Adjust valves cold... how cold is okay?

[cwitt]

Hi all,

So I know we're supposed to perform valve adjustments when the engine is cold, as in: get the car up in the air and let it sit overnight.

My question is this: Just how cold is okay?

Clearly the temperature difference between operating temp (say 180-210F) and ambient temp in a normal climate (say 60-80F) has an impact on the adjustment. So what about an unheated garage during a northern winter, where the ambient temp could easily be down in the 20-40F range?

Thanks,

Curtis

[crustychief]

I have no fact based answer for you except, who in their right mind would want to go work on a car in 20-40 degree weather?

[crustychief]

I am guessing 50-80 degrees Fahrenheit.

[Hodgey]

Not to be an anorak but the Germans will probably consider 20 deg C or 68 deg f to be 'normal'

Neil

[James Brown]

"standard day" temp. is 15˚C or 59˚F for all you anorak's, that's around room temperature.

[JJ 911SC]

Originally Posted by crustychief

I have no fact based answer for you except, who in their right mind would want to go work on a car in 20-40 degree weather?

Same guys that does lookout duties in the North Atlantic in December.

I guess you only sail the fair seas

[cwitt]

Originally Posted by crustychief

I have no fact based answer for you except, who in their right mind would want to go work on a car in 20-40 degree weather?

Northerners with cabin fever, that's who.

Our beautiful MN fall weather is deteriorating rapidly, so I could be up against a now-or-wait-till-spring situation.

- Curtis

[Hodgey]

Originally Posted by James Brown

"standard day" temp. is 15˚C or 59˚F for all you anorak's, that's around room temperature.

James,
15 deg C is a little cold: I am from England and throughout my engineering training, any academic studies and calculations were always using instruments calibrated at 20 deg C.....

[Drisump]

Originally Posted by crustychief

I have no fact based answer for you except, who in their right mind would want to go work on a car in 20-40 degree weather?

"Want to" is the key to that phrase.....

[efhughes3]

I'm with the 20c for a nominal temp, which is a nice 68F. 59F is certainly not room temp.

[Hodgey]

Originally Posted by efhughes3

I'm with the 20c for a nominal temp, which is a nice 68F. 59F is certainly not room temp.

59 maybe for an Eskimo

[plumb4u2]

not to be a smart ass but isn't "room temperature" what ever the temperature of the room is

[80-911SC]

can you do an adjustment in 20 deg weather with the gloves you would have to wear i doubt you could hold the screwdriver and the wrench ........ and if you did what oil would you put in ........ and how fun would it be to drive around at 2-3k rpms for the three days it would take the car to warm up ...........

[Walt Fricke]

Leaving banter aside, it really doesn't matter. The clearances expand as they warm. If you set it spot on with the motor "too cold," you could just end up a little on the high side of things when it is at operating temperature. But percentage wise the difference between say 40 degrees F and 70 is a lot less than from 70 to maybe 200F (a reasonable operating temperature). It just won't matter.

Best not to get too worried. We don't need laboratory grade measurements for this kind of thing.

If I have to set hot because a rocker broke and I'm going to chance it at a race and just replace it and forge on, I measure what nearby clearances are at that temp and use them for the replacement. Works.

Walt

[kidrock]

I'm with Walt. I just can't imagine a good German (or any other European for that matter) waiting for the weather to warm up to 68 degrees to perform a valve adjustment.

Everything I've read says to adjust them "cold", not "room temperature" (a tip of the hat to Plumb4u2).

[efhughes3]

For the record, I did not state this needed to be done at 68. I was simply commenting on the "room temp" analysis. I've done mine in low 50's, and I've done them in low 90's. I too say that there is no significance in the differential. It should probably be stated this be done in AMBIENT temps, which would mean no residual heat from operating temp.

[Walt Fricke]

Let the record so reflect.

[James Brown]

For the record I was just stating standard day temp for the aircraft industry. All charts and engine performance is taken at "standard day" and of course corrected for the current conditions. For me, if I can hold the rocker in my bare hand, it's cool enough.

[Hodgey]

Originally Posted by James Brown

For the record I was just stating standard day temp for the aircraft industry. All charts and engine performance is taken at "standard day" and of course corrected for the current conditions. For me, if I can hold the rocker in my bare hand, it's cool enough.

...+1...fair and accurate assessment!!!

[efhughes3]

Hey, we now sound like a bunch of politicians!