spills

iTrader: (9)

I just got my eagle crank, main bearings and oil pump in today from jegs. bearings are std, crank is std, and the line bore on the block is good. Do I still need to plastigauge the crank? I still gotta cleaence the block (stroker), but some of the guys at my work were sayin since its a NEW crank and bearings, and the linebore is good, there really isnt a need to unless I want it to be absolutely flawless. The motor aint gonna be seein over 6k, but I still want it to be pretty solid. Any thoughts?

RB83L69

Don't bother with Plastigage. Mic it. If you don't have a mic, buy one. You're going to be needing it. Don't get a cheap one. Get one that reads down to .0005" or less. No point in trying to build an engine without the most basic of all tools.

http://www.sears.com/sr/javasr/searc...=searchresults
http://www.use-enco.com/CGI/INSRHI?PMSECT=1328
http://www.mcmaster.com/ look in "measuring" section

etc.

spills

iTrader: (9)

so just mic the crank journal and mic the inner bearing circumfrence and find the difference? All the guys ive talked with are just backyard kinda engine builders. they good, but they just use plastigauge, so never really heard of mic'n to find clearence<----engine buildin' noob

RB83L69

I keep around a digital mic (an old Fowler/Telvac), a bore gauge, several C-frame type mics of various sizes, magnetic base dial indicator, valve spring height mic, numerous feeler gauges both flat and wire, as well as the various assembly tools you'll also be needing such as a ring compressor, valve spring compressor, etc. If you're going to "build" an engine, and not just bolt somebody else's work together, you NEED measuring tools. Plastigage is worthless for anything you intend to turn out with any higher quality or greater precision than an Auto Zone cheeeeeepie short block.

ZZsmpch

iTrader: (1)

Good tools aren't cheap, and cheap tools aren't good. If you can only afford cheap tools and don't know how to use them, just take the parts to a machine shop and have them checked, and if you want to, use the plastigage to see what you get compared to the machinist. Don't just throw them in and assume all is well. I've seen "mechanics" who couldn't get the same reading twice off of a mic from the same part. Not trying to say you wouldn't be able to use them, but if you don't know about them and this is your first exposure to them, chances are the plastigage would be more accurate. JMO.

blacksheep-1

You know, the mic idea is good, but being old school, I just have to know what it looks like after the bearing cap is torqued so I still use plastigauge. I wouldn't recomend it in place of a mic, but it is another valuable tool IMO.

spills

iTrader: (9)

well, tools aint a problem. I work at a dealer, so if I aint got money there are plenty of ppl around whos got one. But Ive personally (in my novice experience) never heard of measuring main bearing clearences with a mic. I figured it wud be best to measure it once its installed, which to me means using plastigauge. Is there a way to mic it once installed, or do u have to do it outside the block?

ZZsmpch

iTrader: (1)

You can measure them with an inside micrometer, bore gauge, or in a pinch a snap gauge and outside micrometer.

TomP

I don't see how you'd get a micrometer around anything once the crank was installed... if you really really really want to use plastigage, follow what blacksheep-1 said; use both methods.

I doubt you'd find any "real" machine shop just using plastigage!

spills

iTrader: (9)

ya, I guess an extra hour or so mic'n everything wud be worth it. I was kinda skeptical too when the guys were tellin me "its a new crank, new bearings, dont waste ur time! it aint worth it!"

Fast355

iTrader: (2)

In my opinon plastigauge works great for a quick check on bearing clearances. It shouldn't be used as a replacement for a micrometer but a supplement.

Tibo

iTrader: (15)

If you are putting alot of money in any engine you have to use quality measuring equipment. Calipers are not exact enough. You have to get a micrometer with a friction thimble to properly measure anything an get an accurate reading. You also need to figure out oil clearences. For that you will need the adjustable "T gauges." They are just gauges that are in the shape of a "T" and expamd or contract to measure the bearings once you have them torqued down. Then you have to measure them with a micrometer. Torque angle gauges also are needed.

ede

don't think you'd need a torque angle gauge for a SBC. only place i ever used one is on TTY bolts. as for plasti gauge i don't use it, not used it in 25 years or so. if you're doing engine work you do need some precission measureing tools along with common hand tools.

brutalform

Plastiguage, or mic. I dont trust anybody, and I check everything. No matter if its a new cylinder heads plug threads, or a cranks journal, or an injectors resistance. You just dont know what kind of day the machinist was having when he was cutting your crank. Dont let a guess ruin your expensive engine. Tom

brutalform

Make sure the oil pump is within spec too!

