Author Topic: Looking for answers when a motor is bored  (Read 821 times)

Offline Captain_confederate

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Looking for answers when a motor is bored
« on: March 13, 2019, 12:52:36 PM »
Bare with me please fairly new. If there's any articles about this that you know of please share with me.
When a motor is bored I'm aware that you will need new pistons for the new size bore of the cylinder. What else would be needed? Would you need a new intake or new heads? Not sure if I'm asking the right questions but you gotta start somewhere an I'm willing to learn. Anything at all will help...looking at boring a motor .030 over. I've had people tell me just get new pistons put everything back together and your good to go. Could be true but I would like more info
Thank you.

Offline ehjorten

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Re: Looking for answers when a motor is bored
« Reply #1 on: March 13, 2019, 01:48:11 PM »
If you have tore down the engine; start with taking the bare block to a reputable machine shop.  They will hot-tank the block and inspect it, and will tell you if it needs to be bored or not and to what extent.  If it does need to be bored, and it likely will; you should get new pistons first before it is bored.  The machine shop will measure the pistons and bore and hone the cylinders to have the proper clearance to match those pistons.  You will need new rings for the new pistons as well.

You should also have the Rods re-sized.  That means they take a small amount of material out of the mating surfaces of the cap and rod, bolt them back together with new bolts and then machine the rods to the correct size.  This insures the bearings are properly retained and have the proper clearance to the crank.  The crank may need to be machined as well.  It just depends on the condition of the engine.

You can rebuild the heads and reuse the intake.  You may need to have the heads, mating surface on the block and intake re-surfaced, but they can be reused if in good shape.  Re-surfacing just makes sure the surfaces are dead-flat so that they seal up properly.  The process of doing this, they should take the proper amount off of the top, front and rear of the block so that the intake seals properly all the way around.

It kinda depends on how thorough you want to be and what your plans are for the rebuild.  A basic rebuild, you want to have the block cleaned and inspected.  Determine if an over-bore is needed.  Determine if the crank needs machining.  Then replace all bearings and measure each component that receives a bearing to be sure that it is within spec.  Finally, when you put the crank in the block and when you put the rods on the crank, use plasti-gage to make sure you have the proper clearance.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline Captain_confederate

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Re: Looking for answers when a motor is bored
« Reply #2 on: March 13, 2019, 09:02:22 PM »
I really do appreciate you taking the time to make a response like that. Pretty much exactly the answer I was looking for and very helpful. I got some more questions off of what you said an got quite a few. I'll be grateful for anything you can answer
Now having the motor tore down to bare block. Does the machine shop put in new bearings? (Cam bearing, crank bearing) to check proper clearance? Then removes them when I get the block back? With the heads, crank, an rods possibly needing work done to them I'm assuming I should bring them with the bare block? If I was to possibly buy new performance parts should I bring them anyway?
If you can't get to every question I asked I understand, your initial response exceeded my expectations of an answer in the first place.
Thank you very much

Online Rapid Roy

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Re: Looking for answers when a motor is bored
« Reply #3 on: March 14, 2019, 06:19:35 AM »
Welcome to the site.
1974 Cheyenne 10 LWB 350/TH350/AC/4 BBL Quadrajet

Offline Captain_confederate

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Re: Looking for answers when a motor is bored
« Reply #4 on: March 14, 2019, 11:29:12 AM »
Thanks for welcoming me. Gotta say I've posted in a few other forums and also on some Book Face groups and the answers that I get are really pointless an irrelevant to the questions I ask. Couldn't believe the response I got when posting here. I'll be posting a lot more here! Really appreciate it

Offline Irish_Alley

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Re: Looking for answers when a motor is bored
« Reply #5 on: March 14, 2019, 09:21:29 PM »
we are a tight nit community here, those that tend to give out poor or bad information normally wont last along with the bashing isnt tolerated. on top of all that we have a slue of good information and a great store to get parts from or know where to get good parts at that the store doesnt carry.

welcome from maryland
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Offline roundhouse

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Looking for answers when a motor is bored
« Reply #6 on: March 14, 2019, 09:22:57 PM »
Welcome from Georgia

They will measure the crank and rods and other bearing surfaces to determine if they are worn and need overbore or in the case of the crank
They can polish the crank journals slightly smaller to remove the scratches and use slightly thicker bearings to make up for the material they polish off

Might  be cheaper to buy a crate engine thatís all new and assembled and ready to run

Offline Captain_confederate

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Re: Looking for answers when a motor is bored
« Reply #7 on: March 15, 2019, 08:02:13 AM »
Welcome from Georgia

They will measure the crank and rods and other bearing surfaces to determine if they are worn and need overbore or in the case of the crank
They can polish the crank journals slightly smaller to remove the scratches and use slightly thicker bearings to make up for the material they polish off

Might  be cheaper to buy a crate engine thatís all new and assembled and ready to run
 

It could be cheaper to buy a crate motor. But honestly I got some time an wanna know the ins and outs of doing everything. I understand what will be done a little better by the answers everyone gave.
Let's say we're talking about a Chevy 350 bored .030 over and the crank does not need any work done to it. Are the crank bearings kinda all the same for Chevy 350s? An the only way I would new or different crank bearings is if the crank journals are polished?

Offline Stewart G Griffin

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Re: Looking for answers when a motor is bored
« Reply #8 on: March 16, 2019, 06:44:17 PM »
Would the crank need to be re-balanced if you use larger pistons?

Offline JohnnyPopper

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Re: Looking for answers when a motor is bored
« Reply #9 on: March 18, 2019, 03:42:06 PM »
That's where I was going Stew; it wouldn't hurt to balance the crank and match the weight of the pistons while you are here Captain.

