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Author
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Topic: Lesson #3 : Ignition Timing
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 04-19-2002 11:26 AM
   
SBF engines with flat top pistons do not like much timing no matter what.  Big valves, big chambers, big cams, it doesn't make any difference. If you have a good ignition sysem and a locked in curve, it won't need more than 35 degrees tops to make max power.
We have always gone quicker and faster with "STOCK" 5.0 cars by advancing the sh*t out of the timing. We now understand why. All we were doing was over compensating for the EEC IV's natural retard program. Even though we would change the static timing, the computer would still retard it under a load at least ten degrees.
We used to always figure that non computer FoMoCo motors performed best at 38 degrees. Not so! You might pick up some low end, but you will loose double what you gain overall.
On full boggie race stuff or even just hot S&S motors we tried everything from 42 to 32 degrees. Of the 5 motors tested, all 5 liked 34-35 degrees MAX! You can gain as much as 15 HP by dropping down from 40 degrees.
Lesson is, make certain you have a good balancer, TDC is absolute, lock in your distributor, and set the timing at no more than 35 degrees. Always set the timing at over 4000 RPM unless you have a crank trigger and a belt drive. It WILL change as the RPM goes up. 
PS I always knew that our low compression stuff with quench heads never liked a lot of timing, but never imagined that the 331-347-359 stuff with the great aftermarket unshrouded heads and neat new style pistons would not like 38 degrees.  We just "ASSUMED" that because they ran good that way it was fine.  Additional leson, NEVER ASSUME ANYTHING! ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
US Class Nationals link
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n2oMike
Gearhead Posts: 2831
From: Spencer, WV
Registered: Jan 2001
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posted 04-19-2002 11:54 AM
Hmmm... I've always run my car with around 36 degrees, which is right in line with what you said, but that Joe Sherman 400hp 302 article with the flattops and 289 heads made best power with 42 degrees. He said any more or less cost quite a bit of power. It had a single pattern hydraulic Isky 280 Mega Cam with 232 @ 0.050" and a 108 LSA.Go figure... ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
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V8 Thumper
Gearhead Posts: 4681
From: Phoenix, Arizona
Registered: Dec 2001
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posted 04-19-2002 11:59 AM
Well, I'll be dipped. Any explaination whatsoever ? I'm certainly not contesting your 'research' , in fact I'll total mine out at 34 and probably go down from there.
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n2oMike
Gearhead Posts: 2831
From: Spencer, WV
Registered: Jan 2001
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posted 04-19-2002 12:07 PM
quote:
Originally posted by Moneymaker:
PS I always knew that our low compression stuff with quench heads never liked a lot of timing, but never imagined that the 331-347-359 stuff with the great aftermarket unshrouded heads and neat new style pistons would not like 38 degrees.
The newer heads have had a lot of thought put into their combustion chambers. They are more efficient than the older Ford castings, and therefore require less timing. Some of the new stuff runs best with 30-32 degrees... especially when combined with 'mirror image' reverse dome 'dished' pistons. A combustion chamber like this begins to resemble a sphere... moving the spark plug to the approximate center of this sphere makes for a HIGHLY efficient chamber that requires very little ignition advance. Good Luck!
------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220 [This message has been edited by n2oMike (edited 04-19-2002).]
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n2oMike
Gearhead Posts: 2831
From: Spencer, WV
Registered: Jan 2001
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posted 04-19-2002 02:45 PM
Here's that Joe Sherman budget 400hp street 302 w/289 heads article. A couple of corrections, the ACTUAL compression of the engine was 10.5, not 9.5 like the article listed... and I was mistaken about the total advance, it wanted 41 degrees instead of 42. They said moving it 2 degrees either way cost 5-10 hp.http://www.jason.fletcher.net/tech/sherman/sherman.htm Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220 [This message has been edited by n2oMike (edited 04-19-2002).]
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67Coupster
Gearhead Posts: 189
From: Fortson, GA, USA
Registered: Oct 2001
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posted 04-19-2002 03:34 PM
I currently run 35 degrees on mine. I was thinking of lowering to 33 and see what happens. I have KB 12cc dished pistons on my 393W with AFR185 heads. I'll post if it picks up. ------------------
James
67 Coupe
393W, AFR 185, 4 Speed, 4.11 9 inch
7.09 @ 97MPH 1/8
1.55 60'
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Daniel Jones
Gearhead Posts: 898
From: St. Louis, MO
Registered: Aug 99
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posted 04-19-2002 04:59 PM
That's consistent with Pantera club dyno experience with closed chamber 351C heads. The open chamber stuff seems to need more advance. Both assumes pump gas. Aviation fuel and race gas may burn slower and may require more advance, at least with streetable compression ratios. With higher (dynamic) compression ratios, less advance would be needed so maybe a 13.5:1 motor on race gas would need similar advance to a 10:1 on pump gas. Alex, what sort of compression ratios and octane fuels were used in your tests?Dan Jones
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 04-19-2002 08:02 PM
Four 9 to 1 and one 10 to 1 compression engines. VP C-12 gas except on my SS engine where we used C-11 and C-12. ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
US Class Nationals link
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kcode
Gearhead Posts: 3288
From: alvaton,ky,usa Suburb of Bowling Green, M&M #79, MCA #29208
Registered: Jun 99
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posted 04-19-2002 10:41 PM
I'm from that same old school of alittle timing is good, but more is better. That was until we put a 67 GT-350 on the dyno with an 11.0 to motor. Stock Hipo distributor set at 40*, backed the timing to 34* and increased HP by 8 at 6000 rpm. The only trouble was we had to bump the timing back up just to drive it. Sacrafices have to be made. Mike
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chips67
Gearhead Posts: 663
From: louisville, ky, usa
Registered: Jul 2001
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posted 04-20-2002 03:23 PM
this feels about right. one time i was running at test and tune night and right befor the show i "tested" my timing by lugging the car in 3rd gear to listen for pings. ended up backing it off twice before it quit. the car felt like a slug driving around the lot, but imagine my suprise going form a best of 8.80's to 8.5's just after that change( this was 2 years ago). now as far as where my timing actually is, that i can never know. its a 5.0 motor with an old stylye water pump.....the bottom radiator hose dictated that i remove the factory timing tab....so i really dont know where it is. a 5.0 does have flat-tops right? i guess if these afr heads are as efficient as claimed and i got flat-top pistons then alex's theory (if true) would apply to my case in spades.------------------
67 coupe, 650dp and rpm intake on 5.0 with afr 165 heads, 4 speed, 4.11's.....best so far is [email protected] in 1/8 mile with 1.79 60ft. time.
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Mario428
Journeyman Posts: 82
From: Charlottetown, PEI, Canada
Registered: Nov 2001
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posted 04-21-2002 01:20 PM
My brothers 351 with the old TRW poup pistons and Windsor Sr aluminum heads runs beat at 32 degrees timing. He has tried every possible other number, he refuses to leave the car alone and 32 runs the quickest and fastest.
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kid vishus
Gearhead Posts: 6590
From: middle of NC
Registered: Oct 2000
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posted 04-21-2002 06:37 PM
quote:
Originally posted by Moneymaker:
Lesson is, make certain you have a good balancer, TDC is absolute, lock in your distributor...
OK, since my car has domed pistons, and since it's on alcohol and likes a fair amount of timing (over 40*), I guess I need to buy a start retard box so it will start if I lock out the distributor.
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