140 engine rebuild

[erco]

I can't get my 140 crank unfrozen so it's going to be a bear to tear down, and I dread what I will find after reading the good stuff to think about in this thread....

Yikes that sounds bad, 65Monza140. Any idea how long since the motor last ran, and/or was it stored outside for a long time? If it's all that seized up it might not be a great candidate for rebuilding. Could be a challenging teardown. Start by removing the heads, see if the nuts & rocker studs come off without turning the long cylinder studs in the block. Then remove the top blower cover, which will grant you access to some of the CR nuts, depending on the crank position. You may be able to remove a few CR/piston/cylinder assemblies as a unit. For the others, see if you can slide the cylinders off the pistons, then remove the bolts holding the block together to get the crank out with the remaining CRs.

My 140 sat in my garage for 22 years. When I started the teardown in 2022, I didn't want to turn the motor for fear of scoring cylinders, bearings, etc, but oops, it spun quite freely when I tried to remove the HB bolt. Happily, nothing was damaged and my rebuild was mostly a ring, valve and reseal job. Bearings, cam & lifters were fine, they had only 10K miles on them and had almost no wear.

Good luck with your teardown, penetrating oil and a rubber mallet are your new best friends.

[Dennis66]

I agree with erco. Start with the head bolts (follow sequence - reverse the tightening sequence). Once heads are off, you can determine if / how bad the cylinders are. You may find one or more heavily rusted cylinders (I have a 145 CID that is like that - heads were junk). Often, with heads removed, the engine will turn just pushing the piston / cylinder as a solid unit. If this happens, you will be able to undo the rods. Have a good look at your heads too, valve seats and head gasket sealing surfaces (what made my heads junk).
If you will need cylinders, I have a set of 110 cylinders and pistons from a 66 110 engine that I can make you a great deal on as many as you need. No visible ridges in the cylinders. Dennis

[65Monza140]

Hi Guys, sorry for the delay in reply. Been busy with the family stuff for a while now and have not been able to do much but spray penetrating oil into the cylinders every week or so.

I appreciate the encouragement and the advice. I'm really hoping that it's not bad news for the heads. If the cylinder seat in the head is damaged is this repairable by a good machine shop? Can't removed materiel be compensated for by thicker head gaskets?

Valve seats are another matter, I know.

I'll keep you posted as I get into it, and thanks again for the advice and experience.

I

[65Monza140]

Still not sure why it won't turn, but It's sure damaged:

After removing the block top/fan cover, the #6 rod cap is loose and the #5 is gone. The rod is broken just outboard of the rod journal, and the cylinder base inside the block is blown out, along with the top of the block where the cylinder sleeves into
it. The #6 piston bottom of the skirt is gone on top, and the inside of the block there is pretty beat up.

No other damage is apparent from the top of the engine. Pretty sure this block is not serviceable without a lot of specialty work. I'll pull the heads next and see how bad they are.

Sigh.

[Dennis66]

Yeah, that block is toast. Good chance the top cover is damaged as well. Dennis

[erco]

Ouch! That is serious damage. The crankshaft took a serious beating too. Even if it looks ok, there may be cracks. Magnaflux at a minimum, better to replace it.

Probably best to start looking tor another engine to rebuild now. You may find more damage inside your current motor as you disassemble further. It was was either driven too hard, poorly maintained, or poorly built.

[65Monza140]

It's going to be a complete disassembly and agree, I'll have to use the spare RM block to keep it stock and salvage what I can. Are Right side block halves special? I seem to remember something about the "front" of it around the cam/crank seals? I have several R sides from different blocks, and need to choose the correct one for '65 (RM?) use.

Will at least magnaflux the crank since they are not cheap to replace, and have the cam inspected by a trusted machine shop, and the heads too, if they look ok.

I'll need new rods on top of new pistons, cylinders, lifters, and what's behind door number 3....I think what was left of #5 piston hit the head at speed, so might have valve damage there. Did I mention #6 rod cap is real loose and was on the way out too? Hopefully the L head is OK....

I'll take more pictures as I get into it, at least to have on this thread, but would really appreciate all your thoughts as I go.

Thank you guys!

[66vairguy]

If I understand you statement, you are considering mixing block halves? DO NOT!!

The Corvair engine block crankshaft and cam journals were machined with the block together as a UNIT. Mixing different block halves MAY result in out of round journals!!!!!

