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Dry tappet clearance after Port and Polish.

GEM930

GEM930

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I read some older posts on dry tappet clearance, but none of them ever seem to come up with a clear solution. I was hoping a repost may reveal any new solutions.
I just got my cylinders back from Lycon with a hone, port, polish, and 9:1 ceramic coated piston upgrade……. But I cannot get the dry tappet clearance within spec on 5 of the 8 rockers. I cleaned, dried and bled down the tappets several times and have rotated push rods around the five remaining rockers that are out of spec. Unfortunately, they fall between a size 30 and a 31. A 31 takes the lash down on the five remaining rockers to less than .028 and a 31 places it above .080. I contacted Lycon and I am waiting to hear back from them, but wondering if anybody else has any ideas?
 
Here are my notes on the lash measurements
 

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Make sure the lifters are truly collapsed. Use a block of wood or something and lean on the rockers hard for 30 seconds or more before measuring lash even though you are sure they are dry. Next, make sure that your pushrods are actually the length you think they should be. I had a similar problem when I was building my Superior bottom end, Lycoming top end engine from Lycon. This was some years back, but the Superior pushrods (this was with S brand roller lifters) were mismarked. I kept sending them back and getting others sent to me, but nothing worked to get into spec. I finally obtained a 12" caliper and found the discrepancy. Once I finally got the correct pushrods, I was easily able to get all of the clearances within spec. Aim for the center of the range. Good luck with it.
Ed
 
Something is not right here. I forget the actual number, but each pushrod size increment should add or delete around .040-.050” of lash in my experience. You are getting almost exactly double that, which makes me think the rods are not what you think. Are you sure on the part numbers? Do you have a caliper big enough to measure them?

Are you fully seating the spring in the plunger when you reinstall the halves? You twist a bit and feel it click in.
 
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lr172 said:
Something is not right here. I forget the actual number, but each pushrod size increment should add or delete around .040-.050” of lash in my experience. Are you sure on the part numbers? Do you have a caliper big enough to measure them?

Are you fully seating the spring in the plunger when you reinstall the halves? You twist a bit and feel it click in.
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Also, are you putting the disassembled plungers in gas or solvents? In my experience if there is oil in the check ball area, it will not collapse. I soak in gas and shake them till i hear the ball rattling. Then a very light coat of oil on piston before inserting into the base.
 
I completely disassembled soaked, cleaned and dried the plungers and springs in solvent. I have, however, been unable to get them to “click” into place after compressing and turning them, as everybody has been saying. I am aware of what it should look like as I have seen videos of it but no matter what I do I cannot get these springs and plungers to lock into the other half. I have inspected both halves and there is no kind of machining that would allow these two pieces to lock together with a twist. I thought perhaps maybe it was just a matter of binding it in there, but they will not bind. I figured it must just be some kind of a superior versus lycoming thing. When I checked the lash, I have the rocker arm top completely collapsed. I’m almost 100% certain there is no oil in the tappet. Maybe I will make a video of checking the lash and also of disassembling the tappets. I could be doing something wrong, but they will not lock together in any way. I will see about tracking down a caliper larger than 12 inches.
 
GEM930 said:
I completely disassembled soaked, cleaned and dried the plungers and springs in solvent. I have, however, been unable to get them to “click” into place after compressing and turning them, as everybody has been saying. I am aware of what it should look like as I have seen videos of it but no matter what I do I cannot get these springs and plungers to lock into the other half. I have inspected both halves and there is no kind of machining that would allow these two pieces to lock together with a twist. I thought perhaps maybe it was just a matter of binding it in there, but they will not bind. I figured it must just be some kind of a superior versus lycoming thing. When I checked the lash, I have the rocker arm top completely collapsed. I’m almost 100% certain there is no oil in the tappet. Maybe I will make a video of checking the lash and also of disassembling the tappets. I could be doing something wrong, but they will not lock together in any way. I will see about tracking down a caliper larger than 12 inches.
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While I posted tips, I don't think your issue is in the plungers. Your measurements show very consistenbt differences between pushrods and as long as you are swapping rods without touching the plungers, they are not your problem. I think your pushrod lengths do not match the spec for one or the other part numbers. Meaning your 30's are really 29's or the 31's are really 32's. Your pretty much double what the difference should be, which points me to that conclusion.

The click is not really a locking mechanism. It is just the cut end of the spring splays out a bit and therefore you have to push it in to get past that resistance. Not sure it really clicks, but you can feel it snap past the initial resistance, just like you have to tug and twist a bit to get them apart.. You don't have to push that hard and maybe yours don't have that trait. Every one I have ever done had that, but that doesn't mean it is universal.
 
OK, I got a little more information on collapsing the lifters. It was explained to me that I’m trying to twist the spring tighter which made sense and I was able to get them to click in. However, it does not make any difference on my lash measurements. When pulled the lifters out, the springs are already seated in place so apparently they just pop in on their own when you push in on the top of the rocker to check clearance. Still lost!
 
