'62 Monza convertible "Ralphie"

[66vairguy]

Nice job on the crankshaft. As you learned, just because something is NOS doesn't mean aging hasn't affected it. Are you going to have it magnafluxed?

BTW - one issue with the Vega aluminum blocks was inconsistent pour mix (high silicone mix developed by Reynolds Aluminum). Early on this was such an issue a lot of Vega engines had to be replaced by GM. GM wanted to be re-imbursed by the Reynolds Aluminum, but it was found that the GM guys had "cut costs" by modifying the storage and alloy pour process specified by Reynolds Aluminum per contract. It ended up turning into a big finger pointing legal fiasco between GM and Reynolds Aluminum.

The Corvair "carboned up engine" is a problem I've seen on old Corvair engines I take apart. Some are so bad all the rings are jammed up with carbon. Even today there is a stubborn Corvair myth that you have to increase the jet sizes two to four sizes to keep the engine and heads cool. Not so.

GM did run larger #53 jets on the 64 model year FCs and A/C cars due to the larger displacement engine that caused lean spots in fuel delivery. In model year 65 a power enrichment valve was added to eliminate the lean spot and the jet size returned to #51. The 66 model year jet size dropped to #49 on manuals, #50 on automatics. The new idle emulsion circuit allowed for a smoother idle and off idle transition with a leaner mixture.

I run model year 1965 carburetors with the #51 jets and even on a 85F day with the A/C going the car runs fine, no overheating, no pinging.

As I remind folks, Chevy tested Corvairs at desert proving grounds at high temperatures and they did not overheat with the factory installed carburetor jet sizes. The exception was the model year 1967 emission control engines with air injection and A/C as they did overheat at high temperatures. I suspect this is one of the reasons model year1966 140HP Corvairs with A/C were exempted from the California emissions control devices.

[Dennis66]

Finally!!!!! I haven't updated in about 6 weeks. First: "The Curse of the Corvair". I have to explain. From the last registration I found in the glove box (California, 2005) this car was owned by a guy named Dennis. The crankshaft broke, the car went into a shop, parts were ordered, and somewhere along the line, Dennis #1 died. The car was tied up with storage, estate things, etc., but finally settled and was sold in 2021 to a guy in south Florida named...Dennis. Dennis #2 had restored several cars including a previous Corvair. He started on this one, but got sick. Realizing that he wasn't going to be able to see the project through, the car went back on ebay, where it was purchased in November 2022 by me, Dennis #3.
I typically am pretty healthy and hardly ever get sick. In February, I got a bad case of bursitis in my left elbow and was laid up for about a month. In April, my dermatologist found a basil cell in my neck. Twenty two stitches, and I was down for a few days. On May 8th, I went in the hospital for 3 days to be checked out for double vision and the possibility of a stroke. Completely clear of any stroke possibility, but we're still working on the double vision. If I were superstitious, this Corvair would be going - BUT I'M NOT. I'm going to get this car going and break "the curse"
Moving forward, Saturday I cleaned the crank up. Monday, I got the block set up, put the cam, bearing shells, and crank in, put plastigage on the cam journals, and crank mains, and torqued the block bolts. I then removed the upper half and measured the plastigage, and everything was within specs. I had been worried about the #1 main because of the crank having been broken, but it checked out fine. It was kind of tricky getting the threadlike plastigage in position with my double vision, but I pulled it off. Next step is to mount the cam gear, and put the bottom end together.

Plastigage strip on journal

Plastigige compressed and measured

[66vairguy]

It sounds like you've reached the "Golden Age". As a buddy who just got out of the hospital says -- "It's called the Golden age because the doctors are taking all your gold!".

His seven days in the hospital came to about $100,000.00 without insurance!!! Fortunately he has health care insurance and the hospital was in his insurance group so his out of pocket was minor, relatively speaking.

