twinpack

At the risk of sounding dumb, I need to ask the following.

I posted my barn find a month ago on this fourm. I have been in the process of disassembling for a frame off. Now to my question.

The 1968 has a NoM 327/350HP motor I will be having it rebuilt. I what to know what is ment by Blue Printing a engine. I understand balancing.

My plans are for a driver that my wife can use without grief. But I do what power for me to enjoy.

Please let loose with your advise as usual.

Thanks

marshrat99

Blue printing an engine consits of measuring every part as the engine is assembled to ensure the parts are within the specifications of your application. IE, you don't take chances even if the parts are supposed to be new. For example, let's say your machinist supposedly bored and honed your cyclinders to be .030" over and you have .030" pistons. You'd want to measure each piston within its designated hole to ensure the piston to cylinder clearance is within the piston's manufacturer's specification.

thoyer

Just like when builders use blueprints to build houses, blueprinting an engine is building an engine to a specific set of requirements (plans) and documenting them. You design your engine on paper then document everything as it is built.

I have learned over the years to document everything as I build. From cylinder taper to bearing clearances. Excel is great for making spreadsheets that can be filled in as you build. When I'm done, not only do I have a complete listing of parts, but all critical clearances / tolerances have been recorded.

Others make have a differing opinion on what blueprinting means, but this is what I consider it to consist of.

Tom

BLOCKMAN

I don't think any one on the site would spend the money on having a block blue printed as that would mean line honing the main line to begin with.

(2) Blue print boring the cam tunnel as we never have seen one yet that was to blue print.

(3) A GM deck is suppose to be 9.025 according to the GM blue print so far all the blocks I have machined have not seen one yet. At least the decks should be squared to the main line.

(4) Next would be boring and so far I have only seen a few blocks over the years that were close to blue print on cylinder locations.

(4) Next would be lifter bore placement and GM lifter bores are all over the place and those would have to be bushed back to standard.

OEM blocks are not a good block to try to blue print as I have learned that GM does not drill the same hole twice in the same spot.

Basic build to have a nice machined block would include line hone, square and deck and bore cylinders to original locations and plate hone the cylinders

From their the rods should be check for size, bend and twist and I doubt any one would pay to have the center to center distance blue printed.

Crank should be checked for straightness and if you checked it for proper stroke and phasing you sometimes would have to turn a GM crank .020 under to equalize the stroke and phasing of the crank.

Its funny the GM catalogs show a blue print of a block and everything referances of the crank and cam center lines but when GM machines their blocks that are machined of the pan rails. HMMMMMMMMM

Here is a link on what it takes to blue print a block.
http://www.chevelles.com/forums/showthread.php?t=93124

Goody

BLOCKMAN you hit all the points I was going to mention and more. Nobody that I know of will blueprint a street driven engine because the cost is just too high. Oh they'll say it was done but it wasn't 99.99% of the time.
The cam bore is supposed to be exactly 90.00 degrees centerline to the crank centerline and the list goes on.
Most of the time, blueprinting is used to signify that the block meets factory specs and depending on the area you are working on can vary greatly.

twinpack

Fantastic feedback. I herd different opinions to this question. You have made it very clear for me to understand. Blue Printing is a bit overboard for a daily driver. I will update progress as it happens. Thank you for all your help. I am sure I will be asking for more input as things go along.

Peter

L88Plus

It's become a standard bench racing term, kinda like "ported and polished". Nobody (that has a clue) polishes intake ports any more.
The other part of blueprinting involves recording all the engine specs including bearing clearances, etc. This can be very valuable when it's torn down to check for problems.

BLOCKMAN

On most GM blocks to blue print the cylinders you would have to go .
060 over!!!!

Line honing is an important step when building or rebuilding an engine.

The decks being squared is important mostly if your boring of the decks with a boring bar.

And torque plate honing is required if you want good ring seal as most guy don't have a clue what happens to a cylinder when the heads are torqued on.

Faster Rat

Blockman
Along the same lines as the OPs request for definition of "blueprinted" what is your definition of rebuilding an engine to "zero time" (evidently borrowed from the aviation world)

BLOCKMAN

I have never worked in aviation so I have no clue what zero time means.

Is there any info printed on zero time and what it means??

