Headlight problems on an 1981 with a larger cam.

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Jan 20, 2014 | 12:31 AM

rodmartin

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2nd Gear

Joined: Jan 2013

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Headlight problems on an 1981 with a larger cam.

I am having a heck of a time getting my 81's lights to to work for more than a couple of months. I have a bigger cam and it causes some vacuum problems with the lights. I have spent about $800 on all new kits, actuators and components and labor. Has anyone used a separate vacuum pump for the lights and does it solve the problems? And, OR does anyone know a good mechanic familiar with these problems in the DFW area?

Jan 20, 2014 | 01:40 AM

7t9l82

Le Mans Master

Joined: Oct 2010

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From: melbourne florida

2023 C3 of the Year Finalist - Modified

there are some that use the pump, some use a vacuum canister and others use the electric motors. lots of options, are you sure your hoses are routed correctly and the hoses are still good with no leaks?

Jan 20, 2014 | 06:49 AM

jb78L-82

Le Mans Master

Joined: Oct 2007

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From: RI, Now Franklin/Nashville TN

What are your cam specs? How much vacuum is it suppose to pull and what do you pull now?

Jan 20, 2014 | 07:03 AM

donnie1956

Burning Brakes

Joined: Oct 2010

Posts: 1,192

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From: Wentzville MO

I ended up bypassing my tank to get my lights to work after swapping to LS engine with cam. Double checked all components, swapped components. That was the only combination that got the lights to come up. No leaks and new hoses. They are still sluggish but they come up if you rev the engine.

Jan 20, 2014 | 08:39 AM

Yeller81USNRet

Racer

Joined: Nov 2003

Posts: 386

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From: Grafton WV

I have Summit 1103 in my 81 mostly stock engine and have had no problems with the head lights . I have the canister still installed.

Jan 20, 2014 | 08:43 AM

Street Rat

Le Mans Master

Joined: Aug 2010

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From: Central Texas

I've had success using the vacuum reservoir tanks offered by Summit Racing.

Jan 20, 2014 | 01:24 PM

rodmartin

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2nd Gear

Joined: Jan 2013

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Thanks for the replies folks! I wish I was more of a mechanic and doing the work myself but I have been paying someone that I have doubts about and might need somewhat of a specialist. I bought the car last year and it had a replacement 350 ci ZZ4 motor that the old owner just told me had a "upgraded" cam, that was "not the biggest cam, but a medium step up". I have a vacuum pump installed and a summit reservoir tank, all new hoses, one way valves and actuators. They worked for a couple of months when the new left actuator went out and, a couple of months later, the right side is stuck up and the left side won't stay up, now they come up but won't go back down...very frustrating. I know I can spend another $1200 for the electric actuators [should of done it initially] but would rather not. It took a while to get the brakes right with this cam but now it is just those pesky lights!

Jan 20, 2014 | 01:47 PM

Dave J

Drifting

Joined: Jul 2006

Posts: 1,259

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From: Deplorableville Nebraska

I have become a student of the C3's vacuum systems over the last year. I have a '70 with all stock vacuum components, and through some creative rebuilding of them, I still have vacuum in the system well after shutdown.

I have the ability to evacuate the vacuum system by using a modified medical aspirator (electric vacuum pump). It seems that when a vacuum gauge hooked up in line reaches around 5lbs, my headlights go up. I know that many guys have had problems with vacuum operation when using a big cam, so I'm confused by this.

Out of curiosity, have you tested all the vacuum components for leaks, especially the headlight relays? Also, what is your actual manifold vacuum reading at idle?