The Ford Barn

aussie merc · 09-18-2019, 09:37 AM

did a major tune up [valve set, carb rebuild ], etc engine is 239ci with i believe to be stock cam, compression, heads etc fitted with twin97s and fenton headers after setting carbs best vacum that i could obtain was around 16" at idle 700rpm so advanced ignition previously set at pointer i suspect is 4deg btc when rechecked found i had added added another 6 deg {now at a total of 10 deg} starts ok sounds ok its being fed on 91 octane but im worried it may be over advancing as revs rise your thoughts and experience appreciated

Ol' Ron · 09-18-2019, 09:45 AM

Timing is determined by load, and RPM. To start it should be around 2/4 degs. Idle is around 10. Cruise at 200 Plus is around 26 and under load 20. Thear are only ball park numbers and the stock 8BA, and Early crab come close to tese.

aussie merc · 09-18-2019, 07:58 PM

dizzy has been replaced with mallory unilite non vacuum [this is how i got it]

Tinker · 09-18-2019, 10:55 PM

Low vacuum reading could be due to the fact you now have 4 big holes on top of your intake vs 2.

Lot of questions I'd guess from carbs to chokes etc, at this point.

Maybe ignition, But probably A/F. Just a thought. wrong as it is.
.

Talkwrench · 09-18-2019, 11:00 PM

Carbs should be .043 mains and 69 pvs sea level up to 5000ft.
If the cam is stock you should be able to get it closer to 600 rpm.
Just vacuum time it to best and back off 1" Hg and try it .
listen for detonation and look at your plugs periodically make sure you dont have and silver or black spots on the porcelain.

Tinker · 09-19-2019, 01:01 AM

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Just to be clear. You don't time a engine with vacuum. Even on a 8ba you disconnect the vacuum advance to get initial timing. Spark to cam/crank. Maybe to fine tune the air movement a little. But I would not go hog wild.

JWL · 09-19-2019, 07:50 AM

Actually the "vacuum timing" method works pretty well as a solid starting point.

Ronnieroadster · 09-19-2019, 02:21 PM

You asked how much is to much. Set the initial at 10 degrees and go no higher than 24 for the total when the engine is turning over 2200 RPM. Works perfectly ever time.
Ronnieroadster

Ol' Ron · 09-19-2019, 04:27 PM

Most engines will run "Alright" when the timing is off and the AF readings alittle rich. Unfortunately, most people accept this if the car does what it's supposed to. I consider myself quite capable of tuning my engines better than that. No so ol great one. I had a problem with the 2GC carb on the 280, so i rebuilt it with a new kit with a set of jets an accelerator pump from Daytona carb. My surprise is, it never ran this good before. I think the problem was, i spent too much time on the ignition advance i neglected the AF. Both are very important. i might addd an engine running rick will wear out the rings quicker. I think tha's what was wrong with the280.

frnkeore · 09-20-2019, 09:55 AM

I have a question regarding higher output engines but, have no plans to build one.

With A/F ratio of about 13.8, what would be total advance, timing you'd be expecting to run, on a hard pull, with a 3/8 x 3/8 engine with three, 97's on top and a 400 Jr cam?

Ol' Ron · 09-20-2019, 10:12 AM

Sounds like one of the old stock car/ drag engines. 13.8 is alittle lean for a full power run, but 18/20 would be close. I had a fixed advance of 17 in the stock car, where it ran bett on the track. However, it made more hP around 20 on a chassis dyno. Gota go with what works

Ronnieroadster · 09-20-2019, 12:53 PM

Quote:

Originally Posted by frnkeore

I have a question regarding higher output engines but, have no plans to build one.

With A/F ratio of about 13.8, what would be total advance, timing you'd be expecting to run, on a hard pull, with a 3/8 x 3/8 engine with three, 97's on top and a 400 Jr cam?

Read my post #8 it will give you the number your looking for. Set many records with the stated settings. A/F readings in the 13. range on most runs however not the best economy but the racing gas is only $18.00 a gallon so not a big deal.
Ronnieroadster

frnkeore · 09-20-2019, 02:15 PM

A separate issue but, do you need Av Gas for a flathead or are you talking a blown engine?

Ronnieroadster · 09-20-2019, 04:22 PM

Quote:

Originally Posted by frnkeore

A separate issue but, do you need Av Gas for a flathead or are you talking a blown engine?

Years ago I would use 100 NL Av Gas at the drag strip. But now for the longer runs I use racing gas. For my present combination 118 Octane VP brand.
Ronnieroadster

aussie merc · 09-20-2019, 09:56 PM

not a lover of avgas seen to many problems like bore washing but the i guess to some extent were spoilt here in aus as we can get 98 no ethanol out of the pump at just about any service center

Tinker · 09-20-2019, 10:02 PM

....

