blodi

Hmm...looks like I have stock retainers from those pics. So...last night I reassembled everything. Then reset the lash to .008 and .010 on all the valves. I double and triple checked that #4 intake valve. I then pulled the fuel pump fuse and coil wire and cranked it over probably 100 times and watched that valve closely....no odd movement at all...looked to be operating smoothly at cranking speed at least. I installed the valve cover and fired it up. After a few minutes...the tapping sound came back....so I immediately stopped the engine and pulled the valve cover. I looked over everything and it all looked fine. I checked the lash again on #4 intake....it was fine....nothing seemed out of place at all. Reinstalled valve cover...fired it up and after a little bit the tapping sound came back . I also could see plenty of oil flowing from the cam while I was cranking it with the cover off...so it seems lubrication is not an issue. I then decided to pull out my bore scope and stick it into the #4 intake. Only thing of note that i saw was this pit on the side of the port just above the top of the valve. Not sure if that is anything of concern or not. So at this point...still stumped. Could the valve or guide be damaged and when it heats up the valve becomes a bit sticky and is floating? No obvious issue with the valve springs that I can see. I could get it up to temp again and pull the cover and crank to see if I notice anything different with the movement of the valve when it's hot. Anyways...that's where I'm at....man, this thread got off topic IMG_4509 by blodi, on Flickr

I can probably just check the wipe patterns first. If they all look good...no need to take everything apart and measure everything, right?

I just found this on lash pad sizing...the last line is interesting. "Having the correct cam-lobe wipe pattern is extremely important to ensure the longevity of your cam. This is accomplished by using the procedure below.Coat the contact surface area of the rocker arms with lay-out fluid or black magic marker. Install one rocker arm and set the clearance to the cold specifications. (Intake .008 Exhaust .010) Using the cam sprocket bolt, rotate the cam one complete revolution. Compress the valve spring and remove the rocker, check the wipe pattern to see if it is centered and does not extend off the rocker arm pad. Adjustments are made by using different-thickness lash pads. These are available in 0.010 in. increments and range from 0.150 in. to 0.330 in. Stock lash pads are 0.118 in. (3mm). If the pattern is towards the valve end of the rocker, a thinner lash pad is needed. If the pattern is closer to the pivot end, a thicker lash pad is required. Continue this procedure until all the rockers have been checked. It is not unusual to have as many as five or more different size lash pads to achieve a correct setup. " So maybe it's not odd that i have different sized pads? I'd like to believe Larry knew what he was doing when it built this since he had build "hundreds" of L engine over the years.

Yes, the broken one was .170....MSA (who I guess gets their pads from Rebello) only now stocks .175 and greater. So I got a couple 175's and had them machined down to 170. I think you are right...I'll just pull them all and document the size and wipe pattern and we'll go from there. 3-5 inches of snow here tonight....I guess I got time

Measuring just the flat bottom to the flat top using calipers. None of mine have the recessed part on the bottom. Not measuring the “wings” on the sides.

Yes. This is the same valve as last time. (#4 intake.). These are aftermarket pads that are flat on the bottom. Seems the factory ones would stay put better, no? I just pulled the #3 intake pad out. It measures .19-.20 (with my junk Harbor Freight calipers). I’ll take it into work tomorrow for a accurate measurement. But it is certainly thicker even by eye. The wear pattern on that rocker isn’t as centered as the #4/ .017 valve. Is that normal for the pads to be different sizes for each valve? Also are they different between intake/exhaust valves? Can I still get factory ones? I’d be willing to replace them all with factory ones that are a consistent thickness if that is what it takes.

Yes. This is the same valve as last time. (#4 intake.). These are aftermarket pads that are flat on the bottom. Seems the factory ones would stay put better, no? I just pulled the #3 intake pad out. It measures .19-.20 (with my junk Harbor Freight calipers). I’ll take it into work tomorrow for a accurate measurement. But it is certainly thicker even by eye. The wear pattern on that rocker isn’t as centered as the #4/ .017 valve. Is that normal for the pads to be different sizes for each valve? Also are they different between intake/exhaust valves? Can I still get factory ones? I’d be willing to replace them all with factory ones that are a consistent thickness if that is what it takes.

60+ degree day here yesterday so I fired her up after work. The new choke setup works great! Started immediately. Backed it out the driveway....thought I started hearing that tapping noise again...got a bit down the road and could hear it wasn't hitting on all cylinders..... Later on I pulled the valve cover and ...son of a.....it happened again! IMG_4498 by blodi, on Flickr Found the lash pad...full in tact this time... IMG_4499 by blodi, on Flickr Really confused what might be causing this. I readjusted the valve to .010 when I installed the new lash pad. A quick look has me wondering if the lash pad on this particular valve is thinner than the others.... IMG_4501 by blodi, on Flickr IMG_4500 by blodi, on Flickr I think I'll pull one of the other lash pads and measure it. Maybe when this engine was built a thinner last pad accidentally was installed on this valve. It would still be a bit odd as I had put 3-4k miles on this engine before it had issues. And regardless of the thickness the pad still sits down into the retainer the same amount. What else could cause the lash pad to pop out? Sticky valve? The engine has only the 3-4K I've put on it since it was built and has had a generous amount of oil changes. Maybe I didn't get the spring that holds the rocker valve in place on correctly? I'm just stumped a bit. Ideas?

