72 Lt-1 timing

[James G.]

I just read two articles which were referred to me by Duke Williams on total timing and how to check your distributor functions. Two very good papers. I am getting ready to time the car so my question is after the car is timed (total timing) do I hook the vacuum advance back to the vacuum advance solenoid or to manifold vacuum?

[Jim T.]

Re: 72 Lt-1 timing

The hook up is your preferance. My 70 bought new in August of 70 was switched to full time vacuum in September of 1970 by me.
Lower engine temperature in stop and go traffic and increased gas mileage in city driving is a benefit.
If your 72 is being judged, it is a very simple change to let the solenoid function.

[James G.]

Re: 72 Lt-1 timing

Jim, where did you take your vacuum from?

[Jim T.]

Re: 72 Lt-1 timing

Your 72 has a Holley and my new 70 had the original QJet. I just installed a longer piece of vacuum hose between the carb and the distrubutor vacuum advance completely by passing the solenoid by connecting the vacuum source to the same full time vacuum port the solenoid had the vacuum line running to on the carburator.

In 74 I replaced the QJet with a Holley 650 6210 spreadbore double pumper that bolted on the original intake. I used a full time vacuum port on the Holley. Your full time port should be at the Holley's carburators base. Easy enough to check, if you have vacuum at idle from a port, it is usually full time. This carb has two full time vacuum ports side by side coming from the front base of the carb.

Another Holley I have, 4777 650 double pumper has only one full time vacuum port at the front of the carburator base. I cut a vacuum line running from the fitting located in the intake manifold behind the carb and installed a "plastic T" and ran the vacuum line from the T to the distributor vacuum advance. Do doubt about this connection being full time vacuum since the power brake vacuum hose is also attached at this fitting.

[James G.]

Re: 72 Lt-1 timing

Thanks Jim. My vacuum port is on the carb base, so thats where I will put the dist.vacuum. I have had the car nineteen years and I always thought I had a vacuum leak. I could never get 12 to 19 inches of vacuum even after isolating all the vac lines. After reading those articles I found out that a solid lifter small block only pulls about 9 to 12 inches of vacuum. Always learning.