63 Duntov cam valve adjustments

[Michael G.]

I'm about to adjust the valves on one of my L84 cars to quiet a noisy lifter. I do know the proper procedure, but unfortunately, I don't have my shop manual here to look up the specs. At some point, I had written down the specs of .012" intake and .018" exhaust (plus .003", if cold) that I had recommended to me some time ago. Seems that I was told those numbers came from the shop manual, but I can't check that now.

Complicating matters is that those specs don't jive at all with the paper I found here that Duke and John wrote on valve adjustment. Their specs were .008/.012", cold. That's a pretty big difference. Ordinarily, I'd just do what those guys say, but I am curious why there's such a big difference.

Its a pain to take the FI unit apart to get the valve cover off, so I want to do it just once, so I wonder if someone can explain....

Thanks,

[Michael H.]

Re: 63 Duntov cam valve adjustments

I'm about to adjust the valves on one of my L84 cars to quiet a noisy lifter. I do know the proper procedure, but unfortunately, I don't have my shop manual here to look up the specs. At some point, I had written down the specs of .012" intake and .018" exhaust (plus .003", if cold) that I had recommended to me some time ago. Seems that I was told those numbers came from the shop manual, but I can't check that now.

Complicating matters is that those specs don't jive at all with the paper I found here that Duke and John wrote on valve adjustment. Their specs were .008/.012", cold. That's a pretty big difference. Ordinarily, I'd just do what those guys say, but I am curious why there's such a big difference.

Its a pain to take the FI unit apart to get the valve cover off, so I want to do it just once, so I wonder if someone can explain....

Thanks,

Michael,

Factory valve lash specs for 63 are .008" intake and .018" for exhaust. That's the setting that I use.

[Stuart F.]

Re: 63 Duntov cam valve adjustments

I have used .008" and .016" on my 63 L-76 since new. I only recently did mine using the Williams/Hinckley method. I got a timing tape (semi-permanent) and applied it to the balancer, then used my large 1/2" drive torque wrench and socket on the center bolt of the balancer. By doing so, I found that the bolt wasn't torqued (ah ha!), and it was easy to bar the engine over (CW from the front).

Stu Fox

[Michael G.]

Re: 63 Duntov cam valve adjustments

Stu and Michael, do you use those numbers on a cold engine?

[Duke W.]

Re: 63 Duntov cam valve adjustments

The paper explains the reasons for the differences between the '57-'62 OEM recommendation, the '63 OEM recommendation, and the Hinckley-Williams recommendation.

BTW, you should be using the lastest revision of the paper, 9-23-08. Earlier versions are obsolete and should not be used.

Duke

[Michael G.]

Re: 63 Duntov cam valve adjustments

Duke, Thanks, I have the latest version of your paper and had read it prior to posting.

Note that I didn't initially take the "factory" specs from the Service Manual, those were recommended to me by an engine rebuilder for my other car. That car has a Duntov "clone" cam, rather than the original in my blue car, so I assumed it would be the same clearance.

In any case, I intend to use the .008/.016, (rather than the ones I had), but I guess I just wondered why anyone would set them that wide.

My blue car normally tends to have less valve noise than the other one, so I'm thinking the black car is set too wide. I'm wondering if I ought to try setting the black car by "ear", while running, (like I used to do when I was a kid in the sixties), then check the clearance (after it cools) to see what clearance I ended up with. My guess is that close to .008/.016 will be what I end up with.

[Stuart F.]

Re: 63 Duntov cam valve adjustments

Michael;

I always set mine cold. I used to set them hot and running with clips on the rockers until I got smart. I almost died - overcome by burning oil fumes and carbon mono, even in an open garage during the winter. I had a headache for a week.

Stu Fox

[Michael G.]

Re: 63 Duntov cam valve adjustments

Stu, I agree, setting them cold is the way to go, unless you like oil all over the place, as well as burnt fingers.

I'm just considering doing it once "by sound" to verify the settings for my Duntov "clone" cam in the black car are the same as the original. I'm not sure why the rebuilder would recommend wider gaps unless the new cam required it. The clone may have slightly different (higher?) lobes than the original, so just switching to the .008/.016 settings may not be advisable, without testing.

[Michael G.]

Re: 63 Duntov cam valve adjustments

Stu, I agree, setting them cold is the way to go, unless you like oil all over the place, as well as burnt fingers.

I'm just considering doing it once "by sound" to verify the settings for my Duntov "clone" cam in the black car are the same as the original. I'm not sure why the rebuilder would recommend wider gaps unless the new cam required it. The clone may have slightly different (higher?) lobes than the original, so just switching to the .008/.016 settings may not be advisable, without testing.

[Michael G.]

Re: 63 Duntov cam valve adjustments

What a difference!!! With the correct settings, at idle it just hums, you wouldn't even know it had solids.

Thanks for your help guys.

[Michael H.]

Re: 63 Duntov cam valve adjustments

What a difference!!! With the correct settings, at idle it just hums, you wouldn't even know it had solids.

Thanks for your help guys.

.008 and .016"?

[Michael G.]

Re: 63 Duntov cam valve adjustments

Michael,

Yup, .008" and .016" (cold). Its runs VERY well.

When I'm in Detroit next week, I'll re-set the black car, which has always been noisy with those other specs.