boring an engine

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Ok im just now starting to udnerstand cars and im liking it. Im trying to learn more and my friend told me forums are the best way to learn something were we live because no one really knows a lot about cars around here. I dont understand boring an engine could someone please explain. 1966 Shelby Mustang GT350H if that helps. Oh yes a list of parts needed to bore it please thank you

posted by  66shelby

You can not bore your own engine. It must be done at a machine shop. An easy way to find one is to just look in the yellow pages under engine machine shop.

What is it you ask:

Basically metal is removed from the cylinder walls (where the piston goes up and down) of the block. This can be done for two reasons: 1) to remove scoreing (scratches) or 2) to increase engine displacement (make it go faster)

This is a very basic explaination. Hopefully it should help you ask follow up questions if you do not understand.

Very nice car by the way. You getting ready to restore her?

posted by  corbett_auto

actually i think resotring her would cost more then adding a couple hundred horses to her. Im thinking about just taking her to the local track or something like that. The transmission isnt orginal the last owner replaced it same with about everything but the engine. Supsension redone everything is basically redone except interior, body, carb, and engine. what size bore do you recommend?

posted by  66shelby

Normally an engine is bored between .010" - .030" (thats 10 - 30 thousandths of an inch) basically 1/64" - 1/32" less than 1mm.

Do not take this the wrong way, but I would not recomend any engine modifications at this time. Drive the car the way it is, find out all of its good and bad points. Fix all of the mechanical, especially the brakes. Then when all is well, then work on modifying the engine, by then you will have much more knowledge of the car and know the questions you need to ask.

Also adding a "couple hundred" HP is not cheap. :mrgreen:

You may want to read some of this post (http://www.car-forums.com/talk/showthread.php?t=12191)

Don't get ahead of yourself, take time to smell the roses, enjoy this hobby. It would be a shame to see a beautiful car like this wraped around a tree because you had a 500HP motor and no brakes.

posted by  corbett_auto

You need to go to a machine shop to have them bore it

posted by  99integra

I agree with corbett_auto, take the time to learn about the finer points about teh lovely car that you have.

posted by  Zderad

Yes the brakes are going to be redone. I know it wont be cheap im looking at about 10 grand plus and ive looked into stuff it will be about 10 weeks before i can do anything anyways i plan on finding otu a lot by then

posted by  66shelby

...so if a guy at a machine shop wants to bore his engine, he has to have a coworker do it?... :laughing: :laughing: :hi:

..but definitely get to know your car, first...

posted by  dodger65

LOL I thought about that too after I wrote it. But I figured anyone that asked what is boreing an engine could not do it himself. :laughing:

posted by  corbett_auto

yea i cant do it myself unless i have a machine shop and i know how to do it. :laughing: but thanks now i just have to find one to look into pricing and etc

posted by  66shelby

Almost anyone could bore their own engine. Most people are boring enough. :laughing:

posted by  DodgeRida67

Actually you don't need a machine shop, but it's a fairly cheap thing to have done by a shop.

posted by  Wally

how much on average would it cost for .030 bore?

posted by  66shelby

depends on the shop...

posted by  dodger65

While the engine is there you will want more than just bore the cylinder walls. I forget every thing that gets done, others here can tell you, but one thing I do know is you should get hardened valve seats in the heads to help run unleaded fuel.

I'm more of a paint and body guy, will some one who knows more about engines give him a list of everything he needs done at the machine shop. :thumbs:

posted by  corbett_auto

I paid $100 to bore & hone my block.



What you need to have done at the machine shop...
Well for a good standard rebuild (well, to my standards at least) you need to have a few things done in categories. First off, block prep. First off have it cleaned. Baked, steamed, vatted, whatever method they have available. I prefer to have it vatted . Have the crank saddles checked for alignment to see if it needs align honing or possibly align boring.
If the cylinders need to be bored (please always bore it when doing a rebuild - I'll explain why later) have it bored. About this boring... have them tell you what they are going to bore the thing to ( 20 over, 30 over, 40 over, whatever) and go ahead and order the pistons. When you get the pistons, find out what the piston-to-bore clearance should be. Tell them to "mike" (measure...) the piston skirts level with the pin bore centerline and to be sure and bore the cylinders to that amount + the piston-to-bore clearance. Screw just boring it to a standard oversize, do it right. Of course have the cylinders honed after they are bored using the right angle and finish according to the type of rings you will be using (just tell them what type - they will know what to do). Always replace cam bearings. I don't care who tells you they don’t ever wear out or what book says they don’t wear out - REPLACE THEM. Have your deck(s) checked for warpage. Personally I wouldn't allow more than .001 irregularity before I'd deck the thing. Go ahead and let them install the core plugs and everything for you. Let me mention this although it's a little late... if you can find a machine shop that will bore and hone the cylinders with a torque plate have them do the boring and honing. This should take care of the block prep for a standard rebuild. Now move on to the rotating assembly.
If your crank needs grinding (usually they do) have it ground and polished. To know if it needs grinding just have them mike the journals, and mike the bearing bores with the bearings in them, subtract the difference and half of that number is oil clearance. If it is within spec (and you have a reasonable amount left for wear before you go out of spec) AND out-of-round is within spec (I wouldn't allow any!) - it doesn’t need grinding (this probably won't happen, following what I just said usually constitutes grinding). Now, I always use new rod bolts and I suggest you do the same. One bolt failure and you're engine is junk. A set doesn’t cost much - and it strengthens your bottom end and gives you insurance against breaking a bolt and ruining your engine. It is a good idea to have the rods magnafluxed. Now, if you do use new bolts, you will need to have the rods resized. Now - have the small end of the rods polished, and the pin bores of the pistons polished. Bring in your piston rings, a pair of rod bearings, your pistons, rods, crankshaft, flywheel, crank balancer, and you'll now have the rotating assembly balanced (always balance an engine when rebuilding - even if you don’t replace any part of the rotating assembly because it's balanced crappy at the factory to start with!) Then have the pistons and rods assembled. That covers the short block reconditioning at the machine shop.

