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1938 model 41 248 I-8 pushrod problem(?)


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heres the latest page of the discussion i currently have going about my 38 buick special

http://forums.aaca.org/showflat.php?Cat=...sb=5&o=&fpart=4

JohnD1956 and I have been discussing the fact that some of my pushrods aren't spinning , and some are. i wrote down the non spinning ones the last time i ran it and observed the valvetrain--2,4,6,8,12,14 and 16. thats going from front to back (firewall end to radiator end just to be sure, e.g. 2nd rod from the rear, 4th rod from the rear, etc)

we dont know if rods are supposed to spin or not, and what causes them to spin/what is the purpose of this anomaly.

http://rapidshare.de/files/6981653/Buick10-30-05.wmv.html if you have a broadband connection or dont mind waiting (well try it and see how fast the download is) here is a video i took of the valvetrain, and other stuff, so you can hear the valve noise it makes and see the rods turning. click on the link, scroll to the bottom of the page that comes up, and click the small FREE button. the next page that comes up, at the bottom this time will be a counter telling you how long your wait is. then the download link will appear.

the "valve noise" was something we also discussed, as a few days ago i decided to try and adjust some of the valves to the correct lash (.015). i only got around to 2, 4, and 6, and they didnt start spinning, but they looked a little more like they wanted to after adjustment (they were rocking back and forth a little) and the valve noise was considerably more after adjustment, so i guess their lashes were not correct and were too small. JohnD told me that it is ok to have the valve noise it is not hurting anything, it just comes with larger lash.

we just need expert opinion at this point, as you can see if you read the latest posts i am making headway on the brake lines, and when the time comes that i can drive it, i dont want to be worrying that putting even normal driving loads on the engine is going to cause damage to something like rods, lifters, rocker arms, etc.

thanks for your time, i await your answer in much curiosity. these spinning rods are quite the mystery.

Paul

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I rebuilt my 38-41 Buick motor last winter.The machinist that worked on my engine told me that the push rods should make about a 1/4 turn each time the lifter comes up.The way you get the lifter to do this is to have the proper crown machined on each lifter.The older gentleman that did the machining on my engine said this turning keeps wear uniform, his experience with late thirties buicks is quite extensive.

Good Luck George

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a ha. pretty neat. i did kind of notice that the ones that spin seem to move about that much! interesting. what is the degree of practicality for someone like me to have that done? would getting the lifters out require removal of the camshaft, etc? what do i risk if i dont do it, at least not soon? can i drive it at all? or am i playing with fire?

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  • 2 weeks later...
  • 3 weeks later...

Sorry it took so long to get back to you. I contacted the machinist that did my engine, his opinion is buick would not have done this to their lifters if it was not important(crown them so the pushrods turn).You must consider the fact that he(machinist)is very finichy. I also asked can you run the engine with-out machining the lifters and not hurt the engine? His answer was you can do a lot of things to an engine that are not correct and get away with it. The lifters should come out with out removing the cam. Be sure to number every part and return them to the place you removed them from!!

Hope I Helped George

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The pushrods on my 1932 and 1940 Buiks are not rotating. The 1940 engine is recently restored. In each rocker arm there is an oil passage for carrying oil from the rocker shaft to the push rods. Check that these holes are not clogged. You have to remove the ball stud and locknut in order to clean the oil passage. The oil passage consists of a larger drilled passage from the rocker shaft and ending at the ball stud. A smaller hole is drilled 90 degrees to the larger passage. Oil fed to the push rods makes the mechanism less noisy.

Jan

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GSW38:

no problem! i knew youd be back sometime. it seemed like the machinist was indeed very finicky. however, if i were a machinist, <span style="font-style: italic">i think id be finicky too.</span> if you're going for the best conditions and what will do an engine absolutely best, you can't settle for anything less than the exact settings that it should be set to. i laughed when i read his response. i wasnt tooooo surprised. you see those people with the early 90's dodge minivans blowing oil smoke out the tailpipe? (maybe its just a coincidence, but i see a lot of them smoking, and a lot of the cars that i see smoking are dodge minivans) they're doing just that, excpet just generally poor maintenance. but the engine still keeps going, at least for a little while. engines (especially these old buicks) somehow manage manage to be pretty resilient, i have no idea how, but they just do... tongue.gif

Guffin:

thanks for the tip about the rocker-pushrod connection. ill get around to cleaning those out, as some still do not have a significant amount of oil dripping down them, while others are smothered in it.

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