302 Timing questions
12-06-2006, 09:14 PM
#1
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Posts: 790
302 Timing questions
What is the stock timing supposed ot be set at on a 302? what idle(rpm) and what *. My timing is set at 21* at 1000 RPM.. im kind of lost at what rpm to set it at and to what advance. The engine is running good when sitting thier. a little rough idleing... When i put it in gear and give gas, it cant handle the load unless i ease in. and when i am driving, it sputters and pops once i get to 2k+ and give some heave throttle. If i rev in nutral, its fine. The plugs are black with carbon, and dry. This reams in rich and/or wrong heat range plugs?? I bought new plugs to eliminate that. runnign rich( its a holley 650 4150<--- I think) and its new and the instructions dont say anything about that.. how do i adjust that. lol im a newbie. ** the book says 6* intial timing at 600 RPM i suppose... it idles like crap at that. idles better, but higher at 15-20
On the carb, theirs the high idle and low idle screws. One on theleft and one on the right.. Whats the difference between the 2 and why should i use one instead of the other? is one a large and othe other a fine adjustment??
Does the timing advance change with mods? If i have a cam, does that mean my advance will be different??
Is the PCV system a MUST? If i dont use the hole, put a breather and plug the hole on the carb is this alright?
-Jon
On the carb, theirs the high idle and low idle screws. One on theleft and one on the right.. Whats the difference between the 2 and why should i use one instead of the other? is one a large and othe other a fine adjustment??
Does the timing advance change with mods? If i have a cam, does that mean my advance will be different??
Is the PCV system a MUST? If i dont use the hole, put a breather and plug the hole on the carb is this alright?
-Jon
12-07-2006, 02:07 AM
#2
5th Gear Member
Join Date: Jun 2006
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Posts: 4,089
RE: 302 Timing questions
I run 10* at 1000 rpm. Make sure you have the vacuum advance unplugged (if you have one). 21* is way too much. The factory setting is at the original idle, which would be about 750 rpm or so.
The idle mixture screws on a Holley are on either side of the carb located on the metering block. They are the same thing, just one for each venturi. The idle mixture screws will take care of the idle richness, but the jets will take care of the rest of the rpm range.
You have a new carb, make sure the floats are set properly (fuel should be at the bottom of the site hole when idling). You can dry set the floats by removing the bowls and turning them upside down. Holley has a spec to measure, but I just set them so that they are square inside the bowl (top of the float parallel with the top of the bowl). Also, make sure the needle/seat aren't stuck by lightly tapping the adjustment screw with the plastic handle of a screw driver.
The idle mixture screws on a Holley are on either side of the carb located on the metering block. They are the same thing, just one for each venturi. The idle mixture screws will take care of the idle richness, but the jets will take care of the rest of the rpm range.
You have a new carb, make sure the floats are set properly (fuel should be at the bottom of the site hole when idling). You can dry set the floats by removing the bowls and turning them upside down. Holley has a spec to measure, but I just set them so that they are square inside the bowl (top of the float parallel with the top of the bowl). Also, make sure the needle/seat aren't stuck by lightly tapping the adjustment screw with the plastic handle of a screw driver.
ORIGINAL: Yonco
What is the stock timing supposed ot be set at on a 302? what idle(rpm) and what *. My timing is set at 21* at 1000 RPM.. im kind of lost at what rpm to set it at and to what advance. The engine is running good when sitting thier. a little rough idleing... When i put it in gear and give gas, it cant handle the load unless i ease in. and when i am driving, it sputters and pops once i get to 2k+ and give some heave throttle. If i rev in nutral, its fine. The plugs are black with carbon, and dry. This reams in rich and/or wrong heat range plugs?? I bought new plugs to eliminate that. runnign rich( its a holley 650 4150<--- I think) and its new and the instructions dont say anything about that.. how do i adjust that. lol im a newbie. ** the book says 6* intial timing at 600 RPM i suppose... it idles like crap at that. idles better, but higher at 15-20
On the carb, theirs the high idle and low idle screws. One on theleft and one on the right.. Whats the difference between the 2 and why should i use one instead of the other? is one a large and othe other a fine adjustment??
Does the timing advance change with mods? If i have a cam, does that mean my advance will be different??
Is the PCV system a MUST? If i dont use the hole, put a breather and plug the hole on the carb is this alright?