Let me explain why you need to always bore the cylinders. If you have ANY wear at all on your bores you are infact going to have some taper. When you have this, the new rings will not seat properly. They will never seal correctly and you will always have power loss and more oil being burned than you would have if you have had it bored. It may not be noticeable - but if you were to compare the two you'd see the different. On top of that, when the rings are constantly expanding and contracting because of taper, the ring lands in the pistons get worn which accelerate piston ring wear which lets more oil be burned and more compression to leak. It's just so much better to have it bored in almost every case. It will last so much longer and the performance and oil consumption will be so much better as well.

Now for the top end... for the top end (heads) you need to have the valves cut, the seats ground, new valve guides (either new valve guides or guide inserts - never let a machinist tell you it's OK to just knurl the existing guides - that’s crappy.) I highly recommend new valve springs and new keepers. Trust me, it's worth it. Also have the machinist check for irregularities on the gasket surface. Again, I wouldn't allow any more than .001 before I'd have it milled.

Now you can assemble the engine. Let me gives you some tips here. Let me stress it is VERY VERY VERY VERY VERY VERY important to clean the engine a bazillion times. Wash with a brush set ( can buy from moroso - summit racing carries a set) and clean that engine block! CLEAN! Spray the cylinder bores with a penetrating oil/water dispersant (such as WD-40, I use that) immediately after washing the block and drying the cylinders. Do the same to all other machined surfaces such as the deck(s). Also make sure you spray tons of the stuff in the oil galleries/holes because they will form rust in there if you dont and you will have rust in your oil! BAD. Clean your crankshaft too! (this includes oil holes) I highly suggest that you chase all important threads such as those for the head bolts and those for the main caps. ALWAYS check the ring gap of every ring. Every ring I say. Be sure the top ring makes it on the top, up facing up, and the center ring makes the center, up-side facing up (dont forget rings have an up and down). Check all of the oil clearances with plastigauge (I mike mine, however). This includes all the rods and all the mains. Be sure and learn the orientation of the rods and make sure the RODS go in correctly (facing the right direction and in the right place ("hole")) during assembly. Screw the piston orientation - the rod orientation is very important and this way they will both be right. If the pistons and rods were assembled wrong, it'll show up. A lot of times they can be assembled wrong and if you put the engine together according to the piston orientation only - you'll ruin your engine and never even know the rod orientation was wrong. So assemble it accord to the rod orientation and then when it's together check to see if the piston orientation is right. If it's not - you'll know the machinist assembled the rods and pistons wrong. More tips... Be sure and use molybdenum grease (moly fortified) on bearings, camshaft lobes, valve lifter bottoms, pushrod tips, valve stem tops, rocker fulcrums, all places like that. AND oil them AFTER applying the grease. Don't trust oil and oil alone. Use both! Just be sure and put the grease first - grease won't stick to oil very well if you oil it up first. Be sure and follow all torquing sequences for rod bolts, main cap bolts, head bolts, intake bolts, and header/manifold bolts. These are most critical. It's best to work your way up to a torque figure in sequence. For instant, for torquing rod bolts on a single rod. If they should be torqued to 50ft-lbs, first torque them to 25 and then to 50. Do the same for everything else. When it comes to things such as head bolts and manifolds, follow the torquing sequence (thats an order that you torque the bolts or nuts in) as well as torque them little at a time.

I'm going to throw in some suggestions now for new parts. I highly recommend new valve springs, new keepers, new pushrods, rocker arms, camshaft, lifters, oil pump, timing set.

Now everything is ready to go! Upon that oh-so-important first fire-up, before you start it - prime the oil system by using the appropriate attachment with an electric drill. Be sure and keep on eye on oil pressure and water temperature. When it's started keep it above 2,000RPMs for at least 20 minutes to break in the cam & lifters. Be sure and adjust timing when it's started as well. You'll soon see it takes two people - one to keep the engine RPM above 2,000 and one to check for leaks, funny noises, temp, pressure, and to adjust timing.




I feel like I've written a book. This is building an engine to a high standard. Building them like this, taking care afterwards (changing oil & filter every 3,000 miles and not abusing it) should easily get you 200,000 more miles out of that engine. That is if you ground the crank, bored the cylinders, new cam and lifters. Basically whole new valve train (springs, keepers, rockers, pushrods). Hardened the valve seats, ect. I hope this ramble helps. I know it's limited in applications as I was describing a pushrod engine but the same basics apply to any engine.

posted by  DodgeRida67

why bore engines????

posted by  google.com

how old are you :banghead:

posted by  99integra

15 how old r u

posted by  google.com

you bore an engine to make more displacement/power

posted by  99integra

oh ok just wondering

posted by  google.com

21 and i only ask because it was a stupid question unless you really didn't know

posted by  99integra

i really di not know

posted by  google.com

Hmmm. 2nd post in the thread:

posted by  ChrisV

Great info DodgeRida67. I knew I would have left something out if I tried.

posted by  corbett_auto

Wow that was really detailed i saved it in a word document incase i cant find it again. that means i'm going to have to save up a lot before i can bore because you said it was best to do all that at once and i plan on getting nice cams springs heads and all taht stuff. At a machine shop will they also port and polish heads? thanks

posted by  66shelby

Some will. The ones that do it may not do it right. There is an art to it and you have to care when you do it. I suggest finding a shop that specializes in it.

posted by  DodgeRida67

Use your name.

posted by  abless

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