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How much does ignition timing affect 1/4 mile MPH.
#984830
05/02/11 01:02 PM
05/02/11 01:02 PM
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Joined: Oct 2007
Posts: 288
Birmingham, England
Mick70RR
OP
enthusiast
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OP
enthusiast
Joined: Oct 2007
Posts: 288
Birmingham, England
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I went down to the local drag strip on Saturday and my times were 3 or 4 MPH down. Checked the ignition timing today and it was set at 32 degrees max, I normally run 38 degrees. Don't ask how this happened. I also did a compression test to see if anything was up but all cylinders were within 5psi of 200psi. Engine is a 440 stroked to 505, 10.3:1 compression with the Mopar 528 solid cam. Just wondering if the ignition timing would affect power this much?
1970 Road Runner
505 cid
MCH CNC ported Stealth heads
MP 528 camshaft
4 speed
GV overdrive
11.98 @ 117 on street treads
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Re: How much does ignition timing affect 1/4 mile MPH.
[Re: Mick70RR]
#984831
05/02/11 01:24 PM
05/02/11 01:24 PM
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Joined: Mar 2007
Posts: 3,300
Northern Indiana
Dunnuck Racing
master
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master
Joined: Mar 2007
Posts: 3,300
Northern Indiana
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I would bet that was at least the majority of the car's slowing down. The 440 I have been dyno testing lost an average of 10 horsepower going from 38 to 36 degrees.And adding or subtracting just 1 degree from the 38 that it ran best at lost about 5 hp on average. I could believe it.I read a test result on a pretty well sorted out small block somebody else did that lost 30 hp with a 1 or 2 degree change,30 hp should be around 3 tenths on an average car.  Keith
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Re: How much does ignition timing affect 1/4 mile MPH.
[Re: Mick70RR]
#984833
05/02/11 02:05 PM
05/02/11 02:05 PM
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Joined: Jan 2003
Posts: 549
Bristol, Va
fasteddie
mopar
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mopar
Joined: Jan 2003
Posts: 549
Bristol, Va
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I don't know about a 440, but my 360 with shaved J heads to make a small chamber with .045 quench and flat top pistons slows down with more than 28 degrees timing. I have tested and verified it twice.
2003 Bristol Dragway Sportsman Champion
2016 Bristol Dragway Power Hour Champion
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Re: How much does ignition timing affect 1/4 mile MPH.
[Re: MR_P_BODY]
#984834
05/02/11 02:27 PM
05/02/11 02:27 PM
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Joined: Oct 2007
Posts: 288
Birmingham, England
Mick70RR
OP
enthusiast
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OP
enthusiast
Joined: Oct 2007
Posts: 288
Birmingham, England
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There was a strong head wind also but I doubt enough to account for such a drop in MPH. I've raced into head winds before and never noticed much difference. The car usually runs 115/116 MPH but was down to 111 MPH on Saturday.
1970 Road Runner
505 cid
MCH CNC ported Stealth heads
MP 528 camshaft
4 speed
GV overdrive
11.98 @ 117 on street treads
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Re: How much does ignition timing affect 1/4 mile MPH.
[Re: Mick70RR]
#984836
05/02/11 02:41 PM
05/02/11 02:41 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
There was a strong head wind also but I doubt enough to account for such a drop in MPH. I've raced into head winds before and never noticed much difference. The car usually runs 115/116 MPH but was down to 111 MPH on Saturday.
I think its a combination of both... I've pulled timing
before to slow the car down some and had minimal effect...
I was trying to slow it .2 and didnt get it... that
was 5* and got about.1
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Re: How much does ignition timing affect 1/4 mile MPH.
[Re: MR_P_BODY]
#984837
05/02/11 02:57 PM
05/02/11 02:57 PM
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Joined: Oct 2003
Posts: 7,506
Az
Crizila
master
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master
Joined: Oct 2003
Posts: 7,506
Az
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Don't count out a change in DA also. Quite often when you have a big wind, the DA is bouncing all over the place also.
Fastest 300
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Re: How much does ignition timing affect 1/4 mile MPH.
[Re: Mick70RR]
#984838
05/02/11 04:58 PM
05/02/11 04:58 PM
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Joined: Nov 2004
Posts: 3,544
Syracuse,NY
CompWedgeEngines
master
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master
Joined: Nov 2004
Posts: 3,544
Syracuse,NY
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What were your 60' times, 660 times and 1320 times as compared to your previous runs. The timing usually shows up very early in the run..IE 60'.
What was the DA vs previous runs?
