jaybird81

I almost never drive the car at night so never needed the headlights. However Last year with the stock motor I needed them and they both worked. I have since changed the motor and the one in now has a mild cam. The specs are Advertised duration 280/280, duration @ .050" lift 230/230 valve lift .480 lobe lift .320 lobe separation 110 degrees. not sure if any other info is needed, its a Comp cams magnum 280h. Could the cam not be giving me enough vacuum to get them up? I was able to lift one up manually and it stayed, but couldn't get the other one lifted.

resdoggie

I had that same cam and my vacuum was, iirc, ~14" @ 1000 rpm. My headlights opened without issue at idle or at cruising speed. So, you should have enough vacuum. Did you check it?

jaybird81

I have not checked it yet. This happened last night and I am working. I will check, just thought I would post up and see what advice I get. I first thought it was the cam because It was working with the stock motor, and I know sometimes the cam effects vacuum

Brians1

What year - 81 I assume by your Forum Name - I have an 81 and and a mild comp cam, my headlight are a little slower to pop but they work none the less (i have all new vacuum lines and filters) so you may just have the leak in your vacuum feed to the lights.

sstopczy

This video from Willcox was very helpful. http://willcoxcorvette.com/product_i...ducts_id=27610

jaybird81

Yeah, Its an 81. I left the year out of the details because I figured it didn't matter since it is not stock. Well I really appreciate the responses and looks like its probably not the cam and just another issue. I will start troubleshooting this weekend or some night this week. Thanks.

7T1vette

Most likely a 'leaky' vacuum system. The headlamp vacuum relay[s] is the weak link in that system. Also, the check valve in the vacuum system is important to help maintain maximum vacuum level in the reservoir can.

Good luck.

dochorsepower

Vacuum system, check actuator seals and finally lubricate the operating linkages.

blue427

I have the same cam in my 427 and I have to rev it a little for the headlights to pop up.Somebody on the forum recommended spraying silicone into the headlight vacuum lines.I tried that and it works much better now,still needs a little reving but they pop up faster.

JimT

I would look into the check valve between the engine and the vacuum system. If you pulled the engine, the hose/checkvalve hose assembly had to be removed and maybe not replaced correctly.
Good Luck