Not out of woods yet

[MedPhys]

My previous posts have asked what timing i should use for my programmable timing computer.  I appreciated all of the help.

Now my problem is that my timing computer reads 10* more advance than the motor reads with a timing light.  I found TDC by sticking a rubber hose inside the #1 cylinder and waiting for the puff of air, and the hose to get held in place by piston.  This corresponded with timing mark at zero degrees on my balancer.

The distributor is phased based on this point.  What could be retarding my overall timing by 10*?

should I use a piston stop to be absolutely sure I am at the correct TDC?

If I use 10* of advance on balancer as 0* for computer, would it make sense that when the computer  reads 44* then the  balancer will read 34*.  I know this is  a crap solution, but right now it's my only solution.

Amazing, all this neet computer gadgetry, and I'd be up and running in 30 min. if I went back to a regular orange box and distributor

[firefighter3931]

The only way to properly index a balancer with the engine assembled is with a piston stop. 

If the balancer is old, chances are the outer ring has slipped so you need to at least check and correct it, if that is the case. Here's how i index them :

http://1970chargerregistry.com/70messageboard/viewtopic.php?t=1885


Ron

[TylerCharger69]

Yes...you need a piston stop for sure.  You need to take into consideration the dwell  (how long the piston is in the up position before making its decent)....I think  "dwell"  is the right terminology....if not...I'm  sure I'll be corrected.   I agree with the above post though...your outer ring may have slipped giving you a false reading

[MedPhys]

Ok, sounds good.  I ordered a piston stop.  I am thinking that my "feel the air" method is probably a little suspect.  If hypothetically I had it right to begin with, is there any logical reason for a 10* retard of timing?  Or would it have to be faulty computer equipment?

Thanks again

[TylerCharger69]

well...as was said before...I would make sure you are at TDC with the piston stop  because maybe the outer ring of the balancer might have spun on you.  I would look into that first before ruling it as a computer issue

[mopar1968]

Yes...you need a piston stop for sure.  You need to take into consideration the dwell  (how long the piston is in the up position before making its decent)....I think  "dwell"  is the right terminology....if not...I'm  sure I'll be corrected.   I agree with the above post though...your outer ring may have slipped giving you a false reading

I believe "Dwell" is the measured time of the Points being open.  But, all the other suggestions sound good.  Get her TDC for sure and mark it.  Then go from there.

[dodge freak]

The higher the stroke ratio the longer the piston stays a TDC , not sure what or if its called. Have seen too that short stroke motor can have a little higher compression ratio cause the piston stays at TDC a shorter amount of time and the motor is less likely to ping.

[firefighter3931]

  I am thinking that my "feel the air" method is probably a little suspect.  If hypothetically I had it right to begin with, is there any logical reason for a 10* retard of timing?  Or would it have to be faulty computer equipment?

Thanks again

The feel the air method is not very accurate. As the other guys have mentioned ; the piston can dwell at tdc for several degrees of crankshaft rotation. That is why the piston stop is needed to establish TDC. 


Ron

[rt green]

where did you set your base timing at? wouldnt be 10 degrees would it?

[MedPhys]

Here's my problem with the base timing.   Lets assume that I did in fact find the correct TDC.  I put on my timing tape to show that this point was zero.  I wanted 34* or total timing so I advance the motor to where the timing tap reads 37* (this is where computer sayse to put engine position.  Then I rotated the distibutor housing so that the leading edge of the rotor is aligned with the leading edge of cap post #1. I then adjusted the magnetic pickup sensor so that it was in direct alighnment with the reluctor.

This should be setting the initial timing to zero, and the computer will retard the timing from 34* to what I want at each rpm until it is fully advanced.

[dodge freak]

All I can say is that Holley stop make ignitions this year. Not sure why but maybe cause what you are finding out, its a pain to work with. Have you just kept advancing the timing -at around 4000 rpm's- until it started to get a little rough and not speeding up any more ? If not I would try that, this is how I set mine-I still check it afterwards but it gets me right about 36-38 . Motor seems to run fine , so I leave it right there. What the computer might say where its at , not sure, you could check, but I would go how the motor runs more than what the computer says.

It should still give a better-stronger- spark than the Mopar set up , so I would keep it, if you can get the motor to start and run good.

[firefighter3931]

Here's my problem with the base timing.   Lets assume that I did in fact find the correct TDC.  I put on my timing tape to show that this point was zero.  I wanted 34* or total timing so I advance the motor to where the timing tap reads 37* (this is where computer sayse to put engine position.  Then I rotated the distibutor housing so that the leading edge of the rotor is aligned with the leading edge of cap post #1. I then adjusted the magnetic pickup sensor so that it was in direct alighnment with the reluctor.

This should be setting the initial timing to zero, and the computer will retard the timing from 34* to what I want at each rpm until it is fully advanced.

