I have installed the 1:1:1 ratio rocker with elephant feet. The heads have H-D springs and the cam is the 2880 cheater cam from CB Performance. Since I am only changing the power band with this light cam and not adding additional RPMs above 5K I will use aluminum pushrods. After checking the rocker geometry I find I need shortened pushrods due to the elephant feet adjusters. In this situation, I do I set the adjuster lash at .006"" and then measure the pushrod length or set the lash at zero (just able to spin the pushrod) measure and round down for the final length? Also, it is correct to set the lash cold at .006" when running, right?
Thanks,
pushrod length with swivel/elephant feet and lash setting
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dmend
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Marc
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Re: pushrod length with swivel/elephant feet and lash settin
Stock pushrods should work for you if the HD singles aren't too stiff. Probably still be a good idea to carry a couple of spares in your road-box, though.
The swivelfeet introduce geometry issues because they increase the distance from the rockerarm to the valve. Before using shorter pushrods or excessive rockerstud shim thickness to compensate, the problem should be addressed at its source by grinding off the underside of the rockerarm to allow the adjuster to be backed out farther.*
Take it slow so you don't overheat/soften the metal (if it's turning blue you're going too fast). You'll want to have an m8x1.0 tap to chase the threads clean afterwards.
It's only necessary to grind enough that the valve lash can be set with ½ to 1 turn unused thread travel. That's .020-.040", more than enough to allow for future adjustments.
With the Porsche-style "elephant-toe" adjusters you've also got to ensure that the foot doesn't contact the rocker at the extremes of travel (and won't in the future); with the "Mazda" style captive-ball adjuster that's not an issue. Failure to check this is the primary cause of failure with the elephant-toes.
Note that a few rockers escaped the factory without the oil-passage drilling being welded over. That's no biggie with stock or elephant-toe adjusters, but for the Mazda style you should choose rockers which have the hole shut so there'll be oil pressure supplied to the internal drilling that lubricates the captive ball.
Only after doing this should you start fussing with rockerstud shims and shorter pushrods to set your geometry. The goal is to have the adjuster in-line with the valve stem at ~half-lift, to minimize friction and maximize guide life.
The "zero-lash" technique applies to steel/CrMo pushrods which don't expand as much as the rest of the engine as it heats up; with aluminum p'rods it can result in the running lash being too tight so I wouldn't recommend it. Setting the lash on a running engine is possible, of course, but it's a messy, nasty process that you'll want to avoid except as a last resort (chasing down a mystery valvetrain noise, for example).
Note that early Bus 1500 and Bug/Bus 1300 pushrods are slightly shorter than the ubiquitous 15/1600 p'rods....about 1mm IIRC. They're recognizable by their longer 40HP-style ends or slimmer tubes, respectively. If you just need a few pushrods that're slightly shorter, try searching for some of those rather than screw around with cutting your own.
The stock cold lash spec was .004" for years (with the exception of the long-rocker-stud early 40HP engines) and was bumped up 50% to .006" to provide a little insurance since American owners tended to overlook routine valve adjustments and suffered burnt exhaust valves as a result. There was never an intake-valve-related issue at .004", so personally I've continued to use that. In my experience, once an engine's broken in you can safely set the lash at .004" intake and .006" exhaust and stretch the adjustment interval some...typically at 6,000 miles you'll find them both at ~.005" doing it that way. If you're the fastidious type and will never, ever, go beyond ~3,000mi between adjustments, .004"/.004" still works with stock pushrods.
*be sure to check that the adjusters clear the valvecovers. I like to put a dab of Prussian Blue (or grease) on the ends of the adjusters and squirm a valvecover with no gasket around on the head at all camshaft positions. If there's any contact, dimple the cover as required. This'll ensure that you've at least got as much clearance as the thickness of a compressed gasket when running.
The swivelfeet introduce geometry issues because they increase the distance from the rockerarm to the valve. Before using shorter pushrods or excessive rockerstud shim thickness to compensate, the problem should be addressed at its source by grinding off the underside of the rockerarm to allow the adjuster to be backed out farther.*
Take it slow so you don't overheat/soften the metal (if it's turning blue you're going too fast). You'll want to have an m8x1.0 tap to chase the threads clean afterwards.
It's only necessary to grind enough that the valve lash can be set with ½ to 1 turn unused thread travel. That's .020-.040", more than enough to allow for future adjustments.
With the Porsche-style "elephant-toe" adjusters you've also got to ensure that the foot doesn't contact the rocker at the extremes of travel (and won't in the future); with the "Mazda" style captive-ball adjuster that's not an issue. Failure to check this is the primary cause of failure with the elephant-toes.
Note that a few rockers escaped the factory without the oil-passage drilling being welded over. That's no biggie with stock or elephant-toe adjusters, but for the Mazda style you should choose rockers which have the hole shut so there'll be oil pressure supplied to the internal drilling that lubricates the captive ball.
Only after doing this should you start fussing with rockerstud shims and shorter pushrods to set your geometry. The goal is to have the adjuster in-line with the valve stem at ~half-lift, to minimize friction and maximize guide life.
The "zero-lash" technique applies to steel/CrMo pushrods which don't expand as much as the rest of the engine as it heats up; with aluminum p'rods it can result in the running lash being too tight so I wouldn't recommend it. Setting the lash on a running engine is possible, of course, but it's a messy, nasty process that you'll want to avoid except as a last resort (chasing down a mystery valvetrain noise, for example).
Note that early Bus 1500 and Bug/Bus 1300 pushrods are slightly shorter than the ubiquitous 15/1600 p'rods....about 1mm IIRC. They're recognizable by their longer 40HP-style ends or slimmer tubes, respectively. If you just need a few pushrods that're slightly shorter, try searching for some of those rather than screw around with cutting your own.
The stock cold lash spec was .004" for years (with the exception of the long-rocker-stud early 40HP engines) and was bumped up 50% to .006" to provide a little insurance since American owners tended to overlook routine valve adjustments and suffered burnt exhaust valves as a result. There was never an intake-valve-related issue at .004", so personally I've continued to use that. In my experience, once an engine's broken in you can safely set the lash at .004" intake and .006" exhaust and stretch the adjustment interval some...typically at 6,000 miles you'll find them both at ~.005" doing it that way. If you're the fastidious type and will never, ever, go beyond ~3,000mi between adjustments, .004"/.004" still works with stock pushrods.
*be sure to check that the adjusters clear the valvecovers. I like to put a dab of Prussian Blue (or grease) on the ends of the adjusters and squirm a valvecover with no gasket around on the head at all camshaft positions. If there's any contact, dimple the cover as required. This'll ensure that you've at least got as much clearance as the thickness of a compressed gasket when running.