Announcement

Collapse
No announcement yet.

Main cap girdle's....do they work??

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16

    Re: Main cap girdle's....do they work??

    Re: Main cap girdle's....do they work??

    Remember adding any mass to a harmonic situation will dampen vibration effectively moving the damaging vibration to a higher rpm, all assuming this theory is correct and it is vibration. Harmonic Balancers are an obvious example. Girdles are a regular thing for Big Buicks, but they like to split the block.
    Escaped on a technicality.

    Comment


    • #17

      Re: Main cap girdle's....do they work??

      Re: Main cap girdle's....do they work??

      Thank's guy's this is the type of response's and info that I was looking for and hearing it from guy's like Steve D, Dave F, and Eddie make me feel like I didn't make a wrong decision in buying one for my smallblock mopar, now I just thought of another post to start......billet main cap's ;D

      Comment


      • #18

        Re: Main cap girdle's....do they work??

        Re: Main cap girdle's....do they work??

        At the most simple - its a mass thing - as stated above - adding mass (ever seen weights hanging off a stock exhaust system?) changes the resonant frequency of the system.


        What I DONT understand is aluminum girdles --- that just makes no sense to me at all.


        Please tell me more about the sequence of torques --- say you're running studs - you follow the arp stud & nut tightening procedure and sequence steps.....

        then you put the girdle on, and the next set of nuts to hold the girdle --- do you tighten those in the same sequence? How tight do they need to be to "lock" the girdle to the studs/nuts/caps/block ???

        Then --- how do you get a girdle AND a windage tray to be happy in a baffled oil pan?
        That is where I hit a road block on my stroker build --- ended up not runnig a windage tray and building it that way - then sold it without ever hearing it run! oh well.
        There's always something new to learn.

        Comment


        • #19

          Re: Main cap girdle's....do they work??

          Re: Main cap girdle's....do they work??

          I believe aluminum girdles would be better for dampening harmonics, as the aluminum would actually absorb some of the vibration because of how soft it is in comparison to steel. I don't like that you would be torqueing the mains through a relatively soft plate of aluminum.

          Remember that the main studs are actually just springs held in tension that is lower than their point of deformation. The studs are always stretching a tiny bit and springing back as the engine is running. Its miniscule on an engine with fasteners properly designed for the application, but it is there. The better the material, the more elastic they are (will stretch farther and spring back) and the more force it takes them to stretch.

          If you are really hammering on it, and the caps are trying the bounce because the forces are stretching the studs more than usual, I would think that the aluminum would would help to keep the caps from bouncing for a while, but would deform perminently around the head studs with each time the engines caps tried to bounce - loosening them.

          This is just my theory.

          I have been really thinking about a main girdle in my next BBM. If I get one, I would get steel.

          Comment


          • #20

            Re: Main cap girdle's....do they work??

            Re: Main cap girdle's....do they work??

            Rick
            in my limited experience
            (arp studs, stock main caps, steel girdle)
            you torque the main caps down with one set of hardened washers then nuts on the studs,
            then you put the girdle on top of those nuts, and tighten them down with another set of hardened
            washers then nuts on top of the girdle.

            Where I ran into trouble was getting a stroker crank, H beam rods, steel girdle windage tray and oil pump pick up to all play nice inside the oil pan.

            I think I know now why hamburger and others charge so much for their parts - they've figured all this out and got a system that works all together.
            There's always something new to learn.

            Comment


            • #21

              Re: Main cap girdle's....do they work??

              Re: Main cap girdle's....do they work??

              I looked at one on the internet for the BBM and it wasn't like that. That would be the best setup I would think.

              You put in the studs on the mains and pan rail, dropped the crank in, and put the caps on, then slid little hardend steel spacers that took up the space between the plate and the main cap (and allowed for the main cap to need no machining) then the plate went on over the spacers , and then the washers and nuts. It was a 3/8" thick aluminum plate - which didn't impress me much. I hear someone else has a 3/8" or 1/2" steel plate.

              Comment


              • #22

                Re: Main cap girdle's....do they work??

                Re: Main cap girdle's....do they work??

                I can't speak about use on a Mopar, but on a small Ford stock block over 500 HP they are good for keeping all the pieces in one lump when the block splits. I rank them right up there with that valley girdle crap.

                Comment


                • #23

                  Re: Main cap girdle's....do they work??

                  Re: Main cap girdle's....do they work??

                  I looked at one on the internet for the BBM and it wasn't like that. That would be the best setup I would think.

                  You put in the studs on the mains and pan rail, dropped the crank in, and put the caps on, then slid little hardend steel spacers that took up the space between the plate and the main cap (and allowed for the main cap to need no machining) then the plate went on over the spacers , and then the washers and nuts. It was a 3/8" thick aluminum plate - which didn't impress me much. I hear someone else has a 3/8" or 1/2" steel plate.

                  the one for my smallblock mopar is the type that you speak of but it is made of steel and the one's for the bigblock's as far as I know are made from steel also and are 1/4 thick, the only thing I did different was to do a little extra machining on the cap by making all the spotface's for the main stud's all the same(the height's were as much as .025 different from each other) and then milled the flat on the cap a specific height and then made new hardened spacer's, I thought the spacer's that were sent with the girdle were kind of chinsey, I actually think it makes a good thing a little better.

                  Comment


                  • #24

                    Re: Main cap girdle's....do they work??

                    Re: Main cap girdle's....do they work??

                    on a small Ford stock block over 500 HP they are good for keeping all the pieces in one lump when the block splits.
                    WHEN the block splits. LOL! Sad but true.

                    Comment


                    • #25

                      Re: Main cap girdle's....do they work??

                      Re: Main cap girdle's....do they work??

                      when the block splits down the middle it's officially "all worn out."

                      Comment


                      • #26

                        Re: Main cap girdle's....do they work??

                        Re: Main cap girdle's....do they work??

                        when the block splits down the middle it's officially "all worn out."
                        I would say it's time to go back to the drawing board.

                        Comment


                        • #27

                          Re: Main cap girdle's....do they work??

                          Re: Main cap girdle's....do they work??

                          You guys must not have built many serious small Fords. They split all the time.

                          Comment


                          • #28

                            Re: Main cap girdle's....do they work??

                            Re: Main cap girdle's....do they work??

                            You guys must not have built many serious small Fords. They split all the time.
                            you must not have neutral balanced them and spun them to high LOL

                            stock or stock rebuilds most likely have a 50oz imbalance or maybe even a 28....do a nice zero and a lot of your worries go away, but not completely

                            Comment


                            • #29

                              Re: Main cap girdle's....do they work??

                              Re: Main cap girdle's....do they work??

                              You guys must not have built many serious small Fords. They split all the time.


                              I beg to differ, but then I'm not arguing.

                              Comment


                              • #30

                                Re: Main cap girdle's....do they work??

                                Re: Main cap girdle's....do they work??

                                I'm not normally a big fan of girdles - although I'm sure they help some engines.

                                If you buy into the spring concept for a bolt or stud it'll tell you that the fastener clamp load is all thats holding a main cap in position. Once you exceed the clamp the cap is free to move around fore & aft because the bolt holes are by necessity larger than the shank of the fastener. The fix for eliminating this free movement is a dowel pin. A pin positively locates the cap, and allows the fastener to only be required to handle vertical movement.

                                The pins will not help a marginal main bulkhead - and that is where the girdle may help out - - although I'd pin the girdle to both the mains and the pan rail.

                                And stock block small block Fords will eventually split no matter what at 450-500HP - just not enough metal down there

                                Comment

                                Working...
                                X