MSD TFI with 4bbl carb?

[JunkCollector]

I did some reading and saw that there are/were harnesses to convert your tfi over to msd ignition, but it didnt clarify if that allows you to eliminate the feedback carb and some of the various controls. Is there a way to run a digital MSD box and the 4bbl? Would like to have a 2-step limiter for entertainment purposes, and still have my carb and cam. Once I get done with the titling process, which should be soon, I'm going to start working on it. The intake and carb are sitting on my workbench almost ready to go.

 

[RonD]

The TFI system needed a computer to send it spark advance based on engine load
MSD module can be used to replace computer, but you still use the TFI module
Yes, you wouldn't need the feedback carb any more and computer could be removed

TFI module did have its issues


The Duraspark distributor used vacuum advance, which might be a better idea
Duraspark distributor with HEI module is a good reliable combo, and would probably be less $$$

 

[franklin2]

Most people like me do convert to a older duraspark II setup for the 2.8. A late 70's mustang II or pinto is where the parts come from. You can use a duraspark II box or a GM HEI module to fire the coil. The older distributor will have mechanical advance weights and a vacuum advance for all your engine's timing needs.

The biggest problem with the TFI is no timing control. But MSD does make a box that is programmable and it will work with the Ford TFI. I was researching this, looking for somethere where I could run a carbed setup on a 2.9 v6. Ford never made a old school distributor for a 2.9 v6. So this was my way out of that. You could use it for the 2.8 also, but it's more expensive than the old school 2.8 distributor. The cheapest I could find the MSD box was a refurbished one on ebay for around $300. New they are around $350-$450.

 

[JunkCollector]

Thanks for your help guys, I'll go with the duraspark then. I would like to get a programmable msd computer in the future, but Id rather not spend quite that much money right now. I already did all my research and I can have everything but the duraspark wiring harness for ~$170. This does mean that I can have the wild 2-step programmable box in the future. Might be a good option for turbocharging one of these, which I've always wanted to do.

 

[franklin2]

Here are some pictures of my conversion. I used a duraspark II distributor made for a mustang II with a 2.8 from the parts store. I made my own harness, just using slide on crimp connectors and split loom for the wire.

duraspark to hei wiring by D Franklin, on Flickr

That leads over to a GM HEI module shown in the picture below, driving the original square TFI coil.

2.8 hei conversion by D Franklin, on Flickr

 

[19Walt93]

If you use a 70's duraspark distributor you'll get a big power increase by recurving the centrifugal advance to get it all in by about 3000. One of the things the auto makers did in the 70's trying to meet the emissions standards was retard the timing and delay advance. My 77 Mustang was still advancing at 4500 and not all in yet. A 77 Mustang 302 had 1 3/4 single exhaust with a cat, a resonator, and a muffler, it probably wouldn't run 4500 rpm. The 70's emissions "tune" managed to get a 302 down to 139 hp, the low compression and lousy heads probably didn't help.

 

[ford4wd08]

If you use a 70's duraspark distributor you'll get a big power increase by recurving the centrifugal advance to get it all in by about 3000. One of the things the auto makers did in the 70's trying to meet the emissions standards was retard the timing and delay advance. My 77 Mustang was still advancing at 4500 and not all in yet. A 77 Mustang 302 had 1 3/4 single exhaust with a cat, a resonator, and a muffler, it probably wouldn't run 4500 rpm. The 70's emissions "tune" managed to get a 302 down to 139 hp, the low compression and lousy heads probably didn't help.

This is done by adjusting the tabs that hold the springs right?

Is there a good cheap tach that you can use while working on the vehicle? My B2 doesn't have a tach.

 

[ford4wd08]

Here are some pictures of my conversion. I used a duraspark II distributor made for a mustang II with a 2.8 from the parts store. I made my own harness, just using slide on crimp connectors and split loom for the wire.

duraspark to hei wiring by D Franklin, on Flickr

That leads over to a GM HEI module shown in the picture below, driving the original square TFI coil.

2.8 hei conversion by D Franklin, on Flickr

You can buy the male plug on amazon for the 3 wires to the connector. That's the route I chose. Had to trim one tab, but it fit well and tight after I did that.

 

[pjtoledo]

just curious, what CFM 4bbl carb are you planning to use?

 

[19Walt93]

A 390cfm Holley worked great on the 2.8 I built for my friend's Sunbeam Alpine, bigger isn't better.

This is done by adjusting the tabs that hold the springs right?

Is there a good cheap tach that you can use while working on the vehicle? My B2 doesn't have a tach.

You'll want a tach you can see while watching the timing mark with a light, I use a Snap On dwell-tach I bought in 1972. There are 2 springs under the base plate that control advance, a light one that's in tension at all times and a stiffer one that is loose at low rpm's. If it starts advancing just above idle try bending the tab to make the stiff spring a little looser and see what happens at higher revs. Go easy, a little is a lot.

 

[JunkCollector]

A 390cfm Holley worked great on the 2.8 I built for my friend's Sunbeam Alpine, bigger isn't better.

You'll want a tach you can see while watching the timing mark with a light, I use a Snap On dwell-tach I bought in 1972. There are 2 springs under the base plate that control advance, a light one that's in tension at all times and a stiffer one that is loose at low rpm's. If it starts advancing just above idle try bending the tab to make the stiff spring a little looser and see what happens at higher revs. Go easy, a little is a lot.

Where would one source the replacement springs? I know you can just buy em for MSD distributors but I didnt know there were others available for duraspark units. I'm running a 390cfm as well.
Edit: misread this entirely, I get the tab bending thing now. At first I thought there was a heavy spring and a light spring that could be interchanged. My bad.

 

[19Walt93]

The Ford springs I've got were scavenged out of distributors over the years but I've almost never had to switch springs to get the curve where I wanted it. If you feel confident enough to remove the base plate, you can see the springs and the centrifugal advance mechanism. There are 2 different size openings in the weights and you can get more or less centrifugal advance by repositioning things. Most people don't go that far, they just adjust the base timing to get the total advance they want. I've never been able to leave well enough alone, if there's better I want it.

 

[franklin2]

The Ford springs I've got were scavenged out of distributors over the years but I've almost never had to switch springs to get the curve where I wanted it. If you feel confident enough to remove the base plate, you can see the springs and the centrifugal advance mechanism. There are 2 different size openings in the weights and you can get more or less centrifugal advance by repositioning things. Most people don't go that far, they just adjust the base timing to get the total advance they want. I've never been able to leave well enough alone, if there's better I want it.

That's what I usually do, advancing the base timing as far as it will go and still crank over hot and not have any pinging will really wake a lot of these engines up. But it really fouls up the vacuum advance, you usually can't run the stock vacuum advance unit as is if you up the base timing. But the throttle response and low end is so improved, I sometimes just leave the vacuum advance disconnected.

Advancing the base setting increases the idle speed, so you have to fiddle with the carb settings also. You are on your own as far as the tuning specs when you do all this, no more factory settings for anything. But it' worth it in power and fuel mileage also.