1966 Corsa Convertible

[JohnDB]

It's been a while since I've been back to this topic, the Monza has been getting all the attention lately. Not that the Corsa is being ignored, in fact I've still been putting some miles on it at least once a week.

Last week's run to Lowe's:

Today was a run to Advance Auto to recycle the ATF that came out of the Monza. Need to get the carb rebuilds on the schedule, but it's still not urgent.

[gbullman]

I can relate to the late season miles, I filled up with Sta-bil added a couple of weeks ago and have pretty much gone through that tank. At least one more tank with sta-bil for this season. One of these storms is going to be cold enough to bring out the road treatment then my season is over for a while.

Enjoy it while you can!

[JohnDB]

This feels very familiar:

The Corsa has been getting some miles as well in the past weeks, but I got tired of the oil drips and took the oil filter adapter out again. Next step is to make sure everything is super flat and re-assemble.

[JohnDB]

I spent some time with my homemade milling machine - also known as some sandpaper on a piece of glass - and still had a pretty bad wobble when I put the adapter on top of the engine without the gasket. Decided to take it to work and see what could be done, turns out the middle ribs were high by several thousandths. Didn't take long to get it fixed up though:

I was able to put it back on the engine today with a new gasket and new bolts - a thin smear of black RTV on both sides of the gaskets to be safe, letting it setup for a while before I put the oil filter and fuel pump back in:

Also decided since the fuel pump and lines were out, and I already have the rebuild kits, why not rebuild the carbs. Started with the driver side:

Wasn't too bad inside, but there were a few passages that were at least partially clogged:

Switched to brass floats as the plastic float used in these Holley 5200 carbs has a tendency to absorb fuel:

All back together and remounted:

If all goes well I can get the passenger carb done tomorrow and get back on the road.

[gbullman]

We’re both working on mid season projects!

Glad to see you found the likely culprit for that leak. Never would have expected that but it totally makes sense given what you’ve been going through. Should be fun with the carb rebuilds, let us know how it runs afterwards.

I finally got to freeing up the rear camber and front right caster adjustments so the alignment shop can take another crack at it (appointment tomorrow). While it was up on the lift I replaced the leaking valve cover gasket as well as both heater hoses coming off the engine. All of that went well. I also snugged up the oil pan bolts around the cam gear and that started a significant leak (3/8 of a quart in 5 or 6 days of sitting). I put some fresh sealant on each of those bolts and retightened, so far it is staying dry. I will hopefully get a chance to but some miles on tomorrow after the wheel alignment and see what happens with oil consumption.

I’m planning to head up to the car show at Clark’s in September, should be quite an adventure but my car is ready for it.

[doug6423]

I've never seen a carb setup like that. I'm guessing that is some aftermarket setup from back in the day??

[Dennis66]

Apparently so. I did a brief search and there are some poor pictures on the web of the same setup. One has to ask "is channeling a two barrel into a single hole an improvement? I would imagine that a modification to the intake (who wants to take that risk) might be beneficial, but you would have to be careful. The GM engineers obviously had a reason for where the original (two) carbs were mounted as far as port balance and flow were concerned. Dennis

[JohnDB]

I've never seen a carb setup like that. I'm guessing that is some aftermarket setup from back in the day??

This was a kit sold by Clark's years ago called the "Ultimate Carb Kit" - it consisted of 2 Holley 5200 carbs (licensed copy of a Weber 32/36), manifold adapters, and linkage. These are progressive 2 barrel carbs that were found on Pintos, Vegas, and any other number of cars in the late 70s and early 80s - they were available at just about every parts store as well and parts were everywhere.

Apparently so. I did a brief search and there are some poor pictures on the web of the same setup. One has to ask "is channeling a two barrel into a single hole an improvement? I would imagine that a modification to the intake (who wants to take that risk) might be beneficial, but you would have to be careful. The GM engineers obviously had a reason for where the original (two) carbs were mounted as far as port balance and flow were concerned. Dennis

Hard to say if forcing 2 barrels into one intake port is effective, but I can say it works pretty well. One of the selling features of the carb kit was that the carbs were easier to tune and keep in sync. I've seen a few manifold setups that mount a 2 barrel carb to both intake ports on a 140 head, and other setups to put multiple carbs on heads with only 1 intake port, so there are plenty of options either way - the marketing probably wins over the actual performance in all of these examples

Got the passenger side carb off, cleaned up, and all back together. Overall it was a little dirtier inside, but still not as bad as I expected.

Hopefully tomorrow I can get it back on the manifold, fuel pump hooked back up, toss an oil filter on, and do some carb tuning.