Parrydise7

iTrader: (1)

One more reason to avoid plastigage:

You need to use it fresh. Older stuff will throw the reading off. Not that the reading is that good anyway.

spills

iTrader: (9)

can u elaborate please? what kinda specs are u talkin about? Like backlash internally or something?

brutalform

All small block oil pumps have 2 gears inside. Each one has 7 teeth. As the gears mesh, oil is forced through them and makes its way throughout the engine. Its a good idea to check the clearance between the pump cover, and the gears. Should be between .0025 to .0033. Just a little assurance that a $30.00 part is up to the task of properly oiling your engine...Tom

spills

iTrader: (9)

ahh, no one ever mentioned that to me before. Thanks for the warning, Ill have to check that too once I get the pickup and all ready to install.

brutalform

Rick King

I have been told by a builder that one uses plastage to find out witch cap goes where when the motor has been apart and the person forgets or did not mark where it came from maybe it is bs or maybe not just my 2 cents

GB

rick

CamarosRUS

I'm going to mic my clearnaces but I would also like to follow up with plastigauge just to double check my measuring.

What plastigauge should I get??? There is none on Summits site that reads to the ten thousandths. Only .001-.009...

spills

iTrader: (9)

you can pick it up at just about any local auto parts stores. I picked up like a pack of 10 strips for practically nothing

Apeiron

I think the green plastigauge is for .001-.003?

Sonix

iTrader: (1)

The stuff you are talking about is the red stuff. I don't remember what it's used for. Or wait, no, that's the kit.
Red is .003-.009" I think
blue is .003-.006" or so

The green stuff is .001-.003". I bought the MOPAR kit, comes with all 3 sizes. My engine machinist also tossed a pack at me, with a few packs of rod bolt boots for free. $1800 of machine work gets a few tid bits thrown in

It's not accurate to a tenth of a thou, but about .0003" or so. Grab a pack from a machine shop or something locally (parts stores don't usually have it... Pistons and rings and bearings are things that aren't normally stocked next to the windshield washer fluid and tire gauges ), actually, grab 2 or three, you'll probably screw a few up, or lose some of it, or...

littlebagz

If you do mic the ID of the bearing with a snap gague and a "c" style mic be sure to use the same mic for the OD measurement of the journal. I bought a dial bore gage and had some accuracy / consistency issues to my micrometer. Thats why i miced everything, plastigagued it, and did an "interference test". to make sure i got the same readings from different methods for peace of mind.

The interference method is when you use thin paper (that you mic for a thickness) and install between the bearing and the journal. If the crank turns you have more clearance than the thickness of paper. If it does not you have effectivley exceeeded the clearance. I used an onion skin tracing paper. Start with one piece and then stack more until you reach that interference.

CamarosRUS

I might try the paper idea, thanks.

I was told not to torque the main and rod caps with the bearings in them to measure the diameters but to measure the rods and mains without the bearings installed, measure the thickness of the bearing, then measure the journals; do some math and you got your clearances.

But, I dont have a tip for my micrometer to measure the bearing thickness plus this method seems like it has a wide margin of error since there are two bearings halves and two main or rods halves.

sofakingdom

iTrader: (1)

Plastigage is only good for quality control, like to detect REALLY GROSS errors such as bearings of the wrong undersize. It's not good enough to use as your primary standard for building an engine. Or at least, not MY primary standard; yours may be lower, or possibly even higher, than mine though.

If your block hasn't been wanked on, and your bearings are the right undersize, then the only variable you have left in the whole system, is the machine work on your crank. Which all you need for that, is a mic that goes down to .0005" accuracy. Those other things, you don't need to worry about.

In other words, mic your crank, and then make sure you have the right bearings for it; if all of that is right, then the clearance will be right.