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Re: Race timing [Re: CMcAllister] #2742137
02/11/20 11:57 PM
02/11/20 11:57 PM
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Texas
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RustyM Offline OP
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So, Cm and all: If im reading correctly: Can lock it out, we do have ignition on its own switch, so thats not a problem and, locked out we will lose timing with rpm.
Anyone know at what rpm the reduction starts taking place ?
Is it actually pulling out the right amount etc?
Does it not pull out rpm if your not locked out?

If its 1 degree every thousand rpm above say 2500, that would pull us back to 30 degrees from 34 by 6500 rpm.
But if it starts pulling out at 1500, that would have us at 29 degrees at 6500.

Interesting to think on.

Re: Race timing [Re: RustyM] #2742148
02/12/20 12:44 AM
02/12/20 12:44 AM
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madscientist Offline
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Originally Posted by RustyM
So, Cm and all: If im reading correctly: Can lock it out, we do have ignition on its own switch, so thats not a problem and, locked out we will lose timing with rpm.
Anyone know at what rpm the reduction starts taking place ?
Is it actually pulling out the right amount etc?
Does it not pull out rpm if your not locked out?

If its 1 degree every thousand rpm above say 2500, that would pull us back to 30 degrees from 34 by 6500 rpm.
But if it starts pulling out at 1500, that would have us at 29 degrees at 6500.

Interesting to think on.




It depends on the box. I've got a Chrylser gold box form the early 1980's that doesn't back up until about 8000 and between 8000-12,000 it stays the same. It loses one degree at 8 k and nothing else to 12k.


Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
Re: Race timing [Re: RustyM] #2742179
02/12/20 09:21 AM
02/12/20 09:21 AM
Joined: Jan 2007
Posts: 6,602
Mt Morris Michigan
mopar dave Offline
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Mt Morris Michigan
I use an MSD dist. with an Ice Ignition box and coil. If I lock my timing, it will pull timing and if I remember correctly, it pulled 3* at 4000rpm. It will not pull timing with a curve in it, so I ordered some large bushings from Don@FBO and now run 30* initial and all in at 36*. I think it reaps all the rewards of being locked and without timing pull. My box has a 10* start retard.

Re: Race timing [Re: Thumperdart] #2742353
02/12/20 04:30 PM
02/12/20 04:30 PM
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Posts: 2,285
A garage in England
Tig Offline
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Originally Posted by Thumperdart
Yep called slew rate and mine looses about 1 degree every 1000 rpm's towards max...........
Any one ever done back to back testing, slew v's a flat hi rpm curve? Interested to know if it works and dead easy to do with a grid.


'74 Challenger..9.46 and 145.9 so far, easy pass. 4000lb!!!# N/A, 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 4:10's and 10.5s. Marsh Performance pump gas 655ci.
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 14.18 @ 96.05 Best Mph 98.5
Re: Race timing [Re: dvw] #2742356
02/12/20 04:45 PM
02/12/20 04:45 PM
Joined: Apr 2006
Posts: 3,706
West Plains, MO
DrCharles Offline
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West Plains, MO
Originally Posted by dvw
Originally Posted by Cab_Burge
If you don't have a separate starter switch to spin the motor over before turning on the ignition or a ECIU that won't allow the coil to fire until the crankshaft has spun over several times before firing the plugs good luck on getting any motor started that has a lock out distributor with more than 24 degrees total timing scope


Mine starts at 34 degrees no issue, 15-1, ignition on. Actually starts better with ignition on. 1 revolution and it's running. No crank, crank, crank.

My 10.4:1 (iron head) 451 with 272@.050 begins to fight the starter at more than 24 degrees (when hot). shruggy
Since it's mostly street driven I am not sure about using the super-light springs so it's at full advance as soon as it fires. Running vac advance can instead.

Re: Race timing [Re: DrCharles] #2742362
02/12/20 05:19 PM
02/12/20 05:19 PM
Joined: Sep 2009
Posts: 445
MD
JACK1440 Offline
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I'm having a lot of issue with kick back. Dyno'd it at 34deg but, in the car hot it wants to fight us starting. I actually knocked 3 teeth off a new convertor. Currently I have it at 30 and it starts great. Dist. is locked. I'm running an old msd7C box. I have a new msd 7al with a starter saver box ready to go in. I hope this fixes my problem. 572 in 15:1

Re: Race timing [Re: Tig] #2742403
02/12/20 07:45 PM
02/12/20 07:45 PM
Joined: Feb 2010
Posts: 1,546
Phila. Pa.
Mattax Offline
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Originally Posted by Tig
Any one ever done back to back testing, slew v's a flat hi rpm curve? Interested to know if it works and dead easy to do with a grid.
Coworker of mine tested it, although at the time he didn't know it. Replaced the heavy secondary spring with all sorts of quicker springs and they were losing time (E.T) which in stock class racing is a problem!