This issue has come up before and caused folks a lot of grief until they figured out the block halves were mismatched causing issues with the crank shaft and cam binding in the block, or too loose in the block.

[65Monza140]

Well, that's good to know. I have 4 blocks, all completely disassembled, and no way to know which half goes with which serial number stamped half, then.

Take that back. One FC block is easy to tell due to the fill/dipstick casting on the lower right side.

Any help in this regard is appreciated!

Thank you for letting me know! That would have been an expensive lesson.

[66vairguy]

Well, that's good to know. I have 4 blocks, all completely disassembled, and no way to know which half goes with which serial number stamped half, then.

Take that back. One FC block is easy to tell due to the fill/dipstick casting on the lower right side.

Any help in this regard is appreciated!

Thank you for letting me know! That would have been an expensive lesson.

Just a theory --- with the correct tools you could verify if the journals were round AFTER you bolted the block halves together, bolts torqued to spec. It comes down to a lot of time and possibly the expense of precision bore measuring tools. Unless you have a rare block number, it may not be worth the effort.

A shame GM did not identify both engine block halves, but the extra effort was not justified as they only sold COMPLETE blocks for repairs. People wonder at the penny pinching, but a million pennies is nothing to dismiss.

[65Monza140]

Good point on the money end of GM's block production.

Thank you for the info on measuring the bores after bolting it together. I will see if I can make a good guess as to which right half it is and assemble it to measure. Most of the block pieces seem to be in good shape.

Do you know if there was much difference between 98, 102, 110 and 140 blocks besides the engine number? I think I have those blocks.

Thank you again for your willingness to help! It means a lot.

[Dennis66]

I believe the 98-102 blocks have the 1/8 NPT threaded hole on the right side for the oil pressure sender. Later blocks do not as they had the sender in the alternator adapter block. Depending on how clean the blocks are, you might be able to compare stains to match block halves. Dennis

[65Monza140]

I didn't know about the oil psi sender! Thanks!

Most of the blocks are cleaned up. The spare RM stamped side and another R side are not clean, so I'll start with that one unless it has the psi sender hole.

Thank you again!

This will be a journey, but it's therapy to me. Takes my mind off all the deterioration around us for a while, and is a "building up" of something worthwhile.

I really appreciate all your knowledge and experience!

[erco]

This will be a journey, but it's therapy to me. Takes my mind off all the deterioration around us for a while, and is a "building up" of something worthwhile.

Ain't that the truth! Merry Christmas!

[SpiderMan]

Getting some money some am excited to get back to the 140 engine rebuild.
Status:
Engine in my basement broken down to the block.
Cylinders checked for wear and honed - all ok accept no 6.
Three head studs are toast the outward threads are rusted beyond recognition. They came out of the block Ok. I have since chased the block threads and are ok.
Cleaning/derusting/wire brushing continues.
Both heads have worn exhaust valve guides. All seats look good. I will replace worn guides and recut/polish the seats. I'm throwing the dice and don't plan to spend the money to get them deep seated. Nobody in NE wants to do it anyway.
Both heads need a choke bimetal piece as they are heavily rusted.
Need a new temp sensor which I have as it came with the car.
Oil filler tube missing.
Breather assembly missing - bought one used.

Anything missing I will first try to fill with the parts from the 95 engine with blown head that's currently in the car.

I have not split the block and don't plan to. I have made many measurements with cam and crank still in the block. All measurements are within spec. The crank rotates by hand smoothly with no discernable play.

The lifters are in question because I can't figure out how to get them out to measure and confirm the dome is in tack. Seems like there's a ridge of crud around the opening that prevents progress.
Suggestions?

I have the flywheel/clutch out but not completely apart. The clutch friction pads don't look terribly worn, and neither do both metal friction surfaces. The rivets are all sound. Gonna throw the dice on this one too and not replace with screws since I don't have the gear to accurately drill and retain concentricity.

Is it necessary to get the flywheel resurfaced?

[kmart356]

The lifters are in question because I can't figure out how to get them out to measure and confirm the dome is in tack. Seems like there's a ridge of crud around the opening that prevents progress.
Suggestions?

Try this (non-invasive) approach first. Use a shop-vac to suction away any crud aroud the lifter bore then use a strong magnet that fits in the bore to see if it will "grab" the lifter enough to pull it out.