timing - distributor advance curve
Thread Starter
Racer
Joined: Oct 2005
Posts: 324
Likes: 0
From: Vancouver BC
Originally Posted by MsVetteMan
I believe I suggested that back in post #24 
no that is not what you said. you said I should "trash" my original. That is quite different from buying a new one and "storing" the original!
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Driver I was checking some more distributors and it looks like that bushing will give you about 8* more-that should leave you with 12* initial.You should like the results. Let us know for future reference.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Originally Posted by dwncchs
Driver I was checking some more distributors and it looks like that bushing will give you about 8* more-that should leave you with 12* initial.You should like the results. Let us know for future reference.
be sure your vacuum line is running off a full manifold vacuum source also
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by dwncchs
INITIAL+CENTRIFUGAL=TOTAL+VACUMN=MAX
Why diddnt I think of that.....oh, thats right..... cuz im stoopit
I have two stock 1973 distributors....Is there anything I can measure to help resolve this?
I will say, I bought a Moroso kit before checking my total timing because the car was about 95% stock and to my surprise Im had about (trying to rember) 36* @ 2,700 RPM and 53* (lets try a new word
) Max @ 2,700 or soAnyhow, as far as I can tell there must have been a curve kit installed but its hard for me to beleive because I have talked to both previous owners and there was no mention of any work done on the Dist.... Plus neither one knew which end of a screwdriver to hold and last, the initial timing was set at 8* when I bought the car.
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by BarryK
if that's true than you should be perfect (and easy!!!)........ 12º initial / 36º total plus 15º vacuum advance. Can't ask for much better than that!
be sure your vacuum line is running off a full manifold vacuum source also
be sure your vacuum line is running off a full manifold vacuum source also
I have the same readings but I'm using a ported vacuum for the advance.... Should I try the full vacuum even if it's fine with the ported?
Thanks
Thread Starter
Racer
Joined: Oct 2005
Posts: 324
Likes: 0
From: Vancouver BC
ok guys, here are the results of my new curve with NO bushing at all:
I have the silver springs in - not sure if they are the medium ones or not, but they are not the lightest ones, and original weights.
vacuum disconnected.
700 rpm (idle) 12*
1000 rpm 19*
1200 rpm 22*
1500 rpm 25*
1800 rpm 30*
2000 rpm 31*
2200 rpm 33*
2500 rpm 37*
3000 rpm 38* (all in)
This looks pretty well perfect to me. Barry & others, what do you think?
I have the silver springs in - not sure if they are the medium ones or not, but they are not the lightest ones, and original weights.
vacuum disconnected.
700 rpm (idle) 12*
1000 rpm 19*
1200 rpm 22*
1500 rpm 25*
1800 rpm 30*
2000 rpm 31*
2200 rpm 33*
2500 rpm 37*
3000 rpm 38* (all in)
This looks pretty well perfect to me. Barry & others, what do you think?
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Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by driver68
ok guys, here are the results of my new curve with NO bushing at all:
I have the silver springs in - not sure if they are the medium ones or not, but they are not the lightest ones, and original weights.
vacuum disconnected.
700 rpm (idle) 12*
1000 rpm 19*
1200 rpm 22*
1500 rpm 25*
1800 rpm 30*
2000 rpm 31*
2200 rpm 33*
2500 rpm 37*
3000 rpm 38* (all in)
This looks pretty well perfect to me. Barry & others, what do you think?
I have the silver springs in - not sure if they are the medium ones or not, but they are not the lightest ones, and original weights.
vacuum disconnected.
700 rpm (idle) 12*
1000 rpm 19*
1200 rpm 22*
1500 rpm 25*
1800 rpm 30*
2000 rpm 31*
2200 rpm 33*
2500 rpm 37*
3000 rpm 38* (all in)
This looks pretty well perfect to me. Barry & others, what do you think?
Team Owner
Joined: Jan 2006
Posts: 39,390
Likes: 171
From: Into the Mystic And yet, despite the look on my face, you're still talking TN
St. Jude Donor '09 thru '25
maybe you resolved my issue, also
Don't mean to hijack this thread, but seems like you've solved Driver68's timing question, maybe mine's kinda the same. Using your new terminology, I've got 12 initial plus 18 mech. = 30 total plus 11 vac. = 41 max (did I do that right?) My #'s don't add up right though, when hooked to manifold vac. at idle, I've only got 21 deg which is only 9 vac. Am I making this too complicated, it's giving me a headache.
