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Why don't our engines have cam bearings?
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 05:49AM

Just as the topic says, why are there no cam bearings and what happens when the block surface wears? I'm beginning the rebuild on my Spyder turbo engine and this is an issue to me. I have another question: I'm installing Clark's oversized Pro head studs and the manual states to use an anti seize but another member posted about using 271 Threadlocker. Why?

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Re: Why don't our engines have cam bearings?
Posted by: cnicol ()
Date: January 11, 2020 06:04AM

Unlike regular configuration engines, a horizontally opposed engine with the cam in the middle puts very little load on the cam bearings. Valve spring pressure bears equally on both sides of the cam.

Unfortunately, poor oil quality can result in journal wear and to date, I've never heard of an effective way to repair cam journals. In theory, the cam bores could be align-bored and the block fitted with an oversize-journal cam but the ready availability of substitute engine cases and the Corvair engine's tolerance for loose cam journals has kept us out of the align-bore business.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Why don't our engines have cam bearings?
Posted by: roger65180 ()
Date: January 11, 2020 06:05AM

it doesn't seam to be a big problem or 90 percent would be junk. my question is why are you installing oversized head studs . I have been over 20 lbs of boost when the waste gate failed shut . I had no failure but I believe that is due to my timing curve and boost retard and my intercooler. YMMV. Roger.

Roger R
Madison Wi
62 ct pg turbo
65intercooled 180 4sp,autocrosser
62 Rampy

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Re: Why don't our engines have cam bearings?
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 06:12AM

It had been sitting for many years and the block was covered with so much mouse feces/urine that many of the studs were seized and broke and had to be removed by a machine shop. A few of the holes and threads were damaged so I opted for the oversized studs.
The odometer showed only 17,000 miles, which may or may not be correct. The internals look pretty good and the cam journals are clean with no scarring. Would it be a good idea to go with synthetic oil after breakin? And what oil would you suggest for the breakin?

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Re: Why don't our engines have cam bearings?
Posted by: Lane66m ()
Date: January 11, 2020 06:18AM

Regular 10w30 for break in and first 1500 to allow rings to seat. Then to synthetic. Wise Vair people told me this for my reworked engine.

Al Lane
Ellabell, GA 31308

1966 Monza Coupe, 110 hp, 4 Spd
1966 Monza More Door 110 hp, PG
1968 Camaro SS Coupe 350 CI 295+ hp PG
1964 Greenbrier Deluxe, 6 dr, 80 hp car engine, PG
1947 Farmall A tractor 15 hp


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Re: Why don't our engines have cam bearings?
Posted by: cnicol ()
Date: January 11, 2020 06:26AM

As Al said, 10W30. I will add: Use oil labeled for "diesel". This oil has the ZDDP needed for cam break-in built into the oil. Also, use assembly lube on the cam journals, lobes, and valve train pivots as well as the crankshaft bearings.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts




Edited 1 time(s). Last edit at 01/11/2020 06:28AM by cnicol.

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Re: Why don't our engines have cam bearings?
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 06:31AM

I'm not a professional mechanic but not an inexperienced mechanic. I went through a period of several years that I never want to repeat and haven't touched this project for over 3 years so I'm beginning from scratch on my knowledge. There are many here that are much more knowledgeable than me. I will be posting more questions and would appreciate input whether good or bad. Some questions may seem simple or stupid to some of you but I value the knowledge here. I usually don't take offense to negative input in a constructive way because the poster usually has more experience than me and I want to learn. That being said, give me your true answers/comments.
Thanks,
Chris

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Re: Why don't our engines have cam bearings?
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 06:35AM

cnicol Wrote:
-------------------------------------------------------
> As Al said, 10W30. I will add: Use oil labeled for "diesel". This oil has the ZDDP needed for cam break-in built into the oil. Also, use assembly lube on the cam journals, lobes, and valve train pivots as well as the crankshaft bearings.


I have a 2000 Super Duty with the 7.3 diesel so I usually keep several gallons of Rotella on a shelf. I also use it in vintage generators and small engines that I play with.
Thanks for the info.
Chris

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Re: Why don't our engines have cam bearings?
Posted by: JimBrandberg ()
Date: January 11, 2020 06:58AM

It's a heartbreaker when you're installing a stud and it seizes halfway in, refusing to go further in or come out. Oversize studs are more prone to this and I seldom seem to use them, they are also VERY EXPENSIVE.

If aluminum comes out with the studs I'm not sure an oversize stud will do it. If the aluminum threads seem sound and a stock stud screws in very easy I might use an oversize stud.

When a stud comes out I generally reinstall it with red Loctite. If it goes in too easily I may abort and get it out of there before the Loctite sets while I think about it.

I use the double nuts to remove a stud or a nut welded to the stud if it's already broken off. Heat to the aluminum may help.
I use a rocker stud with a ball bearing inside to install studs, a tech tip I picked up here.
I use a special 13/16 6-point 1/2" drive socket with the end chamfer ground down for more socket to thin hex head engagement, a tip I picked up I think in the CORSA Tech Guide.

