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Converting EM to LM Alternator
Posted by: MattNall ()
Date: December 09, 2010 01:41PM

Coutesy of The Stig and Richard;

Edited 1 time(s). Last edit at 08/22/2017 01:44PM by MattNall.

HEATER fresh air 1961-69
Posted by: MattNall ()
Date: December 26, 2010 08:37AM

Posted by: steve c goodman (
Date: December 26, 2010 08:09AM

In Colorado the temps can dip below the 20 degree (above) mark that everyone is referring to above. I think nothing about using mine in 20 BELOW zero.

The usual comment "SEARCH" probably applies here, there has been much posted about helping the heater systems on this forum. In a nutshell however you need the following to be perfect:

high output blower motor (properly wired with a relay to aid with getting a full 12V to the motor)

heavy duty RUBBER heater hoses (metal tends to let the cool air from the outside cool the heated air passing through the inside)

heater control flaps adjusted correctly (fully open)

heater tubes and defroster tubes inside the cabin all in good condition

fresh air doors repaired for NO leakage of outside cold air

weather seals on the engine installed and fit correctly

thermostats working and adjusted correctly

I warm up the engine for about 4 minutes in cold weather, running on fast idle. That gets the exhaust manifolds nice and warm before driving. If starting out before that, the cold air being pulled through the engine tends to keep the engine cooler for a period of time. Obviously you need NO oil leaks and NO exhaust leaks too, shouldn't have to even type that out......

Typically if the weather is zero degrees or close to it I have to turn down the heater motor before I get to the shop (12 miles) unless the humidity is high, then I need the defroster to keep running. On my spyder I have an addition system, a separate blower motor that takes heat from the pass side heater box and ducts it onto the rear glass through a grill. This keeps the rear glass defogged. Axial flow blowers in the defroster ducts on an early will help put more air onto the windshield too.

Hope the above helps and I apologize to all who have the heater system working well that I made this post so long.

Sincere regards, Steve

1962 spyder 3.0L turbo
1966 corsa 140/4
1968 manx clone 2.7L turbo
1968 monza 110/4

Golden, Colo.

CORSA/RMC/PPCC/Manx club #299

Cylinderhead Temperature Gauge Checkout
Posted by: MattNall ()
Date: December 29, 2010 08:20PM

This is for 65-66 dashes. EM Spyder dashes will be the same except for Wire color / placements

System Check with COLD engine:

1 with key "ON" is gauge"

Always over 600 f = good 12vdc to gauge / no ground

Rises to over 600f = shorted lead to Thermister / shorted T-M.

Needle moved but under 200f = gauge funtioning / open circuit to thermister / T-M bad

Thermister / wiring checks

2 wire plug behind dash / Black with light green stripe should read 4,000-6,000 ohms to GROUND

High Temp lead from T-M should read 4-6k ohms

Thermister should read 4-6k ohms

Gauge Checks

With Dash Harness unplugged:

Black / lt Green wire to dash [ 2nd pin in from row across from open hole] to Black / Purple wire in plug [ 2nd pin over from empty hole]
should read 50 ohms [ gauge good ]

with dash harness pugged in / key ON and T-M disconnected you should see 10 VDC clear
back to T-M.

Visual Tire / Rim calculator BEST YET!
Posted by: MattNall ()
Date: January 24, 2011 10:24PM


link provided by Brock Landers

PDF's of many Corvair Manuals!!
Posted by: MattNall ()
Date: February 02, 2011 01:50PM

How to post pictures to this forum NOT using the "ATTACH" feature
Posted by: BrentF ()
Date: February 07, 2011 11:20AM

This is a great forum. My only complaint is that the restrictions on file sizes makes posting pictures a real pain for computer novices like me.

From another forum I learned a technique that is very easy to use and overcomes the file size restrictions of Corvair Center.

Five easy steps.

(1) first, go here: []

It's a good idea to bookmark this link, for sake of ease.

(2) select photo from your files, for upload, by using "browse" key

(3) Hit "upload" key and answer anti-spam question

(4) Copy the coding contained in the second box entitled: "IMG Code for Forums & Message Boards"

(5) Paste that code into the message that you want to post on Corvair Center.

Done. Simple. Voila!

Edited title after merging into the FAQ's

Edited 8 time(s). Last edit at 08/26/2012 08:07PM by MattNall.

LM car Alignment Specs
Posted by: MattNall ()
Date: February 11, 2011 07:59AM

lm Alignment Specs
Posted by: Steve Oxford
Date: June 06, 2007 09:39AM

Take the specs into the shop with you! Don't count on them having the info available. The following is taken directly from Bryan Blackwell's website - other's may have different ideas:
Once you've got all these cool parts in place, you'll need to align the car to use the tires to their maximum. Alignment plays a very important role in how well the car handles, and if you really want to understand how the alignment specs can influence the handling, I suggest you read a book devoted to the subject, since I've only included a brief description of what effects what. There are three values for each setting: Factory is from the '65 shop manual ('66 up is a even more conservative). Street is a bit radical, but the car won't be too twitchy and you won't kill your street tires. Autocross is what I found worked pretty well for me, you shouldn't consider it gospel, tho, just a good starting point. Also, remember that I am using *radial* tires, these values will not work very well on bias-ply tires (such as Hoosier Autocrossers). For you early owners, the factory specs are a bit different, but these values should apply as a starting point for a more performance minded car.