-Jon
What is the stock timing supposed ot be set at on a 302? what idle(rpm) and what *. My timing is set at 21* at 1000 RPM.. im kind of lost at what rpm to set it at and to what advance. The engine is running good when sitting thier. a little rough idleing... When i put it in gear and give gas, it cant handle the load unless i ease in. and when i am driving, it sputters and pops once i get to 2k+ and give some heave throttle. If i rev in nutral, its fine. The plugs are black with carbon, and dry. This reams in rich and/or wrong heat range plugs?? I bought new plugs to eliminate that. runnign rich( its a holley 650 4150<--- I think) and its new and the instructions dont say anything about that.. how do i adjust that. lol im a newbie. ** the book says 6* intial timing at 600 RPM i suppose... it idles like crap at that. idles better, but higher at 15-20
On the carb, theirs the high idle and low idle screws. One on theleft and one on the right.. Whats the difference between the 2 and why should i use one instead of the other? is one a large and othe other a fine adjustment??
Does the timing advance change with mods? If i have a cam, does that mean my advance will be different??
Is the PCV system a MUST? If i dont use the hole, put a breather and plug the hole on the carb is this alright?
-Jon
12-07-2006, 03:13 AM
#3
Join Date: Aug 2006
Posts: 45
RE: 302 Timing questions
6 degrees BTDC at idle with vacuum line(s) to the distributor disconnected.
As to advance(s) there are two.
One is in relation to Engine RPM and called a centrifugal advance.
One is in relation to Vacuum at the Venturi This one is not always used and is considered to be a fuel economy measure.
Each have an adjustment provision which varies from distributor to distributor.
The springs on the plate inside the dist are to adjust the centrifugal
There is a spring inside the Vacuum unit which on older models comes in various calibrations.
Hope that this answers your question
As to advance(s) there are two.
One is in relation to Engine RPM and called a centrifugal advance.
One is in relation to Vacuum at the Venturi This one is not always used and is considered to be a fuel economy measure.
Each have an adjustment provision which varies from distributor to distributor.
The springs on the plate inside the dist are to adjust the centrifugal
There is a spring inside the Vacuum unit which on older models comes in various calibrations.
Hope that this answers your question
12-07-2006, 06:42 AM
#4
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RE: 302 Timing questions
Your car will run without the PCV hose attached to the carb, but it will run the same with it attached, so why not use it? 6 degrees BTDC is what the manual says about timing, but mine seems to run better at 8.
12-12-2006, 03:27 PM
#6
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Posts: 1,082
RE: 302 Timing questions
well first of all theres not alotta vacum at idle thats why it idles same with pvc hooked usually..there timing at idle and timing at totle..a 302 usually get around 36degrees totle..thats if ya idle timing is at 0///advancing the idle timing and ya will need to rev motor to about 2500 rpms and settiming at 10 degrees more then what it was..most guys say oh i can set the timing at ear,blahblahblah..what ever get a gun,wet it right.. try around 2-8 inital adv go from there on a 302/and around 6-10 initial on a 5.0 go from there //same motors but timing is a lil diff.. i have 9 degrees on my 302 adv at idle and 34 at totle...learn how to do both.or ya are not tuning ya motor right..seting a motor at idle timing is just half of the timing needed..thats why alotta guys run good at idle and back fire at totle... whick is like a wot...wide open throtle//computerd 5.0s take care of totle timing mostly... but a carb set up ya have to do it///
12-13-2006, 12:05 AM
#7
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Join Date: Jun 2006
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Posts: 4,089
RE: 302 Timing questions
If you run that little timing at idle, you're going to hava a hard time with idle. 10 degrees at 800 rpm is a decent starting point. 34-38 total depending on cam and other combustion chamber dynamics.
It is very easy to tune timing by ear. Engines tell you a lot if you take the time to listen to them. I tune mine by ear and use a gun just to see where I am (or to take out a certain amount of timing for crap gas...which can't be tuned by ear because you'll need the engine loaded to hear the ping).
BTW, learn to use '.' instead of '/'
It is very easy to tune timing by ear. Engines tell you a lot if you take the time to listen to them. I tune mine by ear and use a gun just to see where I am (or to take out a certain amount of timing for crap gas...which can't be tuned by ear because you'll need the engine loaded to hear the ping).