RIP Monte Smith
Your work is a reflection of yourself, autograph it with quality.
WD for Diamond Pistons,Sidewinder cylinder heads, Wiseco, K1 rods and cranks,BAM lifters, Morel lifters, Molnar Technologies, Harland Sharp, Pro Gear, Cometic, King Engine Bearings and many others.
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Re: How much does ignition timing affect 1/4 mile MPH.
[Re: CompWedgeEngines]
#984839
05/02/11 05:26 PM
05/02/11 05:26 PM
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Joined: Oct 2007
Posts: 288
Birmingham, England
Mick70RR
OP
enthusiast
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OP
enthusiast
Joined: Oct 2007
Posts: 288
Birmingham, England
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No idea what the DA was, I'm not a serious racer, just like to run the car every month or so during the summer but the car is more street than strip and driven most days. 660 MPH was also down on what it usually runs, 87 MPH compared with a best of 92 and an average of about 90. 60 foot times are a bit hit and miss with this car, it's a 4 speed, didn't notice much difference on Saturday.
1970 Road Runner
505 cid
MCH CNC ported Stealth heads
MP 528 camshaft
4 speed
GV overdrive
11.98 @ 117 on street treads
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Re: How much does ignition timing affect 1/4 mile MPH.
[Re: 540DUSTER]
#984841
05/02/11 06:21 PM
05/02/11 06:21 PM
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Joined: Oct 2007
Posts: 288
Birmingham, England
Mick70RR
OP
enthusiast
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OP
enthusiast
Joined: Oct 2007
Posts: 288
Birmingham, England
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The timing didn't change, I set it myself incorrectly, just a stupid mistake.
1970 Road Runner
505 cid
MCH CNC ported Stealth heads
MP 528 camshaft
4 speed
GV overdrive
11.98 @ 117 on street treads
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Re: How much does ignition timing affect 1/4 mile MPH.
[Re: 540DUSTER]
#984842
05/02/11 07:16 PM
05/02/11 07:16 PM
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Joined: Oct 2003
Posts: 3,698
NE Oklahoma
Von
master
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master
Joined: Oct 2003
Posts: 3,698
NE Oklahoma
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According to Don at FBO, a BB mopar WILL NOT make any more power with more than 34 degrees......   I asked for an explanation (even though I knew better than to ask/argue with him). The explanation was one that only polyspheric could understand.....lol. I guess Im just lucky that going to 38 has almost always gained me some MPH. CMON MAN.......
Last edited by Von; 05/02/11 07:16 PM.
72 RR, Pump gas 440, 452s, 3800 lbs, Corked, ET Radials,. 11.33@117.72.
Same car, bone stock 346s, 9.5 comp, baby solid. 12.24@110.
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Re: How much does ignition timing affect 1/4 mile MPH.
[Re: Von]
#984843
05/02/11 07:21 PM
05/02/11 07:21 PM
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Joined: Jan 2003
Posts: 32,394
Quicktree
I Win
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I Win
Joined: Jan 2003
Posts: 32,394
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Quote:
According to Don at FBO, a BB mopar WILL NOT make any more power with more than 34 degrees...... I asked for an explanation (even though I knew better than to ask/argue with him). The explanation was one that only polyspheric could understand.....lol.
I guess Im just lucky that going to 38 has almost always gained me some MPH.
CMON MAN.......
yea I have to call BS on the 34* also.
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Re: How much does ignition timing affect 1/4 mile MPH.
[Re: Quicktree]
#984845
05/02/11 09:55 PM
05/02/11 09:55 PM
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Joined: Dec 2008
Posts: 415
Peru
cbarracuda
mopar
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mopar
Joined: Dec 2008
Posts: 415
Peru
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Quote:
Quote:
According to Don at FBO, a BB mopar WILL NOT make any more power with more than 34 degrees...... I asked for an explanation (even though I knew better than to ask/argue with him). The explanation was one that only polyspheric could understand.....lol.
I guess Im just lucky that going to 38 has almost always gained me some MPH.
CMON MAN.......
yea I have to call BS on the 34* also.
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Re: How much does ignition timing affect 1/4 mile MPH.
[Re: Chris'sBarracuda]
#984847
05/02/11 10:11 PM
05/02/11 10:11 PM
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Joined: Jan 2003
Posts: 19,377
Las Vegas
Al_Alguire
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 19,377
Las Vegas
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From my experience you will loose more ET than MPH by retarding timing. You will loose some MPH but ET seems affected more. As pointed out wearlier it usually shows up early in the run. Headwinds can KILL MPH as well. So IMO put it back and go run it.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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