? Is the TFI interchangeable with the old style coil ?

I'm using a newer TFI type of distributor in my '66 289 block so that I can take advantage of spark control, anyone know if the old cylinderical type of coil is interchangeable or do I need to buy the newer style coil?

thanx... MKiehl AT austin DOT rr DOT com

Reply to
HiPerformance289
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I think that the computer interfaces between the coil and the distributor. What the purpose of that interface is, I'm not sure. How are you planning to drive the TFI distributor (what electronics will you use to perform the function of controlling spark timing)? I doubt the old coil will work if it needs coil input.

JS

Reply to
JS

You could probably get away with the old style coil but there's a real good chance it may not "saturate" enough to create a good, hot spark. The E-core coils are capable of a much hotter spark than the old cylindrical coils.

Be aware that the TFI module is not capable of advancing the spark timing, this is a function of the PCM. Once the engine has started and the rpm reaches about 600, the PCM starts to control ignition advance...... without the rest of the 'stuff', that TFI distributor is a leap backwards.

Jim Warman snipped-for-privacy@telusplanet.net

Reply to
Jim Warman

Jim....

Perhaps you can answer a question that's been nagging me for quite some time. I have Probst's book on EEC-IV fuel injection systems. I've read it cover to cover (save for the codes and troubleshooting which I use as reference). It's been a while, but I didn't quite get one thing.

I realize that the hall sensor in the distributor is marked somehow to show the computer where cylinder #1 is. How does it know where it is on a cold start, or even a warm start (which is probably more critical due to a cold start requiring more fuel). Does it just pulse all of the injectors until it finds #1, or keep them them all closed until #1 comes around?

I'd figure it would be the latter, but I had a 1986 Mercury Capri 5.0 and I've never seen a car start so quickly in my entire life. This car had

160,000 miles on it and it was almost instantaneous - it was like it fired the first chance it got, every time.

Just curious as to how that all works out.

After mulling over the OP's situation, I'd think it would be pretty tough to do TFI on a carbureted car... even if you had the computer (or an aftermarket system), you'd need to give it some input as to why it should advance/retard the timing. If you used just the vacuum as an input, there wouldn't be much benefit in going away from the vacuum canister and spring advance, right?

JS

Reply to
JS

If you pop of your cap and rotor, you can see the little "shutters" that pass through the hall effect switch. Look closely and you'll notice that one shutter is much narrower than the other seven..... this is the PIP shutter. The PCM computes the rpm that the starter is turning the motor over by counting how many times the hall effect turns on and of in what amount of time. Once it knows the rpm, it can determine when the skinny shutter passes through the switch and knows that this tells it where #1 is.

I'm unsure of the strategy, but I recall hearing that the early SEFIs "bank fired" the injectors at start-up for quicker starts - true or not, I haven't verified. When we first turn the key on, the PCM is a very busy boy....it briefly turns on the fuel pump to make sure the fuel rail is up to pressure, it looks at engine coolant temperature, intake air temperature (through either the IAT or MAF) - on speed density systems, it looks at the MAP to determine barometric pressure.... all in that brief instance before we hit the "START" position.

Older distributors used the vacuum advance to determine engine load and flyweights to determine engine speed - crude, yes, but a good tuner could curve the distributor to work well. My own choice is the MSD ProBillet.... mech advance only and easy to adjust (coupled to the MSD Digital 6 Plus, it's about as good as you'll ever need)..... With the TFI distributor, the PCM takes over the timing chores.... it knows the rpm, it sees throttle position and movement through the TPS, engine load through either MAF or MAP, engine temp, air temp (it already knows the barometric pressure) and sends a signal through the SPOUT telling the TFI module when to open the coil primary circuit. Remember that when we set timing, we remove the SPOUT connector..... this takes the PCM out of the picture and takes us back to base timing.

HTH

Jim Warman snipped-for-privacy@telusplanet.net

Reply to
Jim Warman

Thanks for the replies; The question about the coil comes up as I am installing a Holley EFI system. The system can be programmed (mapped) to add or reduce advance but to make use of that option I need the TFI distributor. I already am using a MSD 6 ignition. Since making the post I have learned that the coil won't make much difference, meaning that I can use the existing cylindrical one that I already have. That means that I don't have to buy a new coil! Best news I had all day. Thanks again...

Reply to
HiPerformance289

Like I said... I'm sure you can "get by" with the stock coil....... but you sound like you're spending a fair chunk of change on the rest of the stuff...... why scrimp now? Especially since you have the benefit of the multisparking from the MSD 6.....

I heartily recommend taking a look at some of the E-core coil offerings from Jacobs, MSD, Moroso et al....... they saturate quicker, deliver a higher amperage spark and have a higher available voltage than "conventional" coils. Just be sure to read the product descriptions closely..... many of these run too hot to be suitable for street use.

Jim Warman snipped-for-privacy@telusplanet.net

distributor.

Reply to
Jim Warman

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