This is the key one. In essence, the tire tries to roll under and corner on the sidewall so we crank in some negative camber to conteract this. However, negative camber will wear out the inside shoulder of the tire more quickly, so think carefully. For both earlies and lates, the front is adjustable, but the early rear camber can only be set by changing the ride height. You can either cut the springs or use clamps.

Factory. Front: Positive 1 degree +/- 0.5. Rear: Negative 1 to zero degrees.
Street. Front: Negative 0.5 degree. Rear: Negative 1.0 degree.
Autocross. Front: Negative 1.0 degree. Rear: Negative 1.5 degrees.

Caster affects both self centering, and also helps crank in more camber. It's only adjustable on the front suspension.

Factory. Front: Positive 2 +/- 0.5 degrees.
Street. Front: Positive 4 degrees.
Autocross. Front: Positive 4 degrees.

This has a lot to do with how the car turns in, but better turn in comes at the expense of stability. The factory setting is really too much for any radials. The value is the *total*. Be *very* careful if you try using toe out and drive the car on the street.

Factory. Front: 1/4" to 3/8" toe in. Rear: 1/8" to 3/8" toe in.
Street: Front: 1/8" toe in. Rear: 1/8" toe in.
Autocross: Front: 1/8" toe out. Rear: 1/8" toe in.

Choosing the right oil for your Corvair by BOB HELT
Posted by: MattNall ()
Date: April 14, 2011 06:52PM

Another reason to buy Bob's Books!!

Home made Corvair Specific Specialty tools.
Posted by: MattNall ()
Date: April 23, 2011 06:33PM

Link to Pics of Homemande Corvair Specialty tools!

Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!

Need parts but have no $$... try this!
Posted by: MattNall ()
Date: April 26, 2011 12:29PM


Ian Harding of the GM Parts Wiki also set this up:

I just added a feature on gmpartswiki where you can indicate that you want a part and if someone else has indicated that they have that part, you will see it on your page. I will eventually set up an alert so you'll get an email, but haven't done it yet.


Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!

Edited 1 time(s). Last edit at 09/12/2012 11:21AM by MattNall.

Re: FAQ'S!!! / Part Number Interchange list and All Other Frequently Asked Questions
Posted by: gwydionjhr ()
Date: May 02, 2011 06:16PM


Corvair Woodruff Cam Keys are the same as SBC Chevy Crankgear Woodruff Keys.

FREE GM Corvair Specification sheets for all years in PDF format!
Posted by: MattNall ()
Date: May 06, 2011 02:47PM


Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!

Rochester Rebuild / setup Instructions
Posted by: MattNall ()
Date: May 08, 2011 03:22PM

Here you go!


Front wheel bearings
Posted by: MattNall ()
Date: May 29, 2011 11:25AM

Just for informations sake, bearing part #s, BCA brand A4 for inner and A1 for outer, Timken brand SET4 for inner and SET1 for outer, these are EM bearings.

LM bearings, A6 for inner and A2 for outer. Most brands use the same number, just different letter prefix.

To the best of my knowledge, only TIMKEN brand is still USA made!!!

These part #s are very common and can be found at most any parts stores!

Richard, Gulf Coast Auto Parts

Total brake shoe swept area
Posted by: MattNall ()
Date: June 07, 2011 09:47PM

EM: 120.8 sq inches
FC: 167.10 sq inches
LM: 169.0 sq inches

Trivia that apparently no one cares about except Bob Helt and I.
Sincere regards, Steve Goodman

Harmonic Balancer?? OR???
Posted by: MattNall ()
Date: June 12, 2011 09:53PM

From Bob Helt..

This device that mounts on the back end of the crankshaft and replaces the
pulley really is a TORSIONAL DAMPER. It reacts to the twisting of the
crankshaft caused by the piston impulses and dampens them. And when these
impulses occur at the crankshaft's natural frequency they build up into a force

that fractures the crankshaft. After many of these occurances the fractures
grow to cracks and then breakage. By dampening these impulses the
crankshaft is preserved.

Bob Helt

Pilot Bushing info by Layton Curtis
Posted by: MattNall ()
Date: June 16, 2011 08:35PM

The dimensions are: .594 inside Diax.904 ODx.75 long. I am looking at an old Dorman products box that has part No 690 73 on it. However,they will have some iron in them, but I've never found that to be a problem. I measured the hardness on a shaft once and found it to be 55-58 Rockwell "C" scale. A shaft with that hardness will be harder than any pilot bushing and the softest material always wears first. O'Rillys stocks them. Also the old Chevy's discussed in this thread all took a larger OD, but the length and ID are the same. I was in a bind one time and and had to turn one down.

Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!

Pictures and instructions on Changing your Fan Bearing at Home!
Posted by: MattNall ()
Date: June 17, 2011 05:55PM


Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!

Re: Pictures and instructions on wiring a Petronix
Posted by: MattNall ()
Date: June 18, 2011 07:37AM

from Steven Barker

Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!

Edited 1 time(s). Last edit at 06/18/2011 01:10PM by MattNall.

Video of testing individual carburetors by lugog
Posted by: MattNall ()
Date: June 18, 2011 01:09PM

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