Valve lash, With WEBCAM #494 Options

[jeffdon]

Ran the 2056 on the stand for a last time to get the oil warm, and do the initial change, and get her ready for installation. Did another valve check. Which got me to thinking.

I am setting it to the spec that came with the cam, .006 for both exhaust and intake. Lift (.465) and duration (280 deg.) are the same for both valves.

Question is, if exhaust valves expand more due to heat than intake, why does webcam recommend .006 for both? Why not .006 and .008 as is standard?

It SEEMS to be running pretty well, but I know i have a good deal of fooling around with jets and such once its on the road and i can test her under load. At one point at about 3500 rpm it started firing back through No 4., but that was right about the time i was running out of gas in my temp. tank. I shut it off, and got a big pop and some flame out the tail pipe.

I would really like address/double check anything now, as its way easier accesing things on the stands.

[Al Meredith]

I think the board would like to know what kind of pushrods you are using. Aluminum or chromoly steel, both use different values.

[jeffdon]

I think the board would like to know what kind of pushrods you are using. Aluminum or chromoly steel, both use different values.

Stocker aluminium

[VaccaRabite]

Stock pushrods? Are you sure your geometry is right?

Zach

[ME733]

...........well I guess some of the other engine experts just don't want to be next....So ok he is what I recommend......USE .oo6ths on the INTAKE, USE .oo8ths on the EXHAUST.after the engine is broken in. ....If the truth be known-EVERY camshaft I have had analyzed came out to be-->008ths as a standard base /radus/lobe/ideal valve lash....This is compatable with all GERMAN cam-grinder design specifications.(for damn near any camshaft for any car)...This subject can get ,lengthly and very complex..(..and i,m just on my first cup of coffee.)...IF YOU HAVE JUST assembled and are running in a new engine---use a -loose .008 ths on intake and exhaust---for about 500 miles., and check your lash a few times. this will ensure that as your NEW valve job, VALVES are seating, there will be a little extra clearance for them to do so.....and NOT hold any valve off it,s seat.....YOU want to hear a little valve rattle.(good)....no valve rattle.(bad) ..(excepting hydrolic lifters)...and you should listen for intake-"cough". which is a sure sign of too tight a valve lash.(assuming everything else is perfect). MY opinion is on a new engine go with a larger valve lash during the break -in -period.->008 ths is a good number, intake and exhaust.................M.M.

[jeffdon]

Stock pushrods? Are you sure your geometry is right?

Zach

Yeah I checked the valve stem/adjuster relations, and it all looked pretty good, actually. Nicely lined up.

[jeffdon]

...........well I guess some of the other engine experts just don't want to be next....So ok he is what I recommend......USE .oo6ths on the INTAKE, USE .oo8ths on the EXHAUST.after the engine is broken in. ....If the truth be known-EVERY camshaft I have had analyzed came out to be-->008ths as a standard base /radus/lobe/ideal valve lash....This is compatable with all GERMAN cam-grinder design specifications.(for damn near any camshaft for any car)...This subject can get ,lengthly and very complex..(..and i,m just on my first cup of coffee.)...IF YOU HAVE JUST assembled and are running in a new engine---use a -loose .008 ths on intake and exhaust---for about 500 miles., and check your lash a few times. this will ensure that as your NEW valve job, VALVES are seating, there will be a little extra clearance for them to do so.....and NOT hold any valve off it,s seat.....YOU want to hear a little valve rattle.(good)....no valve rattle.(bad) ..(excepting hydrolic lifters)...and you should listen for intake-"cough". which is a sure sign of too tight a valve lash.(assuming everything else is perfect). MY opinion is on a new engine go with a larger valve lash during the break -in -period.->008 ths is a good number, intake and exhaust.................M.M.

never heard this. Are you sure that you dont mean break in as in the 20 mins or so of initial Cam break in? Not really relishing the thought of frequent valve measurements under the car.

[ME733]

...........well I guess some of the other engine experts just don't want to be next....So ok here is what I recommend......USE .oo6ths on the INTAKE, USE .oo8ths on the EXHAUST.after the engine is broken in. ....If the truth be known-EVERY camshaft I have had analyzed came out to be-->008ths as a standard base /radus/lobe/ideal valve lash....This is compatable with all GERMAN cam-grinder design specifications.(for damn near any camshaft for any car)...This subject can get ,lengthly and very complex..(..and i,m just on my first cup of coffee.)...IF YOU HAVE JUST assembled and are running in a new engine---use a -loose .008 ths on intake and exhaust---for about 500 miles., and check your lash a few times. this will ensure that as your NEW valve job, VALVES are seating, there will be a little extra clearance for them to do so.....and NOT hold any valve off it,s seat.....YOU want to hear a little valve rattle.(good)....no valve rattle.(bad) ..(excepting hydrolic lifters)...and you should listen for intake-"cough". which is a sure sign of too tight a valve lash.(assuming everything else is perfect). MY opinion is on a new engine go with a larger valve lash during the break -in -period.->008 ths is a good number, intake and exhaust.................M.M.

never heard this. Are you sure that you dont mean break in as in the 20 mins or so of initial Cam break in? Not really relishing the thought of frequent valve measurements under the car.