JSeery · 09-21-2019, 01:28 PM

Quote:

Originally Posted by aussie merc

...guess to some extent were spoilt here in aus as we can get 98 no ethanol out of the pump at just about any service center

That would be nice!

JWL · 09-21-2019, 02:54 PM

Timing is NOT a one-size-fits-all number. The mechanic should strive to minimize negative work while maximizing the energy applied to the crank assembly at periods of the highest leverage.

Negative work is any pressure rise in the chamber which occurs before TDC. This is usually resulting from over advanced timing. Any pressure fights against the rise of the piston and reduces power. Therefor we always look for the minimum timing advance which will provide the highest torque value.

In all my test cases the maximum power was achieved when the timing was reduced from maximum torque numbers by 4 degrees for the upper RPM output tests.

During our Bonneville record runs we used 17 degrees total advance, with the racing gasoline, for the high RPM activities.

For better, more thorough explanations, read my book. I do not have a Stenographer for this typing.

Ronnieroadster · 09-21-2019, 05:01 PM

Quote:

Originally Posted by JWL

Timing is NOT a one-size-fits-all number. The mechanic should strive to minimize negative work while maximizing the energy applied to the crank assembly at periods of the highest leverage.

Negative work is any pressure rise in the chamber which occurs before TDC. This is usually resulting from over advanced timing. Any pressure fights against the rise of the piston and reduces power. Therefor we always look for the minimum timing advance which will provide the highest torque value.

In all my test cases the maximum power was achieved when the timing was reduced from maximum torque numbers by 4 degrees for the upper RPM output tests.

During our Bonneville record runs we used 17 degrees total advance, with the racing gasoline, for the high RPM activities.

For better, more thorough explanations, read my book. I do not have a Stenographer for this typing.

Wow i must be doing something wrong setting all my very FAST records with the old valve in block Ford engines. Along with my real world thousands of miles running these engines just saying. My numbers quoted work perfectly but heck I should wright a book I guess. The title facts in the 21st century.

aussie merc · 09-22-2019, 04:18 AM

thanks to all i asked the question and got several answers and as for them 4 big holes thats how i got it a typical buy and bolt[ looks cool who cares how it runs ] also have checked the advance and it brings on way to much way to early [that explains why it was so retarded when i got it ] so next step recurve the dissy and try again while we are here any thoughts on maybe down sizeing carbs to say 81's instead of 97's

09-18-2019, 09:37 AM	#1
aussie merc Senior Member Join Date: Sep 2016 Location: sydney australia Posts: 1,030	timing advance how much is to much did a major tune up [valve set, carb rebuild ], etc engine is 239ci with i believe to be stock cam, compression, heads etc fitted with twin97s and fenton headers after setting carbs best vacum that i could obtain was around 16" at idle 700rpm so advanced ignition previously set at pointer i suspect is 4deg btc when rechecked found i had added added another 6 deg {now at a total of 10 deg} starts ok sounds ok its being fed on 91 octane but im worried it may be over advancing as revs rise your thoughts and experience appreciated

09-18-2019, 09:45 AM	#2
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,857	Re: timing advance how much is to much Timing is determined by load, and RPM. To start it should be around 2/4 degs. Idle is around 10. Cruise at 200 Plus is around 26 and under load 20. Thear are only ball park numbers and the stock 8BA, and Early crab come close to tese.

09-18-2019, 07:58 PM	#3
aussie merc Senior Member Join Date: Sep 2016 Location: sydney australia Posts: 1,030	Re: timing advance how much is to much dizzy has been replaced with mallory unilite non vacuum [this is how i got it]

09-18-2019, 10:55 PM	#4
Tinker Senior Member Join Date: May 2010 Location: MN Posts: 7,053	Re: timing advance how much is to much Low vacuum reading could be due to the fact you now have 4 big holes on top of your intake vs 2. Lot of questions I'd guess from carbs to chokes etc, at this point. Maybe ignition, But probably A/F. Just a thought. wrong as it is. .

09-18-2019, 11:00 PM	#5
Talkwrench Senior Member Join Date: Aug 2012 Location: Perth, Western Australia Posts: 2,687	Re: timing advance how much is to much Carbs should be .043 mains and 69 pvs sea level up to 5000ft. If the cam is stock you should be able to get it closer to 600 rpm. Just vacuum time it to best and back off 1" Hg and try it . listen for detonation and look at your plugs periodically make sure you dont have and silver or black spots on the porcelain. __________________ *"Came too close to dying to stop living now!"*

09-19-2019, 01:01 AM	#6
Tinker Senior Member Join Date: May 2010 Location: MN Posts: 7,053	Re: timing advance how much is to much Sponsored Links (Register now to hide all advertisements) Just to be clear. You don't time a engine with vacuum. Even on a 8ba you disconnect the vacuum advance to get initial timing. Spark to cam/crank. Maybe to fine tune the air movement a little. But I would not go hog wild. Last edited by Tinker; 09-19-2019 at 01:29 AM.

