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Re: Billet cylinder heads UPDATE!!
Posted by: REM654DPG ()
Date: January 13, 2020 09:27PM

If you lay a set of heads on the bench and look at the chamber side you can see this offset in the lower stud hole and this is what prompted me to come up with this print. The case has the same offset and you can see it just the same with a visual inspection. Being that I did not have the factory print I figured the reverse engineering process would actually be more accurate for what I was doing.

Just to clear up some of the doubt, the dimensions on my print are a compilation of measuring 5 cases and 5 heads - which were on average +/- .005 of each other - and then dividing all the numbers to sum up the average number. I did this measuring on my EZ-Trak mill which has a 4 decimal place DRO, precision lead screws and with a Drake CO-Ax. I needed these actual dimensions to make my new torque plate assembly and wanted to make sure the dimensions mirrored the actual case and heads. I’ll attach a few pictures just for conversation sake.

Thanks for posting the factory print as it confirms the accuracy of my physical measurements. If you do the math from the dimensions shown using GMs tolerances given of +/- .010 on the X&Y and only a .006 spread on the lower rt studs X location, my average numbers show that what we actually have is within the factory specs and that this offset anomaly was purposely designed in from GM for who knows what or why.

Regan Metcalf
Portland, OR

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Re: Billet cylinder heads UPDATE!!
Posted by: John Luscinski ()
Date: January 14, 2020 04:13AM

Reagan just curious, Where did you get the large piece of Aluminum?

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Re: Billet cylinder heads UPDATE!!
Posted by: vairmech ()
Date: January 14, 2020 04:30AM

The only issue with reverse engineering is if something is off but within tolerance, then you make a print from parts that are off but within tolerance and then put tolerances in again, suddenly you have a piece that will be non standard if the piece is made at the limit of the tolerances of the copy.

It then becomes a copy of a copy of a copy and we all know that the quality of the copy down the line is not as good as the original.

BTW, I'm NOT bashing you Reagan.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Billet cylinder heads UPDATE!!
Posted by: jjohnsonjo ()
Date: January 14, 2020 05:48AM

Did GM ever use torque plates when they made them new?

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: Billet cylinder heads UPDATE!!
Posted by: racingguy2 ()
Date: January 14, 2020 08:04AM

GM wouldn't have used torque plates. They are more of a "lets make this as close to perfect as possible" performance thing, rather than a "lets make a lot of these and make a profit." thing.

Beautiful job though!



Edited 1 time(s). Last edit at 01/14/2020 08:05AM by racingguy2.

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Re: Billet cylinder heads UPDATE!!
Posted by: wv-geo ()
Date: January 14, 2020 05:31PM

The bottom two stud holes are offset from the top two so that the bottom two are closer to the valves and could be used as the mounting points for the rockers.

Dan Stark
Hurricane, WV

1961 Lakewood 500, 80HP, PG
1964 Corvair 500 Coupe, 140HP, 4spd (Christine)
1965 Mustang Coupe, 6cyl, 3spd

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Re: Billet cylinder heads UPDATE!!
Posted by: racingguy2 ()
Date: January 14, 2020 06:59PM

On the heads, the plan is to rough machine, heat treat, age, then finish machine so that when I finish the surface that the cylinders seat against I can hold them all within .0005 height or better.

Anybody know how parallel and consistent height the cylinder jugs are?
Or for that matter, how consistent height the shoulders in the case are?

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Re: Billet cylinder heads UPDATE!!
Posted by: racingguy2 ()
Date: January 15, 2020 03:44PM

Finally got our electric installation approved this afternoon! Of course it was another $1000 for a second electrician, but it's done! The electric company is scheduled to connect on the 22nd, but at least it's progress! Meanwhile, we've had plenty of time to organize, so the shop is looking really nice!

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Re: Billet cylinder heads UPDATE!!
Posted by: MattNall ()
Date: January 15, 2020 03:49PM

Hate to hear what you've spent so far... and not a single chip cut!

Just like building a house!

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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