Overheated, Now Dies When Warm

[magnet18]

Ok, it's been awhile, what is an 'iggy'? You mean distributor?
Can't remember what ignition system was used in 74 , that was a long time ago. I can't tune a carburetor anymore but I can tune-a-fish.

Haha, iggy being ignition coil, is that just me? Is that not a common thing?

Check the Duraspark box on driver's fender.

Mustang II engine compartments don't evacuate heat very well, and if it overheated, the resin in the Duraspark box could have melted, which result in a loss of power and stalling when warmed up even though it would start just fine while cool.

Thanks! I'll check that out. Hadn't even crossed my mind yet, I'm used to more resiliant modern solid state stuff.

 

[General karthief]

Duraspark, thats what I was try'n to remember.
I never heard a coil called an iggy either, although I think that was the sound I made when my grandfather told me to hold this then cranked the engine!
We need an emoji face with the eyes bugged out.

 

[magnet18]

Lol, yea, they'll jump and bite you good. my first experiences with them was for the sole purpose of making some fun sparks

I actually didn't know these were electronic until today.

So, looking at options for replacing the duraspark box has me scratching my head. So many options (full dizzy, with or without box, coils and wires... )

Are stock replacements good and reliable, or would I get better reliability switching to something like MSD or pertronix?
My wife likes to drive this to work (it's actually hers), so easy starting and reliability are the key.

I hear MSD is both of those, and if it's money well spent I've got no problem spending it, but that's a big check and if it's overkill I'll put the money elsewhere.

Thanks again for all the help

 

[MustangIIMatt]

A replacement Duraspark box will be cheap and plug-and-play. An MSD box (such as the 6AL) is neither, but is a significant upgrade in capability.

My advice is to check your current Duraspark box's underside for heat damage, and if there is any, make a decision on which route you want to go with in replacing it. If there isn't any heat damage, see if you can find a parts store with an ignition control module tester that still works, and more importantly, someone who still knows how to use it. Have them run the test 5-6 times, and if it fails any of them, replace it. If it still passes that many tests in, it's good.

Duraspark boxes are reliable until they aren't. So are MSD boxes (MSD had a string of quality control issues for a few years that left some people calling them "Mostly Starts Dammit!"). If this is strictly a street car that will never see the high side of 5000rpm, the advantages of an MSD box are minimal. If it ever sees the track, they're big.

 

[magnet18]

Thanks for the input and help! I'll probably go with the stock box. Motorcraft replacement is only $40.
Also ordered a coil as cheap insurance, I think it was my wife's escape a coil intermittently went out. That was fun to troubleshoot.

Also, I saw your thread on installing the universal summit radiator here https://www.stangnet.com/mustang-fo...iversal-radiator-in-a-ii.887468/#post-8932815

but I didn't see any pics, did you post them up somewhere else?

 

[jozsefsz]

90% chance that your valves are adjusted too tight. Now that it's nice & hot outside, and when it overheated earlier, you're noticing. A vacuum gauge can tell you if you're losing vacuum when it starts to crap out, a good symptom of valves that have been adjusted without enough clearance (clearance decreases when hot).

That and pull the plugs, see if you're just running rich and fouling them when it's hot out, making sure the timing's right is good too.

I'd do that before some exotic theory about the module.

Edit: I see you said you adjusted the rockers to 20ft-lbs and the car ran much better, so I now assume you have hydraulic lifters. My advice was for solid lifters, I don't see how re-torquing rocker arms would fix anything otherwise unless they were completely loose. The 20ft-lbs is just part of the process for making sure you have the right pre-load on hydraulic lifters - you also have to count the number of turns after the pushrod makes contact and shim / get different pushrods if you're not on the mark.

If you have solid lifters / adjustable rockers then the 20ft-lbs would definitely be a problem.

 

[magnet18]

Yes, hydraulic lifters

They were overly tight before, i had to back them off

 

[magnet18]

*think* we found the issue
there was a vacuum cap on the back of the carb that was really dry rotted and fell in half when we pulled it off. Replaced that, then adjusted the idle and choke accordingly, things are much better!!

It now is set for 800-900 in park and drops to 500-600 in drive. Does this sound like normal behavior for a C4 tranny?


As for the dying when it warms up, haven't been able to recreate that, hopefully it's now cleared up, time will tell.
replaced the ignition module and got a new coil, I could hear oil sloshing around in the old one, meaning there is air in it.

now to the radiator store...

 

[jozsefsz]

That's good, I think you threw us off by correlating the problem to overheating. Generally if your carb is anywhere close to decently adjusted (~1.5 turns out on the idle mixture) and you have to keep it above 1000rpm to idle, you have a vacuum leak of some kind. Seems like you found it. Your idle speeds look pretty good, it all depends on the engine / cam / etc. but if you feel it's running good then it's good.

 

[magnet18]

Thanks,

I had tried again later that day, I just sat at idle and it started losing power the moment it started warming up. That threw me for a loop. Haven't been able to recreate it since though.

Glad to get a second opinion on the idle speeds. I've never had carb'd, or auto, so it's freaking me out. I think I'll bump it about 100 so I don't have a heart attack every time I come up to a stop sign.

Sounds sweet though

off to the next issue, tranny fluid in the coolant, good thing I'm going to upgrade the radiator anyway