valve adjustment

While I was adjusting the valves on my BJ8 I happened to look at the "owners manual" and the brass plaque on the valve cover. I noticed the valve cover said .012 when hot and the book said .012 when cold. since it was cold when I took the cover off I continued. It seems to be fine but I'm interested if opinions. I'm so slow if I started hot the last valves would have been cold anyway.

Tahoe,

I'll try to remember to look at my factory manual.

SB

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by tahoe healey:
While I was adjusting the valves on my BJ8 I happened to look at the "owners manual" and the brass plaque on the valve cover. I noticed the valve cover said .012 when hot and the book said .012 when cold. since it was cold when I took the cover off I continued. <hr></blockquote>

If the engine has just been rebuilt/assembled, then you have no choice but to do them cold. I recall that's the manual's assumption. In the tuneup situation or after 500 miles when you retorque the head nuts, then they are done hot.

This is one area where the Haynes manual was really useful - I has a guide of which order to do the valves as one rotates the engine.


John

Thanks, I have a shop manual and the owners manual(both say cold) but haven't been able to find the Haynes. I did it cold and it seems to be fine (if I could only get the fuel mixture adjusted for 6300 foot elevation. How did all the Healeys do this summer up here at Tahoe with our thin air? I missed the gathering at Tahoe but I did talk with several who stayed on past the weekend.)
Again thanks,
Rich

Rich,

When you say you have a shop manual, I gather its a R.Bentley book. It shows BN7, BT7, BJ7 &BJ8 as having a clearance of .012" when cold. I have an original BMC shop manual and it shows BN7, BT7 & BJ7 as having a clearance of .012" when hot, just as it says on the engine. Now maybe the BJ8 was changed to a cold setting or it is just a mistake. If you look at both books you will find that the BN4 is given as .012" when hot. I think it is just a mistake as your valve cover says hot.
I also looked at the "Austin Healey Guide" by Donald Healey and Tommy Wisdom and it says the BN7 was set at .012" hot.

SB

Very interesting. My manual is also a BMC workshop manual. It says (on page 10 of general data) .012 inch cold but hot on the BN4??? It cannot be that different in the long run can it?
Thanks for your imput.
Rich

Rich,

It seems to me that when they say set the valves to .015" gap for competition, the engine will be running even hotter than normal and the over all length of the valves will be longer. Hence a wider gap setting to keep the valve heads in the same region in the head. If the valves are set cold then they will be deeper in the head during operation. This could cause the valves to burn.
Of course this is purely speculation on my part.

SB

Rich,

I think this is the thread you're looking for.


John, BN4

From past experience of building engines on the bench at Austin-Healey West in San Francisco:

When setting valves of a newly rebuilt engine (cold) I would use .015"

Try it and then go out for a spin and when you get back, see if they aren't set at .012" when hot.

I don't know about you, but I'd rather work on an engine when it's cold.

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by tahoe healey:
While I was adjusting the valves on my BJ8 I happened to look at the "owners manual" and the brass plaque on the valve cover. I noticed the valve cover said .012 when hot and the book said .012 when cold.

<hr></blockquote>

Ah, what came first, the chicken or the egg?
It's funny that the same questions are continually asked over and over. I suppose it's because new owners of our fine British cars realize that you must work on your LBC to keep it running properly. Versus new modern cars that cover their engines with plastic covers depicting their origin.
Anyway, I've always set the valves when the motor is hot. You shouldn't have to actually handle the tappets that much so there's no fear of getting burnt. Remove the plugs first, and use a wrench to turn the motor over in the direction of rotation, to take up slack in the timing chain.
The "dognut" on the engine is 1- 11/16 inches. Anybody know where to find such a wrench? Or you can buy a large socket with 3/4 inch drive, then a stepdown to 1/2 inch drive adapter. Follow the manual and you'll find it's not very difficult. I've always found it helpful to write the number of valves down, then cross them off as their adjusted.
Hope this helps,
Johnny, 59 BN7

Thanks John. I couldn't find the post. I'm now guessing that the valve cover had been replaced since the HOT appears on the earlier models and mine is a '64. So now I search for the proper brass plack.
Rich

Just remember this, loose valves won't cost you money...

An exhaust valve that is set too tight won't dissipate enough heat and will burn (cooling only takes place with the valve touching the seat).

MGB engines were basically 2/3rds of a Healey. They were always spec'd @ .015" cold.

More wood on the fire: I just set my valves this past week and I used as my source the "Austin Healey 3000 Mark III Driver's Handbook". This book is a reprint of the BMC "original owner's manual" carried in the glove box. Anyway, it states on page 4: "valve clearance (cold) is .012 in (.30 mm)." I sure hope this is correct as the car seems to be running fine. I decided to go with this document as it at least is specifically for the Mark III. Hope this helps, Tahoe.........

I was just reading through the aforementioned manual (see immediately earlier post)and found a section on page 42 that describes the valve adjusting process. It states there also that "The clearance between the valve rockers and valves should be .012 in (.30 mm) when the engine is cold." Additionally, it provides the following helpful information (which is available elsewhere, too):
Adjustments must be made with the tappet on the vack of the cam; testing and adjustments should be carried out in the following order:
No. 1 valve with No. 12 fully open
No. 7 valve with No. 6 fully open
No. 9 " with No. 4 "
No. 2 " with No. 11 "
No. 5 " with No. 8 "
No. 10 " with No. 3 "
No. 12 " with No. 1 "
No. 6 " with No. 7 "
No. 4 " with No. 9 "
No. 11 " with No. 2 "
No. 8 " with No. 5 "
No. 3 " with No. 10 "

Another tidbit: "Always re-check the clearance in case adjustment has been disturbed during the process of tightening the locknut". And "the crankshaft can be turned by putting the car in top gear and pushing the car slowly forward whilst observing the rise and fall of the push rods" ( I found observing the spring movement easier).

Hope the above is useful info for you.

Correction to above: "Adjustments must be made with the tappet on the vack of the cam..." should be "Adjustments must be made with the tappet on the BACK of the cam..." Sorry for the typo.