GEM930 said:
I will see about tracking down a caliper larger than 12 inches.
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You may get close enough with a good ruler. The difference in length between sizes should be around .045". 1/32 is .031" and 1/16 is .062", so looking for a difference of about 3/64" or half way between 1/16" and 1/32" I think they are .090", which would be 3/32"
 
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GEM930 said:
OK, I got a little more information on collapsing the lifters. It was explained to me that I’m trying to twist the spring tighter which made sense and I was able to get them to click in. However, it does not make any difference on my lash measurements. When pulled the lifters out, the springs are already seated in place so apparently they just pop in on their own when you push in on the top of the rocker to check clearance. Still lost!
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I didn't think that was your issue. Believe half the rods have incorrect part numbers. Have no idea if it is the 30's or 31's.
 
I hear what you are saying about the push lengths. What’s confusing is this was a brand new superior XP engine with only 60 hours on it. Unfortunately, the engine sat for a few years and developed some corrosion on the cylinder walls. Hence, the reason for removing and having Lycon do their magic. Luckily the camshaft and everything else was fine!!! These were the push rods that were removed. Now, granted they may not have been in spec when I got the motor as I never checked it, and I understand that Lycon doing the port and polishing and valve job will change those but what I don’t understand is why is a -31 too big on almost any given cylinder and a -30 too small?
 
GEM930 said:
I hear what you are saying about the push lengths. What’s confusing is this was a brand new superior XP engine with only 60 hours on it. Unfortunately, the engine sat for a few years and developed some corrosion on the cylinder walls. Hence, the reason for removing and having Lycon do their magic. Luckily the camshaft and everything else was fine!!! These were the push rods that were removed. Now, granted they may not have been in spec when I got the motor as I never checked it, and I understand that Lycon doing the port and polishing and valve job will change those but what I don’t understand is why is a -31 too big on almost any given cylinder and a -30 too small?
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Sure, mislabelled from the start, but no one cared because the lash was in spec. Then you had a valve job, which changes the valve height and requires new rods to get back. The fact that they were wrtong from the start is not related to current problem.
 
After talking to an engine builder yesterday ( I still have not heard back from Lycon) he suggested separating all the pushrods as you stated, and there was a noticeable difference between the 30s and 31s. However, I then used two ends on a combination square and was able to put the 30s in order on which ones were slightly larger and slightly shorter and do the same thing with the 31s. I was obviously unable to actually measure them as it was just down to how tight each one slid between the stop. He then told me that because my rockers are all identical. I should basically play musical rockers and push rods until I can get everything in spec or as close as possible. I was apprehensive about doing this as I thought you were supposed to keep the rockers and push rods on the original valve they came from, but he told me it did not matter (wives tale ???) and also since all of my parts were reconditioned, it wouldn’t make a difference anyway. After doing this, I have been able to get everything within inspect with the exception of the number two and number four exhaust valves. The number two has a -30 in it and is way too wide and the number four has a - 31 and is too tight. his recommendation is to shim under the rotator cap of the number two with it, a brass shim and install a -30 in the number four and shim the same way. What does the brain trust think of this solution?
 
I placed a 30 and a 31 on my CNC table and use the gantry to square everything up, then using the depth gauge on my digital caliper. I was able to measure a difference of .049. Not exactly precision but .050 looks about right.Here’s a picture of it on a scale.
 

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I betcha the mismarked SL pushrods that I was having trouble with in around '014 are still in Lycon's stock. When I identified the problem, I called for them to be destroyed, but....
I got the correct pushrods directly from Superior. They told me that there had been a production batch mismarked some time before and they had thought they were all gone. You might still be getting parts from that original batch.
Ed
 
When you say ported and polished and also reconditioned, that leaves some doubt in my mind what all was done. Reconditioned would possibly mean the seats, valve tips, and rockers had been ground. That would obviously change the clearances. If they were resurfaced, relative position would no longer even matter as any wear patterns would be gone. Shouldn't have been a ton of wear on the valve tips and rockers in 60 hrs anyway.
Ed
 
GEM930 said:
I placed a 30 and a 31 on my CNC table and use the gantry to square everything up, then using the depth gauge on my digital caliper. I was able to measure a difference of .049. Not exactly precision but .050 looks about right.Here’s a picture of it on a scale.
Click to expand...
360, correct? I looked up the rod lengths and the difference is about.025” between rod sizes. The rocker ratio should be 1.4:1, so an .025 difference in rod length should net a lash change of .035”. You are measuring a difference of .050” in the rods, so you are jumping two sizes not one. One set of rods is mis marked.

Sorry i mislead you earlier, as i was thinking lash dimensions not rod dimensions. Quickly composed internet advice is always less reliable than well thought out diagnostics.
 
Ken at Lycon called back. He said the siz
lr172 said:
360, correct? I looked up the rod lengths and the difference is about.025” between rod sizes. The rocker ratio should be 1.4:1, so an .025 difference in rod length should net a lash change of .035”. You are measuring a difference of .050” in the rods, so you are jumping two sizes not one. One set of rods is mis marked.

Sorry i mislead you earlier, as i was thinking lash dimensions not rod dimensions. Quickly composed internet advice is always less reliable than well thought out diagnostics.
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It appears you are right!!!
Ken and Lycon called and advised the same after I told him I measured the difference between the two at almost.050. Thx for all the help!!!!!

G3
 
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