Anyway, could my distributor also be set up for only 18 deg. of cent. advance? '79 L82 & I've got the springs that give me all in by 2600 rpm.
If I crank in more initial, won't that be too much at idle? I'm at 21 deg. now.
Again, not trying to hijack your thread, Driver68, but sounds like I've got the same thing.
Thanks, ya'll. This forum is a tremendous asset for us people that know which end of a screwdriver to hold (tip of the hat to Bob Onit
), we're just not sure what to do with it!
Anyway, could my distributor also be set up for only 18 deg. of cent. advance? '79 L82 & I've got the springs that give me all in by 2600 rpm.
If I crank in more initial, won't that be too much at idle? I'm at 21 deg. now.
Again, not trying to hijack your thread, Driver68, but sounds like I've got the same thing.
Thanks, ya'll. This forum is a tremendous asset for us people that know which end of a screwdriver to hold (tip of the hat to Bob Onit
), we're just not sure what to do with it!
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Originally Posted by Bob Onit
Hey Barry!
I have the same readings but I'm using a ported vacuum for the advance.... Should I try the full vacuum even if it's fine with the ported?
Thanks
I have the same readings but I'm using a ported vacuum for the advance.... Should I try the full vacuum even if it's fine with the ported?
Thanks
full manifold vacuum advance typically gives better idle characteristics, better throttle response, a cooler running motor, & better fuel economy.
There seem to be some cases where it runs better on the ported, but usually it will be better on Full manifold vacuum. Try switching it and see.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Originally Posted by driver68
ok guys, here are the results of my new curve with NO bushing at all:
I have the silver springs in - not sure if they are the medium ones or not, but they are not the lightest ones, and original weights.
vacuum disconnected.
700 rpm (idle) 12*
1000 rpm 19*
1200 rpm 22*
1500 rpm 25*
1800 rpm 30*
2000 rpm 31*
2200 rpm 33*
2500 rpm 37*
3000 rpm 38* (all in)
This looks pretty well perfect to me. Barry & others, what do you think?
I have the silver springs in - not sure if they are the medium ones or not, but they are not the lightest ones, and original weights.
vacuum disconnected.
700 rpm (idle) 12*
1000 rpm 19*
1200 rpm 22*
1500 rpm 25*
1800 rpm 30*
2000 rpm 31*
2200 rpm 33*
2500 rpm 37*
3000 rpm 38* (all in)
This looks pretty well perfect to me. Barry & others, what do you think?
driver, if you try it without the bushing, and are getting the same numbers, and IF it detonayes, just back it down 2º at a time until the detonation stops.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Originally Posted by Capt. Shark
Don't mean to hijack this thread, but seems like you've solved Driver68's timing question, maybe mine's kinda the same. Using your new terminology, I've got 12 initial plus 18 mech. = 30 total plus 11 vac. = 41 max (did I do that right?) My #'s don't add up right though, when hooked to manifold vac. at idle, I've only got 21 deg which is only 9 vac. Am I making this too complicated, it's giving me a headache.
Anyway, could my distributor also be set up for only 18 deg. of cent. advance? '79 L82 & I've got the springs that give me all in by 2600 rpm.
If I crank in more initial, won't that be too much at idle? I'm at 21 deg. now.
Again, not trying to hijack your thread, Driver68, but sounds like I've got the same thing.
Thanks, ya'll. This forum is a tremendous asset for us people that know which end of a screwdriver to hold (tip of the hat to Bob Onit ), we're just not sure what to do with it!
Anyway, could my distributor also be set up for only 18 deg. of cent. advance? '79 L82 & I've got the springs that give me all in by 2600 rpm.
If I crank in more initial, won't that be too much at idle? I'm at 21 deg. now.
Again, not trying to hijack your thread, Driver68, but sounds like I've got the same thing.
Thanks, ya'll. This forum is a tremendous asset for us people that know which end of a screwdriver to hold (tip of the hat to Bob Onit
), we're just not sure what to do with it!one POSSIBLE reason that the numbers don't seem to add up is that the mechanical may be coming in too soon so your 12º initial at idle might possibly be including some of the mechanical
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by BarryK
yes I would.
full manifold vacuum advance typically gives better idle characteristics, better throttle response, a cooler running motor, & better fuel economy.
