1st time valve adjustment

[spmdr]

Yes, they increase about .004 from cold to hot.

So .008 and .010 are good cold starting points (stock cam).

Here is another thread on Valves:

Valve clearance

Work shop manual gives valve clearance ( HOT ) at 14 thow exhaust and 12 thow intake. Getting my 1725 ready to fire up after a mild rebuild. I have added 2 thow to those numbers as I have set the valves COLD. So 16 thow exhaust and 14 thow intake. Hoping this will be good enough for start up and...

forum.sunbeamalpine.org

DW

 

[ernestovumbles]

Yes, they increase about .004 from cold to hot.

So .008 and .010 are good cold starting points (stock cam).

DW

Cool.. I thought the clearances got smaller so I would be too close with the cold setting. Thank you!!

 

[Shannon Boal]

Well, regarding hot or cold, your mileage may vary....Aluminum expands at a much greater rate as it heats than iron. Some pushrods are steel, some are aluminum. My cylinder head is aluminium, but an iron head would, in theory be different. . Get the engine temperature gauge up to at least 160 and set the valves....

 

[RootesRooter]

I guess I've been lucky. Every time I've done cold, then hot settings, the differences were never more than .001.

If you have the later, four-bladed fan, I recommend against turning the engine by hand, even with plugs removed. I've lost two fan blades thru the bonnet.

 

[ernestovumbles]

I recommend against turning the engine by hand, even with plugs removed. I've lost two fan blades thru the bonnet.

Since we have a car with a hand crank, I gotta take advantage of that experience..

 

[Hodee]

Call me the “you’re doing it wrong guy”, but I always set mine cold at 8 and 10 thou. So much easier and faster than trying not to get burned or scalded. I don’t bother checking them warm or hot. Who’s to say what is the exact temperature to check them ? Car runs fine , no excessive clatter but not tight either. Just my opinion and it works for me. No burns , no fuss.

 

[RootesRooter]

I once helped a friend with an engine swap on his customer's Series II. From outward appearances, the 1592, procured from a usually reliable source, looked to be in very good condition. Because the opportunity was there with the valve cover off, I decided to measure the gaps. What a surprise. 8 or 9 thou on all valves. My friend said we'll take our chances so we plowed ahead with standard gaps. It ran great the first time until it got good and hot. Then the backfiring started, about once every 5-10 seconds. Yup. Burned valve.

 

[Hodee]

I once helped a friend with an engine swap on his customer's Series II. From outward appearances, the 1592, procured from a usually reliable source, looked to be in very good condition. Because the opportunity was there with the valve cover off, I decided to measure the gaps. What a surprise. 8 or 9 thou on all valves. My friend said we'll take our chances so we plowed ahead with standard gaps. It ran great the first time until it got good and hot. Then the backfiring started, about once every 5-10 seconds. Yup. Burned valve.

I’m certain that can happen. But I’ve had this Ser V for 10 years and about 10,000 miles. About 5-6 valve checks in that timeframe. Always pretty darn close to where they started. I’ll consider myself fortunate indeed. Matching numbers on Vin and block and I knew the previous owner of 42 years. It was a rare find from my childhood, going back to purchase it was pure luck and karma. Lucky for sure.

 

[Alpine 1789]

"1st Time Valve Adjustment" makes me think about the first time I did it. I doubt you will be a stupid as I was, but just to be safe, I recommend you read my write up of that experience in Rock Auto's Repair Mistakes and Blunders from a few years ago:

RockAuto July Newsletter

At least I eventually got a nice hat for my troubles.

 

[ernestovumbles]

I recommend you read my write up of that experience in Rock Auto's Repair Mistakes and Blunders from a few years ago:

Fun read for someone else's miss, but sorry it was you.

Finding the right spot to measure has been my biggest worry.. That was why I went thru measurement/practice while it was cold so I can take my time and figure it out.. Havent had a chance yet to do it hot.. hoping for next weekend.

 

[ernestovumbles]

Finally did my valve adjustment done hot. Most exhausts were reduced by .001 to get it to .012 and a couple intakes also reduced by same amount to get it to .010

Took the car for a spin afterwards and nothing felt amiss.. The car doesn't feel different after adjusting, but glad I have everything verified.. I believe it has been at least 6 years since it was last checked.
New cork gasket is doing a good job keeping the wet stuff inside, but I have plenty of leaks elsewhere.

Thanks to all for their input and help!! I've been worrying about doing this for a long time.. wasnt terrible (but glad I messed around for an hour or so when it was cold to figure it all out first)

 

[Tim R]

What I have found is that over time, particularly if you drive the car hard, as we tend to do the gaps close up until they are too small. I usually check mine about every six months or 6,000 miles. I checked about a week ago and three were tighter than they should have been, the rest were as expected. Presumably this is as a result of the valve slowly wearing into the seat. If you drive gently and cover a low mileage you won't see much change year to year.
Tim R

 

[ernestovumbles]

the gaps close up until they are too small. I usually check mine about every six months or 6,000 miles.

Do you get any warning signs/sounds when the gaps are getting too small or is it just after the expensive noises happen?

 

[Tim R]

Ernesto, I don't mean that they close up so much that they cause problems. I just notice that they are smaller than they were when I set them previously. I suppose if you just carried on driving the car hard and never checking them you would get problems but it is not something to worry excessively about. I expect if you check your car in a year's time there won't have been much change.

Tim R

 

[ernestovumbles]

I don't mean that they close up so much that they cause problems

Thanks Tim R. got it.
Just paying extra attention/extra worry now since I have just adjusted them myself in case I did something wrong (took it for a drive and all seems fine)
I drive the car weekly and not great distances so I'll add this to my maintenance routine to check in the future.

 

[GlennB]

Can someone explain the science of the gaps increasing with temp? I assumed the expansion in the pushrods would cause the gaps to decrease. I first set up my engine cold at 25 thou (a bit rattly) and then found I had to reduce the gaps maybe another 5 thou more when hot.

 

[Shannon Boal]

Can someone explain the science of the gaps increasing with temp? I assumed the expansion in the pushrods would cause the gaps to decrease. I first set up my engine cold at 25 thou (a bit rattly) and then found I had to reduce the gaps maybe another 5 thou more when hot.

I do not know, but can take a swing at it. The distance from the cam lobe base circle to the top of the valve stem tip is one thing when cold and more hot. That may grow by one/half percent, and if it were ten inches cold would add 0.050". But, the pushrods grow too. If they are nine inches and grow one/half percent, that would be 0.045" opposing the first figure, loosening up the lash.
Sometimes valve lash grows with mileage, I think because of wear on the valve train rub interface parts, like cam/tappet. When one exhaust valve lash shrinks with mileage I worry. This used to happen on air cooled VW engines just before the valve broke off. Now it could be valve seat recession (wear).
Why do some engines specify hot lash, and others cold? The automotive engineers who were working in the late forties through the sixties are not around to ask. Who are the current camshaft gurus?

 

[Mike O'D]

Probably has more to do with the aluminum head expanding more than the steel/iron parts.

 

[Scotty]

Yeah, Different metals involved heating up. Aluminum is really easy to warp if you get it too hot.

 

[Shannon Boal]

Yeah, Different metals involved heating up. Aluminum is really easy to warp if you get it too hot.

Yes....if you overheat an iron head, the valves usually still seal. If you overheat an aluminum head, you may have to regrind the valve seats!