Checking / Adjusting Valve Lash

[Ron H]

I’m going to check/adjust the valve lash on my slightly built poly after a couple thousand miles. The build included solid lifters. It’s only been 45-years since doing this on a GTO, so quite rusty. I’ve been researching the drill and came across a vid from Summit that says you only need to rotate motor twice to do exhaust and intake step one, #1 then rotate to #6 and do the remaining exhaust and intake. Cam-card has the tolerances for intake & exhaust. Don’t recall this drill.

Can any gurus on this offer their advice? Thanks.

 

[fourgearsavoy]

I use the EOIC method on my engines. There are quite a few videos out there showing how it's done. I adjust one cylinder at a time and get them all lashed in about 15 minutes.
Gus

 

[66 Sat]

Ron,
Set them to .012 cold if they cam card calls for .014 hot. They'll open up a bit when hot. Some information you'll see says they tighten when hot, but not in my experience.

When I did mine the first time I set them looser cold based on the attached articles. I set them at .016 cold thinking they would tighten up.

“What I Learned Today” With Jeff Smith — Cold Lash Vs. Hot Lash

From the article:

Thermal Expansion Table​

Because the engine dimensions will change with the heat of operating temperature, Crane Cams came up with a chart that we’ve reproduced here that compensates for cold lash settings compared to the published specs for an engine fully warmed up:

Block Material	Head Material	Lash Adjustment
Iron	Iron	Add 0.002”
Iron	Aluminum	Subtract 0.006”
Aluminum	Aluminum	Subtract 0.012”

This article from Motortrend had slightly different advice but a similar theme:
https://www.motortrend.com/how-to/1707-how-to-set-valve-lash/#:~:text=Generally speaking, if you are running an engine,of an inch tighter than your hot number.

This is a repeat of the top article, with Crane Cams again as the source:
Rockin’ The Lash: Setting Valves Cold With Hot Lash Settings


There was a big debate on A Bodies about it, so I checked them hot (not a fun job) and the articles were incorrect in my case - they loosened up when hot (so they were all at .018). Read it here: How tight to set solid lifters

I had to re-do them all. Lesson learned - real world experience vs theoretical.

 

[Bird 426]

Cast block, aluminum heads, mine loosen about .005 when hot. If your timing tape or balancer is correct on rotatation for .090° at a time, the rotation of your engine twice will work. I found out down the road that mine was off. I do the individual cyl way now. I have it written down, don't qoute me here but, something like when the intake starts to open, adj the exhaust. Etc. Google it or someone else will chime in. This is why I write it down!

 

[SlinktRR]

EOIC is all you need to know. Exhaust opening intake closing.

I use a starter trigger switch and can finish in 20 minutes, usually check twice a year.

 

[RemCharger]

I use the EOIC method on my engines. There are quite a few videos out there showing how it's done. I adjust one cylinder at a time and get them all lashed in about 15 minutes.
Gus

I have it written down, don't qoute me here but, something like when the intake starts to open, adj the exhaust. Etc. Google it or someone else will chime in. This is why I write it down!

EOIC is all you need to know. Exhaust opening intake closing.

I use a starter trigger switch and can finish in 20 minutes, usually check twice a year.

I will add, EOIC , in case it hasn't been mentioned.

 

[Geoff 2]

Ron,
Summit is correct. So is Chrys. Below is the chart from Chrys.

 

[dvw]

Get the engine hot. Check the lash and right it down. One bank is sufficient. Let it cool over night. Recheck lash. Compare those numbers to the hot numbers. You'll get an average of how far they change. Now use that change number to set them cold. The exhaust and intake may different. I use a bump button on the starter relay. Set the intake lash when the exhaust valve starts to open. Do all the intakes on one bank Just watch for the next exhaust valve to start moving. Mark each rocker with a sharpie as you go. When all the intakes on that bank are done start on the exhaust's. When a intake valve just starts to close adjust that exhaust. Same procededure. Mark each when done and watch for the next movement. If you go to far on the rotation just bump it around. No need to go down the line for 1,3,5 etc. Then do the opposite bank.
I do my racecar every 20-25 passes. It takes me 15-20 minutes.
Doug

 

[SlinktRR]

This is the way thanks DVW. I go cylinder by cylinder (exhaust and intake) which is slower and requires more bumping the starter but it's easier for me to track. Geoffs method is from mopar and economizes how much you turn the motor over but I prefer using the bump starter and just going cylinders 1-3-5-7 then 2-4-6-8. Once you do it a couple of times it becomes routine.

 

[not so famous bob]

Get the engine hot. Check the lash and right it down. One bank is sufficient. Let it cool over night. Recheck lash. Compare those numbers to the hot numbers. You'll get an average of how far they change. Now use that change number to set them cold. The exhaust and intake may different. I use a bump button on the starter relay. Set the intake lash when the exhaust valve starts to open. Do all the intakes on one bank Just watch for the next exhaust valve to start moving. Mark each rocker with a sharpie as you go. When all the intakes on that bank are done start on the exhaust's. When a intake valve just starts to close adjust that exhaust. Same procededure. Mark each when done and watch for the next movement. If you go to far on the rotation just bump it around. No need to go down the line for 1,3,5 etc. Then do the opposite bank.
I do my racecar every 20-25 passes. It takes me 15-20 minutes.
Doug

at my age , it takes longer than that to get my covers off ...lol

 

[dvw]

This is the way thanks DVW. I go cylinder by cylinder (exhaust and intake) which is slower and requires more bumping the starter but it's easier for me to track. Geoffs method is from mopar and economizes how much you turn the motor over but I prefer using the bump starter and just going cylinders 1-3-5-7 then 2-4-6-8. Once you do it a couple of times it becomes routine.

If you have a button. (mine is mounted on the firewall). And follow my method (dont start with both valves #1, then both #3 , etc. Do all one bank Exh. Then all one bank Int. You will only bump the motor over a few times.
Doug

 

[66 Sat]

One more thing to look out for Ron - the adjustment screws for the rockers are an interference fit and can get loose over the years. If you find any that turn too easily and don't grab you'll need to address that. I had 2 like that, 1 of them had backed right off which was the whole reason I checked them in the first place - to address a loud ticking that developed.
One suggestion for tightening the fit was to remove the rocker, turn it on it's side and carefully hit it with a hammer on the area around the hole, to oval it slightly.

Another suggestion was to remove the screw, clean the threads, and use some thread locker. This is what I did and they've held ok.