I think Bill Baldwin who has tested it, and not accidently.
https://board.moparts.org/ubbthread...ry-unilite-timing-issue.html#Post2488599

https://www.facebook.com/baldwinperformancecarbs/videos/529140844222174/

Bill Jones has tested the retard.
https://www.speed-talk.com/forum/viewtopic.php?p=201470

Apparently back when electronic ignitions were new to racing, some smart folks scratched their heads when the cars ran faster with dual points. Guys like Yunick and Jenkins.
Originally Posted by Tuner
The mechanical advance compensates for the retard in the electronics to provide a flat static total or continue to advance all the way through the RPM range, however the engine likes it and you set it up.

This is a technique I have used for distributor curves since the 60's, though I didn't come to understand the reasoning behind it until the early 70's when I replaced a points ignition that did not retard as RPM climbed with an electronic ignition that, like all electronic ignitions, has slew-rate retard, and the car slowed down.

A-B-A-B it was faster with the GM dual-points distributor, even though the spark energy was higher with the electronic, a GM Magna-Pulse, and the electronic had the same “curve” except for the retard after the “total” was reached at 2500. Jenkins book “The Small Block Chevrolet Racing Engine” details the high-RPM curve and explains his reasoning..
Snipped from RFS Forum

Re: Race timing [Re: JACK1440] #2742411
02/12/20 08:08 PM
02/12/20 08:08 PM
Joined: Oct 2005
Posts: 1,535
Ringtown, Pa.
Dartsport540 Offline
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Ringtown, Pa.
Originally Posted by JACK1440
I'm having a lot of issue with kick back. Dyno'd it at 34deg but, in the car hot it wants to fight us starting. I actually knocked 3 teeth off a new convertor. Currently I have it at 30 and it starts great. Dist. is locked. I'm running an old msd7C box. I have a new msd 7al with a starter saver box ready to go in. I hope this fixes my problem. 572 in 15:1


Hello, my name is Paul, from Ringtown , Pa.

I have a 540 cu.in. in my car. A little over 14.6 to 1 compression. MSD distributor, with MSD 7AL2 ignition, NO crank trigger. Last spring, I locked out my distributor. Then sometimes it would kick back . I broke 1 flex plate, and 3 starters. 2 starters had a billet front piece. I tried everything. MSD Starter Saver didn't help. Ended up being Rotor Phasing. MSD makes a phase able or adjustable rotor. Rotor tip was out 16*.. Spark would sometimes jump to next terminal on distributor cap, causing motor to kick back.

I sent you a PM. It is easier to talk to you than typing it out..

Thanks, Paul

Last edited by Dartsport540; 02/13/20 05:12 PM.

540 cu, in. , CRT 727 auto trans, Alston Chassis. 8.981et at 149.46 mph. 1.204et - 60 foot, So Far....
Re: Race timing [Re: Dartsport540] #2742498
02/13/20 06:23 AM
02/13/20 06:23 AM
Joined: Mar 2006
Posts: 7,880
MI, usa
dvw Offline
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If the rotor is correct they start fine. Mine is crank trigger. The rotor is phased. I never start it by cranking and then hitting the ignition. Same starter (stock) 7 years . Never hurt a converter tooth. 630 passes and counting.
Doug

Last edited by dvw; 02/13/20 06:24 AM.
Re: Race timing [Re: Mattax] #2742513
02/13/20 09:10 AM
02/13/20 09:10 AM
Joined: Jan 2007
Posts: 6,602
Mt Morris Michigan
mopar dave Offline
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Thanks for posting those lincs mattax. Great read.

Re: Race timing [Re: mopar dave] #2742617
02/13/20 04:28 PM
02/13/20 04:28 PM
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Texas
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RustyM Offline OP
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Ditto- thanks !

Re: Race timing [Re: RustyM] #2742725
02/14/20 07:51 AM
02/14/20 07:51 AM
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Posts: 1,468
NW Indiana
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fbs63 Offline
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Here is what I do with race motor MSD distributors. Use 1 light spring and both weights. 1 weight will need an e-clip or wire on the stud to retain it. Select the bushing with the max mechanical advance you want. That way the engine cranks with reasonable advance but as soon as it starts it's at full advance.