BTW, learn to use '.' instead of '/'
ORIGINAL: hellas85stang
well first of all theres not alotta vacum at idle thats why it idles same with pvc hooked usually..there timing at idle and timing at totle..a 302 usually get around 36degrees totle..thats if ya idle timing is at 0///advancing the idle timing and ya will need to rev motor to about 2500 rpms and settiming at 10 degrees more then what it was..most guys say oh i can set the timing at ear,blahblahblah..what ever get a gun,wet it right.. try around 2-8 inital adv go from there on a 302/and around 6-10 initial on a 5.0 go from there //same motors but timing is a lil diff.. i have 9 degrees on my 302 adv at idle and 34 at totle...learn how to do both.or ya are not tuning ya motor right..seting a motor at idle timing is just half of the timing needed..thats why alotta guys run good at idle and back fire at totle... whick is like a wot...wide open throtle//computerd 5.0s take care of totle timing mostly... but a carb set up ya have to do it///
well first of all theres not alotta vacum at idle thats why it idles same with pvc hooked usually..there timing at idle and timing at totle..a 302 usually get around 36degrees totle..thats if ya idle timing is at 0///advancing the idle timing and ya will need to rev motor to about 2500 rpms and settiming at 10 degrees more then what it was..most guys say oh i can set the timing at ear,blahblahblah..what ever get a gun,wet it right.. try around 2-8 inital adv go from there on a 302/and around 6-10 initial on a 5.0 go from there //same motors but timing is a lil diff.. i have 9 degrees on my 302 adv at idle and 34 at totle...learn how to do both.or ya are not tuning ya motor right..seting a motor at idle timing is just half of the timing needed..thats why alotta guys run good at idle and back fire at totle... whick is like a wot...wide open throtle//computerd 5.0s take care of totle timing mostly... but a carb set up ya have to do it///
12-13-2006, 12:40 AM
#8
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Join Date: Apr 2006
Location: The unemployment epicenter, Detroit, MI
Posts: 432
RE: 302 Timing questions
This is what I had posted in your last *help* thread, not sure if you saw it. What Ive said here wont necessarily get you the most power, but it will get you a lot closer than what it sounds like you are now.
a holley jet #65 does NOT mean a .065 opening. Some aftermarket jets are measured this way, but the stock holley is not. You say it backfired when you were originally tried to start it, so it may have blown the power valve. The easiest way to check this is by turning the idle mixture screws in all the way. If it stalls before you get all the way in (no fuel flow) chances are good that the power valve is fine. If you can run both of them in all the way and it keeps on running fine, its blown. Also dont forget exactly how far you turned each screw so you can put it back to its original setting. Your choke should be wide open, straight up and down. To eliminate the possibility of a 'choking choke', wire it open somehow. Make sure your floats are set correct. To do this on a holley, get the engine warmed up and while its running, pull the sight plug off the float bowl. The fuel should just just dribble out of the hole. No fuel coming out means the float is too low, flooding out means its too high. If while setting the float you cant seem to get it low enough and have run out of thread, pull the needle and seat out and clean or replace. Once you have done all this, go back and reset the idle mixture screws using either a vacuum gauge or 1000 rpm tach to achieve the highest vacuum and/or highest idle rpm, then reset idle speed as necessary using the idle speed screw. Dont forget that for your carb settings to be accurate, you need to have clean plugs to start with. Fouled plugs make it basically impossible to tune your carb, especially at idle.
Also, you say your base timing is at 6*, thats pretty weak. Try disconnecting any vacuum source to the distributor and bumping it up to 10-12*, then reconnect vacuum source.
Fine tuning a carb can be an intimidating task, especially if you dont have a lot of experience with it, but stick with it and it can be VERY rewarding in terms of power, driveability, gas mileage, and overall fun and feel of the car. Lastly, unless you have a really big cam or odd combination, Holleys stock jet sizes are usually pretty close to what you will need.
Also, you say your base timing is at 6*, thats pretty weak. Try disconnecting any vacuum source to the distributor and bumping it up to 10-12*, then reconnect vacuum source.
Fine tuning a carb can be an intimidating task, especially if you dont have a lot of experience with it, but stick with it and it can be VERY rewarding in terms of power, driveability, gas mileage, and overall fun and feel of the car. Lastly, unless you have a really big cam or odd combination, Holleys stock jet sizes are usually pretty close to what you will need.
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