Vacuum advance hook up
Using a ported spark advance will still allow the vacuum advance to do its job at steady cruising, but all of the benefits of idle cooling will be lost. As you apply more throttle, air rushes through the carb, into the intake manifold increasing pressure and pushing the diaphragm in the vacuum can right back out, retarding timing back to wherever it would normally be, given engine RPM and mechanical advance.
In a situation with a roots blower, the vacuum feed to the distributor should be routed underneath the blower.
Timing is Everything
For that reason, it is best paired with another form of ignition advance: Actually Steve, I was talking about the density of the air in the cylinders. Now, switch the vacuum advance to a direct source of vacuum and again check the idle rpm? I hooked the vacuum advance to ported vacuum on my Holley carb. This is because the throttle is mostly closed and the engine is pulling against this restriction. Note that passwords are case-sensitive.
Do you already have an account? May 5, at 1: Originally Posted by Scottd That much I understand Thanked 2 Times in 2 Posts. What vacuum advance hook up of timing should I be running and should I disconnect the vacuum advance? Next thing to work on is your vacuum advance hook up timing. Inside the can is a diaphragm that, when exposed to high manifold vacuum, pulls on a linkage to rotate the position of the reluctor tabs.
When you go to WOT you do not want advance from both the vac canister and the weights. Lets say you encounter a hill or go to pass another car while cruising down the highway.
Send a private message to Scottd. Internet forums are rife with opinions on both sides of the argument.
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To fix this issue, and have enough timing at idle, and have good off idle response, I went to ported vacuum. When I put the car in gear, the idle would drop, the vacuum would drop also, it would lose ignition timing and would begin to stall.
All times are GMT Log In Remember Me? It should be no problem to T into the manifold power brake fitting. Is this where I hook up Vacuum Advance on a Holley ?
Note that passwords are case-sensitive. September 8, at 6: You can get around this with an ignition cut-out so that the engine cranks and then you hit the ignition circuit, but this is unnecessarily complex for a street car.
BlewJan 29,in forum: If you are having higher rpm cruise pinging but not wot pinging you may have too much vacuum advance in the canister. But theres no MPG differences or anything. All carbureted cars were set up with direct vacuum to the distributor before more stringent emissions requirements reared their heads.