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Old 07-17-2003, 02:20 AM
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Where can I obtain factory GM block blueprints?

I want to have BHJ make up some specialized tooling fixtures for a vintage engine that will become a race engine ('59-64 394 Olds), but they will not do it unless they have factory GM block blueprints with all the spec's and reference points on it (I'm not just talking about what the standard bore size was here, it's more involved than that). I want to locate the factory prints for the '59-64 Olds 394 engines, but would consider any prints for the '49-58 303/324/371 as well. At minimum, I need prints for the block, but will also gladly take prints for the heads, crank, and camshaft as well. Help! Where do I look for such a thing? It seems to me that GM must have an archive of blueprints, because all these reproduction parts companies seem to have no trouble locating factory blueprints, dies, etc. etc. If anyone can help, or offer a useful suggestion, please e-mail me at jec2@gte.net THANKS!!!

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Old 07-21-2003, 08:36 AM
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The original GM engine blueprints are not available to outsiders. One reason is that the original factory engine prints are drawn to full scale and are very large. Many times the GM engineers have them spread out on the floor or across very large tables. The prints for components purchased from outside vendors, such as crankshaft, pistons, rods, bearings, rings, valves, springs, etc., etc. are available from the manufacturer - IF they have an aftermarket version of the part. The OE production version of the purchased parts are also owned by the OE manufacturer and are very guarded.
I would think that a company like BHJ could reverse-engineer the block measurements and come up with the dimensions needed for your tooling. (That is what off-shore suppliers do to manufacture cheap replacement parts for domestic engines). If not, then maybe a local machine shop could produce the fixture you are seeking.
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Old 07-25-2003, 10:57 PM
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Thanks for the reply, engineguy!

It's starting to look like I may do just that-- reverse engineer by taking measurements of all 8 blocks I have here and then taking the most consistent measurement as being what it's supposed to be. Or taking an average if the measurements are all hovering around something.

But BHJ refuses to make fixtures to anything but blueprint. They specifically told me that they do not and will not reverse engineer or take any measurements from a block.

I just wanted to be able to get the lifter bores exactly perpendicular to the camshaft centerline so that the rollers sit flush and not on edge. You wouldn't think it would be that hard...

One other option I am going to start exploring is the possible use of the oh-so-expensive Schubeck radius lifters in the stock .921 size, and getting a custom-cut cam to take advantage of those large-radii lifters, instead of bushing down to a .842 bore and utilizing late roller lifters...

But, as this is ongoing, I would still appreciate any input from anyone on this matter.

After I posted that, I got to wondering where exactly BHJ has acquired the factory blueprints that they say they have for the applications that they do fixtures for currently???

Also-- if anyone knows of a full-service racing engine shop near SoCal that may also be the right shop to make up some "BHJ-style" fixtures for a custom application where there is no blueprint available, PLEASE e-mail me at jec2@gte.net with some leads! Thanks!

Last edited by Blownolds; 07-25-2003 at 10:57 PM.
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Old 08-09-2003, 11:47 PM
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Well, an update. After searching the internet, I have found two instances where people have said that the Schubeck radiused lifters failed on them. I suspect it's because the lifters may have slapped back onto the cam after coming off the nose on a radical grind. I hate to be a guinea pig, so I'm in no hurry to duplicate that disaster.

But, the Schubeck flat solid lifters seem to be working for people, and I may be able to get a custom solid cam ground to take advantage of the large .921 lifter size. That would certainly simplify things since I would not need to sleeve the lifter bores. Heck, I don't even need a set of custom Schubeck lifters for that, since I already have a few sets of solid lifters here.

One other option IF I could get a fixture made, might be the possibility of using the Schubeck "Roller X" roller lifters which have a 1-inch O.D on the outer bushing. But same deal, I would need a way of reaming the lifter bore holes perfectly perpendicular to the cam centerline. Not only that, I have been trying to get some feedback from people using the "Roller X" lifters and have not yet found a single person who has tried them. Maybe it's the $900 price tag, who knows.

More and more I'm starting to think that I may try a big custom solid flat tappet cam and see how I like it. I may just use some of these .921 solids I have here on hand. Hmmm...

Any input is still appreciated, I ain't done fishing yet.
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