1976 MG Midget

[Loren]

Who doesn't like videos?

I couldn't resist a quick sample with the open collector. It's obnoxiously loud IN the car, but not as bad as I thought from outside. I mean, it's LOUD, but it's not as loud as I thought it would be. (this is after I finished fixing the header, was just turning the car around to work on the back end)



This is the finished product in basically the same scene for comparison. Very quiet. I think the cooling fan whine is louder than the exhaust!



Now, I have to admit, the car sounds COOL and RACY with the open collector, and part of me may have enjoyed a slightly louder exhaust to hear more of that. But, a bigger part of me hates a droning exhaust when I'm cruising at 60 mph, plus I have chronic tinnitus and no desire to make my hearing any worse! So, quiet is what I wanted, and quiet is what I got. Plus added flow with the 1.75" pipe. Win-win!

This was all finished yesterday, and I didn't really drive the car until today. It's quiet, but not so quiet that you can't hear what's going on. Downright DELIGHTFUL to cruise in.

I didn't think to turn the music off, but Blues makes everything better, anyway. This is a run up to about 50-55.

[Loren]

Made myself check a couple things off of the list today. Keeping a smaller list of things to do on a whiteboard in the garage seems to be helping. Having the daunting list of "everything" here in this thread (first post) on the forum doesn't motivate me to do anything.

So, I fixed the coolant leak. Due to a difference in the manifold that came with the car and the one I put on it with the new carb, there's an extra heater hose port that needs to be plugged. The way I did it initially didn't hold up. (cheap rubber plug was cracking) Didn't have any 1/2" solid stock laying around, but I found a piece of 1/2" OD tube. I gots a welder. Smashed the end of the tube, welded it shut, cut it to a 1.5" length. Used that to plug a piece of 1/2" hose. Good to go. I even painted the tube/plug before installing it.

Then, I did something I've been putting off for about a year and a half. I've had the part sitting there forever. I replaced the thermostat. That was exactly as easy as you'd expect. I spent a few extra minutes cleaning things. That'll be good probably until an engine rebuild is required.

This car as always run cool. According to the gauge... the only time it ever reached the straight up "normal" position was after the first time I swapped the manifold and had a big air bubble in the system... even then, it barely went past half, then came right back down. Normal running position is about 1/3 of scale.

The car is also really slow to get up to full temp. (not by the coolant temp gauge, but by the oil pressure settling down significantly lower when it's warm) I figured either the gauge is inaccurate, or somebody's fitted a 160 degree thermostat... or no thermostat.

Turns out it did have a 180 degree thermostat, and now it has a new 180 degree thermostat. No change in behavior. So, it's either an inaccurate gauge, or that's just the way it's meant to be.

A little research says that the Smith's temperature gauge should be at about 90 degrees C mid-range. That's 194 degrees. So, if it's holding 180 degrees, that would be a bit left of center. Gonna call that good!

[Loren]

Doing some more Internet sleuthing, I think I'm honing in on what some of my potential problems are:

Even after fitting the PCV valve, I still get smoke on decel from high RPM. (high being 4500+, doesn't seem to care about 4k) That's probably worn valve guides. This engine did not come with valve stem seals from the factory. It is said that they can be fitted, particularly to the intake valves, and it will help a lot with this problem. Makes sense. So, unless I decide to just buy a spare head and do a full head rebuild... I'll probably look at slipping some valve stem seals in there.

I was thinking that my smoke could be from leaked oil burning off of the exhaust. But, given the nature of the smoke... it seems like valve guides.

But, I'm definitely spewing a lot of oil from the front of the engine!

So, I'll be doing a re-seal on the timing cover and replacing the front crank seal. There's some fiddly-ness to it, but it's pretty straightforward. Word is that I should replace the timing chain tensioner and inspect the chain while I'm in there. I'll probably do all of this while the engine is out for trans mount replacement. Gonna be doing a lot of work at that time.

[Loren]

Meanwhile...

I've been sitting on a new battery since the initial header install a couple months back. One of my first thoughts (before I figured out that I had a massive intake manifold leak due to the header interfering with the manifold) was that maybe the car wasn't starting because the battery voltage was low and causing the Pertronix module in the distributor to not function. (fun fact: These cars all came with old school points distributors, but a common upgrade is to replace the points with a Pertronix "ignitor" module. It just takes the place of the points and fires the coil... but, no maintenance required. No adjustment, no points fouling, etc. Basically takes care of one of the most common problems with an old car.)

