Problem with lash closing up
 

Today we were running an engine on the dyno . We broke in the engine , and afterwards re-lashed the valves hot . Ran a few more pulls and decided to check the lash again , and one of the cylinders had closed up .003" . The initial valve lash was done using the Honda valve lash method which has worked well for me for many years . Has anyone else had problems like this ? These are shaft rockers , with solid flat tappets . Thanks for any help and ideas .

Re: Problem with lash closing up
 

Russ,
All new parts? I'd be curious about the valves, and where they were made.

Re: Problem with lash closing up
 

Shaft rockers do have a torque setting when checking valve lash. Had a friend this summer setting the lash at the track. He says the lash was tightening up on the intakes. As I watched him, I noticed he was really over tightening the adjustors. I borrowed him my LSM torque wrench, preset at 24 ft. lbs and problem fixed. He was shocked because he has been setting them that way for years. Just a thought.

Re: Problem with lash closing up
 

What's the Honda method? Never heard of it. I always set the intake when the exhaust just starts to move and the exhaust as the intake is almost closed.

Re: Problem with lash closing up
 

Yup , That's the Honda method , Honda wrote a SAE paper on that way of lashing valves years ago , documenting the benefits .

Re: Problem with lash closing up
 

These shaft rockers are Harlan Sharp which have been on this engine for the last 4 years without any problems . They are tightened by hand , but not crammed down and the final adjustment is checked after the lash adjuster is tightened . We have a lot of experience using these rockers , and never had this problem . So that is why we are asking if other folks have had this problem . BTW , why would over torqueing the adjuster nut cause the lash to close up ?

Re: Problem with lash closing up
 

Not new parts , same Manley valves that were used last year . I was wondering if they could possibly stretch , but will need to take apart the heads to compare the valves and seats with other cylinders that did not have any lash problems .

Re: Problem with lash closing up
 

I would assume over tightening distorts the adjusters causing lash movement when heated up. Harlen Sharp website calls
for 20 ft lbs on their rockers.

Re: Problem with lash closing up
 

From what you state, you have a one cylinder problem. Has to be assumed that all 16 valves are adjusted using the same technique, so torquing of the adjuster nuts is probably not the problem. I would ask myself some questions, at this point. Are both intake and exhaust valve lash closing up, or just one of them? Does lash return to its original cold setting when the engine cools, or has lash now decreased by .003, both cold and hot? Is there ANYTHING different about the pieces used on that one cylinder (e.g. new/different rocker stand, new bolts securing the rocker stand to the head, repair to the cylinder head threads into which the rocker stand is screwed, previous cracked head repair in that immediate area, new/different valves on that cylinder, new/different lifter pair on that cylinder, valve seats replaced on that cylinder, and on and on). Good luck.

Re: Problem with lash closing up
 

No new parts were installed this year , we lashed the valves hot at .015 and cylinder 4 closed up to .012 after we ran a few pulls . That is what concerns us . Now the engine is dead cold and cylinder 4 has .015 lash on both intake and exhaust . All other cylinders are .018 . Thanks for your comments .

Re: Problem with lash closing up
 

Did the seat sink or did the valve bend at seat contact area.

Re: Problem with lash closing up
 

Given all of what you say, there can only be a couple possible causes. To get my head around the problem, I think "which components would be capable of making the valvetrain get "longer" on the #4 cylinder?" The "longer" the valvetrain gets (from the surface of each cam lobe to the head of each valve on the seat), the less lash there would be. I would first very closely examine the lifters, because removing them will give you a chance to examine the cam lobes (which are not a likely cause), the lifter wheels, axles and roller bearings or bushings, and the lifter bore bushings. I wouldn't waste much time on pushrods, because they're under tension, and can therefore only get "shorter", through bending, breaking, etc., which would increase lash. Then look carefully at the rocker arms, again, looking for anything that could cause that theoretical, "overall length" to be reduced. Then, I'd look at the valves, springs, retainers, keepers and shims, to see if something has "shifted" (like the fit between the retainers and keepers, or between the springs and retainers); Look closely for metal flakes in the area. I would also look to see if the heads are beginning to pull off of the valve stems (they can stretch, which reduces lash) Weird-looking keeper grooves are sometimes a giveaway. Finally, I would look at the valve heads and seats for things like old-fashioned "tuliping", though with today's outstanding materials, I think that's virtually a thing of the past. If I had to bet $100 on the cause, I would say that you might just have an anomaly, which is part of running in a newly assembled engine. Sometimes, a cigar is just a cigar, and the only way you confirm (beyond a doubt) that you've actually got a problem is to readjust #4 to .018 cold, and put a couple more pulls on it. If it moves again, you KNOW you're in trouble; if it stabilizes, you can feel reasonably confident that you've dodged a bullet. Scariest thing of the whole deal is that the lash loss is confined to both valves on ONE cylinder. I have had a similar (though not identical) situation, and it is very worrisome. Hope that helps.