I just leave studs alone if they don't come out. Even the rusted away top studs usually since the portion with thread engagement is usually okay. It's a different story if you're lowering the C/R with thicker gaskets but I'm usually not.

Sometimes the cam bearing surfaces are pitted if there's been water or something in there to cause aluminum corrosion.

Back in the day not many people cared about crankcase stamping, it's somewhat of an increasing collectibility phenomena. Used to be we'd rationalize using something like a 95 PG case since it probably had an easy first life. Maybe that was just something in the go faster crowd, I never used to be much of a Concours or Stock Original guy, but I'm gaining new appreciations.

Just my opinions and I could be wrong. I'd like to read more.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Why don't our engines have cam bearings?
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 07:10AM

JimBrandberg Wrote:
-------------------------------------------------------
> It's a heartbreaker when you're installing a stud and it seizes halfway in, refusing to go further in or come out. Oversize studs are more prone to this and I seldom seem to use them, they are also VERY EXPENSIVE.
>
> If aluminum comes out with the studs I'm not sure an oversize stud will do it. If the aluminum threads seem sound and a stock stud screws in very easy I might use an oversize stud.
>
> When a stud comes out I generally reinstall it with red Loctite. If it goes in too easily I may abort and get it out of there before the Loctite sets while I think about it.
>
> I use the double nuts to remove a stud or a nut welded to the stud if it's already broken off. Heat to the aluminum may help.
> I use a rocker stud with a ball bearing inside to install studs, a tech tip I picked up here.
> I use a special 13/16 6-point 1/2" drive socket with the end chamfer ground down for more socket to thin hex head engagement, a tip I picked up I think in the CORSA Tech Guide.
>
> I just leave studs alone if they don't come out. Even the rusted away top studs usually since the portion with thread engagement is usually okay. It's a different story if you're lowering the C/R with thicker gaskets but I'm usually not.
>
> Sometimes the cam bearing surfaces are pitted if there's been water or something in there to cause aluminum corrosion.
>
> Back in the day not many people cared about crankcase stamping, it's somewhat of an increasing collectibility phenomena. Used to be we'd rationalize using something like a 95 PG case since it probably had an easy first life. Maybe that was just something in the go faster crowd, I never used to be much of a Concours or Stock Original guy, but I'm gaining new appreciations.
>
> Just my opinions and I could be wrong. I'd like to read more.

The oversized studs have already been purchased (3years ago). Quite a few of the original studs had to be cut so this is where I'm at...I'm getting ready to drill and tap the holes for the new studs and I'm very nervous about it. I've put a lot of hours in prepping this block, cleaning, removing excess flashing, etc. to trash the block and then the expense of finding another turbo block. My next dilemma is whether to use the original stock cam or replace it. I guess that I'll have to have a machine shop check it for proper dimensions before I make that decision. That will probably be another thread I'll start after I get the results.

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Re: Why don't our engines have cam bearings?
Posted by: 63turbo ()
Date: January 11, 2020 07:42AM

I've been through this before with O.S. studs... basically if the stock stud comes out, and does not damage the threads, put a new stock stud in and measure the torque required to turn it after it is at its full installed depth. If it takes 15 ft-lbs or more to move it, leave it alone! Less than that, remove it and go to the next oversize, OR re- install the same stock stud with copious amounts of red locktite. Both methods work well, I've tried them both. What you do not want to do, is automatically assume that it "needs" oversize studs, just because the stock ones were taken out. I guarantee you, if those stock studs have never been out before, the oversize ones wont go all the way in and you will have a bigger problem on your hands!

More about the cam to journal bearing clearance... if there's excessive clearance it will normally be on the big journal that supports the cam gear. If this one is out of spec, the best and most cost effective thing to do is have a custom cam ground with oversized journals to make up the excessive clearance. Another way is to have a stock cam spray welded on the journals and re-ground to the new size. This method is not new, and is done literally all the time for old engines that don't have "off the shelf" replacement cams.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Why don't our engines have cam bearings?
Posted by: jjohnsonjo ()
Date: January 11, 2020 07:59AM

Even with the studs and crank out you can plastic gauge the cam journals. Maybe 20 minutes or so to put it together and torque the the block studs, probably don't even need a full pull. If clearances are good, that is one more thing off your mind so you can focus on the rest of your build.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa


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Re: Why don't our engines have cam bearings?
Posted by: steve c goodman ()
Date: January 11, 2020 08:06AM

I would be more concerned over the integrity of the aluminum where the urine has corroded (maybe weakened?) the case halves. I have found case half pairs with worn cam bearing journals, always crummy oil or poor oil change schedule.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo---1965 Crown V8
1967 monza 110/4---1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC/V8 Registry

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Re: Why don't our engines have cam bearings?
Posted by: Wagon Master ()
Date: January 11, 2020 08:11AM

jjohnsonjo Wrote:
-------------------------------------------------------
> Even with the studs and crank out you can plastic gauge the cam journals. Maybe 20 minutes or so to put it together and torque the the block studs, probably don't even need a full pull. If clearances are good, that is one more thing off your mind so you can focus on the rest of your build.