[Dennis66]

I'm fortunate on three accounts: The hospital is less than 10 minutes away. I have good insurance, and it's in network. My older daughter is the Charge Nurse for the floor I was on, so before I was even fully admitted, she already had her best nurse assigned to me (and their shift hadn't started yet), and about an hour after I was in place, I was moved to a private room with great treatment.
Back to Corvairs: So I now have a theory on broken crankshafts. Note in the picture how deep the balancing hole is bored in the broken crank - where it broke - and how shallow the hole is drilled in the new crank. Dennis

crank comparison

[Dennis66]

No pictures (yet), but cam gear installed tonight. Everyone seems to have their own interpretation of what is "right". My method was to use a bearing separator on the #1 journal - flat side towards the journal. I then used a two way slotted puller, a spacer larger than the cam end, a thick flat washer as a press. I greased the camshaft hub, positioned the gear snugged everything, and checked level / square. I then heated the cam gear for a bit and LIGHTLY tightened the gear puller drawing the gear down onto the hub. I put it on about halfway, then applied a little more heat and continued until it bottomed. Tomorrow, after it has set overnight, I will check clearance of the washer. Some said they kept pressure on the gear while it cooled. I didn't. If there is any play tomorrow, I can always add a little heat again, snug it down and then let it cool. I figure after the caveman beat down the last guy did on this, I have to have done a better job. There had been no runout on the cam hub after I removed the old gear. Dennis

[66vairguy]

The deep balance hole might have contributed, but there is an abundance of evidence showing Corvair cranks typically break in this area. An opposed engine should be well balanced, but the rod journals require the pistons on one side to be offset from the other side and this promotes crankshaft flexing. The failures typically happen at the 5/6 rod area since that end of the crankshaft reacts with the flywheel motion. This is why the Corvair flywheel is a three piece damping unit.

Corvair enginner Benzinger explained this at a Corvair convention, and before anyone finger points --- the original Corvair engine was designed ONLY for a PG with a flexplate connecting the converter to the crankshaft (typical). The last minute decision to install a 3 speed manual was when Benzinger and team found the infamous #5/6 issue with a solid flywheel. Their fix was design a unique flex-flywheel, otherwise there never would have been a manual transmission Corvair!!

BTW --- Porsche first six cylinder prototype was similar in layout to the Corvair engine. No Porsche DID NOT have anything to do with the Corvair engine design, but they had a friendly relationship with GM and there are pictures of Corvairs parked outside Porsche headquarters. GM looked upon Porsche in the 50's and 60's as a "cute" little company and they often welcomed Porsche folks at GM to observe and learn (at that time GM got a lot of respect from European manufacturers). Porsche quickly discovered the flat boxer six crank flex issue. Their next prototype increased the number of main journals and there were TWO at the flywheel end. The rest is history!

Keep in mind the Corvair engine was suppose to be an econobox engine that far exceeded original expectations and the Porsche engine was designed as a premium vehicle engine so higher costs were acceptable.

[Dennis66]

Ever wonder what those two big holes in the factory cam are for? So yesterday's project was cleaning and painting the cylinder studs (on the case halves). After drying overnight, today was bottom end assembly day. First order was thoroughly clean the case halves (again). I took the two allen head plugs from the front of the lifter galleries and ran brake cleaner and then compressed air through all oil passages. Then I did the same with all oil passages in the crankshaft. I sat the left case on a milk crate, installed the bearing shells, smeared a coat of clean motor oil on the shells, and carefully sat the crank in place. Next I positioned the crank keyway at the 9 o'clock position, carefully aligned the cam gear, and rolled the cam into position (cam keyway at the 6 o'clock position. Kind of hard to see the marks through the flywheel bolt hole, but they were there. I rolled everything 720 degrees, and it all still lined up okay. Now I put sealer on the three corners of the left case, and carefully positioned the right case. I installed the 4 outer corner case bolts and nuts hand tight, them put he whole assembly on top of the crate resting on it's lower (pan) surface. I put the remaining 4 bolts in. and followed sequence tightening them to 25 ft lbs first, then the final torque of 55 ft lbs. Again, I spun the rotating assembly another 720 degrees and everything is fine. I mounted the bellhousing face of the block to my engine stand. I mounted the fuel pump eccentric (probably won't see any use), the little spacer, and the distributor drive gear. Oops! There's the pipe plugs still sitting on the bench . Yes, they go BEHIND the cam gear. Fortunately, the holes line up perfectly, and the plugs just fit through the holes
After oiling and wrapping the crankpins, I wrapped the engine up and decided to start checking ring gap. I removed the piston from #6, removed the rings, and while the .020 pistons are in excellent shape (hardly any wear), the cylinders have no ridge, and a little cross hatch still showing, the rings seem to have about .020 of end gap. I did a search for rings (Hastings, Mahle, and Grant) and .020 seems to be a more rare oversize. I ended up in my Clark's catalogue, and will probably place an order Tuesday. Dennis

