthy for a gasoline engine as usually 120psi is the minimum.
                        I just need one more tool,just one!


                        • #13
                          They want $42K for a lousy truck? uh-uh. I was stupid enough to buy new Fords twice, and that will never happen again. I have a reliable Dakota 4x4 and when it explodes I will worry about another "well used" vehicle then. This one will probably outlive me anyway. Pissed enough money away on cars and trucks to do me a lifetime or four and I refuse to play the game anymore. Hell, I was drooling on a CNC Mini-mill the other night on eBay and I showed incredible restraint in not buying it (but I am still watching it...). So if I can refrain from buying 800Lbs of Table top Joy-joy, I am certainly not going to get sucked into a "free" hemi in a $42K truck that is only really worth $5K...

                          And I am not cranky - I had too many veggies.


                          • #14
                            Au-shucks Thrud,like everything else nothing is the same anyway!The new one is probibly a quad-cattle coverter piss poor v-6 anyway.Overpriced for sure round here $50,000 still buys a decent house!Want to really piss some money away buy a Geo!Electic motor balls for wheel bearings gee thanks G.M. PROBIBLY GROUND OUT IF YOU RAN OVER A SQUIRREL!
                            I just need one more tool,just one!


                            • #15
                              You can't even buy an empty lot for that anymore here. Vancouver a Outhouse is $1/2 a million. Here the average 1200" house with a full basement is about $110-140,000 (five bucks US). Farmland is still somewhat resonable - the farther north the cheaper it gets (to a point, then you start to pay by the pound for the black flies and no-see-ums).

                              And if it can't squish a gopher, I ain't buying it.