.............I,m sure........You may get a different opinion from every engine builder thats alive/or dead....This technique ain't the simple way....It does ensure seated valves., which is a good thing for longevity. After all how long does it take to check the valve lash?.....you'll get good at it, and it won't be nearly such a chore as you think.....................M.M.

[Cap'n Krusty]

The .008" number is specified ONLY for T4 engines with Sodium filled exhaust valves. All others use .006 for stock setups, or what the camshaft or pushrod manufacturer recommends.

The Cap'n

[jeffdon]

The .008" number is specified ONLY for T4 engines with Sodium filled exhaust valves. All others use .006 for stock setups, or what the camshaft or pushrod manufacturer recommends.

The Cap'n

Hey Cap'n - So you would not go with the "run em loose" for break in advise???

[Don M]

If you really want to know whats going on with your particular set up, check the valves at TDC cold and recheck after you put some heat in the engine for comparison.

[Jake Raby]

I'd expect that you didn't carry out any valvetrain geometry procedures?? I've never seen a 494 come close to optimizing with a stock length pushrod.

The 494 has a fast ramp, it must have geometry carried out to prevent valvetrain wear, especially valve guides.

[Cap'n Krusty]

The .008" number is specified ONLY for T4 engines with Sodium filled exhaust valves. All others use .006 for stock setups, or what the camshaft or pushrod manufacturer recommends.

The Cap'n

Hey Cap'n - So you would not go with the "run em loose" for break in advise???

I run'em where they're supposed to be, whatever that is for the particular application. After cranking for oil pressure with the plugs out, I run pushrod engines for 20-30 minutes at 1500-2000 RPM, then fine tune the carbs and timing before shutting it down and allowing it to cool down for 3-4 hours. I then check and adjust the valves before installing the engine. On FI engines I do the same thing, only in the car.

The Cap'n

[Jake Raby]

Running loose retards valve timing events and wears components. I have never understood why people do this.

[Cap'n Krusty]

I confess to knowing that loose valve settings also contribute to a HUGE reduction in HCs when done in conjunction with an emissions test. Not that I would ever resort to that nefarious strategy to get one of my customers' 1976 or newer Type 1 cabbie or 914 through a smog test............

The Cap'n

[VaccaRabite]

I confess to knowing that loose valve settings also contribute to a HUGE reduction in HCs when done in conjunction with an emissions test. Not that I would ever resort to that nefarious strategy to get one of my customers' 1976 or newer Type 1 cabbie or 914 through a smog test............

The Cap'n

This made me LOL for real. (IMG:style_emoticons/default/smile.gif)
Zach

[TheCabinetmaker]

I confess to knowing that loose valve settings also contribute to a HUGE reduction in HCs when done in conjunction with an emissions test. Not that I would ever resort to that nefarious strategy to get one of my customers' 1976 or newer Type 1 cabbie or 914 through a smog test............

The Cap'n

This made me LOL for real. (IMG:style_emoticons/default/smile.gif)
Zach

Gotta good chuckle here too. (IMG:style_emoticons/default/biggrin.gif)

[jeffdon]

I'd expect that you didn't carry out any valvetrain geometry procedures?? I've never seen a 494 come close to optimizing with a stock length pushrod.

The 494 has a fast ramp, it must have geometry carried out to prevent valvetrain wear, especially valve guides.

I did a dry assembly and did a quick and dirty visual check of the adjuster/pushrod relation, and it looked pretty well aligned throughout its cycle. Then again, i only looked at one cylinder and just assumed that it would be the same for all others. Probably hosed myself on that one, but at this point, I dont think i want to pull her apart again.

[VaccaRabite]

I'd expect that you didn't carry out any valvetrain geometry procedures?? I've never seen a 494 come close to optimizing with a stock length pushrod.

The 494 has a fast ramp, it must have geometry carried out to prevent valvetrain wear, especially valve guides.

I did a dry assembly and did a quick and dirty visual check of the adjuster/pushrod relation, and it looked pretty well aligned throughout its cycle. Then again, i only looked at one cylinder and just assumed that it would be the same for all others. Probably hosed myself on that one, but at this point, I dont think i want to pull her apart again.

It could be the difference between a 5,000 mile engine and a 100,000 mile engine. It would take a weekend to make sure its right.

If you did not measure the valve lift, you are leaving power on the table, and might end up with a very difficult to tune motor that runs too hot. If you did not make sure that the valve stem and and valve foot were on the same plane at exactly 1/2 lift, you are going to have excessive wear to your valve guides and seats.

And it would only take a weekend to check it, if the engine is not in your car yet.

Even if you don't have a dial indicator, a 1 inch indicator with a vise-grip flex mount is only ~$30 from harbor freight.

Learn from my mistakes. I cut corners on the first motor that I built. I had to rebuild it 6 months later (with only about 10 miles on the motor). its better to only do it once and have it done right.

Once you get the procedure down for the first pushrod, making the next 7 is EASY! But the first one will take ~2 hours to make.

Zach

[brant]

Zach,

I apologize for not using the search feature
I'm sure that Jake covers this very well on his site somewhere also.

but do you have a link to the correct procedure
I need to learn this

tia
brant