Re: Problem with lash closing up
 

Probably should have said right from the start that this is a stocker engine with a flat tappet cam . Today we pulled the intake and examined each lifter and cam lobes . This is the second year on these parts and they still look brand new . It has cast iron heads , and the valve seats are not replaced , they are just machined into the casting . This year the valve job still looked OK so the valves were lapped and re-installed . Springs were not replaced and are still at 200 on the seat just like when it was reassembled . Engine has about 10 pulls since re-assembled . These are good parts , Trend lifters DLC coated , Steel cam , PAC springs .

The next step I think will be to try and measure the length of each valve , and see if Cylinder 4 valves are .003 longer than the others . I would think when the original valve job was done , all the valve lengths should have been ground to the identical length .

Thanks for all the ideas , it helps .

Re: Problem with lash closing up
 

Could you swap a set of rockers from another cylinder and retest? Might find the source of problem or rule out 1 of the problems.

Re: Problem with lash closing up
 

Your Lash was off the first time? Maybe you should get your old P&G out and use it!

Re: Problem with lash closing up
 

After checking all the components , we ran the engine of the dyno again . Ran well so once the engine cools down lash will be checked again .

Re: Problem with lash closing up
 

What was your EGT on that pull????

Stretching the valve or sinking the seat??????

Re: Problem with lash closing up
 

Ran into this with my bbc with titanium valves. The sealing surface of the valve began to erode causing the lash to close up a little over time.

Re: Problem with lash closing up
 

If the valve was stretching due to getting really hot , I agree this could be a cause . This engine runs at WOT on the dyno for a very short time . A test is a sweep test lasts only about 10 seconds at WOT . So I have a hard time thinking that these valves get hot enough to stretch . Anything is possible . Don't have EGT's running , but the O2 sensors are saying the A/F ratio is around 12.8 .

Re: Problem with lash closing up
 

So now, after all this grief , we checked the lash cold and lo and behold they all measure exactly what they were set at . Glad we checked everything , and don't regret being concerned , but all is well now . Thanks for all the ideas and comments .

Re: Problem with lash closing up
 

So was the Lash off the first go round? Sounds like it.

Re: Problem with lash closing up
 

Best deal to verify and control accuracy of valve lash is from Precision Measurement Supply in San Antonio. Little valve gapper with dial indicator. Amazing how far off the "feeler" gauge method can be.
Regards,
HB2:)
Dissident

Re: Problem with lash closing up
 

P&G made one a log time ago! I have 2 kits .

Re: Problem with lash closing up
 

What is a P&G ? We thought that was a tool for checking engine displacement .

Re: Problem with lash closing up
 

Valve gapper tool, young fella ;-)

Re: Problem with lash closing up
 

P&G made the valve gapper and the cubic inch tester (pump)...gsa612

Re: Problem with lash closing up
 

Many of us old farts set our valves that way before we ever saw a Honda.

Re: Problem with lash closing up
 

You got that right Ed still got mine I ended up with two complete kit with various adapters. Learned about them from the late Les Ritchie

Re: Problem with lash closing up
 

Yep, I have an old antique P&G from back in the day, but they haven't been made for decades. :D



That is why I listed the piece from Precision Measurement Supply in San Antonio.....sure beats the heck out of feeler gauges. We ran a test a long time ago with a setup to see who got the correct lash and many name engine builders were all over the map when the setting was measured with a dial indicator.....jus' sayin'.

Regards,
HB2:)
Dissident

Re: Problem with lash closing up
 

You are right on on this!

Re: Problem with lash closing up
 

I learned to get the feel with a feeler blade, that checked correctly with my “P&G Valve Gapper. Ran no faster, showed no better on the dyno using it, than the “feeler blade” after learning that. Seems many set them too tight with feeler blades. If you found what lash runs quickest with feeler blades, there is no power to be gained, in my limited experience, using the P&G. If they are even still made & sold. Worked with mine about 1970. I don’t think I know everything, just sharing what I experienced.

Re: Problem with lash closing up
 

There is a guy that is selling one of those P&G gappers on Craigslist Detroit . Says its for a 427 Ford .

I agree , seems like once you get the feel right on a feeler gauge setting lash goes pretty fast . I would be very interested in how the factory adjusted a solid lifter engines back in the early days . On hydraulics, many engines had no adjustments , like Pontiac , Oldsmobile , etc .

Re: Problem with lash closing up
 

Ford had go nogo feeler gauges on the FE 427 line at Dearborn Engine plant!