Let's talk valve wipe pattern & also piston rings
Let's talk valve wipe pattern & also piston rings I know that many spin the engine 7K+ on stock rockers. However, I have noticed that even w/ proper lifter pre-load & pushrod length that the non-adjustable stockers cannot be dialed in as well as a set of adjustable post mounted roller rockers, in terms of valve wipe pattern. Seems like valve guide wear & even the potential for valve float would be increased by the wider valve wipe pattern created by the stockers (stock rockers maybe 3/16" wide & centered, adjustables 1/16" wide & centered). May sound like a redundant question, but have read many, many posts where guys swear by the stock rockers, but never is a comparison made to an adjustable valve wipe pattern or is the need for earlier head rebuilds noted, as a result of using the stock rockers (not that I've found anyway). Comments?
Am replacing the piston rings in my back-up short block. The moly based top ring seems to be more prone to heat damage. What is the preffered file-fit set-up/material or replacement kit for street/road course use? Ductile iron top ring, manufacturer X's ring kit, zero gap rings.....???
Thanks in advance
Am replacing the piston rings in my back-up short block. The moly based top ring seems to be more prone to heat damage. What is the preffered file-fit set-up/material or replacement kit for street/road course use? Ductile iron top ring, manufacturer X's ring kit, zero gap rings.....???
Thanks in advance
As far as the rockers go, those are two different contact tip designs, so both will show a different wipe pattern. The stock rocker has literally been known as a "scuff pad" design, insinuating more friction. The wipe pattern will be larger as a result of this design. I don't think with the valvetrains meant for street cars, and good geometry of course, there is need to worry about excess wear on the valves, guides, etc. (maybe just the needle bearings) caused by the stock rocker design. There is more than one way to skin a cat as far as finding your "ideal" rocker geometry, the wipe pattern is only one of them. It's quick, easy, and close enough for most guys, but I don't think it works well for stock rockers.
Lifter preload and pushrod length won't effect the wipe as it would on a stud mounted rocker. You need to physically move the rocker up and down to find the sweet spot. One engine builder (well known) has stated he has found they need to be lowered. There are aftermarket rocker stands (such as LPE) that can be bought and machined for this purpose. I reached a point of frustration with mine and went with Yella Terra's instead, which were easier to adjust the height of to obtain a good geometry.
Didn't know that after market stands were sold in order to machine & lower for a better geometry/pattern. With the new cam, went back to 1.7 stock rockers from 1.8 stud mounted adjustables. I'm gonna upgrade to stud mount 1.7 adjustable rollers, as you've mentioned, to make it easy.
What about the rings for my back-up short block? More than once, I've had an overheat cause ringland (ring) issues in an LSX block. Pistons, vlaves & heads would be fine, but the rings no longer sealed properly. I think it only happens w/ the moly based rings.
What about the rings for my back-up short block? More than once, I've had an overheat cause ringland (ring) issues in an LSX block. Pistons, vlaves & heads would be fine, but the rings no longer sealed properly. I think it only happens w/ the moly based rings.
I have been researching piston rings recently for a 250 shot. As of now it looks like the iron ductal top ring set up is the way to go for putting a lot of heat and cyl preassure.
Akerly & childs (HTD) offers a nice set as does Total Seal (Hellfire) and Diamond makes them with a Iron ductal top ring also I think. I think they are close is quality and features. It will more than likely come down to price for me.
Akerly & childs (HTD) offers a nice set as does Total Seal (Hellfire) and Diamond makes them with a Iron ductal top ring also I think. I think they are close is quality and features. It will more than likely come down to price for me.
