Valve Lash Specs on Unknown Cam

[Garys1969RR]

I bought another 69 Roadrunner last summer, 440 auto with a solid lifter cam. He didnt know anything about the cam, and I want to adjust the valve lash. It isn't real noisy, but a few seem to be a little louder than the others. I thought I would start by checking the tightest ones, then go from there. Comp cams lists most of their cams at .016 int and .018 ex., so will use that as a guideline. Any ideas on how to proceed? I plan to use the int open, ex open, method. Adjust the ex with the int valve all the way open, and the int when the ex starts to open. Engine hot. Does this sound right? Any suggestions helpful.

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This cam has a smoother idle than my 451 which has a 509 cam in it.

 

[Jackpot50]

Always works for me. Good place to start.

 

[Garys1969RR]

Jackpot, are you saying to use the .016 and .018 valve lash specs?

 

[69Bee]

Adjust exhaust when the intake is almost closed.

 

[lewtot184]

if i didn't know the specs i'd use .010" at the lobe hot as a minimum. multiply .010" by the true rocker ratio and use that number as a minimum hot setting.

 

[dvw]

if i didn't know the specs i'd use .010" at the lobe hot as a minimum. multiply .010" by the true rocker ratio and use that number as a minimum hot setting.

I agree, wouldn't run them any looser than .028" hot either. I like to set mine cold. With aluminum heads .004"-.006" tighter cold is a good starting point. Then check a few hot and due the math.
Doug

 

[Garys1969RR]

if i didn't know the specs i'd use .010" at the lobe hot as a minimum. multiply .010" by the true rocker ratio and use that number as a minimum hot setting.

Sounds like a good way to proceed. .010 at the lobe would be .015 at the valve with 1.5 ratio rocker arms. With that in mind, I will go .014 int and .016 ex cold settings. Or .016 and .018 hot with iron heads.

 

[lewtot184]

Sounds like a good way to proceed. .010 at the lobe would be .015 at the valve with 1.5 ratio rocker arms. With that in mind, I will go .014 int and .016 ex cold settings. Or .016 and .018 hot with iron heads.

sometimes iron heads don't grow much when hot. also, if you haven't checked the rocker ratio you will find that the advertised numbers can be misleading. if you have 1.5's i'd assume 1.6 to be safe; if 1.6 use 1.65. and, before anyone chimes in, stamped rockers are not 1.38 as one vendor claims! assuming a rocker is at it's advertised number is a very good way to get in trouble with a hydraulic cam.

 

[HEMI-ITIS]

I agree, wouldn't run them any looser than .028" hot either. I like to set mine cold. With aluminum heads .004"-.006" tighter cold is a good starting point. Then check a few hot and due the math.
Doug

Iron heads only grow .001 to .002,Adjusted cold then rechecked hot,,,,,I like cold:eusa_whistle:

 

[Jackpot50]

I would go with the tightest and set rest
Intake then exhaust