I would only use plasigauge if 1: completely stock engine( not a performance stock engine either) and 2: I wasn't going to keep it. I have heard of people, including magazines use it in their buildups but I estimate to have over 5k in my engine and I CAN"T afford to do it again cause I made a stupid mistake(using plastigauge). Do it right and do it right the first time Plasti gauge has its uses but not in a hi-po build up

 

How much money you got going into this?? if it's your life savings, i'd say have a professional do it......if your running a $1000 dollar crank, i'd say look for the best There are so many clearances you could miss.

I have thought of the same thing. I came to the conclusion that if it was a budget buildup i'd do it--with following that book mentioned earlier, but if it's the real deal and some real ponies..pay the extra $$$



I have that book right in front of me........it's a great book....tells you all the stock clearances.

 

I have heard of Plasti gauge, but can't remember what it is...i know it's for measuring, but how do you use it or what is it?

 

It's an extruded plastic strip that crushes to specific widths at various clearance distances. The green (.001 to .003) is what most people use, but it's also available in red (.002 to .006), yellow (.004 to .009), and blue (.009 to .020) for increasingly larger clearance checking. As had already been said though, it's not accurate enough for "performance" builds that rely on tight tolerance to control the life blood of an engine. In my opinion, it's also highly subjective in interpretation too, leading to even greater potential mis-reading of specs.

Dave C.

 

I'm doing kind of a hybrid. My machinist is mounting the pistons and rings, checking bearing tolerances etc. In other words completely mocking up the engine. I'm going to do the final assembly, but I'll act as if none of the tolerances have been checked and re-check them myself. That way I get the experience with much less risk.

 

Spend the $300 to have the shortblock assembled and forget about DIY. If anything goes wrong with it you have some recourse since you didn't put it together assuming it's a reputable builder. If you aren't sure to quote you " (For example: I can't think of what "bearing clearance" would be) " and you don't have a ring compressor and think you might break rings putting the pistons in which is a easy job you shouldn't be attempting the bottom end. Why risk it for $300

 

I know what you say when you want to save a few bucks and there is always the pride of doing something yourself but when or if it goes up, the old ego seems to deflate rapidly.A few dollars spent now can save thousands down the road later. If you aren't sure, have someone else do it, like what others have said.

 

Thanks to all.
If I can't find a highly recommended machine shop within about 200 miles of Manassas VA (I've had an unanswered post on this for a couple weeks in the Regional board) I will probably do it myself. All the tools are in possession or should be borrowable, except the rod vise. I trust myself to do the measurements better than an employee at a shop who thinks he's not being paid enough and who's in a hurry to finish the job so he can beat the traffic home, you know what I mean.
I'm also curious as to what you could do if some of the clearances are off, e.g. you measure and find the inside diameter of the main bearing is smaller than the outside diameter of the crank or something like that? From my limited knowledge it seems that the clearances are what they are whether you measure or not and that the only thing you or the shop can adjust when you put it together is the torque on the bolts, and the gap on the rings.
I'm guessing that the importance of precise measurements is not so that you can adjust anything, like grinding down the crankshaft with an aluminum oxide pad (ha ha) or carving out the inside of a bearing with a pocket knife, but so that if a clearance or bore diameter is off, you find out before-hand so that you don't put it in the engine and have it wobble, grind, or otherwise destroy itself and maybe other stuff over time. Is this right? And if it is, does this mean the only option if something is off is to send it all back to where you bought it?

 

The reason for all the measurements is for the machine shop to correct the problem(they can) and try to make all the clearances as close to the same as possible,ie. you don't want one bearing fit in the block to be .150 looser than the other 4, this will lead to a spun brg. Also you don't want any of the brg fits all over the map-- rod's or main's and you don't want to put your largest piston in the smallest hole.

There is more to it than you think and I know I wouldn't lend my engine measureing tools to my wife much less a guy down the block. They cost to much and you gotta know how to use them. My dial bore guage alone is 700.00 dollars. My intramike set to measure the mains, rod,and cam brgs was 1400.00 though you can do them with a dial bore guage.

 

--> Sorry Larry, you beat me to the punch. I was typing at the same time you were. hehe..

Umm.. Well, lemme try this..

OK, lets say for instance that you get your block and crank back from the machine shop, measure it and find that the ID of the main caps is smaller than the OD of the crank journals. Well, thats simple. TAKE IT BACK TO THE MACHINE SHOP! They screwed something up in a MAJOR MAJOR way, and will have to fix it on their dime.

Ok, same scenario. You get your engine back, measure things and you find that you have a main clearence of .0038, and you wanted .0028 (not an uncommon occurance BTW). Well, when you order your bearings for the motor, your gonna want to put whats called a +1 bearing in there (standard size + .001). you can adjust the bearing clearences this way. THATS the whole point to being able to accurately measure things yourself. You NEVER KNOW what your gonna get back from the machine shop and you should NEVER TRUST ANYONE! Might be spot on , might be crap, but make no mistake, you CAN do something about innacurate machining and clearences that arent right (up to a point.)

This same thinking applies to both crank and rod bearings. Also, if you find that the crank isn't true, IT can be brought back into spec as well if the damage isn't too bad. It's funny that you were making a joke of using sand paper to fix the crank, because thats EXACTLY what the machine shop uses to polish the journals with. A fairly low tech belt sander on the crank fixture. Now as to the taking the pocket knife to the bearings.

Well.....Um. no.

Dave C.

 

Oh. It appears that there might be more to it than I thought.

 

If you used a brg scraper (they make them for brass and babbit brgs) well....... not.
You are correct in your stated thoughts IMO.

 

Dial Bore guages go for like 100 bucks. A little overkill there ya think Must be made of gold....lol


No wonder i have only heard rumors of this plastigate stuff....it's junk...lol

 

I don't know if you shop at K-Mart but when I checked they didn't have any.Try to get a2"-6" Fowler for less!!!!! Visit their website and see.
This ain't no K-Mart come apart and it's accurate!!!

 

All my stuff is Starrett. Not super expensive, but not junk either Dial bore is damn skippy more than 100 bucks though!

It's just like hand tools folks; You get what you pay for.

Dave C.