blue

I'm thinking about putting together the rotating assembly and throwing it in the block myself. I figure this would save $300 or so at the machine shop. But is this not recommended? (I'm fairly capable and I have expert help.) It seems to me that most of it would be simple, but a couple things may not be.

easy:
-put in main and connecting rod bearings
-put piston rings on
-attach connecting rods to crankshaft
-bolt on caps

maybe not easy:

-get pistons into cylinders without breaking rings
-put in piston pins

We have every reasonably non-special automotive tool (except I don't think we have a piston ring tool). So is this about right? Is assembly of a 383 rotating assembly and insertion in the block easy for an average mechanic, or are there a ton of intricate professional level assembly details and stuff you want to check to within .001 inches and things like that I don't know about? And would a balanced kit from say CNC need to be checked to be sure it's balanced right, or could it just be thrown in?

jonota

I'm a staunch DIYer, so I say go for it. HOWEVER, I always like to have seen something done by a veteran if it's something very important, such as completely redoing the bottom end. Getting the pistons in is VERY easy, the piston ring compressor tool and a small rubber mallet will do just fine... make sure you keep a good oil sheen on ALL parts while doing it... and checking clearances is always recommended, there aren't that many tools needed for that though...

Jonota

94zgreenmachine

I would have the machine shop press the pins thru the rod into the piston. Your right, that would be hardand you'll most likely break or wreck something . Getting the pistons into the cylinder is easy. Buy a ring compressor. Autozone for , like, $10. Can't remember exactly, its been almost 10 years since I bought mine. You simply put the compressor around the piston and rings. Lube it with engine oil first. Then lube the cylinder bore and put the compressor into the bore. Lightly tap the piston(wood handle, rubber mallet) into the bore. It is so easy. Take your time and don't use crappy plastigauge to measure bearing clearance and such. Do it right and take your time!!

RE AND CHERYL

The machine shop will also have to clearance the block for the 383 rotating assembly. If you have never assembled an engine or have someone helping you that has, I would pay the extra money to have it professionally done.

94zgreenmachine

A whole lot of info can be had from buying the book: How to rebuild the lt1 engine by hp books. While the 383 does need to have the block clearanced the assembly for the engine it self is pretty much the same for any engine and the lt1 book would be a huge help. I have even seen them for sale on ebay for $18. I have had mine forever and read it about a million times. Seems like every time I look in it I learn something new, try it, it is a big help.

blue

Gracias.

The machine shop will have to clearance the block, but I just have to tell them the specs of the assembly and say grind away, right? As I understand it they shouldn't even need to see the rotating assembly. I do not want to just pay the money for the shop to do it if it's as easy as I think it must be. (Except the piston pins, thanks for the answer.)

Checking clearances:

I won't try to elicit like a textbook response here that I can print and follow on all the clearances to check and how to do it, but can any of you give a reference that will give a step by step? I think actually the Haynes manual may give a followable instruction section for assembling the bottom end, but I'm not sure. (For example: I can't think of what "bearing clearance" would be)
Is all you need feeler gauges, or how many other gap checkers do you need? Oh, and is a balanced assembly from somewhere like CMotorsports or CNC trustworthy as being balanced so that I could just put it in and not worry about it?

blue

I was writing while you posted. This answers one question.

blue

I can find a few books that are close like
"John Lingenfelter on Modifying Small-Block Chevy Engines: High Performance Engine Building and Tuning for Street and Racing"
but not the one you mentioned on ebay or Amazon.

djfuzzy

Here is the link for a good LT1 rebuild book, might even be the one he is talking about. I ordered one and plan on reading it front to back before I do my 383 build this summer.

http://www.impalasuperstore.com/nais...xd.asp?id=1130

94zgreenmachine

Thats the one!

CCCCCYA

I would let the shop screw it together. If you don't have the proper equipment, specifically the tools to measure evertything, then you would be going on faith, and the FIRST rule of engine building is to trust no one! on top of that, you wont be able to press the pins on. You have to heat up the small end of the rod pretty high to get them to press in, and unless you have a rod oven, you're just not gonna get it done. Full floaters are easy, but press in's are a different story.

Biggest thing is the measurements. Ask yourself these questions, and rule out assembling it yourself if you say no to any of these.:

Do you have a good set of Mic's (out to .0001 - preferably to .00005)?
Do you have a good dial indicator (out to .001)
Do you have either a dial bore gauge or a set of snap gauges out to 4+ inch?
Do you have a a set of feeler gauges?
Are you going to file fit the rings, and if so, have you ever done this before? Got a nice fine cut flat file?
Last but no least, do you have a known good torque wrench (calibrated)?

If no to anything above, then let the shop build it.. Plastigage is ok, but has it's limitations..

Dave C.

Jameslt1TA

What is wrong with plastigauge ... im starting to put the bottom end together and was planning on using plastigauge. What else is there to check bearing clearances?

93ZM6Tally

Answer is really above: Outside Diameters - Micrometer, Inside Diameters - Inside, (Telescoping Mic's), or a Bore Guage. All of this stuff gets pretty pricey. Bearing clearances are best checked using micrometer, install bearing torque main caps, measure inside diameter, measure outside diameter of crank main journals, difference is bearing clearance. Same thing with rod bearings, install bearings, caps, torque ( in a rod vice!!) rod bolts. Measure difference. Mic's take a while to get a feel and it's easy if you don't practice to have a couple of thousandths difference between measurements if you're inexperienced.

To me the good tools are too expensive if you're going to build only one engine, because you can have a good machine shop put the bottom end together for less than the price of a quality set of measurement instruments.

CCCCCYA

There's nothing inherently wrong with Plastigage. It's just not as accurate as a dial bore, or a set of snap-gauges and a MIC. The tolerences on modern engines have gotten very very tight to allow for thinner and thinner oils. Your engine's life is directly determined by how well it's put together. Plastigage has a resolution of .00x, depending on what the person using it "see's" , and you need to be able to accurate measure down to .000x to get it within tolerance.

Example: you can't tell the difference with Plastigage between .0020 and .0028, but thats a substantial difference when building a performance engine.

I suppose it's fine for some folks, and many people build engines using it. I'm just not one of 'em.

Dave C.

1racerdude

Plastigage is bliss=what they don't know won't hurt them,until it bites them in the pocketbook.
Plastigage will get you "close" and that's only good in hand grenades.