Still haven't driven the car anymore, but the weather is just starting to turn it seems. I did rig up my chokes finally. Went to the local hobby shop and got about $15 worth of R/C airplane linkage parts and it seems to work pretty good! IMG_4474 by blodi, on Flickr IMG_4476 by blodi, on Flickr

Got the 175's machined down to 170. Popped one in last night...should be all good to go!.....well...in a couple months once I get everything else done on the car and it's warm/dry enough.

Glad others are all getting something out of this! Started this just to educate myself, but happy others can learn with me! esmit208, I don't know if my tuner has an altimeter, but I'll look. It was varying temps when I did various pulls, so I always kept that in mind. I think we are between the last two setups as far as e tubes and such...then just figuring out the accell circuit. Hopefully tuning can resume March/April once the snow here in Michigan clears. In the meantime I have plenty to do: lash pad fix, rear disc conversion, some small electrical fixes...etc.

They are flat on the bottom. I supposed I could get the 175's and maybe have the metal shop here at work knock them down for me.

So I ordered my lash pad from MSA (.170")....which was then backrordered...but now they said they no longer carry smaller than .175". Just my luck. Anyone have a 170? Or know where to get one? I don't want to change all 12 to 175 if I can help it.

Lash pad is back-ordered for 3-4 weeks....oh well. I got time now that the snow is piling up outside right now.

I did run a magnet around the head last night, but no luck finding the small part. Ordered new lash pad (.170") and got a couple rare earth magnets here at work. Should be back up and running soon!

“That theres ur problem”. Broken lash pad. The other small part that broke off it I cannot find so it probably dropped to the pan. I’ll check the thickness tomorrow and order one. Do I have to remove the camshaft to install a new one?

Not at all...still ran/started great. Plenty of power.

went from bad to worse...tapping turned to #4 cylinder not firing at all. Got spark and fuel....compression test showed 90 psi on that cylinder. So, I'm suspecting a stuck or bent valve....going to pull valve cover to inspect when I have a chance here.

Drove the Z into work today since it's the last day in sight for 50+ degree temps. Ran great all the way until I was almost to work and then the tapping came back. I'll see what happens on the drive home. Good point on checking for throttle plate screws..yikes. I'm also wondering if I'm getting a bit of knock due to timing since the temps have gotten colder. I am running a lot of timing so maybe I need to back it down a bit and see if that changes it. I will try the blocking of the accel jets in the spring and we will see what we get.

Just an update...kinda...the car has pretty much been parked for the last month and half as I've been dealing with moving and new house projects. I did take it for a short drive a few days ago..the engine was doing the tapping intermittently for a little while then it went away completely after a while. So, not really sure what it was/is. Car was running great though. Not sure if I'll have chance to drive it again this season to do anymore tuning/tapping investigation...snow will be upon us soon Just wanted to make sure everyone knew i hadn't forgotten the thread...but it may go dormant for a while here.

I re adjusted the valves to .010 and .012 and put in new plugs.....no change. Noise also now seems to happen at idle sometimes and during constant RPM when I hold the throttle open. But, the noise does seem to be a bit intermittent. I'm suspecting maybe exhaust leak (I can't see signs of one) or maybe an oil spray bar issue? The bar is intact and no obvious blockage just from a visual inspection. I also hooked up my timing light and the noise is certainly not a fast as the timing light flashes. Probably won't have time to dive much more into it for a couple weeks here. I'm afraid I may not then get much more done on the tuning either before winter sets in. We will see.

Will do! Bare with me here over the next few weeks. Going to be out of town and then am moving over the next two week after that. I checked a few valves last night and they are all tight .008 and .010 respectively as I set them. The chain did have a good amount of slack in it on the drivers side, but then I realized that was because I had moved the cam gear by hand. I turned it over a few times with the starter and the slack seemed tight/good. I got some new plugs too that I'll throw in for good measure. Might be next week til I can go through every valve thoroughly. Really hoping it's not a rod knock. Seemed to start randomly as I was driving into work last week out of nowhere, hadn't done any pulls or anything.

Pulled each plug wire...no change. Which I understand to be good news as it would maybe indicate rod knock? You really hear it mostly on decel after reving. Sound like it's coming from the top end. Pulled the valve cover and nothing obvious...I'll check valve lash. No signs of exhaust leak around the header that I could find either.

Yeah, going to try to pull the valve cover and check lash this weekend. I adjusted it all when before i installed the engine (1.5 years ago)...I'll check it again. It's a bit of an unnerving sound.

While waiting for the 140/240's to show up I was curious and installed the F16's with 155/185 as originally stated on the engine when I bought it. I did this with the 36mm chokes before but, not with the current 35's.... F16 155/185..... 10517-2 by blodi, on Flickr 10517-1 by blodi, on Flickr The 140/240's showed up tonight and I installed them. I'll report back with data. But, also ran into a tapping noise that I am not thrilled about today too.