The Stovebolt Site Forums The Shop Area Engine Shop Balancing and blueprinting???

You always here how hot rod engines are balanced and blueprinted. I think I understand the concept of balancing an engine. You spin the crank on a specialized machine and machine as necessary to make sure there inst any "wobble". You then mate the connecting rods to the pistons and weigh them all to make sure they are exactly the same. In theory the resulting engine will turn as efficiently as possible.

So what is blueprinting? How is it done and what benefit does it provide? Can it be done in a home shop?

"Balanced and blueprinted" is a phrase that identifies an amateur.
The next question is "where do you get the blueprints", and the answer is "there aren't any".

The first article was my understanding of blueprinting. The second article has a slight different explanation to me. What they call blueprinting seems like just normal and proper engine rebuilding to me.

I think matching weights between rods and pistons and balancing everything is important. Take it one step further and ensure your flywheel,clutch and dampener are all balanced at the same time with the crank.

I was lucky enough to have a fellow member lend me his boring plate for my 261 rebuild. My machine shop was very happy to see that i wanted it done with the plate as they reassured me it makes a difference.

If,
then, "_______ & _________" identifies a professional.

Fill in the blank , panic. So we can get our terminology right.

Brad

I grew up around a race shop in the early 1950's, watching my father build alcohol-fueled flathead Ford V8's for the dirt tracks around middle Tennessee. What's called "blueprinting" these days was just routine practice building those engines. Engine prep started out with line-boring the block to establish a baseline for all the other operations. Then the top of the block is shaved a little (using the main bearing bores as a reference) to assure that the crank and the top of the block are parallel. Bore the cylinders, using the top of the block as a reference, so everything is square and straight. Hone the cylinders with a stress plate bolted on to assure the cylinders are round when the heads are torqued down. Measure the center to center length of all the connecting rods to find the shortest one, then recondition all the other rods to the same length. Every moving part gets weight-matched to 1/10 gram. (A dollar bill weighs one gram). Spin-balance the crankshaft.

Buy a BUNCH of rod and main bearings and measure the wall thickness of each one to match them up, then check for correct oil clearance on every bearing when they're assembled in the block and rods. Race engine clearances will be approximately double those needed for a street engine. We're building for max power, not longevity. A race engine with mufflers sounds like there are a bunch of little guys with sledgehammers inside, trying to get out! Test-assemble the engine and measure piston deck height. Tear it down and deck the block a second time to get minimum deck clearance. Once the block and rotating assembly is correctly matched, do the same sort of procedure on the heads, degree the cam, decide how much advance or retard the cam needs, assemble and dyno-test the engine and adjust valve and ignition timing for max torque and/or horsepower.

Run the engine less than 1,000 miles on the race track, and if it survives, do it all over again! Doing this sort of stuff to a street engine is stupid!
Jerry

Blueprinting as mentioned is attention to detail to an extreme. It is also limited only by imagination. As Jerry said, a good common sense build with extra time and attention.

Years back, I read an article on building a drag race super stock engine. The super stock was essentially building an engine to the max using stock specification parts whose only real improvement relates to durability. One of the steps that stuck in my mind was after checking clearances, ring end gaps, etc. He loaded the pistons with rings and pulled them through their bore with a weight scale to make sure they all had the exact same drag. He may have to switch rings around until he got the exact same pull. If you think about it, it makes good sense but I myself would never have thought about that. Seeing the amount of horsepower gained with just those types of modifications was un-real. On a six cylinder, the power is probably not the goal but the reliability and longevity of such a rebuild could be.

Blueprinting as mentioned is attention to detail to an extreme. It is also limited only by imagination. As Jerry said, a good common sense build with extra time and attention.

