Olds 403 ignition

[CamaroAdam73]

Alright so i've ordered a new dizzy, didn't come with caps/ coil. I've got a set of caps but no coil. However the store i work at does carry one i'm looking at, the problem is it doesn't list its for a 403 on the back, it does however list that it will work for an olds 305/ 350 from 1977, as well as an 73-75 olds 455. Its an accel 140003

http://www.summitracing.com/parts/ACC-140003

Says its a 45000v


So my next question is, if that one works is it worth the money? 60$ for an accel coil

If not i'm just going to order a factory replacement no frills coil. Which i'm not trying to do, because i'd like to get alittle more out of this ignition than just standard.

 

[Bonnewagon]

I've tried all sorts of coils and they all worked the same. Bottom line is the coil will put out exactly what voltage is needed for the spark to jump the plug gap- no more, no less. So a mega-watt coil will still only put out what is needed. If you have other issues, like bad wires, old plugs, rich mixture, high compression, etc, the high output coils will be a band-aid fix, but eventually cause other things like burnt rotors and caps. I have found the stock coils to be just fine for a street motor and they are more than reasonably priced these days. Check out these-http://www.rockauto.com/catalog/x,carcode,1250604,parttype,7060

 

[els-]

The pro comp stuff is good, and cheap to.

http://www.store.procompelectronics.com ... t_id=36832

 

[CamaroAdam73]

I bought a procomp dizzy once, and had a bad experience. Somehow it got hot enough inside the cylinder for the plug gap to be forced back together and ground out the coil. BUT that engine at the time had other problems too, so i can't say it was the dizzys fault.

Yeah our store has a OEM specs replacement coil for 18$ and thats the one i'm getting.

Here's a question though, lets say i did get a hotter coil, like a 50k, how much wider could i make the plug gap to utilize this benefit?

 

[Bonnewagon]

GM used gaps as wide as .080" on some early 70's motors, but this was in the early low compression, new HEI, crude emissions days. Low compression, lean mixtures, makes it easy to jump a wide gap, high compression and rich mixtures take more juice. Think about this; imagine if you rig a distributor (no plug wires) to fire while off the car by running a battery ground to the distributor body, a battery hot wire to the "batt" connector on the cap, separate the cap from the distributor and run another ground wire so it is close but not touching the carbon button in the cap, then spin the distributor with your hand, how far do you think you can get the spark to jump? My personal best is about a foot! And to jump that gap, the coil cranks out a mega-juice spark that will scare you. Did I mention this was with a stock coil? By the way this procedure is my own test that I use for a distributor, since being off the car nothing can influence the results.

 

[CamaroAdam73]

This might sound backwards but, I've assumed that if you can pull off using a wider gap you could use less advance because you're getting the mixture burning faster? Obviously this is minor, i'm not saying wider the gap and drop the timing by 5 degrees

That's a pretty cool test wagon, i'm going to remember that.


Just thought about this, i have to be careful with how much i advance the timing on this 403, being that I've got a nice low rear gear this engines under heavy load all the time. For now i just want to get it tuned in and running A1 under normal tuning specifications, but once im there i want to toy around.

It's a low comp engine, with a wider gap and a slightly leaner mix i think it would make just alittle more power?

 

[Bonnewagon]

I don't think burning faster is as important as burning completely. I like MSD multispark in that regard, because you have a series of backup spark events to get it all ignited. Burning too fast can lead to pre-ignition problems. The biggest factor in controlled, complete combustion is combustion chamber shape. The best example of this is the famous Honda CVCC chamber which placed the spark plug in a tiny chamber away from the main chamber. The plug ignited this small chamber which then ignited the main chamber kind of like how a blasting cap ignites C-4. In your case, a stock motor only needs stock ignition. Once you add the usual power enhancers like cam, headers, intake manifold, then the ignition becomes a candidate for upgrade. But keep in mind that all the "muscle" cars of the 60's did quite well with simple points ignition.

 

[CamaroAdam73]

Yeah it's a mostly stock engine, i'm positive it's not the factory spec cam though. With the timing advanced slightly at 20 degrees idling at 900-1000 RPM it will fluctuate about 100 RPM steadily. Holds 20-19 inchs of vacc and that fluctuates with the RPMs. When you throttle up the vacc readout drops instantly to almost 0 hah, and that's not even close to full throttle.

still got allot of testing too do but so far it's running nice, strong. I think i might end up needing some friends help tuning in this carb, i noticed the overall throttle response is shitty. If after its warmed up, i give it a good hard stomp to full throttle it'll hesitate, or spit back through the carb. and by spit i mean spit unburnt fuel, it doesn't backfire.

Get this though, the new dizzy is under lifetime warranty cap and rotor have a five year, and the coil is lifetime as well.
I can get 7 bucks back fore a "core" if i turn in my old dizzy, but no. I'd rather keep the old one and eventually rebuild it with some D.U.I electronics.


Just so you know, although power and performance are high up on the priority list for this build, it's not the most important thing. There's a GOOD chance i'll end up not selling this bird and driving it to south Carolina next year, so she's going to end up seeing allot of highway milage. Which makes the 2.19's in the rear perfect. So that's why i'm a little dissapointed it's not the factory spec cam. To be put short, with this bird Driveability > performance.

From what i've learned so far about olds engines, they seem like one of the best picks for a nice street warrior. I could build up a disgusting 355, or 406 but it wouldn't behave at all. And driving an engine like that the whole way from PA to SC isn't the best idea.

 

[Bonnewagon]

Do you have access to a dial indicator with a magnetic stand? You could measure the valve lift and compare it to stock specs. Measuring duration is a bit more involved using a degree wheel on the crank snout, but a timing tape on the balancer would be close enough for a ballpark idea.

 

[CamaroAdam73]

No, but how much would a dial indicator and a magnetic stand cost me? No better time than now to buy one.

My next pay might be the last money i spend on this car for awhile. So a fender is first priority. Then some materials to get the front end ready to be put back on. After that if i can pickup a dial indicator, and magnetic stand for a reasonable price i will.