Lash pads

[ryderfmjones21]

My lash adjustment loosened up sending my rocker with it and breaking the ear off a lash pad. I’ve been looking for replacement lash pads and can’t find any. They are .250” thick the biggest I could find online we’re .165”.
Anybody know where I can get ahold of some?

[ryderfmjones21]

It may be a little larger around .260”. Don’t have any calipers handy with me today

[JT68]

Is this a U20? Are you sure .25"? that is way off from standard at .082". Sounds very odd, send me some photos of the retainers&lash pads (top and bottom). PO engine build?

Lash pads are probably not something you can make easily. They need to be precision ground from tool steel and hardened- they"ll fail every time if made from other materials.

Was the lash adjuster nut actually loose? That almost never happens either-it may have shed the rocker due to the way it is set up. Sounds bizarre.

[ryderfmjones21]

The motor had a lot of “odd” stuff on it when I got it. I guess you would say racing parts. Had a dealer option aluminum flywheel. Dellortos has a b cam. It was parked in 86. I think the tall lash pads are odd as well. I don’t know if I can get it right with the stock .165” ones.

[ryderfmjones21]

The lash nut was actually loose yes. I could rotate it with my fingers. I found it at the lowest setting. I am not sure who built the motor the guy I bought it from was a bit of a nut and hadn’t done anything with the car anyway ha.

[ryderfmjones21]

Could I just use the .165 lash pads and adjust the lash to work with that? Seems to far out

[ryderfmjones21]

[ryderfmjones21]

I was considering just making one out of 4140 but like you said not sure how well that would work out...

[ryderfmjones21]

Could someone have put a 510 pad in there? Dimension is close. Can’t find a width for it.

[JT68]

Yep, I think you might be right. Is the OD 14mm? if so that is L-series. U20 is 15mm. A bad combination (rocker and pad are free to bop around laterally. bad, bad, bad)

Valve 6 looks like a roadster lash pad, but valve 5 looks like it could be an L as well. Bad plan, Kinda obviously not a good setup if that is the case.

[ryderfmjones21]

It looks like all the exhaust valve pads are like that except #4. That’s crazy... I’ll have to go through the whole top end.learned my lesson I guess. Some of the pads seem to fit more snug while the broken one seems to have lots of slop at the top of the valve spring.

I will have to look into ordering new ones from dean. Somebody is actually making them for quite cheap on ebay out of Germany now. Only one size though.

[ryderfmjones21]

The o.d is 14mm. It looks like it’s been like that for a long time. There’s a bit of wear on the pad. Surprised nothing major happened.

[jrusso07]

Looks like you are running a C cam now? The wear pattern on the one photo tells me the pad is rotating, probably why the ear broke. Like JT sad, this is bad...Did you say you have different thicknesses on different valves?

Here are some excerpts from a modifying a L-series engine book (by Tom Monroe). The book says lash pads need to be matched to cam wipe. Maybe cam is not uniform? Or nuts were loose

[JT68]

So whomever put the head together "didn't quite have a particularly good understanding of the requirements" to be PC. As Joe mentions, some major badness. The pads that fit well are likely correct for the U-20 retainer, small ones will all cause a failure at some point as you have seen.

Using an L-pad in a U retainer is a major snafu, throws ALL the engine work into question, certainly the head work.

The easy way to correct this is bolt on a fresh head. Otherwise pull that head and start correcting all the dorkage.

As Joe mentioned, its either an dual grind cam and/or someone dorked up the stem heights badly or both.

Let's hope the previous builder did not touch the bottom end.

I have some Isky retainers around here somewhere that are machined for L pads and roadster valves. That might fix you up, but THE ENTIRE HEAD needs to be checked out. Who knows what valves, springs, pressures, installed heights you have. None of it should be trusted unfortunately. Very sorry for your misfortune.

[Gregs672000]

Agree with JT, but it may be worth more investigation. My head is pretty modified, and part of that mod was to use L-series spring retainers and lash pads, but I run custom valves. They make one (that i believe Dean sells, maybe others) that will allow you to run thicker lash pads more safely. You have an Isky cam. Hard to tell from the pic, but it looks like I see a Z-196. Take the numbers off the end of the cam that you posted and call Isky, they will tell you what the grind etc is. I run an Isky cam as do a few others here. Mine is a no longer listed "Z-197" (246 duration at .50 thousands, 536 lift with our rocker ratio... B cam duration with a lot more lift). The still listed Z-196 is a lot more cam with more lift and duration which would require even more engine adjustments to work well. I believe that Spyder adjusted the cam timing to make it work well with his highly modified engine for the street. Do a forum search for Isky or z196, etc. So, depending on what you have, it will determine if this cam makes any sense, and if not you will need to locate another B or C, or get an A and have it ground, as well as either regrinding your rocker arms or replacing them.
I'm very familiar with Dellorto carbs, so feel free to contact me if you have questions. We're here to help!