f1rob

I have a 1969 427 L68 with the original T.I distributor. Since buying the car, I have had problems with rich idle, and the car not running smooth off idle up to 1,500RPM.

I have had the carbs rebuilt, and then torn down and reassembled by another Holley specialist. I am fairly confident that the carbs are set up OK.

One item we did find was the spark at idle, and revving up through 3,000RPM was inconsistent, and the spark advance did not increase smoothly as the RPM increased. What would the problem be with my ignition? Amplifier, Module, etc?

I have heard through some people that the old T.I. ignitions are not very good, and this could contribute to the fuel not being fully burned, and therefore exhaust smelling rich.

What experience do people have with this? Am I getting bad advice?

One solution is to get another electronic distributor that would it inside the ignition shield, if this will solve my problem. If so, can anyone recommend a disti that does not need an external ignition box?

Big Block Dave

The only distributor that will work without an ignition box, that also has the tach drive assembly, will be a factory distributor. If you want to get fancy, a Pertronix ignitor can be used to replace the points set up.

derekderek

https://www.ebay.com/p/Chevy-Corvett...235fe7fff4cae9

TimAT

A MSD Tach drive magnetic pickup distributor will work just fine with your TI system. The TI distributor in my 69 had enough end play and bushing wear the end of the shaft moved like a football is shaped. Pulled the original out and dropped the MSD in. Works just fine with the original TI amplifier, coil and wiring. And it's pretty much the same size as the TI.
One thing I'm still trying to figure out- why the cap and rotor on the new MSD doesn't work. No spark at the plugs until I swapped the cap and rotor from the original to the new MSD. Fired right up after that.

3X2

T.I. distributors are good into the 9000 rpm range. Have you checked for vacuum leaks and the float levels? Contact Lars on this forum for his papers on distributors and vacuum advance.

Jebbysan

It would have to be the button not hitting I would think.

I am a staunch promoter of the MSD unit for the simple fact that it is too easy to put in a correct curve. The curve is extremely important for tuning and is one of the most overlooked things on an engine from my experience. The MSD will also come with an adjustable vacuum advance can.
Now you can take the stock unit and find someone with a Sun distributor machine to set it up for you (I believe Lars has one).......this is sneaky cool, but not everyone has access to do this.
The factory curve is not conducive for performance.

Jebby

lars

As noted by 3X2 and Jebby above, drop me an e-mail if you'd like a copy of my papers about setting up a good timing curve. Also, I have posted this info here before, but it warrants an occasional re-hash. Bottom line: Buy, use and install whatever ignition system you are comfortable with tuning.
V8FastCars@msn.com

Here is a re-post of an article I did not long ago:

What Distributor and Ignition System is "The Best" for my Street Car?
By Lars

The "best" distributor and ignition system to use is the one you're comfortable with setting up and tuning. Any two systems, set up with the same timing curve, will perform virtually the same on a mild street car. For a mild performance street-driven car, I also highly recommend getting one with vacuum advance, and there are many to choose from.
To demonstrate the equivalent performance from one system to another, I actually did dyno testing at Westech with Hot Rod Magazine several years ago. Here are the results that I've published here on the Forum before:

A few years ago, I did a bit of dyno testing at Westech Performance with Matt King, former Editor of Hot Rod Magazine. We tested several of the aftermarket capacitive discharge systems and top-end distributors against a plain ol' points-type distributor. The engine was a nice street-type 302 Ford putting out 370 horsepower. We tested ignition systems and distributors from Crane, MSD, and Mallory, making sure that each distributor had exactly the same centrifugal advance curve in it with the same total timing. Once these nice aftermarket systems were tested, we went out in the parking lot and pulled the stock points distributor out of Matt King's crap Falcon: We set it up with the same advance curve on Westech's distributor machine and dropped it in the 302 test engine. Results: There was no change in the engine's performance whatsoever at any point on the rpm curve. Absolutely none.

So here's the recommendation: Run whatever distributor you're comfortable with tuning and curving, and set it up with a good performance curve to match the needs of your engine. Whether this is a tach-drive points-type distributor, an HEI, or an MSD ProBillet is completely irrelevant as long as you can get it set up right. Buy something of good quality that is easily tunable, and make sure you run vacuum advance on any street-driven engine. Trigger boxes, amplifiers, huge coils, and fancy systems will not gain you anything on a moderate performance street engine - spend your time getting the curve and total timing set up right on whatever system you use - that's where the power is.

