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Help with timing

Chief Brody

Chief Brody

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I am trying to set the timing because I put a new distributor in and it was running a little hotter than normal.

I decided to set the timing with a timing light and a vacuum gauge.

The problem is that I get the most vacuum at about 25* Before TDC (about 25 on the vacuum)
If i back it down to 16* it drops down to 20 on vacuum gauge

That sound high????

I was running it at 12" and it is running about 25% hotter on the gauge.
 
Are you setting the timing with the vacuum advance still hooked to the distributor ?
 
I thought "most vacuum possible" was the sweet spot"
 
Well 25* lead without the vacuum hooked up is a lot. It will likely detonate or have a hard time starting due to cylinder pressure

Once you hook the vac back up, it will add timing
 
So, the last time I did this I punted and went with 10*
 
I feel like it is running rich and I wanted to set the time right first, or should I do it the other way around?
 
All the sbc’s I’ve tuned like between 8-12 base timing.
 
10-12 works good

Not sure it matters what order unless it’s really screwed up. Sounds like you are on the road though
 
I set it at 10* and lost vacuum from 20 to 18, but I guess it is the "safe" route
 
Hell, I don't know if it is right....it is set to 10* timing , 750 RPM idle, and I adjusted the air / fuel mixture screws much leaner...I turned them all the way in and backed out 2.5 turns and ended up closer to 2 turns than 2 and a half....based on vacuum gauge.
 
My old plugs told me it was running a little rich...my nose told me too...
 
What I did on my trucks was plug off the vacuum advance and set the base timing to spec,it ranges from 4 to 10 degrees BTDC on most small blocks ..

Then I used a vacuum gauge to adjust the carb after the engine was fully warmed up ,after a ride..adjust the mixture strews to the highest and steadiest reading,then back them out 1/3 of a turn or so until the vacuum starts to drop an inch--this allows for the idle mixture to be rich enough when cold ,if you skip that step you may find it might want to stall at idle until its warmed up completely..a hot engine tolerates a lean idle mixture a lot better than a cold one or one that's still in the warm up stage..

You can use the vacuum gauge to set the timing,and though you may get the "best" & highest reading with it advanced much more at idle sitting still ,it will spark knock under load and be hard to crank after its been shut off hot for a few minutes..

I used to re-connect the vacuum advance and go for a ride,find a hill or a place you can boot it and see if it will spark knock,if it does,keep retarding the timing until you can barely detect any spark knock under wide open throttle ..if it still cranks hard hot, you may need to back it off a bit more..
Often I've gotten engines to perform much better with the timing advanced a bit more than the specs said using the vacuum gauge as a guide..
 
Back when my ford was still carbureted, with a standard type distributor (its multi-port EFI with full computer control timing now) I usually liked to set my all-in timing only, and then the base, or initial timing will be what it will be; unless I wanted to get into tuning the weights in the distributor. Course, the ford is my hotrod, and I was usually looking for power.


I think the mechanical advance on most OE distributors is all-in by about 2500, to 2800 rpm, and I think the timing number is usually around 34°-36° (this is mechanical ONLY, no vacuum advance at all, and my ford preferred 34, though I hear that most Chevy's like 36)
I can't remember the last time I set timing on my K5, since it's so stock that I've honestly never had to touch it.
If or when I do mess around with my K5 though, I'll be timing it by plugging off the vacuum advance, swinging it up to 3000 RPM, and setting the timing to 36°. I'll lock it down, and to hell with the initial setting.


Anyways, for initial timing, more timing will often run cooler, as you found, but too much initial can make it hard to start, and worse, too much initial will advance the all-in mechanical timing too much, possibly to the point of detonation or pinging.
Too much initial will also have a negative effect on emissions (if you care, I never did)
 
This is the same truck that was sputtering and missing,,,,maybe now that all cylinders are firing like they should, the engine may be producing more heat..

Is it building up pressure in the cooling system or pushing out any coolant?

If you test the temperature with a infrared
and it matches close to whatever temp
thermostat you have, I wouldn't worry about it..
 
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