C2- Cylinder boring

[brumbach]

Does anyone have a feel for a reasonable price to rebore an engine? I know prices vary from one place to another. Just looking for a ball park price. By the way, no sleeves required. Thanks -- Bill

 

[OLDCHEV]

Here in Phoenix, Az. my machine shop charges $ 125.00 for a Vat, bore, hone & new cam bearings.

 

[brumbach]

Here in Phoenix, Az. my machine shop charges $ 125.00 for a Vat, bore, hone & new cam bearings.

Too bad you're in AZ and I'm in KY. Hopefully I can find someone around here that is as reasonable and qualified. Any advise in picking the right shop?

 

[allcoupedup]

Shop out here in the 'burbs of chicago charged me $290 for bore and hone.

tank, cam bearings, and freeze plus (installed) ran me $220. My shop was expensive.
My block was standard and he told me a I needed .030 over. I don't think he even measured to see if I could get away with .020..... lazy. Go in and talk to the owners and get a tour of their shop. You'll get a feel for who is skilled, who is a mess, and who could care less about your business.

My builder was good but didn't give me the time of day because I was a $1000 customer and everyone else was building big $$$ race engines. He half-assed my stuff.


Brian

 

[brumbach]

Wondering? If he had bored it at .020, would you have had difficulty in getting pistons to match? Pistons at +30, +40 and +60 seem to be readily available but anything else appears to require special ordering @ additional costs. The reason I ask is that I've finally located a standard bore block and I think I'll need to specify boring size to the machine shop to match available pistons. Your thoughts?

Thanks,

Bill

Shop out here in the 'burbs of chicago charged me $290 for bore and hone.

tank, cam bearings, and freeze plus (installed) ran me $220. My shop was expensive.
My block was standard and he told me a I needed .030 over. I don't think he even measured to see if I could get away with .020..... lazy. Go in and talk to the owners and get a tour of their shop. You'll get a feel for who is skilled, who is a mess, and who could care less about your business.

My builder was good but didn't give me the time of day because I was a $1000 customer and everyone else was building big $$$ race engines. He half-assed my stuff.


Brian

 

[allcoupedup]

.020 over is a little less common but still considered "standard". .010 used to be sold but are pretty much considered custom. I never priced custom made pistons... with the work people go through to fins correctly dated blocks, custome pistons sound like a viable option.

TRW offers .020 forged domed pistons that are equivalent to the OE SHP pistons
http://store.summitracing.com/default.asp?target=partdetail.asp&part=TRW-L2166NF30&N=120%204294925232%204294922410%20301942

$40/each

The .030 version that I used was the same price. SO.... be sure your builder measures carefully instead of just going to .030. Many prefer .030 because chances are that their machine is set up for .030.

Make sure your builder has pistons in hand before he bores the motor. You post indicated you might fit the pistons to the bore. To do things correctly, you need to fit the bore to the piston.

Brian

 

[Vettewine]

.020 over is a little less common but still considered "standard". .010 used to be sold but are pretty much considered custom. I never priced custom made pistons... with the work people go through to fins correctly dated blocks, custome pistons sound like a viable option.

TRW offers .020 forged domed pistons that are equivalent to the OE SHP pistons
http://store.summitracing.com/default.asp?target=partdetail.asp&part=TRW-L2166NF30&N=120%204294925232%204294922410%20301942

$40/each

The .030 version that I used was the same price. SO.... be sure your builder measures carefully instead of just going to .030. Many prefer .030 because chances are that their machine is set up for .030.

Make sure your builder has pistons in hand before he bores the motor. You post indicated you might fit the pistons to the bore. To do things correctly, you need to fit the bore to the piston.

Brian

Right on , Brian!

Always have pistons and rings in hand before boring and fit the bore to them!!! Also, have all parts dynamically balanced by a professional as it will eliminate rotary vibration and makes it run so-o-o-o smo-o-o-o-th...