Here's Matt King (black shirt) and me setting up the points distributor from his Falcon in the 302 test engine to run head-to-head against the top-end capacitive discharge systems:


Notice that we even used the old crap wires out of Matt's Falcon for the testing:


Here's the same engine with one of the fancy aftermarket systems in it and some really nice red plug wires:


Famed Westech Dyno Operator Steve Brule (left) overseeing the testing:


Results: Absolutely no change in power whatsoever from one system to another, as long as the advance curve remained the same (note Matt King's astounded "I can't freakin believe it" expression):


Here is my own 407 that's in my '64 Roadster on the engine dyno. It puts out 500 hp with 500 ft/lbs torque. I run the stock tach drive distributor with a nice set of points and an aggressive advance curve which nails the optimum total timing for max power and performance. All you need is to get the curve right and the total timing right in a system you know how to tune. Everything else is fluff:


Running the additional benefit from vacuum advance (limited to 12 degrees) hooked up to manifold vacuum makes a huge difference in idle quality and engine operating temperature of this big-cammed, solid roller engine:

Jebbysan

One other thing.....as I had a 69' L68......are your end carbs 100% shut? This can cause all kinds of confusing symptoms.....one of which an overrich idle condition. They need to be shut as they have no idle circuit...the center takes care of that and if one or both carbs are bleeding it can confuse the signal to the transfer slot and/or try to draw fuel from the boosters on the end carbs at idle.

Lars, Steve has more hair in these pics......how long ago was this!

Jebby

TimAT

That was my first thought too- I swapped the rotor, no help, put the new one in and swapped the cap, no help. Changed both to the ones that were on the original TI,
and away we go.

jackson

Google Dave Fiedler his company T I Specialty
parts, restoration, repairs, consultation, NCRS
I have no experience with this gent

3X2

Dave is a great guy to deal with. A wealth of knowledge. I got a rotating pole piece and coil from him. Op may also have a coil issue. Stay far away from the aftermarket t.i.coils, His website is http://tispecialty.com/

Les

MSD provides you with graphs that show what the curves will be with the various spring and bushing combos. My two older toys both have this distributor and each one picked up a big improvement after I dialed in the curve and total advance.

f1rob

Hi TimAT:

Thanks for the heads-up. Are you referring to the MSD 8572? It looks like their only tach drive distributor, but the website says it requires a 6,7, or 8 series ignition to work. Did you plug the T.I amplifier, or TI coil directly into the distributor, without the MSD ignition? If so, how? Did this fit inside the factory ignition shield without modifications? What wires did you use, and plugs (what gap)?

Cheers,

Rob

f1rob

Hi Jebby:

It looks like the throttle plates are closing fully on the outboard carbs, both to me and one of the tuners that looked at them. I even removed the linkage for the outboard carbs, and still the same, stinky rich idle. It also stinks in the garage very heavily for a couple of days(like raw fuel), and when I have removed the carbs before, I have had small puddles of gas in the upper plenum of the manifold.

I know I have an ignition problem , as the timing jumps around at idle, and has a miss. The rich idle and overall fuel consumption has been a problem for some time and troubleshooting with a few people has not net any positive results. It sucks driving this car, and I'm at the point of just buying 3 new carbs and a new ignition so that I can enjoy the car without having to shower afterwards from the gas sell in my clothes, etc.

Rob

f1rob

Hi 3X2:

Yes, floats are set right, and all vacuum lines are fine, and the carbs appear to have no leaks - both with a smoke test and by spraying a starting fluid around the manifold, base of carbs, and the carbs themselves. If there were a vacuum leak on the underside of the manifold, I would expect it to suck oil, and burn through the exhaust. No blue smoke, only black soot.

Rob

f1rob

derekderek:

Thanks for this - the listing does not indicate the manufacturer, and I cannot find it by googling the upc code or listing code in the description. Price looks enticing, so want to look into it more to see if they have an installation description to confirm the wiring setup. Thanks for the suggestion.
Rob

Rob

TimAT

Naturally MSD wants to sell you one of their 6AL or better boxes. I measured the output of the MSD 8572 and the output of the old TI distributor, turning both by hand. There is not enough difference between them to measure. (at least with the meters I have). I don't use the shielding, but side by side the distributors are externally real close. I did change the cap to a socket style, but there's no reason the HEI style can't be used. The wires I'm running now are Accel ceramic boots. Got tired of fighting the 1 and 3 boots burning on the headers. And they come with both sets of ends so you can match the cap. Same plugs and same gap.
Somewhere I have a drawing of the connector to the distributor wiring- I even dug out an old harness and made up the same as factory connector for the MSD pigtail.

TimAT

There is a guy selling an MSD Tach Drive in the for sale section right now---

Jebbysan

I, at this point would swap out the primary metering block. I believe this center carb is bleeding past the metering block and main body and sucking unwanted fuel through the booster.
Focus only on the center carb as the end carbs are dummies.......they know nothing but to mix air with fuel when they open.
Snag that Tach Drive MSD in the for sale parts section right now......it is a bargain. Curve it and put it in.

Jebby