TedH

Short of blueprinting an engine, for a 'streat rebuild' I would recommend following the prescribed engine fastener torque and assembly instructions defined in the shop manual for your vehicle/engine.

When I had my L48 block and crank prepped for the rebuild in 1999, the machine shop performed some standard activities for the block:

Bore and hone the cylinders .020" to resolve taper (bored with torque plates)
Hot tank/clean the block (I would assume this occured after the boring since the block would be full of metal shavings/solvents... but, the shop knows the proper order)
Install new cam bearings
'Turn' the crankshaft journals .020" under and polish journals
Freeze/galley Plug installation

Since I was using a replacement set of heads, I didn't have the original cylinder heads resurfaced/cleaned, the valve guides repaired, the cylinder castings sonic tested for cracks around the valve seats, 3-angle valve cut applied to all valves, valve springs (retainers/locks may not require replacement). If you are going to have your cylinder heads refreshed, verify what the 'valve job' includes. From my recollection, the above actions are part of a typical valve job. I would recommend valve spring replacement as there is no worse feeling (other than perhaps throwing a rod, grenade'ing a piston or breaking a crankshaft) than that of experiencing a valve valve spring failure after installing a new high lift cam/lifters & rocker arms and dropping a valve on a fresh piston once the spring fails from the loads applied with that higher lift, 'extreme energy' cam...

Knowing the crank was turned .020" under and the cylinders bored .020" over, I was sure to specify this information when I ordered my engine rebuild kit from Northern Auto Parts. I stepped up to a nice flat-top piston, Speed Pro H345NP (.020" over) for my L48 (350) as well as a nice Crane Energizer cam (.454/.454 max lift). The kit also included good name-brand moly rings, oil pump, crank/cam/rod bearings, full gasket set, freeze plugs, timing chain/gear, etc. Under $400 still today, this is an exceptional 'Street Performance' rebuild kit.

Since I ordered the kit once I knew the shop had bored the cylinders and turned the crank, I had to drop my cam bearings off for installation by the shop once I received the kit by mail.

I've read that it is a good idea to use a mild dish soap and warm water to clean out the block of any residual metal shavings/solvents. I'm not clear on the details for a thorough cleaning (all of the different brushes to get into the many crevaces and bolt holes in the block, etc.). However, I did 'chase' all of the bolt holes with the appropriate bolt hole tap to ensure there were no surprises left from the machining/cleaning. Beyond chasing all of the threads, in my experience, I mounted the block on my engine stand and wheeled it into my driveway for a general rinse with warm water and mild dish soap (I didn't have the engine brushes required to do a thorough cleaning). Be sure to blast the block dry using compressed air and coat all of the internal surfaces that will see engine oil with a light oil (I've heard Marvel Mystery oil is a good, inexpensive choice). If you are not going to assemble the engine right away, be sure to 'bag it' either with two 'hefty' green leaf bags or an engine bag (heavier plastic).

Be sure to get a new set of hardened push rods. Most rebuild kits don't include them. Same goes for a set of rocker arms/pivot *****. I went economy and bought a set of 1.5 ratio from Summit along with the OEM length pushrods (as recommended by the cylinder head supplier given the new assembled cylinder heads I was installing). NOTE: If you are going aftermarket on cylinder heads, your may have to buy slightly different intake gaskets to accomodate the cylinder head ports. The DART heads I purchased included intake gasket recommendations. I recall mine were slightly larger than stock but not by much.

Then, when you are ready to begin the assembly, bribe a buddy or two that has gone through the rebuild experience with some cold brew and a meal and commence the re-assembly process. Be sure you have all of the necessary wrenches, socket sets, other tools and all of the engine parts that will be included in the assembly. If you stop before you finish the engine assembly (ie. before you install the oil pan, valve covers, intake/carb), be sure to re-bag it to keep foreign materials 'out'.

I've heard that a new set of engine fasteners (main cap bolts, piston/rod bolts, cylinder heads, intake bolts, timing cover, oil pan, etc.) from a supplier such as Milodon or ARP is recommended. However, since I was rebuilding my L48 for the first time, I reused the stock fasteners with the exception of the intake bolts; I bought ARP. Next time (2nd rebuild), I'll use new fasteners on the bottom end and cylinder heads also.

