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Author
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Topic: more timing?
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Jay302
Journeyman Posts: 36
From: Louisville,ohio
Registered: Dec 2004
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posted 06-21-2005 09:43 PM
   
ive got msd ignition (pro billit dizzy) my timing is 12 initial 36 total by 3500rpm. the car runs great until i shift into 3rd. as soon as i shift it just stops pulling. some other people suggested more timing 18 initial 42 total if it will crank ok. do u think this will help? it is a street car so i cant lock the timing ------------------
77 triumph tr-7 with a ford 302,c-4,and soon to have a 9"rear end
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grego37
Gearhead Posts: 363
From: los angeles,CA,USA
Registered: May 2004
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posted 06-22-2005 10:50 AM
12 and 36 are usually good numbers give or take. The MSD Dist. comes with 4 advance bushings 18*,21*,25*,28* it sounds like you're running the 25* bushing and with 12* initial you should have 37* total. (12+25=37)Rule of thumb on initial timing is give it as much as it will take where it will still turn over without any problems when its hot. keep the 25* advance bushing in and bump up your initial 2* , take test drive, record if it hurt or helped you , See if it fires right back up when its hot. Repeat as neccessary. If you bump up the initial allot, you may need to go in and change the advance bushing down to 21*.
Dont forget to re-adjust your carb when you change the timing.
Is the Dist. centrifigal (springs) or vacuum advance? MSD also has a tech line you can call
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74merc
Gearhead Posts: 1266
From: Demopolis AL
Registered: Jun 99
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posted 06-22-2005 11:26 AM
How bad does it drop off? Does it bog or just kinda lay down?
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Jay302
Journeyman Posts: 36
From: Louisville,ohio
Registered: Dec 2004
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posted 06-22-2005 11:47 AM
it just lays down. it pulls great through 1st and 2nd. ya i am running the 25 but when i put the light on i was only get 36 total.the dist is mechanical advance.as soon as i get the ball joints finished on the thing ill give it a try.i wana get it running its best for fun ford weekend at norwalk------------------
77 triumph tr-7 with a ford 302,c-4,and soon to have a 9"rear end
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grego37
Gearhead Posts: 363
From: los angeles,CA,USA
Registered: May 2004
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posted 06-22-2005 12:03 PM
did you change the spring combo and bushing .
Or was it installed the way it came from MSD?
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Jay302
Journeyman Posts: 36
From: Louisville,ohio
Registered: Dec 2004
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posted 06-22-2005 12:51 PM
silver bushing and 2 blue springs------------------
77 triumph tr-7 with a ford 302,c-4,and soon to have a 9"rear end
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grego37
Gearhead Posts: 363
From: los angeles,CA,USA
Registered: May 2004
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posted 06-22-2005 01:12 PM
According to MSD instruction sheet , with that combo, you have full advance at about 3400 rpm.Rate of advance rule of thumb:
You want full advance ASAP , however if you have pinging (detonation)while accellerating its comming in too fast, back down to the next slowest rate, until gone. Try leave your timing where it is and change it to the next fastest advance rate (1 light silver, 1 light blue) see if it helps your situation. You'll have full advance at about 2800-2900 RPM. And depending on your gear ratio, cam powerband, stall converter etc... it just might be what you're looking for. If you get detonation upon accelleration, your advance rate is too fast, you'd need to back down to the next slower rate.
good luck
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Jay302
Journeyman Posts: 36
From: Louisville,ohio
Registered: Dec 2004
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posted 06-22-2005 02:27 PM
thanks
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77 triumph tr-7 with a ford 302,c-4,and soon to have a 9"rear end
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70rancheroGT
Journeyman Posts: 24
From: Durham, NC
Registered: Mar 2005
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posted 06-22-2005 04:19 PM
Why do you think its the timing? What's the RPM after the 2/3 shift?
Are you sure its not a problem with fuel delivery?
