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Pushrod length
Posted: Thu Jan 12, 2006 11:38 pm
by jr_vw2
I am pretty sure that I know the answer to this question but I have to ask anyway to double check myself and be sure. When running 1.25:1 rockers with standard deck height on a non stroked motor you still have to cut your pushrods to length right? to make up for the different "rock" on the rocker...right??
Posted: Thu Jan 12, 2006 11:59 pm
by newmanx59
You will have to setup the rocker arm geometry during the mockup build of your engine. Take your time and make sure it's dead on. A properly setup valvetrain will make more HP and improve the longevity of the heads, cam and lifters, not to mention make the engine run much quieter. I use an adjustable pushrod and a soft spring (hardware store) in place of the stock valve spring for setup purposes. This allows you to push the valve down at full lift to check for interference, piston to valve. It is also a little easier to adjust the pushrod as needed. Do this with the head torqued and no pushrod tubes. Once the geometry is correct be sure to test it with the valve springs you are going to run and check for coil bind at full lift before you cut pushrods.
Posted: Fri Jan 13, 2006 12:00 am
by Gene-C
I don't know for sure but that would make sense. I think the real question is what is the proper length? and how do you cut them to that length?
Posted: Fri Jan 13, 2006 12:54 am
by Gene-C
tubing cutter
Posted: Fri Jan 13, 2006 1:10 am
by Gene-C
I was lead to believe that the neat thing about the 1.25:1 rockers was that you didn't have to mess with pushrod length on a stocker motor. They are not bolt and go, either, however. You still have to get the geometry dialed in with shims, etc. Is this not correct?
Posted: Fri Jan 13, 2006 1:12 am
by Gene-C
You should check geometry on ANY engine whenever you make change. It took me hours to set mine up, yes hours.
Posted: Fri Jan 13, 2006 4:07 am
by newmanx59
1.25:1 rockers can and will sometimes work with just some rocker stand shimming but if you are building a fresh engine with a new case, heads and cylinders you need to start at square 1 on the valvetrain geometry. Do not take a shortcut on the geometry. I am not a big fan of 1.25:1 rockers, they are typically more difficult to setup and cost the same amount of money as 1.4:1 rockers. 1.4:1 rockers give you more performance for the same money. This link has everything you need to know about setting up VW valvetrains although it is lacking in the picture department a bit.
http://www.vdubn.com/sandrailing/engine/valvetrain.htm