[66vairguy]

Ever wonder what those two big holes in the factory cam are for? So yesterday's project was cleaning and painting the cylinder studs (on the case halves). After drying overnight, today was bottom end assembly day. First order was thoroughly clean the case halves (again). I took the two allen head plugs from the front of the lifter galleries and ran brake cleaner and then compressed air through all oil passages. Then I did the same with all oil passages in the crankshaft. I sat the left case on a milk crate, installed the bearing shells, smeared a coat of clean motor oil on the shells, and carefully sat the crank in place. Next I positioned the crank keyway at the 9 o'clock position, carefully aligned the cam gear, and rolled the cam into position (cam keyway at the 6 o'clock position. Kind of hard to see the marks through the flywheel bolt hole, but they were there. I rolled everything 720 degrees, and it all still lined up okay. Now I put sealer on the three corners of the left case, and carefully positioned the right case. I installed the 4 outer corner case bolts and nuts hand tight, them put he whole assembly on top of the crate resting on it's lower (pan) surface. I put the remaining 4 bolts in. and followed sequence tightening them to 25 ft lbs first, then the final torque of 55 ft lbs. Again, I spun the rotating assembly another 720 degrees and everything is fine. I mounted the bellhousing face of the block to my engine stand. I mounted the fuel pump eccentric (probably won't see any use), the little spacer, and the distributor drive gear. Oops! There's the pipe plugs still sitting on the bench . Yes, they go BEHIND the cam gear. Fortunately, the holes line up perfectly, and the plugs just fit through the holes
After oiling and wrapping the crankpins, I wrapped the engine up and decided to start checking ring gap. I removed the piston from #6, removed the rings, and while the .020 pistons are in excellent shape (hardly any wear), the cylinders have no ridge, and a little cross hatch still showing, the rings seem to have about .020 of end gap. I did a search for rings (Hastings, Mahle, and Grant) and .020 seems to be a more rare oversize. I ended up in my Clark's catalogue, and will probably place an order Tuesday. Dennis Cam installed.jpg

LM engine factory "compression" ring gap is 0.013 - 0.025". NEVER go to the minimum, especially with a slightly larger bore. Years ago I looked at what the successful rebuilders were doing and they said 0.018" is typical, that is the gap I used. Of course oil ring gap is different - 0.015 - 0.055

If the cylinders still show some cross hatch, piston groove gap, and the rings look good with a 0.020" cylinder gap, then I would put the existing pistons and rings back in place (to same cylinder they came out of). New rings and honning the cylinders is tempting, but are you going to put over 50,000 miles on the car? Just my 2 cents.

I used Hastings "chrome" plated cast iron rings on one engine and it took a LOOONG time to seat well. The fellow who did my heads said "There is nothing wrong with a quality cast iron ring and they will seat within a few hundred miles (they did). On my second cars engine I used Grant cast iron piston rings from Calif. Corvair. Since I'll never put over 50,000 miles on my car the cast iron rings will be fine.

Over the years there have been complaints on Corvair forums about "Deeves" piston rings.

I sure you know new rings will require re-doing the cross hatch cylinder pattern, especially with a Moly or chrome plated cast iron ring.

[Dennis66]

Thanks. I believe I will go that route (and save about 150.00 ). I was thinking back to the Greenbrier I rebuilt a few years back and IIRC, I went .016 on that one. I saw where someone on the CORSA forum said .013, and decided .020 was too far out. Last night O looked in my manual and it said .010 - .020, so depending on how the other cylinders look, I may be good to go. Itching to get this back together as a disassembled engine (or whole vehicle) takes up a whole lot more space than an assembled one. Dennis

[66vairguy]

Thanks. I believe I will go that route (and save about 150.00 ). I was thinking back to the Greenbrier I rebuilt a few years back and IIRC, I went .016 on that one. I saw where someone on the CORSA forum said .013, and decided .020 was too far out. Last night O looked in my manual and it said .010 - .020, so depending on how the other cylinders look, I may be good to go. Itching to get this back together as a disassembled engine (or whole vehicle) takes up a whole lot more space than an assembled one. Dennis

Some folks like the ring gap as small as possible to minimize blow-by. While that is logical, the reduction in blow-by is not much more than at 0.020, in fact one fellow took apart an engine with "some" blow- by only to discover a ring gap of 0.185"!!!!!!!!!!!