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Jay302
Journeyman Posts: 36
From: Louisville,ohio
Registered: Dec 2004
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posted 06-22-2005 07:20 PM
that is another option but its quicker,easier and free to try timing first. i shift at 4500, not exactly sure of rpm after somewhere around 3500?------------------
77 triumph tr-7 with a ford 302,c-4,and soon to have a 9"rear end
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Ci8UUP
Gearhead Posts: 183
From: Renton, Washington
Registered: May 2005
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posted 06-22-2005 07:44 PM
quote:
Originally posted by grego37:
12 and 36 are usually good numbers give or take. The MSD Dist. comes with 4 advance bushings 18*,21*,25*,28* it sounds like you're running the 25* bushing and with 12* initial you should have 37* total. (12+25=37)Rule of thumb on initial timing is give it as much as it will take where it will still turn over without any problems when its hot. keep the 25* advance bushing in and bump up your initial 2* , take test drive, record if it hurt or helped you , See if it fires right back up when its hot. Repeat as neccessary. If you bump up the initial allot, you may need to go in and change the advance bushing down to 21*.
Dont forget to re-adjust your carb when you change the timing.
Is the Dist. centrifigal (springs) or vacuum advance? MSD also has a tech line you can call
Someone help me to understand where MSD gets their advance numbers? If there is 25 into the distributor then it should double at the crank giving you 50. I don't know why they figure in the distributor advance and the crankshaft all in one.
It's supposed to be 12 (distributor)12 (at the crank), and then whatever initial you set it to.
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70rancheroGT
Journeyman Posts: 24
From: Durham, NC
Registered: Mar 2005
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posted 06-23-2005 10:27 AM
Jay,
If your timing is all in by 3500, and your RPM's after the 2/3 shift is 3500, then I don't see how adjusting the timing curve will help. You said it pulls hard in 1st and 2nd, then lays down in 3rd. That tells me the curve is fine. You don't mention the rest of the ignition system, what coil are you running, what control box, if any. Maybe the plugs are gapped too wide?
Ci8UUP-timing curves and timing nomenclature are always in crank degrees. The cam spins at half the speed of the crank, therefore so does the distributor. 12 degrees at the distributor equalls 24 degrees at the crank. You don't add 12 (crank)+ 12 (dist)to get 24. You take 12 (dist) multiplied by 2 to get 24.
Hope this helps,
James
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Ci8UUP
Gearhead Posts: 183
From: Renton, Washington
Registered: May 2005
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posted 06-23-2005 10:11 PM
What's the difference? last time I checked 12+12 = 12 X 2
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70rancheroGT
Journeyman Posts: 24
From: Durham, NC
Registered: Mar 2005
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posted 06-24-2005 11:37 AM
I was attempting to illustrate a point by using math. Yes 12+12=24 but you don't add "crank timing" and "distributor timing" to get advance. Your use of "crank timing" is a misnomer. Advance at the distributor is multiplied by two to get crank timing.
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Ci8UUP
Gearhead Posts: 183
From: Renton, Washington
Registered: May 2005
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posted 06-25-2005 12:31 PM
Point noted.But not all distributors and their advance takes into account crank degrees. Take a look at the picture in this link
http://www.bob2000.com/dist.htm So how come when you put in an offset cam key or bushing it's not measured in crank degrees?
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mike70351w
Journeyman Posts: 82
From: Altus AFB OKlahoma
Registered: Dec 2004
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posted 06-26-2005 01:30 PM
That's a great article, The picture is worth a thousand word too. I pulled my distro apart and saw my number are 13L and 16L (mine is set to 13L. What year or model car distro should I ask the parts guy for? is I wanted to buy with the 10L? My spare distro is 21L & 16L so I do not want to use that. Thanks
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mike70351w
Journeyman Posts: 82
From: Altus AFB OKlahoma
Registered: Dec 2004
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posted 06-26-2005 03:51 PM
oppps distro will a duraspark for a 351W
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