The battery has been a little low on voltage since I ran it flat (TWICE!) while working out the electrical system. So, the new one was there, and I was just waiting for the old one to give up before installing it.

The car has been happy starting and running with a battery at about 11.6-11.8V. Last week, I did notice a sluggish start, so I knew it was coming. Sure enough, I went out to make a grocery run Saturday, and the engine fired RIGHT up, but I wasn't quick enough on pushing the choke back in to settle into an idle and it stalled. (happens) And I got about a half a turn out of the engine after that... then nothing!

Time to install the new battery. That should take about 5 minutes, right?

Pulled the old battery out. It's an undersized battery. The new one is a full-size unit. But, not the CORRECT full-size unit. (relevant fact) The correct battery for this car is either rare or unavailable. I measured before I bought it, and the replacement battery is a good fit in length, width and height. No problem. Or so I thought.

Went to put the new battery in. Did I mention that the battery sits in the center of the car behind the engine at the very back of the engine compartment? Yeah. And guess what? I can't fit the battery into its slot because it won't clear the hood!

Did a little research and found that it's not uncommon to have to remove the hood on this car to replace the battery. Geez. Okay. Another option might be to remove the heater box that's in front of the battery, but I didn't want to mess with that. Easier to just remove the hood.

Steve came by to give me a hand. (thanks, Steve!) Pulled the hood off. Went to install the new battery again. Are you fucking kidding me? The base of the battery is very fat, designed for one of those bottom clamp mounting setups. It's exactly the size it's supposed to be, but it is a little bigger than the actual body of the battery. And it's hanging up between the firewall and the heater box. Absolutely will not go in there! Gonna have to either get a smaller battery (this one was ordered online and is past its return window) or remove the heater box to fit the battery.

Fine, I'll pull the heater box. It's held in by 6 Phillips screws, and has heater hoses going to it. Of course, the screws are all painted over, and the 3 at the back look like they're already stripped. Spoiler alert, they WERE stripped. The front three came right out, the back three I had to drill the heads off of. But, the heater box is out!

Had to clean up some surface rust under there and hit it with some paint. We put the hood on while waiting for the paint to dry.

With that, fitting the battery took about 3 minutes. I still need to make a proper bracket for it (the original is long gone), but I have a proper strap holding it.

The car starts with AUTHORITY now. 12.5V spins that engine like it's nothing and it fires up after about a half a revolultion. So, that's good.

Now, I have to decide...

Do I want to drill out those 3 screws for the heater box and refit it? If I did... how would I ever be able to install those screws UNDER the battery that's in there? I've seen a lot of these cars running without a heater box, now I know why!

I really don't care about the heater, I've never actually used it. Even the fan has been disconnected since I did the electrical system. (I put in a relay for it, and never got around to hooking it up!) I've not had a heater, and I've not missed it. For the driving I do with this car, here in FL, not a big deal. But, I WOULD Like to have some airflow. It gets a little toasty in the footwell.

Options:

1. Get a smaller battery and put the stock heater box back in. (what? and admit defeat?)

2. Modify the heater box to make it shorter so that the battery can be more easily installed. (not sure this is even possible... maybe)

3. Fabricate a low-profile plenum to connect the 4" fresh air duct from the front of the car to, and fit a 4" inline fan in it.

I'm leaning towards #3. It would allow battery installation without removing the hood. Would give me ample fresh air. And, bonus points, I could easily run the cold air intake from my carb to the same plenum that's already getting fresh, cool air from the front of the car.

Little bit of sheet metal, some screws and a $30 fan... how hard could to be?

And how much of a priority do I want to make it? It's actually fairly low priority, but it should be pretty easy to make and install, and I do like a "creative" project.

[Loren]

Have some "new" old parts on the way, too. Somebody on the MG forum was cleaning house. I'm getting a head, rocker assembly and camshaft for the cost of shipping. Also ordered a trunk prop rod from eBay.

The prop rod on this car is one that latches open. To close it, you have to lift up on the trunk, reach over and flip the release button, then close the trunk. Kind of a pain when you're grabbing something out of the trunk and only have one hand free!

The Spitfire uses a nearly identical mechanism, but it automatically flips the latch when you lift up on the open trunk. One-handed operation. I finally learned that that latch is a fit for this car and ordered one!

[Loren]

And, I'm locked in!

