When setting base timing unhook vacuum can, temporarily plug off the vac signal.
Done.
Street car/daily driver moderate CR use ported/timed vacuum advance signal.
Race use manifold vac or none.
My emissions have been gutted out and I have no computer. I'm told because of this that the vacuum advance must be ran off of full manifold, and not ported...true or false?
When throttle is closed and everything set right and no vac leaks in system the manifold vac signal will be at its highest value.
So I had a confusing issue with reading the vacuum levels. I have two vacuum gauges, I have one as a tool that I can hook up anywhere in the engine bay and I have one that I bought on eBay to use for the inside of the car. Since I have installed the one in the car, I have been going off its reading and not using the one I bought as a tool, and it's been giving me a reading of 13 to 14 Hg... However, yesterday when I pulled out the tool and hooked it up to the full manifold vacuum source on my carburetor base plate and the engine at operating temperature, I get a steady vacuum reading of 21 Hg... Clearly the interior gauge is off by 4 or 5 Hg levels, the hose that came with it was a transparent hose (like a fish tank hose and I'm not sure if it pinches or not, but the damn thing reads wrong for sure.
On a race unit vac to manifold brings in max timing that the vacuum actuator can do at the distributor. There is no mechanical advance as the RPM value is still low. At launch you go from Idle to WOT and you lose vac signal to the distributor. Mechanical advance comes on full and vac advance is no longer in play.
On a daily driver manifold vac is high at idle, no vac signal at the ported vacuum. Distributor attached to ported vacuum. Most vacuum Cans start moving at or about 6 inches and full on at or about 12 inches of vacuum.
As you accelerate normally in normal traffic, ported signal comes on and starts applying advance needed to accelerate and not lug the engine. As you give more gas, throttle plates continues to open and vac signal will decrease, but RPMs are up and mechanical advance starts coming in.
That goes back to my original question about my emissions and computer being ripped out.. should I run full manifold or should I run ported manifold ? Would ported still save me on gas without the emissions and computer being part of my system ?
Where ever your max total timing is set, it is set at that RPM. That is the max and it will not go any higher. The only thing you can do at that point is WHEN you get total timing.
Total timing should be set at 3000 to 3500... Why these numbers and which one is good for daily driving and racing ? I don't intend on doing any racing but I don't like to turn down a challenge lol... what's good for daily driving but also for a little racing when I need to ?
Heavier weights and lighter springs makes total timing come on sooner. While lighter weights and heavier springs will make timing come on later.
I bought a spring and weight recurve kit for my distributor.. but I did what I was told, I was told to only switch out the springs with lighter springs and to leave the stock weights in.. I still have the kit if you think I should put in the heavier weights with those lighter springs.
Your static CR will set your base timing. High compression needs lower base timing 0 to 6 BTDC, while lower Static CR will have higher base timing 12 to 14 BTDC.
I love this answer here because I've never been told this before and it clears up a lot of things, but this is where I'm at a standstill because I don't know what my compression ratio is which is why I was asking about a manometer and another thread so that way hi I can get my compression ratio without disassembling and/or removing the engine. 👇🏾
Your cam lift and duration, valve overlap, dynamic compression and heat control at the head will affect detonation (pinging); when and how much, for any given octane rating. Higher octane fuel will have better properties to resist detonation, (knock/pinging). While poorer quality and lower octane rated fuels will knock, ping and create engine damage.
I'm not for sure about cam lift and duration, valve overlap, or dynamic compression... I do know that the engine doesn't overheat because I don't have drivability issues or engine smoking. I flushed out my entire cooling system not too long ago and I replaced the water with coolant. I made my own mixture by buying pure green antifreeze and mixing it half and half with distilled water.
I have played with 91 gas before, but it had 10% ethanol in it and I think that killed the original carburetor that was on the motor when I bought it. The engine did run a lot better and didn't ping as much or nearly at all on the 91 then the 87 that has no ethanol.. currently trying to find a gas station with 91 to 93 octane no ethanol fuel that I can use regularly.
There is a couple of Kum & goes in my area that have 93 gas but I'm not for sure if it's got ethanol in it or not. I guess I could call those gas stations and ask them specifically. If do contain ethanol, there's a race track about 40 miles from me that has a gas station with up to 110 octane fuel with no ethanol. But damn that's 40 miles away.