Ok so I recently installed a Comp Cams nitrous cam in my 383
specs: http://www.compcams.com/Technical/Search/CamDetails.asp?PartNumber=12-564-4
I am getting ready for spray and I wiped a lobe on the previous cam and also needed to pull the heads to get the valve seats re-cut. I went with a complete kit that came with the cam, lifters, springs, and all the other hardware. So my question is are the anti-pump up lifters supposed to make alot more noise? My machinist recomended setting the valve lash at zero and letting them tick while idling for the best performance, but isn't this going to create more wear on the valvetrain?

i got a set on my car, basically set them just like you would with regular hydraulic Lifters. what they are designed to do is help keep the valves from floating when you are revving the motor really high. so instead of pumping up and causing the valves to float, it bleeds off.

another you can do is call them and make sure, but that is what they told me when i called them.

My machinist recomended setting the valve lash at zero and letting them tick while idling

I think it's time to find a new machinist. That's absurd! There HYDRAULIC lifters. Adjust them correctly. If you want a second, third or 4th opinion,, call Comp Cams.

slow down here guys. The only real difference in the two is the retaining ring. No bs here. Weve taken them apart and theres no difference other than the retaining ring on the lifter. A std hyd you need to preload the lifter . Thats when you take out all the slack and then give an additional 1/2 turn. The real reason that even the oem car manf. preloads a lifter more than zero is to allow for parts wear. If they only gave a lifter zero , the car would come back for noisy lifters . Costing the car company money. So the preload a lifter more than it really has to have to make sure it will never develop valve lash until something is way out of warranty. Now in a racing application, the motor usually has a higher pump volume and or pressure than the stock oil pump. Also a racing engines is operated at a higher rpm level. So what happens now is the oil flow & pressure now can push the preload out of a lifter usually gaining ground when the valve is at its lightest point , when its just beginning its closing ramp from max lift. So as the lifter pushes the preload out,it is raising the center of the lifter where the pushrod is located. This push will not allow the valve to return to the seat what ever the amount of preload is pushed out. So to eliminate this high rpm push, you just eliminate the preload and run the rocker at "zero" lash. No lash at the valve tip but also no preload. Now this is where the anti pump lifter comes to play. The stock lifter will have a little wire snap ring that holds the internal parts of the lifter in it. When you run the lifter at zero the wire can pop out,allowing the lifter to come apart if the pushrod dosent keep it tigether. So the anti pump has a better retaining collar to keep the lifter together , you can run zero lash.
I am in the works of developing a true racing hyd lifter, that will have a limited plunger travel, and some other goodies so it will adjust like a std hyd lifter to please the track tech, but will only have .015 after the preload, it will be able to use solid spring pressures introducing 7500 rpm hyd cams. :bowtie:

doechsle:
So what about on a street strip engine? My car sees the street no more than twice a week and the track at least twice a month. I do have a high volume (std pressure) oil pump, so should I not be concerned about the extra noise? I understand that this could give me added performance but, could it also put my virtually brand new valve train through more wear and tear? I just don't want to be tearing this thing down more than I have to.
By the way keep us posted on those lifters sounds very interesting.....

as a rule of thumb I advise anyone wanting to turn their engine over 5500 rpm's is obviously looking for performance, so use them in that application. Here's the real deal, if the valve springs are good enough to keep the lifter compressed through the rpm range, then the anti pump will gain notinng. But using the std lifter in this enviroment will enter the ability of the lifter doing it if the conditions allow. A anti pump at zero lash eliminates the lifters ability to push, because it's as far out as it can go already.

doechsle's right, b/c I lashed mine to solid once and later blew a retaining clip outta one,

It sure would rpm tho!!

That's why I just said ta heck w/ hy-cams and now like MILD to MEDIUM solid lifter cams!!

That and a solid cam will make between 3 and 4 percent more power everywhere than a same spec'd hy-cam!!

Just make sure to listen for a lashing time and to run needed GOOD valve springs b/c one will flat rpm, regardless!!

pdq67

If your rocker arm geometry is correct you can run 1/8 turn after zero. I have had mine set this way for 20 years plus with no issues what so ever. My 355 will rev without valve float to 7500 rpm, I usally shift around 6.5-7K. The 1/8 setting gives you a little more preload than zero and no valve train noise. Valve spring preasure is key, using the correct pressure is critical.:bowtie: