1970 Timing Question
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Intermediate
Joined: Jul 2019
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1970 Timing Question
Reading many threads about ignition timing they all state about where you connect the vacuum hose, either to the base of the carburetor or off of the manifold. The engine I am working on has a small canister with wires and a port to connect the vacuum hose on the right side next to the carburetor laying on the top edge of the valve cover.
I have noticed that at a stand still when you shift into 3rd gear the engine will speed up a little.
Is there a special procedure I should use to set the timing and what is this canister called?
This car is used just for touring and will probably never see 4000 RPM's
I have noticed that at a stand still when you shift into 3rd gear the engine will speed up a little.
Is there a special procedure I should use to set the timing and what is this canister called?
This car is used just for touring and will probably never see 4000 RPM's
Race Director
Joined: May 2006
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The canister is part of the emissions system. It prevents vacuum advance from kicking in until you are in 4th gear for a manual transmission. By pass it and connect the vacuum advance to a full time source. You make no mention of which engine or transmission.
Last edited by MelWff; Mar 8, 2020 at 07:11 PM.
Team Owner
Joined: Jan 2006
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From: Crossville TN
For nearly all stock GM engines of that vintage, your engine operates and survives better with manifold vacuum being fed directly to the dist. vacuum advance can...all the time.
All that 'stuff' connected into that advance can vacuum line was meant to reduce emissions....in a very limited and rudimentary way. You don't need that stuff, unless your locality and/or state requires that it be present on the engine and functional to have it pass emissions muster. You can leave all the [extra[ hardware on the intake manifold/engine. Just bypass it all with a vacuum line that connects directly to a fitting on the intake or to a 'manifold vacuum' fitting on the carb. If you are not sure, provide a photo of what you have and we will try to assist.
All that 'stuff' connected into that advance can vacuum line was meant to reduce emissions....in a very limited and rudimentary way. You don't need that stuff, unless your locality and/or state requires that it be present on the engine and functional to have it pass emissions muster. You can leave all the [extra[ hardware on the intake manifold/engine. Just bypass it all with a vacuum line that connects directly to a fitting on the intake or to a 'manifold vacuum' fitting on the carb. If you are not sure, provide a photo of what you have and we will try to assist.
Last edited by 7T1vette; Mar 10, 2020 at 01:36 AM.