Years back, I read an article on building a drag race super stock engine. The super stock was essentially building an engine to the max using stock specification parts whose only real improvement relates to durability. One of the steps that stuck in my mind was after checking clearances, ring end gaps, etc. He loaded the pistons with rings and pulled them through their bore with a weight scale to make sure they all had the exact same drag. He may have to switch rings around until he got the exact same pull. If you think about it, it makes good sense but I myself would never have thought about that. Seeing the amount of horsepower gained with just those types of modifications was un-real. On a six cylinder, the power is probably not the goal but the reliability and longevity of such a rebuild could be.

On balancing, I am told that the long crank cannot be spun balanced the same as a V8. I believe that as I recall was the differenced between static balancing and dynamic balancing. Someone more informed than me can carry that explanation on.

For a race engine, "balanced and blueprinted" is not only assumed, mentioning it means you just walked into the shop.
It's the equivalent of watching the World Series and remarking that the team with the highest score wins.

I figured as much; good analogy.

Brad

Jerry, you astound me. There are people that ASSEMBLE engines, ones that BUILD engines, and a few that MAKE engines. We are of the dying breed that do the latter. To make an engine for the pull tractor or truck a crankshaft main bearing bore is the first machine operation and then EVERYTHING is indexed off of this. The decks are 45* off TDC of the mandrel through the mains for 90* total; not 89.99999 or 90.00001 but 90. The cylinders are bored exactly perpendicular to the crank and bore spacing is exact. Even the front of the block, the bell housing surface, the pan rail and the top of the block are indexed off of the main mandrel. We then bore the wrist pin holes into rod blanks and piston blanks so center to center on rods and compression height on pistons is exact. The crankshaft is turned from a billet with each rod journal having the exact


center line separation, zero run out on thrust, flywheel, and crank snout, and our preferred journal to counter weight radii. Cam bore and lifter bores are indexed off the main mandrel. We make our own single plug or twin plug hemi heads with two or four valves. All is done on five axis mill and computer controlled everything and runs six figure in cost for TRUE blueprinting. Your Dad was doing this as close as his instruments could measure back in the 50's,truly ahead of his times and probably garnered championships along the way---amazing.
http://s32.photobucket.com/user/coilover/media/dans%2049%20034.jpg.html
http://s32.photobucket.com/user/coilover/media/dans%2049%20035_1.jpg.html

Continuing with the baseball analogy: "The batter just hit a grand slam homer with the bases loaded".

Actually, "blueprints" haven't been been "blue" for a good many years, although I do have many from the 1920's.

However, if one checks the tolerances on older "drawings", one finds high tolerance and low tolerance. Race engines will be more precise than the "blueprints". On street engines, the extra expense is pretty much wasted.

But if someone uses the phrase, be easy on them; none of us were born with the knowledge, we all had to learn. The kid that mentions "balancing and blueprinting" today just might be the enthusiast that purchases your truck from your estate!

Jon.

Evan, I have watched Dad move the centerline of the cylinders away from a thin spot that exists in the flathead Ford block where the exhaust passages go between the two center cylinders. He was boring blocks to 3 7/16"(.250" oversize) and using a feeler gauge blade under one of the cats' paws on a Van Norman boring bar to offset the bore centerline as he bored the four center cylinders. Then he had to grind the wrist pin end of the connecting rods on those cylinders to let the pistons center up in the new bores. He ran a 4" stroke Mercury crankshaft offset-ground 1/16" for 85 HP connecting rods, resulting in a 4 1/8" stroke. The guys with 4 1/4" welded strokers or 4 1/2" billet cranks couldn't wind up as tight as those short stroke engines. A sign in the shop read "Build 'em little, wind 'em tight, and get the chemicals just right!" We ran a mix of methanol and very strong (20% concentration) Hydrogen Peroxide. The fuel would eat holes in the float bowl of the carburetor unless the carb was run dry every time they stopped the engine!

