Removing heads

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King68
Posts: 22
Joined: Sat Jan 03, 2015 7:30 am

Removing heads

Post by King68 »

I am removing the 98HP heads from my '68 Monza project which I intend to replace with the 140HP ones I bought out of California some months ago. The upper row of nuts on the cylinder head tie rods have been bathing in Sea Foam "Deep Creep" for about 10 days now. Must I worry about the order in which I remove them? Is warping the heads an issue when loosening the nuts, or is it only an issue when tightening them? I'd like these heads to be useful to someone when I am done with them.

joelsplace
Posts: 926
Joined: Wed Oct 13, 2010 12:51 pm
Location: Northlake, TX

Re: Removing heads

Post by joelsplace »

I've never worried about it but I guess I've always removed them in a reverse pattern from installation. People have been removing the lower row 2 at a time to replace o-rings for 50 plus years with no issues.
114 Corvairs, 5 Ultravans and counting
Northlake, TX

King68
Posts: 22
Joined: Sat Jan 03, 2015 7:30 am

Re: Removing heads

Post by King68 »

Thank you. so, how far do the studs themselves have to rotate before I must replace/reset them? 1/8 turn? 1/16 turn? the very slightest amount at all?

joelsplace
Posts: 926
Joined: Wed Oct 13, 2010 12:51 pm
Location: Northlake, TX

Re: Removing heads

Post by joelsplace »

Try not to let them rotate at all. If they will hold the proper torque and aren't badly rust damaged no need to replace them.
114 Corvairs, 5 Ultravans and counting
Northlake, TX

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bbodie52
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Re: Removing heads

Post by bbodie52 »

These links may be useful to you...

Removing Corvair Cylinder Heads
:link: viewtopic.php?f=225&t=4063


NEW MECHANICS: Engine Rebuilding & Maintenance Tips
:link: viewtopic.php?f=225&t=4064


Vintage Valve Service and Adjusting video
:link: viewtopic.php?f=225&t=5630&p=38305#p38305


Vintage Corvair Engine Tune up Video
:link: viewtopic.php?f=225&t=5631&p=38306#p38306

HOW TO VIDEOS...

:link: https://www.youtube.com/user/davemotohead1/videos



Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

Wagon Master
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Joined: Thu Jul 28, 2011 6:36 pm

Re: Removing heads

Post by Wagon Master »

Which method do you plan to use to make up the difference in a early cylinder and a late head?

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bbodie52
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Re: Removing heads

Post by bbodie52 »

Installing 4-carburetor 140 hp big valve heads on a 95 hp base engine leaves with the incorrect camshaft, wrong distributor, and a need for 140 hp carburetors and dual exhaust system. The exhaust manifolds and muffler from your 95 hp engine will not fit, as the exhaust ports on the 140 hp heads are larger. The correct bottom end for those heads also uses a harmonic balancer in place of the cast pulley, which was only installed on the low horsepower engine. the 110 hp (2-carburetor) and 140 hp (4-carburetor) engines had the harmonic balancer and the correct 110hp/140hp camshaft, and the 140 hp engine also was fitted with a larger 12 plate oil cooler. A different top sheet metal shroud was fitted to clear the four carburetor mounts and to properly match the larger oil cooler.
This will give you some idea of the differences between the 140 hp engine and the 110 hp engine.

140 hp vs. 110 hp...
  • Same high-performance camshaft on both 140 hp and 110 hp engines. Low performance camshaft in the 95 hp engine.
  • Same 164 Cubic Inch displacement with same bore and stroke on all 1964-1969 engines.
  • Stronger, nitrided crankshaft on the 140 hp and 180 hp turbocharged engines. (Nitriding is a heat treating process that diffuses nitrogen into the surface of a metal to create a case-hardened surface).
  • On the 140 hp engine, a 4x1 carburetor arrangement, with two primary and 2 secondary 1-barrel carburetors, connected with a progressive linkage to open the secondary carburetors as you approach full throttle. (Equivalent to a 4 barrel carburetor on the 140 hp engine, vs. a 2 barrel carburetor (2x1) on the 110 hp and 95 hp engine).
  • Dual muffler, dual exhaust with larger exhaust ports and larger exhaust manifolds on the 140 hp engine. Single exhaust on the 110 hp and 95 hp engine.
  • 9.0:1 Compression Ratio in both 140 hp and 110 hp engines. 8.0:1 CR on the 95 hp engine.
140 hp Heads...

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It's all about better breathing at full throttle at the high RPM ranges. At lower RPM the big valves and dual exhaust don't make much difference, and the secondary carburetors are not open for business.


110 hp Heads...

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What are the final two letters on your engine serial number (see sample below for location)?

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Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

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