Opted to order a 120mm high flow (230 cfm, typical car has about 150-200) computer fan, with an adapter flange to go to a 4" duct. Also got a flange for the CAI. And, a trick adjustable fan speed controller. I can set it to come on at like 75-80 degrees, and it will ramp its speed up from there. That way it won't be running full-tilt all the time, and I don't have to worry about how to manually control it. (the car just has an on/off switch for the fan, which I can use as a bypass for full-fan, or I could just wire it as a master off switch, whichever it needs more)

Gotta see if I have suitable sheet metal out in the garage. Kicking myself for not gutting the stainless steel BBQ grill that my neighbor threw out last week! It had some nice, flat doors on it!

[Loren]

Some of my parts showed up, so I started mocking up the fan box. Old school CAD. (cardboard aided design)

It looked so small when I put it all together in the living room.



But, when I test fit it to the car... it's too fuckin' big! Yes, I measured things. I thought I had 12" of width and it would stuff in behind and almost under the starter solenoid. Nah, the starter solenoid is bulkier than I thought. It needs to be about 1.5" shorter to clear that!

Otherwise, not too bad. I did almost make it too big front-to-back. It's really close, about 1/8" bigger than it should be. (gotta remake it, anyway... good thing this is in mock-up stage!) For some reason, I had it in my head that the OE fan box is 5" in that direction, it's actually 4.5". But, it's mounting flanges are 3/4", so it adds up to just a touch over 6". I made it 5" with 5/8" flanges... so, I'm about 6.25".

Otherwise, it fits fine. Height is plenty low enough. I'll revise my mock-up, make sure it fits... maybe even run the fan for a bit until it blows itself apart!

The fan and controller arrived. Did some testing there. Unfortunately, the fan controller is not compatible with my fan. It said it would work with a 4-pin fan, it does not. 4-pin computer fans have some built-in logic. You supply power on 2 wires, and a PWM signal on another wire. The way the controller works, it just wanted to send a PWM voltage on the power wires. It sort of worked in that the temperature control worked, it would turn the fan on and off. But, when it came on, it was 100% on or off, no speed control. And this fan BLASTS some air, I don't want it on full all the time!

Sending that one back. Ordered another one. It seems like a much better unit with more precise temperature control and an actual 4-pin fan connector. Should work. Unless I've damaged the fan.

Did some more research on the CFM requirements of the engine, since I'm trying to pull intake air from that same air box. The fan is supposed to deliver up to 230 CFM, and throttled a bit... probably still 150-180. The max flow of the CD175 carb is something around 200 CFM. But, the CFM requirement for 80 HP is about 50 CFM. (I don't understand carb sizing... the original CD150 carb should have had more than enough flow for this engine... I guess it comes down to reality vs flow bench theoretical maximums) So, just puttering around, the engine won't be pulling more than 40 cfm, which won't have a huge effect on my cabin airflow. And that whole system should offer a great source of cold air for the engine.

The steel to build the box is going to cost about $20 from Lowe's. Could get it cheaper, but shipping would actually make it cost MORE. Could source it from an outfit in Tampa, but then I'd have to drive to Tampa. Who wants to do that?

The fan and controller were about $30. The 4" flange for the fan and the 3" flange for the intake were about $5 each. Guess I'm gonna have to buy some sealant for the box, and some paint, too. I think I need one more piece of hose for the intake. This whole thing's gonna cost me $100 by the time I'm done. But, if it gets me cool air for the carb, and a trick automatic variable speed fan to get some cool air into the cabin... it's worth it.

[Loren]

New fan controller module showed up, finally got around to hooking it up. I thought it was way more than I needed. It's got a digital display and rudimentary electronic controls (no knobs, just buttons). Turns out, it's exactly what I needed and works perfectly!

It doesn't have a lot of parameters, just what you need:
Fan on temp - set to 75 degrees
Fan initial speed - 17% (about as low as it will go and still feel like it's moving air)
Fan hysteresis - 2 degrees (C), this is to keep it from cycling on and off too quickly, I don't really care
Fan full-speed temp - set to 96 degrees
Fan full-speed - 100%
Temperature correction - I guess I could calibrate it if I wanted to, but it seems accurate enough

The only thing I don't like is that I had to set the initial fan on speed higher than I wanted (would like to have "some" airflow at like 60 degrees) also had to set the full speed temp a little higher than I wanted.