The problem, as I see it, is air cooled engines operate over a wider range of temperatures vs. a water cooled engine. The hotter the piston the smaller the ring gap gets. If rings bind due to a too small gap then you've got a broken ring and often a gouged cylinder.

On a daily driver I want the closest rebuild specs for a long lived engine. On a hobby car (probably won't see 40,000 in my lifetime) I go loosey goosey and the engine runs strong due to lower parasitic friction losses. Just me.

[Dennis66]

So today's project (while waiting for confirmation on my bearing question). Checking piston rings. I'm removing each piston from it's cylinder. The pistons / rods are all numbered, so I lightly engraved each cylinder with it's corresponding number. I did this on the little block on the top base. It's been determined that so far, all my gaps were within acceptable specifications. I've noticed that the left bank (2-4-6) has considerably more carbon buildup in the ring grooves. I also found this: Top groove - square, middle groove one bevel, with a dot on the opposite side of the bevel. The dots were facing DOWN, towards the crankshaft. This put the bevels facing UP, towards the combustion chamber. Now I've rebuilt plenty of engines. Usually, I use new rings, which come with detailed instructions. Here, I'm going behind an obvious "less than quality" rebuild job. I've always heard or learned that a DOT should go UP. I've done plenty of engines where the top ring had a bevel and the bevel went up, facing the combustion chamber (square rings don't seem to matter in most cases, unless the have a dot). I'm seeing where the second ring should have the bevel facing DOWN (this would jibe with the dot facing UP). This is my plan unless someone says otherwise. Dennis

[66vairguy]

So today's project (while waiting for confirmation on my bearing question). Checking piston rings. I'm removing each piston from it's cylinder. The pistons / rods are all numbered, so I lightly engraved each cylinder with it's corresponding number. I did this on the little block on the top base. It's been determined that so far, all my gaps were within acceptable specifications. I've noticed that the left bank (2-4-6) has considerably more carbon buildup in the ring grooves. I also found this: Top groove - square, middle groove one bevel, with a dot on the opposite side of the bevel. The dots were facing DOWN, towards the crankshaft. This put the bevels facing UP, towards the combustion chamber. Now I've rebuilt plenty of engines. Usually, I use new rings, which come with detailed instructions. Here, I'm going behind an obvious "less than quality" rebuild job. I've always heard or learned that a DOT should go UP. I've done plenty of engines where the top ring had a bevel and the bevel went up, facing the combustion chamber (square rings don't seem to matter in most cases, unless the have a dot). I'm seeing where the second ring should have the bevel facing DOWN (this would jibe with the dot facing UP). This is my plan unless someone says otherwise. Dennis

The Grant and Hastings ring instructions show the DOT facing up. Usually the inner bevel is facing up EXCEPT the Hasting Type 126, 610 ring called a "Reverse Torsional Taper Face" that has the DOT facing up and the inner bevel FACING DOWN. Not sure if it was used on the Corvair ring sets.

[Dennis66]

