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Author Topic: Another question on timing-  (Read 36845 times)

Offline philo_beddoe

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Another question on timing-
« on: December 18, 2015, 07:04:24 pm »
I know my setting is 8 degrees btdc, the manual states that as well as the decal on top of the rad support. But that is for a stock factory application.

How do you determine your timing when you make changes or modifications? Such as a different carb (different barrels) or the intake or even a different engine? What do you use as a reference?
« Last Edit: December 18, 2015, 10:27:23 pm by philobeddoe »
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Offline enaberif

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Re: Another question on timing-
« Reply #1 on: December 18, 2015, 09:05:31 pm »
Whatever the truck wants and doesn't ping. I'm running 16* BTDC right now.
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Offline philo_beddoe

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Re: Another question on timing-
« Reply #2 on: December 18, 2015, 10:32:20 pm »
Ok, because i have a 4 bbl qjet and a gm intake. Factory it came with a two bbl carb on my 305. I also recolect that a little advanced is better in regards of a little more power and better gas mileage.
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Offline Irish_Alley

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Re: Another question on timing-
« Reply #3 on: December 19, 2015, 07:04:34 am »
the more timing you can get generally the more HP. on our mud trucks most times right when the starter starts to have problems starting the engine is where we sit at. with open headers you cant hear the ping but its the rule of thumb we use and as long as we dont overheat (due to pre-detonation) we keep it there
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Offline Stewart G Griffin

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Re: Another question on timing-
« Reply #4 on: December 19, 2015, 09:31:30 am »
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Offline Irish_Alley

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Re: Another question on timing-
« Reply #5 on: December 19, 2015, 09:34:25 am »
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Offline VileZambonie

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Re: Another question on timing-
« Reply #6 on: December 19, 2015, 12:59:04 pm »
Think of your base setting as nothing more than a baseline setting. There are many variables when it comes to playing with timing, carburetor settings and finding a good mix for your driving needs and without any adverse effects. The old school method of advancing it until it pings and then backing it off is an easy way to see how much advance your engine can handle. Do this on a hot day with regular octane fuel in the tank. Then recheck your timing and record your settings. This will help you understand your particular engines timing spectrum so you can really dial it in.
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Offline philo_beddoe

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Another question on timing-
« Reply #7 on: December 19, 2015, 08:00:39 pm »
Ok, hear this...right now my engine seems stuttery, if i start it cold then turn it off, its hard to start it again, like im flooding it. Almost to a point where it feels vibrating or wobbling. The timing just feels off, please tell me this makes sense. The bulb on my timing light blew. Can i just slightly advance or retard till she smoothes out?
« Last Edit: December 19, 2015, 08:04:19 pm by philobeddoe »
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Offline VileZambonie

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Re: Another question on timing-
« Reply #8 on: December 19, 2015, 09:12:10 pm »
That sounds like a choke issue not a timing issue
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Offline philo_beddoe

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Another question on timing-
« Reply #9 on: December 20, 2015, 06:43:06 am »
Ok, i'll buy that. I'm not an expert on carbs and chokes, what can i do?

 As a matter of fact, lately its been kind of tough to start up, really have to work the pedal to get it going when cold. After its fully warm, as long as i dont touch the gas pedal, it will start pretty quick like it should.

A while back i messed with the fast idle screw, could that be it??
« Last Edit: December 20, 2015, 06:53:27 am by philobeddoe »
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Offline Irish_Alley

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Re: Another question on timing-
« Reply #10 on: December 20, 2015, 07:34:33 am »
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Offline philo_beddoe

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Another question on timing-
« Reply #11 on: December 20, 2015, 08:21:26 am »
Ok, thanks. I think Vile nailed it though!! Or i did something right by accident. I turned the fast idle screw in one full turn, then it started at the touch of the key, it took a couple minutes to kick down as it was in the 30's last night.

After the engine reached temp i tapped the pedal and it kicked down. I let it idle for a minute and turned it off, waited a few seconds then she started again at the touch of the key! Bam! And i did NOT put my foot on the pedal.

Here's the thing, i had that fast idle screw backed out to much from summer when i did not want it to idle fast at start up. And now thats it cold-cold, it chugged when starting. (before i adjusted the fast idle screw)

Question- under normal applications, basically a factory set-up, how should these engines idle at first start up, and how long until it should kick down to normal warm idle? Are we supposed to just sit there and wait until the idle drops before putting into gear and taking off? What if we dont have patience to sit and wait, what if we are late for work in the morning and need to just go and the engine is still racing?

Does this all make sense? Whats the purpose/function of that fast idle screw that sits under the choke?  Thanks...
« Last Edit: December 20, 2015, 08:25:21 am by philobeddoe »
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Offline TGPJr

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Re: Another question on timing-
« Reply #12 on: December 20, 2015, 08:29:55 am »
Use a Vacuum gauge and set the timing to the highest reading at idle.
You will be very close.
If you like you can then advance it a little until it fuel knock or hard start (hot)
Then back up a degree or two.
Tom
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Offline philo_beddoe

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Another question on timing-
« Reply #13 on: December 20, 2015, 12:47:12 pm »
Ok, so whats a optimum reading. 22 ft. ?
« Last Edit: December 20, 2015, 01:16:03 pm by philobeddoe »
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Offline VileZambonie

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Re: Another question on timing-
« Reply #14 on: December 20, 2015, 04:07:33 pm »
Philo,

Don't set your timing based on vacuum readings.

To answer your other questions, let's start with what carburetor you have?
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