The problem is with your distributor most likely. Whe tuning the ignition curve you need to shorten the mechanical advance so that you can dial in more base timing. If your distributor has say 26* of mechanical advance and you set it at 34* total then it would only have 8* at idle which isn't enough. You need to index the balancer first and tune from a known reference point that is reliable. 


Ron

[MedPhys]

I'm using a lean burn distributor that has no mechanical advance.  I figured it would be easier to use a lean burn than lock out the meck. advance on a regular distributor.

[firefighter3931]

I'm using a lean burn distributor that has no mechanical advance.  I figured it would be easier to use a lean burn than lock out the meck. advance on a regular distributor.

That could very well be your problem. Do you have another distributor available to try out ? Fwiw, i use the standard distributor and tailor the advance curve to what works best after the base timing requirements have been determined. I also disable any vacuum advance mechanism during the tuning process and leave it disconnected.


Ron

[dodge freak]

I use the Mopar dist. too with the mechanical advance but I use the lean burn pick up coil plate that is one piece. This way there is nothing to move or screw or weld down. Works great. Yes I have no vacuum can on the dist and after a few months it is a liitle hard to turn but it can be done and my timing once I set it does not change so it works fine. Use the cover thats on your lean burn dist to block the vacuum can hole. I am able to use both the light springs in the dist, but you would have to see if your motor pings that way. You might find that one heavy spring and one light one works out good for your motor. Let the dist . advance the timing. I found a new old stock mopar dist on ebay for $65 and swap the pick up coil plate-lean burn- and a set of light springs  and a Accel cap and rotor-all brand new - cost me close to $125 but it works perfect and should last a while, might change the cap in a year but that should be it. Guess I could got a MSD dist for $210 but this seems fine.

[MedPhys]

Unfortunately I end up learning from my errors.  I had a perfectly goo distributor that I paid to have the mech. advance welded.  Then I couldn't move the magnetic pickup correctly to phase it.  Now I have two distributors with no mechanical advance.  I guess I could have the weld untacked, but the residual weld could effect the advance curve. 

I'm hoping that it is just a simple problem based on me not accurately finding the zero timing mark.  I should be able to correctly find the zero mark next weekend since I'll hava a piston stop.  If this isn't the problem, then I might be in over my head.  I will have to wait and see for now.

For this computer setup, ideally I am looking for no advance fromt the distributor so that the timing adjustments are performed ideally by the computer.  This is a perfect example of "If it ain't broke , don't fix it." I should have left well enough alone and used my regular distributor.  Hindsight right?

[dodge freak]

Well MSD does make a timing computer also and they do claim its better cause you can dial in how much timing you want , at what rpm it start to come in and how fast. You can even back the timing off a little a high rpm's. Thats more than any dist can do and you don't even have to open the hood.

Have you call up Holley and talk to the tech guys ? Its their unit and its not that long since they sold them, maybe they could help you out. I look at those Holley systems but went with MSD cause they been making spark boxes for around 30 years now. Holley is for carbs, and they have been around now for around 100 years so its Holley for carbs. and MSD for spark.

[MedPhys]

The tech guy from holley said that I really need a crank trigger,  it says in the instructions that a crank trigger is best, but a magnetic pickup distributor will work, and it shows you how to phase it.  He then said I need a special distributor that allows me to rotate th cap to align the reluctor and magnetic pickup, and said I couldn't do it with my distributor.  Well, I believe his ideas would make the job easier, but t can also be done with my distributor (it's in the instructions).  So beyond ideal scenerios with the holley ignition, I don't think they are much help.

[dodge freak]

No I guess not-heck a crank trigger would cost more than a new MSD dist. I though you could not have the computer do any timing and have the dist do it. I never seen or had a holley ignition so I don't know what to say now.

[MedPhys]

The pro strip annihilator setup is similar I believe to the mallory Hyfire-VIIsc.  The distributor has all timing capability removed from it, and the computer controls when and at what point the spark is fired based on engine rpm and time required for computer calculation to take place. (generall 1/2* of thinking time for every 1000 rpm).  I use a hand held controller inside the car to plug in the timing curve in 500 rpm increments.

I actually regret the decision to use this setup since I don't really plan to race the car.  I am a little older now than when I bought the setup, and have a better understanding of Want and Need

[dodge freak]

Well if it makes you feel any better I have done the same thing-buy a part then a few years later find out I could have gotten something better for the same amount of cash. You want some EX. I got 3.23 gears then a few years later got 3.91-Got a MSD 6a box then later on got a MSD 7al box- got a eddy perform intake then later got a offy 360 intake. So it happens, All you can do now is try to make just thing work how you like, if you can't well move on and get what you can afford to get it running  right. Sounds like you need a dist. and a spark box, you could get a dist. from a junk yard and use that pick up plate coil in the dist. you have now-you don't need vacuum advance, get some light springs for it and try 1 heavy and 1 light spring and maybe get a spark box off e-bay, if you can't get get it just to supply the spark and not change the timing. Did I tell you about the 1970 cutlass-in great shape- that I wreck -well thats another day.