09-19-2019, 07:50 AM	#7
JWL Member Emeritus Join Date: May 2010 Location: Fitzgerald, Georgia Posts: 2,204	Re: timing advance how much is to much Actually the "vacuum timing" method works pretty well as a solid starting point.

09-19-2019, 02:21 PM	#8
Ronnieroadster Senior Member Join Date: Dec 2010 Location: East Coast in CT Posts: 1,524	Re: timing advance how much is to much You asked how much is to much. Set the initial at 10 degrees and go no higher than 24 for the total when the engine is turning over 2200 RPM. Works perfectly ever time. Ronnieroadster __________________ I use the F word a lot no not that word these words Flathead , Focus and Finish. "Life Member of the Bonneville 200 MPH Club using a Ford Flathead block" Owner , Builder, Driver of the First Ford Flathead bodied roadster to run 200 MPH Record July 13, 2018 LTA timing association 200.921 in one and a half miles burning gasoline. First ever gas burning Ford flathead powered roadster to run 200 MPH at Bonneville Salt Flats setting the record August 7th 2021 at 205.744 MPH

09-19-2019, 04:27 PM	#9
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,857	Re: timing advance how much is to much Most engines will run "Alright" when the timing is off and the AF readings alittle rich. Unfortunately, most people accept this if the car does what it's supposed to. I consider myself quite capable of tuning my engines better than that. No so ol great one. I had a problem with the 2GC carb on the 280, so i rebuilt it with a new kit with a set of jets an accelerator pump from Daytona carb. My surprise is, it never ran this good before. I think the problem was, i spent too much time on the ignition advance i neglected the AF. Both are very important. i might addd an engine running rick will wear out the rings quicker. I think tha's what was wrong with the280.

09-20-2019, 09:55 AM	#10
frnkeore Senior Member Join Date: Jul 2019 Location: Southern Oregon Posts: 782	Re: timing advance how much is to much I have a question regarding higher output engines but, have no plans to build one. With A/F ratio of about 13.8, what would be total advance, timing you'd be expecting to run, on a hard pull, with a 3/8 x 3/8 engine with three, 97's on top and a 400 Jr cam? Last edited by frnkeore; 09-20-2019 at 10:46 AM.

09-20-2019, 10:12 AM	#11
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,857	Re: timing advance how much is to much Sounds like one of the old stock car/ drag engines. 13.8 is alittle lean for a full power run, but 18/20 would be close. I had a fixed advance of 17 in the stock car, where it ran bett on the track. However, it made more hP around 20 on a chassis dyno. Gota go with what works

09-20-2019, 02:15 PM	#13
frnkeore Senior Member Join Date: Jul 2019 Location: Southern Oregon Posts: 782	Re: timing advance how much is to much A separate issue but, do you need Av Gas for a flathead or are you talking a blown engine?

09-20-2019, 09:56 PM	#15
aussie merc Senior Member Join Date: Sep 2016 Location: sydney australia Posts: 1,030	Re: timing advance how much is to much not a lover of avgas seen to many problems like bore washing but the i guess to some extent were spoilt here in aus as we can get 98 no ethanol out of the pump at just about any service center

09-20-2019, 10:02 PM	#16
Tinker Senior Member Join Date: May 2010 Location: MN Posts: 7,053	Re: timing advance how much is to much .... Last edited by Tinker; 09-20-2019 at 10:29 PM.

09-21-2019, 02:54 PM	#18
JWL Member Emeritus Join Date: May 2010 Location: Fitzgerald, Georgia Posts: 2,204	Re: timing advance how much is to much Timing is NOT a one-size-fits-all number. The mechanic should strive to minimize negative work while maximizing the energy applied to the crank assembly at periods of the highest leverage. Negative work is any pressure rise in the chamber which occurs before TDC. This is usually resulting from over advanced timing. Any pressure fights against the rise of the piston and reduces power. Therefor we always look for the minimum timing advance which will provide the highest torque value. In all my test cases the maximum power was achieved when the timing was reduced from maximum torque numbers by 4 degrees for the upper RPM output tests. During our Bonneville record runs we used 17 degrees total advance, with the racing gasoline, for the high RPM activities. For better, more thorough explanations, read my book. I do not have a Stenographer for this typing.

09-22-2019, 04:18 AM	#20
aussie merc Senior Member Join Date: Sep 2016 Location: sydney australia Posts: 1,030	Re: timing advance how much is to much thanks to all i asked the question and got several answers and as for them 4 big holes thats how i got it a typical buy and bolt[ looks cool who cares how it runs ] also have checked the advance and it brings on way to much way to early [that explains why it was so retarded when i got it ] so next step recurve the dissy and try again while we are here any thoughts on maybe down sizeing carbs to say 81's instead of 97's