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WTF!!!! Why is setting timing soo hard

evobuilder

Jr. Member
Joined
Nov 13, 2013
Messages
79
Loc.
Seattle, WA
so.... I have scoured Google, Bing, youTube, etc and have found very little good info on setting timing on a early Ford 302. Lots of general tips, but all vague at best. Here is what I found....

set timing to 6 degrees BTDC or.... set timing to 15 degrees BTDC (whaaa..... seriously, who is right???)

I have a stock 302 in my 72 Bronco, but have a 4bbl, headers and turbo mufflers with dual exhaust (no cross over).

Do I want 6, 8, 10, 14. 18..... geesh! You cannot get a solid answer. If I had a SBC, I could find a MILLION answers, videos, blogs, forums, etc. but you'd think that the SBF community is keeping a secret :)

Also.... do I time with the vacuum line attached or disconnected????
- I just ordered a new carb so I can eliminate that as an issue
- I have new plugs, wires, cap and rotor
- with the new carb installed, where do I set the timing (and do I do it with the vacuum line connected to the distributor or not)?

Thoughts?
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
If you're vacuum advance is correctly connected to the timed port, you can leave it connected to do the adjustment. If you don't know, disconnect and plug the line. I believe 6 degrees at 600 RPM is the base setting for a stock cam and stock compression. You can usually advance it a few degrees for better response. Beyond that and it will be sort of experimenting to see what works best. Some will advance just short of creating a ping. I feel that is too far advanced. It doesn't allow for variations in elevation, temperature, and fuel octane.
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
In general its no different than the sbc there are lots of different settings all depends on what works best for your engine and driving style. If you get a milllion answers for the sbc then there must be a whole range of answers for that as well. I dont really see how your confused with less answers for the sbf.
As was said 6 is the stock setting. Then you play with it from there to see what works best for your engine. Every engine is different. You can usually go up to 10-12 degrees without much issue. You want to run as much timing as you can as long as you dont get hard hot starts, dieseling on shutdown or pinging when driving. Just be aware that if you have emissions testing you may need to back the timing down to stock specs to pass idle tests.
 
OP
OP
evobuilder

evobuilder

Jr. Member
Joined
Nov 13, 2013
Messages
79
Loc.
Seattle, WA
all great feedback

yes.... I know its all recommendations and it truly depends on the specific setup. I am sure that my carb is the core of my issues.... once I install the new carb, it should be much easier to isolate the main tuning issues.
 

DJs74

Bronco Guru
Joined
Apr 1, 2014
Messages
1,135
Hello evobuilder,

whether you are looking at SBC or SBF data, it is all just truly theory and should be considered a starting point and target for your particular 302

As mentioned, a good starting point is an initial timing of 6 - 8° for a stock 302 but in my opinion, initial timing is no more than a first step in setting ignition timing - the more important goal is finding and setting your total timing (which is your initial + whatever mechanical advance you have).
If you are running a distributor with vacuum advance, then this is your mechanism to obtain total ignition timing.
For me personally on my SBF and BBF, I shoot for 34 - 36° total ignition timing at say 3000-4000 RPM.
I don't run a vacuum advance distributor but rather all mechanical (centrifugal advance) types but no matter the type, the total advance occurs above idle in the "power band" RPM range.

So, having said all that... what I recommend for you (after you get your carburetor issues taken care of)
►unhook your vacuum advance and plug your vacuum port
►set your initial timing in the 6 - 8° range
►reconnect the vacuum advance
►check your total timing in the higher RPM band (3000 - 3500 RPM) and see what you get

If you are in the low to mid 30s for total timing, I'd say you are pretty close - take a test run and see how it acts. If it feels like it still needs more, then play with the initial timing by increasing it a couple of degrees and then check the total again - test drive and so on.

I also recommend a note pad and pen and jot down all your numbers so you know where you started and what you ended up with and stick it in the dash for reference.

a totally different "old school" approach is to simply rotate your distributor to a point where the motor drags slightly at cranking, then back it off a little and try it. Optimal ignition timing is going to be somewhere just prior to spark knock (pre-detonation) and a slow dragging engine crank. I am not recommending or endorsing this approach but lots of people use it when a timing light is not available.


Good luck

DJs74
 

Fairlane514

Sr. Member
Joined
Oct 28, 2013
Messages
508
Loc.
Houston
If he has his vacuum advance connected while checking his total at 3000 rpm he will be in the mid 40-50 on his timing marks.

He should check total with it disconnected and plugged at the vacuum source.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,834
Who is right? Everybody and nobody.
There is no single "right" answer.
Engine should start and run pretty good with 6-10° of initial timing.
You have a modified engine, stock settings are at this point just a guideline.

I go with the theory of "the least amount of timing without losing power".
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
Yes, the carb will have a lot to do with the timing allowed. Mine would ping even at 6 degrees advanced until I got the correct pick-up springs on the new carburetor. With that corrected, I was able to bump it up in stages to 12 degrees without an issue.
 

DJs74

Bronco Guru
Joined
Apr 1, 2014
Messages
1,135
I was only suggesting that the total ignition timing be checked and verified with all advance influences in play and accounted for - and was assuming that ported vacuum was being used.
numbers in my head was 6° initial / 15° centrifugal / 15° vacuum for a total of 36°

but then again, I don't run any vacuum advance distributors so I should have just kept shut

sorry if i added any confusion on this

DJs74
 

Timmy390

Bronco Guru
Joined
Jan 1, 2011
Messages
5,609
Loc.
Conway, AR
Who is right? Everybody and nobody.
There is no single "right" answer.
Engine should start and run pretty good with 6-10° of initial timing.
You have a modified engine, stock settings are at this point just a guideline.