I had mine done at .040 over (mine was already at .030 over) as I was able to get Keith Black hypereutechnic (sp?) pistons in that size. Came out great and no vibes up to around 6500 r's (haven't gone any higher than that!)...

 

[Vipermike]

Make sure whatever machine shop you decide on uses torque plates on the block when they hone it. They usually charge about $60 more for this but it's well worth money.

 

[brumbach]

Now for the biggest of questions???

Well, I've ordered the block. It's the correct block for my car. My existing block is a 68 (non-vette). The engine runs great. Why am I changing it? I want to return the car to originality. Not making a show car. It'll always be a driver for me. I enjoy driving it so much that I don't want to shut it down until I have a complete, correct engine to install. I'll buy engine parts as funds become available. You advised me to have the engine bored when I had the pistons in hand so I'll wait until then. I'm new at this so I need more of you help. I'm building a 65 L79 327/350 hp. Can you point me to the best suppliers and exact part # for all of the main internal parts I'll need to make the long block? I've got the heads and intake already. I also have the Jeg's catalog if that helps. Advise on crank, cam, piston, etc would be great. Oh yes, the block is currently standard bore so I'd imagine +30 will be likely according to the supplier. Help if you can. Thanks in advance. Bill

ps. wouldn't mind pushing the hp up a little if necessary to get the optimum component mix. Wouldn't want to go the other way, however.

 

[allcoupedup]

Brumbach -
Start by measuring the combustion chamber volume on the heads. If the block us undecked you can esytimate the piston/deck clearance at about .030 (you should probably do some research here). If your combustion chambers are small you might need flat-tops. If not (around 62-64CC) you could probably do a "stock" rebuild. By stock I mean using domed pistons, composition gaskets, etc....

use a steel 327 crank - 4577 or 2680

Before buying bearings you'll need to check the journals as the bearings need to be fit to the crank. Need to hold off on buying pistons and rings until your builder tells you .020 or .030 over.

Soooo many part numbers....

here's my build (note you might have to hit refresh a few times)
http://65corvette.nonethewiser.net/part.htm

I purchased most of my build stuff from Competition Products in Wisconsin. Their prices were much better than JEGS.

http://www.primediapowerpages.com/cgi-bin/ePages.storefront/422b5fa20055053f0000c0a801b8057e/ePages/Customer/Vanity/easy/competitionproducts



Brian

 

[brumbach]

I'm a little confused. You say hold off buying pistons until it's been determined .020 or .030. Earlier you said have pistons in hand before boring. Sounds like the process is iterative. First determine what must be done to restore the cylinders, i.e., .020 or .030 or whatever, then obtain the exact measurements of the pistons within one of those ranges to finalize the exactness of the boring specifications. Is that right? Sorry for being dense. All this is new to me.

The block is located in WI whereas I live in KY. The WI supplier (reliable source) will bore the block before shipping. This will be very helpful to me. My objective is to mount the block on a stand when recieved and over several months build the engine on site. I think I can handle the assembly work (with some technical direction) but that'll be my upper limit.
Machine work will have to be outsourced. I'd like to stay away from receiving a heavy component such as block, locating a reliable local machine shop and delivering and picking up the component after machining. Might not be feasible to do but would minimize logistical requirements.

Your thoughts?

Brumbach -
Start by measuring the combustion chamber volume on the heads. If the block us undecked you can esytimate the piston/deck clearance at about .030 (you should probably do some research here). If your combustion chambers are small you might need flat-tops. If not (around 62-64CC) you could probably do a "stock" rebuild. By stock I mean using domed pistons, composition gaskets, etc....

use a steel 327 crank - 4577 or 2680

Before buying bearings you'll need to check the journals as the bearings need to be fit to the crank. Need to hold off on buying pistons and rings until your builder tells you .020 or .030 over.