There seem to be some cases where it runs better on the ported, but usually it will be better on Full manifold vacuum. Try switching it and see.
full manifold vacuum advance typically gives better idle characteristics, better throttle response, a cooler running motor, & better fuel economy.
There seem to be some cases where it runs better on the ported, but usually it will be better on Full manifold vacuum. Try switching it and see.
Thanks again!
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by Capt. Shark
Don't mean to hijack this thread, but seems like you've solved Driver68's timing question, maybe mine's kinda the same. Using your new terminology, I've got 12 initial plus 18 mech. = 30 total plus 11 vac. = 41 max (did I do that right?) My #'s don't add up right though, when hooked to manifold vac. at idle, I've only got 21 deg which is only 9 vac. Am I making this too complicated, it's giving me a headache.
Anyway, could my distributor also be set up for only 18 deg. of cent. advance? '79 L82 & I've got the springs that give me all in by 2600 rpm.
If I crank in more initial, won't that be too much at idle? I'm at 21 deg. now.
Again, not trying to hijack your thread, Driver68, but sounds like I've got the same thing.
Thanks, ya'll. This forum is a tremendous asset for us people that know which end of a screwdriver to hold (tip of the hat to Bob Onit ), we're just not sure what to do with it!
Anyway, could my distributor also be set up for only 18 deg. of cent. advance? '79 L82 & I've got the springs that give me all in by 2600 rpm.
If I crank in more initial, won't that be too much at idle? I'm at 21 deg. now.
Again, not trying to hijack your thread, Driver68, but sounds like I've got the same thing.
Thanks, ya'll. This forum is a tremendous asset for us people that know which end of a screwdriver to hold (tip of the hat to Bob Onit
), we're just not sure what to do with it!
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by driver68
ok guys, here are the results of my new curve with NO bushing at all:
I have the silver springs in - not sure if they are the medium ones or not, but they are not the lightest ones, and original weights.
vacuum disconnected.
700 rpm (idle) 12*
1000 rpm 19*
1200 rpm 22*
1500 rpm 25*
1800 rpm 30*
2000 rpm 31*
2200 rpm 33*
2500 rpm 37*
3000 rpm 38* (all in)
This looks pretty well perfect to me. Barry & others, what do you think?
I have the silver springs in - not sure if they are the medium ones or not, but they are not the lightest ones, and original weights.
vacuum disconnected.
700 rpm (idle) 12*
1000 rpm 19*
1200 rpm 22*
1500 rpm 25*
1800 rpm 30*
2000 rpm 31*
2200 rpm 33*
2500 rpm 37*
3000 rpm 38* (all in)
This looks pretty well perfect to me. Barry & others, what do you think?
Let us know if it woke it up!!!
Melting Slicks
Joined: Jan 2005
Posts: 3,028
Likes: 0
From: Madison Ms
Originally Posted by driver68
Not quite the same as Barry's advise!
I guess you don't realize that this---> means one is joking. Don't make a chit to me who helped ya, glad you got some help.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by BarryK
works for me as long as he doesn't get detonation at the 38º. some motors can go that high, others will detonate. He can only try it and see what happens. Nat tomention that his particular distributor may end up giving a slightly different amount of timing by a degree or two based on it's condition, etc.
driver, if you try it without the bushing, and are getting the same numbers, and IF it detonayes, just back it down 2º at a time until the detonation stops.
driver, if you try it without the bushing, and are getting the same numbers, and IF it detonayes, just back it down 2º at a time until the detonation stops.
Barry- sounds like Driver got 10* by removing bushing-I measured the bushing and it .035 thick so by removing it gave .070 more movement forward and back.So for every .007 total- you change by 1*
Team Owner
Joined: Jan 2006
Posts: 39,390
Likes: 171
From: Into the Mystic And yet, despite the look on my face, you're still talking TN
St. Jude Donor '09 thru '25
Thanks, dwncchs. Sounds like the distributor is on specs. That's pretty much the #'s I have. Can I do anything to increase the mech. advance & will I benefit from it? Driver68 removed a bushing. Can I do the same on my HEI dist? When I got it, the mech. advance was jammed & not working, so it's already much better. This as far as I can go with it?
Thanks a lot.
Thanks a lot.