Remember that new rod bolts may have to be pressed into the rods and new pistons have to be 'hung' on the rods. This is something the machine shop that processes your block can perform for you. Also, have them mark your main caps (#1, #2, #3, #4, etc.) or do this yourself before you remove the main caps to install your crank and bearings. Another thing to consider is having the pistons/rod assemblies 'balanced'. However, I didn't have this done on my engine since I wasn't going 'large' on the pistons (just flat tops with valve reliefs, .020" over). Others may recommend you have the new pistons on the rods balanced by the shop when the pistons are hung on the rods regardless.

If you are reusing the intake, have it cleaned by the shop along with the block and be sure to clean it along with the block when you get it back. One thing I did (since I was reusing my bolts) was to be sure that the machine shop included the bolts in the cleaning process. This saved my having to clean them.

While the block is at the shop, have the carb and distributor rebuilt, and be sure to pick up a fresh water pump, clean/paint the engine pulleys and the stock air cleaner (if you are reusing) and, if you are going to reuse or buy a new fuel pump. I used the old one but cleaned it up. But, remember to buy the new rubber hoses to connect your fuel pump. Also, don't forget all of your heater hoses, water hoses and belts that will run the accessories on the front of the engine. And, if your fuel line was cut up by prior owners and you are using the orig carb, get a new fuel line that is bent for your application. It will improve the 'finished' look of your engine whenever you pop the hood.

Take this opportunity to either have your radiator re-cored or replaced and, if your radiator support is rusted out, get a new support from the likes of Dr Rebuild, Corvette Central or Zip (to name a few). I replaced mine during the rebuild since I had the engine bay apart and it just made sense to do it at that time.

Don't forget a new set of engine mounts

Also, a great time to detail the engine compartment (clean/paint) and even address the front suspension components, brakes, spindles, shocks... you get the idea!!!

Above all, have fun and be sure to have a 'plan of attack'.

NOTE: I rented a 'cherry picker' from the local auto parts store. Twice, since I had to pull the engine and then install it. Have (strong) helpers when removing/installing the hood as it is heavy and impossible to handle by yourself. Also, I found that maneuvering the engine/cherry picker from either the right or left side of the car (removing the wheel/tire) is ideal for installation.


Sorry for the rambling. Oh, I also had a master mechanic guiding me through the re-assembly... he lived right across the street from me and I had full access to his Snap-On tool set but, except for a couple specialty tools (speed wrench, breaker bar, etc.), my trusty Craftsman set was sufficient. I did take the opportunity to add to my collection; visiting Sears several times during the course of the rebuild.

Have fun!

rcread

I've always defined blue printing an engine as building it to one's own specs, not necessarily the factory specs. The personal blue print will have narrower tolerances and specs, with the intended application of the engine in mind. I grew up around funny cars and crew chiefs all had their own personal recipes. I'm building a street engine and have micrometers and gauges required to make sure everything is in tolerance. I don't consider that blue printing, but I think it's adequate preparation for a street/strip car.

Faster Rat

I just did an internet search and found this:

http://www.aero-venture.com/zerotime.html

My rebuilder told me he essentially "zero timed" my engine. Never heard his definition, but sure got a lengthy invoice. According to the above aviation definition, only the OEM can make this claim.

BLOCKMAN

Thanks that was interesting to read

billla

Another aspect to consider is that one of the primary reasons for "blueprinting" is the ability to get consistent results across engines and be able to replace sub-assemblies for racing. For an engine making less than about 1.4 HP/CID there's no reason to go crazy, but a good shop with the right equipment can establish the right basic dimensions (squaring the block, etc.) for not a lot of money.

Blueprinting is not about achieving original factory specs - it's about setting specs and being able to replicate them on demand.

The comments regarding aviation are correct - only an OEM can provide a zero-time overhaul and associated logbook entry. Note that this doesn't really mean much - the processes followed are virtually identical. But it's a big deal on the value of the aircraft....I've got another 800 hours before I have to make that decision.

whitehause

Yep....blueprinting is all about being able to duplicate exactly what you have. You see it mostly in the racing circuit. You know that all your parts are exactly the same, so you can swap out parts from one motor to another, or grab a part off the shelf, without having to worry about tolerances being the same. It's a big "buzz" word that doesn't mean much to the home builder doing one motor.

It is a good idea to keep some specs from the build handy for future reference....piston weight, rod weight, along with all the bore sizes.