Question Posted By: stroker on 8-10-2010
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||Drilling out lifter blocks on shovel-heads
||I read that drilling out the return oil orfice, holes in the lifter blocks helps return the oil faster,,to the bottem end. Has anyone tried this???
- Not necessary. The pushrod tubes get a small splash and some condensed oil vapor, but not enough to warrant drilling out the return holes. Anybody telling you they recommend doing that had an oiling problem they were trying to cure. By: 47Knuckle-Dragger on: 8-10-2010
- 47KD,,,I think that idea came from Easy Rider teck-tips,, and it was to cure over oiled top ends. Guest,, on these years,,the oil returns through the tubes,,not the jugs,,,,If I get time,,I'll check the teck-tips to be sure. This is a good tip site. I also use the what-fits what and the other books in that series. Denish'es books are the best I've come across so far. By: stroker on: 8-11-2010
- Yep...Thats what I'm talking about.I even had an idea that I could just drill the front block,,That way you would still get more oil to the front cover,,and still get a good return to the cam chest!!!!! By: stroker on: 8-12-2010
- "Guest,, on these years,,the oil returns through the tubes,,not the jugs,,,,If I get time,,I'll check the teck-tips to be sure."
No need to check your teck-tips; the oil from the rockers returns through a hole at the exhaust end of the head, down through the barrels, then out a hole just below the BDC travel of the piston skirt. Check your service manual, section 3A, page 6 (you do have a service manual, right?) By: 47Knuckle-Dragger on: 8-12-2010
- As to getting the oil to the camchest "faster", that's not an issue. If the oil was draining too slow it would back up the pushrod tube. There is only so much oil going to return through the pushrod tubes...drilling the lifter block return holes larger won't increase that amount. By: 47Knuckle-Dragger on: 8-12-2010
- How can I make this clearer? If oil were to build up in the pushrod tubes to the extent that you'd have to wait 5 minutes in order to remove the retainer clip and raise the pushrod tube; then yes, drilling out the return holes to a larger size might gain you a teaspoon or so in flow per minute. But it doesn't...no matter how many Shovelhead engines you've built the oil that accumulates in the pushrod tube comes from condensed oil vapor and rocker arm splash. If, in fact, more oil than normal accumulates in the pushrod tube..then drilling out the return holes is a band-aid fix to a bigger problem. As to your question, "will it hurt anything?" No. I never said it would "hurt" anything...I said it was "not necessary". By: 47Knuckle-Dragger on: 8-13-2010
- This idea came from Jim Thompson,,Thompson cyl. head service and machine service,,,MA. Easy-Riders Tech-tips #3,,Pg.24. All kinds of tappet trivia. By: stroker on: 8-15-2010
- PS. Yes I use service manuals...Only an idiot would work on one without it.Not every thing is in the manuals. for Example,,,, No torque specks for tappet blocks till 1970,,,,no cam cover bolt torque specks till 78!!!!!and I do use other books quite often also.Denish High-performance Guide Vol-1 is one of the best!!! I wish he would print#2 By: stroker on: 8-15-2010
- Thanks for all the responce. This is how we all learn,,,I have found that you ask 10 different mechanics,,you get 10 diff. anwsers!!!!! By: stroker on: 8-17-2010