If I had the range set to like 60 and 90, then the middle is right at 75 degrees, with a working range of essentially 20-100%, that puts the fan at 60% at 75 degrees. That feels like a lot. (will be able to adjust once it's actually in the car, I could be wrong)

So, raising the on temp to 75 and the max temp to 96, the middle is right about 85, which seems more appropriate for 60% fan. And it ramps up from there. But, no forced air below 75 degrees. Should be fine. Remember, I've not had the fan connected at all for the past 18 months, and I never used it even when it was connected. (because I didn't have the duct to pull air from the front of the car... it would have been blowing under-hood air into the cabin, fumes and all)

Pretty pleased with how this setup works. I especially like that it's sort of like an "automatic thermostat". I don't have to adjust the fan speed, it adjusts itself based on temperature.

By the way, when I ordered this controller from Amazon, I got TWO for $14. If anybody has a need for a controller for a 12V 4-pin computer fan, I can hook you up. (literally!)

Now I can get back to correcting my "CAD" mock-up box.

[Loren]

Gettin' dusty in here again. I guess that's a good thing as long as the car is running. And it is.

I've fiddled with my fan box a little more. Had to make it a little smaller to fit. And then I took a few weeks to just "think about it". Decided to attach it differently. Rather than using 2 or 3 screws on each side to hold it down, because it's so light (the OE box had a heavy squirrel-cage fan and a heater core in it!), I'm just going to use a single bolt in the center to hold it down with a good rubber seal around the perimeter. Sort of like an air filter assembly on a carb.

Been noticing that my alternator isn't charging. It's been that way for a while, but it's gotten worse. I don't think it ever charged properly, never more than about 12.8V that I recall, maybe 13.1. But, lately, it's not even charging at 12.2 with the lights off. And when I drove it tonight, I STARTED with an 11.9V battery... and that voltage got as low as 11.6 and never showed charging more than 11.8 while I was driving. So, yeah... something in the alternator has failed. Either a diode or the regulator. What to do?

I gave some thought to just rebuilding it. But, it's a cheap Chinese unit. Who knows what other part will fail next?

I could replace it with another drop-in unit. There are basically two to choose from. The original Lucas unit (I have one that needs bearings) and the one in the car is a Bosch style from a 1978-80 Ford Festiva. Those are the only ones that are bolt-in and fit the factory wiring harness. You can get new replacements, but they're all made in China. Which is what I have now.

Lots of people retrofit other alternators, and many of them say "oh, just put a 90-amp GM alternator in there". Mid-90's Saturn alternator is popular. The claimed benefit there is that even if it fails, you can get a replacement at the local parts store, and they'll give you a lifetime replacement. Yay... replacing crap alternators every other year. Pass.

I really don't feel the need to run an 80-100A alternator and put extra load on the engine unnecessarily. It's probably pushing less than 60HP as it is! I don't even really want a 55A alternator, which is very common.

Another option that I like a lot better: There's a TINY Nippondenso alternator that's used in Kubota (and other) tractors. It's got an internal fan, and it's about the size of a softball. It only puts out 40 amps, which some people balk at. But, the OE alternator was only 35A! The replacement that I used is "upgraded" to 43A. But, really... since I went with LED headlights, I don't even really need 35A. 40A is more than enough, and I don't have to worry about upgrading the charge wire to the battery (or melting it if I don't).

I like the fact that it's smaller and lighter, of course. But, I also like the fact that it's slightly "newer tech". It's a 90's era alternator rather than a 70's era alternator.

I spent the better part of the evening exploring this option. Mechanically, it'll fit. I'll have to fidget with the lower bracket, maybe make some kind of spacer. No biggie. And the wiring pigtail to connect to it is readily available. The connections are the same, B to the battery, IG to the ignition switch, and L to the light.

Replacements are VERY readily available. Some decent looking ones on Amazon for $70-80. Even one for something like $56. Even some over $100 and up to $200. But, they all look exactly the same (maybe two variants), all made in China. I aaaaaalmost ordered a cheap one.

But, if I'm going to convert to a Denso alternator, the biggest benefit is that it be a genuine DENSO alternator! And that proved to be hard to find! Couple crappy looking used ones on eBay for over $100 each. New ones popping up in UK and Australia for decent prices. ONE boat parts outfit had one in the US for over $300! I was about to give up. Finally stumbled upon an outfit in Oregon that had one for $158. It's slightly different, but the only difference is that the B post comes out the side rather than the back. I have clearance for that, and it might even be better. Same 40A output. And it's a brand new Denso alternator. Should outlast me. So, I ordered it. $20 or so for shipping.

One more thing to mess with, I suppose. But, once that's done, I shouldn't have to worry about it any more.

Meanwhile, my drive this evening was delightful, in spite of the volt meter being a little sad. The LED lights were rock-steady and didn't dim at all, of course.