Back to progress. Yesterday was removing pistons from cylinders (they've been in the same position since 2005 - not rusty, but needed a little help and some WD-40). I removed all the rings, cleaned carbon from the ring grooves (more buildup on the left bank). Found all the scraper rings (second ring) to be mounted with the tops facing the crankshaft (upside down). I checked gaps on all rings and found all the scrapers to be right around .020, all the compression right at or just over .020, and the oil rails at around .030 - .040.
After this, I very lightly honed the cylinders. There was still some cross hatch showing from the last rebuild (it's .020 oversized), but the cylinders were also slightly glazed. I oiled the cylinders, then gave them an external scrubbing with vinegar and a wire brush. Then I scrubbed them down with a baking soda / water mix, hosed them off, blew them off, a shot of brake cleaner, blow off again, then each got a good coat of paint. Note: to protect the cylinder tops from getting painted, a Folgers Coffee can is a perfect fit.
I let the cylinders dry overnight, and this afternoon I scrubbed the INSIDES with soap and water (purple power). I rinsed them, and oiled them, then I double checked ring positioning (oil rails at 9 and 3, scraper at 12, and compression at 6) and lightly oiled the rings and piston skirts. I used a compressor and installed all pistons in their respective cylinders. I sat the cylinders on a defective Corvair cylinder (from a previous build) to install the pistons and rods. For those who may not have experience, I install the compressor (wind up type) set the piston skirt in the top of the cylinder, then lightly tap all around the top of the compressor to make sure it's evenly seated all around the top of the cylinder (having the edge of a ring pop out and break is a pain and expensive. When all assembled, I wrapped them all in plastic grocery bags and stored them on my bench until ready to install on the block. The rod bearing shells will be fitted at that time.

[Dennis66]

Well, today was "Judgement Day". Pulled the case halves apart, pulled bearing shells and I did find that there were two separate numbers with the #4s having a number 2005, and 2-3 being 2111. Interestingly ALL except the flanged bearing did have a bit of orange paint on the edge - all of them. One half the offset was on #4 and one half was on #2. There was no sign of scuffing. I can move forward now. Dennis

[66vairguy]

Well, today was "Judgement Day". Pulled the case halves apart, pulled bearing shells and I did find that there were two separate numbers with the #4s having a number 2005, and 2-3 being 2111. Interestingly ALL except the flanged bearing did have a bit of orange paint on the edge - all of them. One half the offset was on #4 and one half was on #2. There was no sign of scuffing. I can move forward now. Dennis

Well that was worth the effort. Glad you caught it. Thanks for posting the number differences.

[Dennis66]

So progress report time. Started off Friday afternoon by greasing the blower bearing. I hear about tool to do this. I ended up drilling and tapping a 1-1/2 freeze plug and installing a 1/8 NPT grease fitting. ALMOST worked. I used a piece of 1/8 cork to make a gasket, took a really big washer and made 4 notches to align with the 4 holes on my 1966 top cover / blower bearing. THAT did the trick. I could then slowly pump grease and I felt it go past the seal. Pumped a little more and saw just a trace from the bottom seal. Being concerned about the grease expanding and oozing over my engine, I then took a propane torch and heated the hub up a little. Some excess grease came out of the top seal. I cleaned that off, let it cool a bit them spun it up using the wire wheel on my bench grinder. Just a little more grease and i wiped it off and believe it's good to go.
While doing this, the self etching primer on my short block was drying. I had made covers for the cylinder holes and masked everything else off. After the primer dried good, the block got a good coat of machine gray. While most of the block had been in fairly good shape, some of the aluminum parts had a light powder, so everything got cleaned and painted.
After drying overnight, I installed the 6 cylinders and rear cover. NOTE 1: when doing this, don't forget the oil slinger (I didn't). Note 2 when installing bearing shells in the block and rods, make double sure everything is clean - block and rod surfaces where shells will go, block mating surfaces, rod caps and rod surfaces, inside and outside of bearing shells. A light smear of oil on each bearing surface and bolt it all up. The # 1 rod cap seems to be the most difficult to torque. There is a large crank counterweight there and the right combination of socket and torque wrench to fit in. Note 3: I used copper cylinder base gaskets. There seems to be "some do, and some don't" as far as putting anything on those gaskets. I didn't. My thought pattern: I don't put anything on a copper oil plug gasket, why should this be any different? Note 4:when assembling the block, don't forget to reinstall the oil pickup tube I I figure a lot of builders will be excited at this point and a little reminder of these things may save someone from having to "go back in". It feels good to finally have these bearing all put together and sealed up. The top covers in the picture are just on with a few bolts as an extra measure of keeping any dust or dirt out of there. The garbage bag wraps go over everything else. Next up painting and installing lower cylinder covers, and starting on the heads. Dennis

Cylinders and pistons installed