[Dennis66]

Ran a few of those carbs. The original Holley ones on my Vegas back in the day, I never could get to work right. I replaced them with the earlier manifolds and Rochester 2BBL carbs. Had a few Webers on my Isuzus. Those were good carbs. If you can, make a picture of the adapter before you put the carb back on. Thanks, Dennis

[JohnDB]

Ran a few of those carbs. The original Holley ones on my Vegas back in the day, I never could get to work right. I replaced them with the earlier manifolds and Rochester 2BBL carbs. Had a few Webers on my Isuzus. Those were good carbs. If you can, make a picture of the adapter before you put the carb back on. Thanks, Dennis

Sorry, I didn't see your post before I put everything back together. The adapters are made by Offenhauser, there might be a few pictures a few pages back in this thread when I had them off to do the top cover and fan bearing. They show up on eBay sometimes too.

So far so good with everything reinstalled. I'm seeing a little bit of oil on the engine number still, but hard to say if it was hiding under the shroud and still getting blown around, I cleaned up as much as I could, but I'm sure I didn't get it all. The carbs seem pretty good, throttle response is better and idle is steady so far (had idle creep up to 1000 or so sometimes when it was hot, thinking there may have been a vacuum leak somewhere). Need to get some more miles on it and do a little tuning - I tried to get a unisyn hooked up with a plastic yogurt container as an adapter but it had too many leaks and never moved the ball. I think I have a vacuum gauge so that might be the next step.

[gbullman]

Nice, hope you get a chance for some miles. I’m good to go for a while, nothing urgent that needs doing right away.

[Dennis66]

I just noticed that there IS a good shot of the adapter in the post showing the Weber disassembled. Dennis

[JohnDB]

Well, I got a few miles on the car and it still leaks oil. Probably about as bad as it previously leaked. At this point, I think the rear housing is the next likely culprit, but I'm not in a hurry to swap it at this point. I have another housing that I need to check over and rebuild the oil pump before I take this one apart.

And it turns out the carbs aren't too happy either. After it got good and warmed up, it stalled a few times at traffic lights and was hard to restart, seemed to be flooding out. I did some digging and found a different spec for brass floats in a similar Weber 32/36, so I pulled the tops and reset to that spec. It seems a little better, but still wants to stall when hot sometimes. Going to check fuel pressure next, since it seems easier than pulling the carb tops again. I picked up a few fittings and have a gauge that should get here tomorrow to setup a test line that will run to the right carb. Most of what I can find online says these carbs like 4psi max, so we'll see how it goes.

[JohnDB]

Got some time today to setup my fuel pressure test line. I was planning to go to the right carb, but everything worked out better to go to the left carb. Not super happy with the brass tee I got from the FLAPS, had to fix the threads on 2 ports before anything would fit properly.

In place and ready:

The weather is terrible here today, currently raining sideways into the garage door. I did catch a break in the rain and got it started, that's too much:

I was hoping to get a few miles on it with the gauge in place to see what it does when it gets hot, but the tee is leaking from at least 2 sides. With that much pressure, and carbs that only want 4 psi max, I don't think there is much point to taking a drive anyhow.

Going to do some research, but I've been slowly collecting parts to convert to an electric pump so maybe now is the time?

[gbullman]

I’m about 2 years with an electric pump and no regrets. I bought the pump from Clark’s Q3 2021 when my mechanical pump started leaking externally. I am only using an inertial safety switch, putting oil pressure sensing inline seemed too complex to me and I’ve had cars with factory electric pumps that only had an inertial switch so it seemed good enough for this application.

Solved my valve cover gasket leak but oil pan is fighting harder to continue leaking. Expect to change that gasket before the run up to Clark’s in September.

[JohnDB]

I’m about 2 years with an electric pump and no regrets. I bought the pump from Clark’s Q3 2021 when my mechanical pump started leaking externally. I am only using an inertial safety switch, putting oil pressure sensing inline seemed too complex to me and I’ve had cars with factory electric pumps that only had an inertial switch so it seemed good enough for this application.

Solved my valve cover gasket leak but oil pan is fighting harder to continue leaking. Expect to change that gasket before the run up to Clark’s in September.

I looked at plumbing in a fuel pressure regulator, but by the time I modify all the lines to add the regulator on the output of the mechanical pump, I decided to make the move to an electric pump. Some fittings are on the way, along with a Revolution Electric fuel pump controller, and some tubing to make new lines to the carbs. I picked up the fuel pump plug from Clark's a while ago and plan to run the lines to the front of the engine bay. I've got a Carter P4070 pump, suggested all over the Internet for the carbs I'm running, and hopefully I can get the install started this weekend.