Re: Race timing [Re: Mattax] #2742816
02/14/20 11:56 AM
02/14/20 11:56 AM
Joined: Jan 2007
Posts: 6,602
Mt Morris Michigan
mopar dave Offline
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Just to add something here, I once had this timing issue on my small block as well with the MSD dist locked. I installed a crank trigger and timing would only loose about 1/2* as I rev'ed the engine. So, if the engine is speeding up in the same amount of time as described and the electronics can't keep up, then why doesn't the same amount of retard take place with the crank trigger? Not to answer my own question, but it must have something to do with the elimination of the electronics in the dist itself i'm guessing? Its the only thing being eliminated from the system. If so, than the dist is at most fault for the severe retard with rpm, not so much the box when its locked out.

Re: Race timing [Re: Cab_Burge] #2744830
02/20/20 04:10 AM
02/20/20 04:10 AM
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Posts: 27,330
Balt. Md
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383man Offline
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Balt. Md
Originally Posted by Cab_Burge
I remember hearing that at a Mopar drag racing seminar that retarding the timing 4 degrees in high gear would help the car go faster and quicker, I've never had the parts needed to do that shruggy
Maybe with the MSD grid I can do some testing with that to find out wrench luck


There was an article by Bill Jenkins on that in a Car Craft mag back around 1971. It actually told how he uses a dual point dist to bring in the second set of points in high gear to retard the timing in high gear for more power. Ron

Re: Race timing [Re: RustyM] #2744887
02/20/20 11:22 AM
02/20/20 11:22 AM
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USA, New Jersey
Border-shadow Offline
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USA, New Jersey
msd has a kit for locking out!

Re: Race timing [Re: Border-shadow] #2744919
02/20/20 12:36 PM
02/20/20 12:36 PM
Joined: Dec 2005
Posts: 1,422
Shelby mi.
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JAKE68 Offline
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Shelby mi.
I had a odd problem one time. I tried to lock dist on my hemi car and it was hard to start. kept kicking back. So I put the curve back in it. Latter I put a crank trigger in it and same total timing as before when locked out and no more kicking back. Since then all the motors I have done with crank trigger never kick back. Jake


JAKES AUTOMOTIVE
Re: Race timing [Re: JAKE68] #2744934
02/20/20 01:55 PM
02/20/20 01:55 PM
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Posts: 12,812
So. Burlington, Vt.
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fast68plymouth Offline
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So. Burlington, Vt.
If you’re worried about the electronics retarding the timing at high rpm...... just check the timing at high rpm and see if it’s happening or not.

A lot of times it ends up being the cam walking, which changes the timing.
That’s a good reason to run a crank trigger.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: Race timing [Re: fast68plymouth] #2745468
02/22/20 12:51 PM
02/22/20 12:51 PM
Joined: Dec 2007
Posts: 12,211
Great Neck,LI,new york
hemi-itis Offline
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I have tried to discuss this in the past. I have the 6al programmable that allows me to put the timing anywhere I want like every 500 RPM.Starts at 24* and is up to 30* by 800 RPM for idle. Depending on the boost level I am running I start taking timing out at 2500 RPM. I could also use the boost retard to take timing out and leave the timing curve at 30* for street driving.
So I ask the guys in the know,,,when should I start pulling timing,,,,and how much total.I can take it gradual as it is totally programmable with a laptop, work


HEMI-ITIS has no cure. My condition is fully BLOWN!!!

New best 60ft,, 1.42,1/8, 6.0 @117,, 9.38 @146.75 with 6 lbs boost @3700 lbs
Re: Race timing [Re: fbs63] #2745478
02/22/20 01:25 PM
02/22/20 01:25 PM
Joined: Jan 2003
Posts: 1,223
Phoenix, AZ
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Belvedere1 Offline
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Phoenix, AZ
What spring would a guy use in a Firecore distributor to have a similar set up where you can have it crank with no potential for started kickback yet have full advance on start up. There are only 3 different springs in the Firecore set.

Re: Race timing [Re: Belvedere1] #2745499
02/22/20 02:22 PM
02/22/20 02:22 PM
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Posts: 34,491
Bend,OR USA
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Cab_Burge Offline
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Bend,OR USA
It sounds like your going to have to find out on yours wrench
Please let us know what you find out scope
I would put the thinnest one in first and see what you get wrench scope twocents
I've never seen one of those distributors, can you limit the mechanical advance also?
If so I would shoot for 15 to 18 crankshaft degrees max advance in the distributor and then set the initial timing around 14 to 18 BTDC and make sure to not exceed 34 to 36 degree max advance when revved up up scope

Last edited by Cab_Burge; 02/22/20 02:26 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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