This ^^^^

Initial timing is just that. It's a starting point to get running. After that each engine will like different timing depending on the variables of the build. Some build will like more timing and others not so much.

I think my big block 390FE is ended up at 16 initial and 36 total all in at 3K. That's off the top of my head.

Tim
 

WheelHorse

Bronco Guru
Joined
Nov 22, 2004
Messages
2,491
I was only suggesting that the total ignition timing be checked and verified with all advance influences in play and accounted for - and was assuming that ported vacuum was being used.
numbers in my head was 6° initial / 15° centrifugal / 15° vacuum for a total of 36°

but then again, I don't run any vacuum advance distributors so I should have just kept shut

sorry if i added any confusion on this

DJs74

Meh, don't feel bad over it. Bronco's are like people, no two are alike.

I got a chuckle out of the 6/15/15. That assumes people first care enough to read and learn about it and how each plays a part, when they play, how they over lap and to actually confirm it. ADHD society doesn't want to do this anymore.

"Just tell me where to put it on the balancer" is what I see a lot of. This goes back to my Bronco trends over the years thread. Port vs. full: no matter just tell me where to plug in disregarding the why Ford did what in the first place.

No one wants to sneak up on a tune. No one want to spin 'em up on the rollers and see the difference. Read plugs...yeah right. A lot just want to talk about theory and what they've read, but seldom anything backs it up and then that turns into a theory battle looking for self-glorification.

So don't feel bad. I've learned to dumb it down and keep it simple.

Separate from my response above:

Evobuilder: Stock Ford timing is 6 degrees BTDC. Some go as high as 12 without an issue on 87 R+M/2. This assumes your air fuel ratio is correct. Only way to tell is with a wideband.

Vacuum, if hooked to port (no vac at idle) then no, you don't have to disconnect. This was Ford's emissions era stock location. Always confirm with a vacuum gauge or a finger.

If you run full, you will need to get a handle on what else is going on with the rest of your timing and adjust accordingly (springs, mechanical advance setting and vac adj). You will need to disconnect to see base timing.
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
1974 ford set it at 6 Before top dead center. Now if you want to really drive the thing start advancing it from there. I run 12 degrees myself with no engine issues. The difference in driveability around town is like adding an extra cylinder or 2. Fords smog efficient tuning leaves alot of meat on the table. It would be nice if we all had wide ban tuners and dyno's available but we don't and most can't afford the time and money to get it done. What does it really cost to drop off a Bronco and get it properly tuned? What $800 to $1500 by the time you pay the time and parts?
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,345
And all of that depends on whether you have the correct timing marks to work with.

If you're new to Broncos, and don't know if this is the original engine, or in it's original front accessory drive form, then better search for some pictures of what you're looking for, as far as timing marks and pointers are concerned.
Or all could be for naught...

Paul
 

jw0747

Contributor
Bronco Guru
Joined
Nov 22, 2006
Messages
2,434
Loc.
San Antonio, TX
And all of that depends on whether you have the correct timing marks to work with.

If you're new to Broncos, and don't know if this is the original engine, or in it's original front accessory drive form, then better search for some pictures of what you're looking for, as far as timing marks and pointers are concerned.
Or all could be for naught...

Paul
X2...Your timing marks could be off. Go ahead and do one of the exercises on the net to determine TDC and when you find it check the timing marks to see if they're lined up on TDC. If they are then pull the distributor vacuum line and plug it and set the timing at 6 degree BTDC. Then plug in the vacuum line and be done with it. This is how the factory recommended doing it on stock 302s. Then if its idling badly you probably have a carb issue.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,345
I have a stock 302 in my 72 Bronco, but have a 4bbl, headers and turbo mufflers with dual exhaust (no cross over).

You can't expect anyone on the internet talking about their experience to give you an exact timing setting for yours. Only generic starting points, as was already mentioned.
It's no longer stock, nobody knows how the carb is jetted, where you live, how you drive, what other mods have been done (changed the distributor advance type for instance) like ignition upgrades.
And what type/brand/grade of gas you use.
Or what plug heat range you use.
Or if your distributor has ever been changed, which might mean (in addition to the previously mentioned issues) it has a different max advance setting and rate.
Or how your EB is set up in general. Tire size, gearing, transmission type, age and condition of engine. Whether you'll only drive it in the summer, the winter, or all year. Overall weight even...
Every one of which can effect how your timing would be best set.

Maybe all of that had been said already, but it's the truth, so worth saying again.
Set yours based on how it runs. My '71 with some of your mods was supposed to be about 6 too, if I remember, but definitely worked best at 12 BTDC.
We just fired up a friend's 351w carbureted and it's fairly happy with 10° initial, but REEEEEEELLLLLY liked at least 30° or more at the 2500 rpm level. Just sounded ok with any less, but really started to sing when the timing was advanced to the higher levels even at that modest rpm.

See? Simple and consistent, yes? ;D
Just like a Ford... Yeah right! %)

Paul
 

roundhouse

Bronco Guru
Joined
Sep 5, 2003
Messages
2,886
I just advance it a little at a time until it knocks running full throttle up a hill
Then back off just a little

I have a 90 mustang motor with the mustang efi. And it's currently at 37 degrees
 
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