I built truck pull engines in the mid-1990's for some local pullers here in middle Tennessee, 440 Mopars for the Super Stock class, and 426 Hemi's for the Douthit brothers who competed around the southeast. One engine was a dry block setup with the cooling passages filled with epoxy that ended up at 547 cubic inches. I bored the cylinders for flanged sleeves, so big I took out all of the cylinder wall in places. They ran a truck they called "Little Red Wagon" until some dam-yankee who had the name copyrighted sued them out of business. My friends went bankrupt and lost a big dairy farm while fighting those suits.
Jerry

And the beat goes on. During six + decades in the trade, I've heard many say that blueprinting and balancing either doesn't exist or adds nothing to the engine. They usually don't finish the race. Anyone building/experimenting engines has compiled their own specs, "prints" and log. Empirical knowledge. We often shift cyl bore centers to favor major thrust walls after a full sonic mapping. I do have a set of original signed Ardun blueprints among others. Just sent two Hemi Ford flatheads for a salt attempt. My Daytona Nat Champ engs run between 18 & 21 grand steady. They must be carefully machined and balanced. Yesterday a "76 deg crankshaft" (Google it) from England arrived to be balanced. Amongst prox 80 engs here, there's a 12 piston experimental eng here that operates w/o a crankshaft. (Google Axial internal combustion engines)Another fun eng is the Neander. It's easy to become static in our thinking and believe there's only one way to do things. Not true. Stay loose, have fun. David

Yeah, there are a lot of people out there that believe there is only one way to do things. That narrow focus makes them oblivious to innovation and really slows progress to a stall. There are many new things we are learning, even about the vintage stuff, every day. It's always good to hear from the guys who have been there, but that is just the beginning of the conversation.

I agree, without innovation nothing is assured except a dead end. Some of your projects have me green with envy and when Deve was fabricating his no jack shaft shifter I wanted to head to Kansas just to watch but decided no young guy wanted a gas passing 80 year old glued to his elbow offering useless advice. It seems that people who make no mistakes also make no progress. Here is a "big improvement idea" on an Arias design twin plug head that is taking it easy in the scrap bin. Learned what NOT to do. I'd give my eye teeth to have spent some time with Jerry's Dad.
http://s32.photobucket.com/user/coilover/media/dans%2049%20036.jpg.html

Coilover, I always remind myself of Smokey Unick's words, when following mistakes or even when falling on the ice, laying there in pain. "What did we learn here". Those words always brings a situation back to reality and puts your mind on a alternative / corrective path instead of being "ticked off" at the moment.
Don't think for a moment that a younger person can't gain from you some important, maybe career enhancing information. You'll probably never know how important your help can be and appreciated. Well, maybe not the gas. David

Another one of Dad's tricks was modifying a Lincoln Zephyr V12 distributor to run on the flathead V8 Ford engine. The Zephyr had two HUGE coils, and each set of points ran 6 cylinders. By modifying the distributor cam and the rotor, and using 8 of the 12 plug wire terminals, he got a system that could run about 75 degrees of dwell for each firing impulse. Since the race cars didn't run a generator, we ran the ignition and the starter on an 8 volt battery for quick starting and a hot spark for a full night of racing.

Dad passed away in December of 2014, one month short of his 90th. birthday. In October, he was stretched out in the floor of the assisted living facility where he and Mom lived, drilling and tapping the frame of his Hoveround so he could install a different design of footrest!
Jerry

Jerry - that is a GREAT memory!!!

Jon.

Can't be done, no one has said "think outside the box" yet.

I kind of got busy and forgot to look at this post for a little. I started quite the conversation.

So for the general home assembler/builder balancing and blue printing is probably more than we'd be capable of and way more than we need.

If I ever buy a rebuilt engine from somebody I'll ask him if it was balanced and blueprinted. If the guy laughs at me and throws me out of the shop I'll buy it. If he says "you bet, nothing but the best" I'll run the other way.

Want to test him, and have him take you seriously?
"What's the bob weight on that crank?"

Here is a "big improvement idea" on an Arias design twin plug head

And that's what dual plug hemi heads looked like in 1920...