That's what I do and they usually come in at .0015-.002. It's just part of my short block assembly process. Although I torque the block to spec. and check the crank mains at the same time.

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Re: Why don't our engines have cam bearings?
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 08:31AM

steve c goodman Wrote:
-------------------------------------------------------
> I would be more concerned over the integrity of the aluminum where the urine has corroded (maybe weakened?) the case halves. I have found case half pairs with worn cam bearing journals, always crummy oil or poor oil change schedule.

The cylinder fins and head fins were almost completely clogged but the block seems to be in pretty good shape. The heads have already been rebuilt by a reputable shop with hardened valve seats, new valves and springs installed. The cylinders have been deflashed and honed oversized by another shop as many of the pistons were seized. I have new Clark's cast pistons. The cam bearing journals are varnished but no pitting or grooves.

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Re: Why don't our engines have cam bearings?
Posted by: joelsplace ()
Date: January 11, 2020 09:01AM

"hardened valve seats"
I hope that is a misunderstanding or typo. Maybe you meant deep seats? Corvairs come with hardened seats and any reputable head rebuilder would know that even if they don't know Corvairs.
Align boring a block would take material off the mating surfaces of the cases and then cut the cam bores back to stock size or at least that's how mains on regular engines are done. No oversize cam needed.

Joel
Northlake, TX
5 Ultravans, 114 Corvairs and counting...




Edited 1 time(s). Last edit at 01/11/2020 09:03AM by joelsplace.

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Re: Why don't our engines have cam bearings?
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 09:11AM

joelsplace Wrote:
-------------------------------------------------------
> "hardened valve seats"
> I hope that is a misunderstanding or typo. Maybe you meant deep seats? Corvairs come with hardened seats and any reputable head rebuilder would know that even if they don't know Corvairs.

Yes, deep seats were installed.

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Re: Why don't our engines have cam bearings?
Posted by: RexJohnson ()
Date: January 11, 2020 09:14AM

Years ago I rebuilt a Jeep F head engine (intake valves in the head and exhaust valves in the block) and it only had 1 cam bearing. That was next to the cam gears, all of the rest of the journals were on the cast iron block. The cam and the crank should both float on a film of oil and on that F head engine I don't think that the valve springs had that much pressure.

RJ tools
Salem,Oregon

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Re: Why don't our engines have cam bearings?
Posted by: vairmech ()
Date: January 11, 2020 10:28AM

You already have the oversized studs. You already have the stock studs out of the block that a machine shop had to remove some.

Given that, use what you have, drill with the proper bit for the size of thread you are using. If you have a good eye you can just use a drill motor for the bit, otherwise put it on a mill to drill the holes and also to run the tap through. If you have none of that start an old stud in a couple of holes away from where you are drilling. Why? because you can use them for sighting if you are drilling straight! The same goes for when you start the tap, use the other studs for sight guides.

As far as using loctite on new studs and holes? I don't think so! You will get about half way in and the loctite will set up from the friction and then you will cut the stud and want to go back to the machine shop! Use the anti seize.

I didn't always have machines to help me! LOL If you happen to get a stud off angle by a few degrees you will have to flex it to get it around the jug and in the head. If it is grossly off the the hole will have to be drilles way oversize and a bushing made.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Why don't our engines have cam bearings?
Posted by: 63 Spyder Ragtop ()
Date: January 11, 2020 10:41AM

vairmech Wrote:
-------------------------------------------------------
> You already have the oversized studs. You already have the stock studs out of the block that a machine shop had to remove some.
>
> Given that, use what you have, drill with the proper bit for the size of thread you are using. If you have a good eye you can just use a drill motor for the bit, otherwise put it on a mill to drill the holes and also to run the tap through. If you have none of that start an old stud in a couple of holes away from where you are drilling. Why? because you can use them for sighting if you are drilling straight! The same goes for when you start the tap, use the other studs for sight guides.

I've got my drillpress set up and verified that the bit is perpendicular to the table. I posted another thread about drilling the block and another member responded that the new stud will pull out when torqued so I don't know what to do. He suggested using Time Certs but would, again, call for me to drill and tap the block as well as buying new standard studs.
>
> As far as using loctite on new studs and holes? I don't think so! You will get about half way in and the loctite will set up from the friction and then you will cut the stud and want to go back to the machine shop! Use the anti seize.

That makes sense especially since the factory manual says to use anti-seize.
>
> I didn't always have machines to help me! LOL If you happen to get a stud off angle by a few degrees you will have to flex it to get it around the jug and in the head. If it is grossly off the the hole will have to be drilles way oversize and a bushing made.

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