Hangin' in Da Groj - March 9

[Loren]

It's been a while, let's do another tech session! I've still got a never-ending list of things to do on the MG, as well as general cleaning/organizing of garage space. Plenty of space to work on other cars, as well.

So, come help keep me motivated! Come work on your own stuff. Come learn stuff. Come hang out. Come help me eat lunch (the most important meal of the day). Come check out the current state of the Midget!

Who: Me. You? Whomever.
What: Wrenching on the MG and whatever. Doing groj stuff.
Where: Loren's place in Safety Harbor (PM me if you need the address)
When: Saturday, March 9, 9am-4pm.
Why: I don't trust other people to work on my cars! Plus, it's fun!

Who's coming? What else do we have to work on?

So far:
Me - MG Stuff, probably replacing trans mount, and changing trans and diff oil. Maybe more.
Steve - something

[Native]

I'll be there. Not sure with what to do, but I'm sure I can come up with something.

[Loren]

Nice, casual day in the Groj. Steve, Philip, Ben and Andrew came by.

Steve got some dash lights and plastic bits replaced on his Toyota pickup. Philip got some pointless plastic bits removed from his Dodge, er... BMW. I got a lot of stuff done on the MG, and it's back to operational status.

I kept going over the list of things that I got done and wanted to do on the car... I knew I was forgetting something. Now I remember. I was supposed to do a compression test!

Things that were done on the MG:
Rear brake hose replaced, brakes bled.
Driveshaft bolts checked/tightened.
Multi-piece speedo cable removed, but not replaced (one piece replacement cable was wrong part).
Trans and diff fluid levels checked. Both were full, and very clean, so didn't bother to change fluids.
Didn't replace the trans mounts, gonna have to pull the engine to do that, dang it!
Removed, cleaned and regapped spark plugs. Checked plug wires, distributor cap and rotor. All good.
Put a bore scope down the cylinders. Things look clean, and I found the flat-top pistons that I hoped to see. (any other year of 1500 Triumph engine has dished pistons and lower compression, the 76 is supposed to have flat-tops)

[Native]

Yep, was a good day, with good company.

I did replace some dash lights - there are 6, and only 4 were working (and, cuz I was in there, I did the one that lights the ashtray too - why not?).
Well, when I was done, I couldn't see any of 'em - figured it was bright sunlight and my cruddy vision. Nope. When I got home, and got to where I could see, I could see - I had no dash lights at all.
So, I took it all apart again, and in so doing learned I'd not plugged in the dimmer switch. Doh! So, I did, the lights all work, and I put it back together. Wanted to see it in the actual darkness, so went back out later. Sure, they all work, but now I have an airbag light on! Double-doh! Well, some quick interwebz tells me there's several things I coulda done that might have pissed-off the SRS system, and I decided to let it wait til this morning.

And good karma fell upon me, as when I started the truck, the light went off. And all the bulbs still work! Whew.

I can't even change a lightbulb... lol.

[Loren]

I can't even change a lightbulb... lol.

I spent half the night looking at carburetor options, and did order a carb and manifold from England. But, ended up with exactly the same carb (maybe slightly older version, maybe without the auto choke) as what's on the car.

I find talk about carbs to be a lot like talk about suspension on a Miata. You have an old car, parts are worn out. You put on a cheap coilover kit, and it's better... but, not "best". You could spend a LOT more money and time on perfection, but unless you're racing... why? Or... you could just put fresh stock components back on the car and make it like it was when it was new, and be happy!

Ditto carbs. The "cheap coilover kit" option would be the Weber downdraft carb kit. Easy to install, works fairly well and probably better performance than a 40-year-old carb that needs to be rebuilt. But, it's not "all of it", and it does have its quirks. The "ultimate" is the OE dual carb setup that was used on these engines in Europe, but not here. That option is getting pricey due to availability of parts, and I really don't want to futz with dual carbs.

The easy button: just rebuild the existing carb! It may have already been rebuilt, and just needs to be adjusted.

The other option that I was seriously considering was the larger version of the same carb. This one is a "CD150", 1.5" bore. A "CD175" 1.75" bore is also available, and could be made to fit the stock manifold with minimal modification. And, or course, these carbs are "Zenith-Stromberg" brand carbs... the old timers are huge fans of the SU carbs, which are almost exactly the same, just some minor differences. I could get the SU equivalent 1.5 or 1.75" carb... or the metric equivalent!

But, then I got to the science of the matter. Bigger is not always better. This engine, at 6000 rpm (and you really don't want to rev this long-stroke beast beyond that a whole lot, piston speeds get insanely high, not good for the bottom end at all!) should flow 135 cfm. Even slightly warmed over (ported, cammed, etc), it's still only going to flow 150 cfm. The 1.5" carbs should flow about 137 cfm max, which means the engine would run out of steam at 6k... but, I kind of WANT it to do that to not encourage over-revving! The 1.75's are good for around 210 cfm, which would be overkill and probably not idle as well.

So, I'm leaning towards just rebuilding that carb that I'm getting from UK. Get it in good working order, and with an old school manual choke.

Oh, the manifold? And why did I order it?

The stock single-carb Spitfire/Midget 1500 manifold is a "log" manifold. Carb goes into a log, and 4 ports go out to the engine. 90-degree angles for airflow EVERYWHERE, and it is known that the two center cylinders tend to run richer. It's not ideal, but it works.

I found reference to, and then FOUND ONE on eBay, a manifold that was used on the Triumph Herald 13/60... same engine, same carb, different manifold. This manifold has nice curved runners that split neatly to the intake ports on the head. That should put more of that carb cfm actually INTO the engine! It's known to fit the engine, AND fit in the car, should be a good simple improvement.

I also looked into the strange "chipping" that appeared to exist inside one of my cylinders. That just led to confusion. I'm going to need to look in there again and really wrap my head around what I'm seeing. I may want to pull the head, give it a look, and replace the head gasket. But, that's not as hard as it sounds. Because the cam is in the block... there's not much involved in removing the head!

[Native]

I'm leaning towards just rebuilding that carb that I'm getting from UK

If you're going to rebuild a carb, and you purchased the same carb you have, why not just rebuild the one you have?

[Loren]

Two reasons:

1. Having a spare means that I can take my time rebuilding the carb, and the car is only down for the time it takes to swap it. Plus, if I screw it up, I can still put the functional old one back on!

2. Pretty sure the one I'm getting has manual choke. I'm one of those silly people who wants a manual choke. Visceral, old school stuff. If it's not, there is a kit to convert from water-choke to manual choke.

2a. I'm just digging into this, and specific info is hard to find regarding which specific carb was fitted to which car 50 years ago. But, the Herald 13/60 that this carb came from ended production in 1971, so should be the simpler CD or CD-S version. Fewer parts, easier to rebuild, less to go wrong. My 1976 Midget is very much "emissions era", probably a CD-SE carb with all sorts of cold-start and emissions doo-dads added to it. All I can tell for sure is that both carbs are "CD150" carbs, mine has a water choke, and the one I bought appears to not have that. The one I bought also has the needle adjustment on the bottom, where mine is done through the top with a special wrench. Details, details.

But, yeah... I'd hate to tear apart my functional-but-imperfect carb only to put it together wrong and make it worse... and then not be able to drive the car until I figure it out. That's the big reason for getting a spare to play with.

[Native]

Spares/Plan B. Got it.