If you ask him about a bobweight on an inline 6 cylinder crankshaft, he will probably help you out the door with a little shoe leather for trying to trap him with a trick question. That's what I'd do to a yamdankee who pulled that in my shop!
Jerry

Panic,
The twin plugs were not the improvement, airplanes had twin plugs (and magnetos) almost from the beginning and my friends 1920's LaFrance firetruck has them, h*ll, even my 1998 Ranger. The improvement was supposed to be in air flow which was up some but not enough to justify the money spent. We often make several different port/chamber/runner/angle designs in the same head to test on the flow bench especially if we have an already botched head available. Otherwise just a single cylinder is made out of a 6 inch aluminum cube to flow test.

Larry 58 Burb, I hope this thread hasn't made you cynical about blueprinting and balancing. Both procedures are most beneficial and a very good investment, when honestly done. Therein lies the rub. Mr Coilover, Twin plugs are typically very beneficial. Aircraft engs have almost always had them w/ separate mags,especially as redundancy. Mags I've tested have a prox 1/2 milsec duration. Not long enough to create a large flame front. Especially on old low C. R. non turbulent chambers. Dual plugs were almost necessary. I still build aught year T Head engs like Pierce Arrows and some Marine units. Todays ignition systems have longer spark durations, prox 2 mil sec. That starts a good burn. It can be seen in exh temps and exh gas analysis. You can adjust spark duration w/ changes in plug wire types, rotors and plugs to work best w/ your chamber shapes and induction variables. Lots of fun.
Mr Lincoln, FYI, There are many times an inline 4,6,or 8 cyl crank absolutely needs to be bobweighted for balancing. David

Because every one knows that L6 engines don't have counterweights...

The improvement was supposed to be in air flow?
How does that happen?
BTW: aircraft requires dual systems, not an option.

Mr. Panic, More than once I've seen the term L6. What is an L6 and why don't they need ctrwts? Being an older guy, I'm not familiar w/ that. L used to mean side valve or flathead engs. The letter I referred to an overhead like a 216, 235, 261 Chev and any valve arrangement of the type. Was that L6 term added in the last few years to mean something else? Would appreciate an update. Experimental aircraft can run single ignition. The Diesels don't need it at all. Thanks, David

L6 - in-Line 6
or
I6 - In-line 6

https://en.wikipedia.org/wiki/Straight-six_engine
https://en.wikipedia.org/wiki/Straight-six_engine#Balance_and_smoothness
https://www.quora.com/What-are-the-pros-and-cons-of-V6-and-inline-6-engines

The flathead L Head engine was a different design.

"A straight-six doesn't need split crankpins, balance shafts, or big counterweights, because each of its cylinders has a twin that's doing the opposite thing, at the same time and in the same plane, canceling out the other's forces. That lack of internal dissonance gives the same perfect balance as a V12. There's a reason museum-piece marques like Rolls-Royce, Mercedes-Benz, Jaguar, Aston Martin, and Alfa Romeo earned their reputations with inline-sixes."

"It's a dream aligned in one straight line."

Tim, Your quote there is mixing apples and oranges and I won't get into explaining why none of it applies. V type engs have a totally different method of balancing whether split throw or not. Torsional oscillation, natural frequency and node damping, etc, etc. All shaft types utilized on this Stovebolt Forum will have ctrwts mainly to deal w/ secondary forces. The 120 degree jrnl phasing can deal w/ primary forces when component wts are ck'd. There's much more to it but we're not writing a book here.It has always been that the "L" meant side valve or flathead as I posted. An old Briggs and Statton flathead is an L head. Yes, they did make them with overhead intakes and a flathead exhaust. That configuration is called "F" head. These different arrangements and many others have been around since the 1870's. Some don't even have valves or camshafts. David

Tim, I read the Wiki stuff. It appears to have been presented by someone that knows nothing of the subject, read lots of articles, mismatched the info and drew some amateurish, incorrect conclusions. Take w/ a grain of salt. David