If it's a manual transmission, have the flywheel balanced too.

Makes for a smoother running engine when all parts are in sync and not fighting each other.

Regarding the bearings, you won't know till the crank is measured by your machine shop. You may get to use standard size 350 bearings, you may have to have the crank ground to the next size down.

Welcome from SoCal, you will find this site very helpful.


Offline Captain_confederate

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Re: Looking for answers when a motor is bored
« Reply #10 on: March 22, 2019, 09:23:48 AM »
That's where I was going Stew; it wouldn't hurt to balance the crank and match the weight of the pistons while you are here Captain.

If it's a manual transmission, have the flywheel balanced too.

Makes for a smoother running engine when all parts are in sync and not fighting each other.

Regarding the bearings, you won't know till the crank is measured by your machine shop. You may get to use standard size 350 bearings, you may have to have the crank ground to the next size down.

Welcome from SoCal, you will find this site very helpful.

Thank you Johnny.
So after everybody's input and the more research I have done I have a better understanding of what needs to be done and the different routes I can go. My initial plan was to take the 350 out of my 85c10 an have it bored out an everything machined (Crank, heads, rods) whole 9 yards..
The past weekend I had a buddy of mine contact me. Long story short he ended up giving me a Chevy 454 mated to a turbo 400. It came out of an R/V. Been sitting for a years I guess. Tried taking the tranny apart Sunday night but the motor is stuck an I can't get the flywheel to move. Have not disassembled anything off the motor yet as it what late. If the block is not damaged I will be swapping the 350 for this. I wanted to wait to reply an get all the casting numbers off it but work has been busy. The casting number I did get was 14015543 off the block. Question is, would getting the parts machined on the old R/V motor be worth it? Or won't be able to tell until I break it down?
If the block is ok I plan on getting it bored out. Getting it bored out would I go the route of getting newer high performance parts rather than the stock R/V parts after they are machined?
I'm going to be using this as my daily driver. I don't drive much just to an from work everyday not a far drive. Running off pump gas. I have a decent budget I wanna spend but don't wanna get to ridiculous. I wanna get new performance parts but if It is not needed then that's a plus.
Thanks for the input guys.
« Last Edit: March 22, 2019, 09:30:00 AM by Captain_confederate »

Offline JohnnyPopper

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Re: Looking for answers when a motor is bored
« Reply #11 on: March 22, 2019, 01:42:19 PM »
Aye Captain! Welcome to the world of Big Block power!

Sounds like the motor is frozen from sitting.

Try some PB Blaster in each spark plug hole and use a crow bar to gently move the flywheel till you break her free.

Careful using the the words "big block & performance" - big money will follow!


Offline Captain_confederate

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Re: Looking for answers when a motor is bored
« Reply #12 on: March 22, 2019, 08:21:45 PM »
Aye Captain! Welcome to the world of Big Block power!

Sounds like the motor is frozen from sitting.

Try some PB Blaster in each spark plug hole and use a crow bar to gently move the flywheel till you break her free.

Careful using the the words "big block & performance" - big money will follow!

This will be my first one to! So I'm really looking forward to this. Once I tear it down and get some casting numbers, I'll research what I got an see what I wanna keep or replace.

I read that some of these motors have steel cranks. If I there's one in there I'll get that machined as well as the heads. Possibly new rods or get them machined as well. New pistons, cam, timing chain, lifters, rockers, intake, carb.

Now choosing what parts to use is a little difficult 😂 just don't know what to go with and what's good or not. Still doing some research!

Offline roundhouse

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Re: Looking for answers when a motor is bored
« Reply #13 on: March 22, 2019, 08:54:21 PM »
How long was it sitting ?
And was it outside uncovered or in still in the RV?

Take the spark plugs  out and maybe get a cheap camera scope for your smartphone and look inside the spark plug holes

See how bad itís rusted

Keep the plugs out
Put some auto transmission fluid in each cylinder
Let it sit for a day or so and try moving the flywheel

Or maybe a giant pipe wrench on the crank pulley

Donít try to turn the engine using the bolt in the center of the crank pulley
 It will break off inside the crankshaft

Take the valve covers off so you can see if the rocker arms are
Moving

When you disassemble the engine
Watch some YouTube videos and get some ideas about keeping the parts in order

Unless youíre going to replace the lifters rockers pushrods etc
 
If youíre planning on reusing them

Get a cardboard box and label it and punch holes for everything and keep everything in the exact order it was removed

If you replace the cam , you will usually need to replace the lifters too

Old worn lifters on a new cam will wear out the cam in a hurry

The heads in a RV engine will Probabaly be low compression for long life in a very heavy vehicle and super hot environment if it was a cab over rig like most motor homes
Not much airflow over the engine to cool off the outside of the engine

I used to have a P chassis bus/RV with the van cab
And a TBI 454 and it would get so hot it would literally melt the plug wires and was regularly cracking the exhaust manifolds

 

Offline Captain_confederate

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Re: Looking for answers when a motor is bored
« Reply #14 on: March 23, 2019, 06:49:20 AM »
Motor has been sitting for about a year or so my buddy said. I was told it was covered up. As for rust, from what I can see through the distributor hole it doesn't look to bad.  But I can only see very little. Once I break her down I'll be able to see more. I put some oil in the spark plug holes the first night I couldn't get it to move. Been sitting since Sunday night with fluid in it so hopefully she'll break free.

Breaking down the motor won't be an issue. But I really appreciate your advice and input. I've personally never had an engined bored out or a real performance motor. But from all the advice that I'm getting it shouldn't be to hard