Soooo many part numbers....

here's my build (note you might have to hit refresh a few times)
http://65corvette.nonethewiser.net/part.htm

I purchased most of my build stuff from Competition Products in Wisconsin. Their prices were much better than JEGS.

http://www.primediapowerpages.com/cgi-bin/ePages.storefront/422b5fa20055053f0000c0a801b8057e/ePages/Customer/Vanity/easy/competitionproducts



Brian

 

[allcoupedup]

You got it! It is an iterative process. The first step is to measure the bore to see what kind of machining has to be done ... .020, .030, etc. Lets say that you can get away with .020 - the shop won't actually go all the way to .020. They will leave enough material for a final hone. This final hone is what will make sure your pistons fit just right in the bore. If all the machine work needs to be done in WI, I'd do the following:

Have them tell you if the block can go .020 or has to go .030. Select your pistons and buy them. Send them to the shop in WI. Have them measure the pistons and bore/hone accordingly. Have them send you all the stuff back.

You have to have pistons in hand so that they can by measured. The piston/bore clearance is different for cast and forged pistons so a good builder will require the pistons in hand before putting the final finish on the bores.

Speaking of iterations, I've heard of cases where the shortblock gets assembled, and the piston/deck clearance is not right so everything has to be disassembled and the block decked. During the build you will be taking all kinds of measurements -- journal clearance, thrust, deck height,.... if any of these don't work out then you'll have to disassemble, take action, and measure again.

Engine building is great IMO because it is relatively straightforward. Build, measure, build, measure - everything has ranges and instructions. Body work is a different story - haven't been down that avenue yet.

You can definately handle the assembly work. An engine rebuild is a great project - it will build a lot of confidence and you will really understand how the engine works (if you don't already). I recommend the book "how to rebuild your small block chevy" by Dave Vizard. That book, along with your shop manual will get you 95% there. The other 5% can be answered here!

good luck.
Brian

 

[vette rod]

Shop out here in the 'burbs of chicago charged me $290 for bore and hone.

tank, cam bearings, and freeze plus (installed) ran me $220. My shop was expensive.
My block was standard and he told me a I needed .030 over. I don't think he even measured to see if I could get away with .020..... lazy. Go in and talk to the owners and get a tour of their shop. You'll get a feel for who is skilled, who is a mess, and who could care less about your business.

My builder was good but didn't give me the time of day because I was a $1000 customer and everyone else was building big $$$ race engines. He half-assed my stuff.


Brian

What shop did your stuff?

 

[allcoupedup]

Precision engine rebuilders in Plainfield. I wouldn't recommend them. They are probably great for big$$ race motors but I was definately a 2nd class citizen and some of the work had to be redone at my expense. I've been using R&R engineering in Addison for the little stuff lately.

Who do you use?

Brian

 

[67HEAVEN]

....but I was definately a 2nd class citizen...

Brian

Not around here, you're not.

 

[brumbach]

Great info. Thanks so much. Speaking of decking, before this forum discussions began, I'd already arranged to have the block decked and stamped. Hasn't been done yet. Based on your comments, appears the amount of decking will be driven by piston selection too. Do I have it right? I wouldn't want to have to re-deck once received because that would remove the stamping and broach marks that costs considerably.

Thanks,

You got it! It is an iterative process. The first step is to measure the bore to see what kind of machining has to be done ... .020, .030, etc. Lets say that you can get away with .020 - the shop won't actually go all the way to .020. They will leave enough material for a final hone. This final hone is what will make sure your pistons fit just right in the bore. If all the machine work needs to be done in WI, I'd do the following:

Have them tell you if the block can go .020 or has to go .030. Select your pistons and buy them. Send them to the shop in WI. Have them measure the pistons and bore/hone accordingly. Have them send you all the stuff back.

You have to have pistons in hand so that they can by measured. The piston/bore clearance is different for cast and forged pistons so a good builder will require the pistons in hand before putting the final finish on the bores.

Speaking of iterations, I've heard of cases where the shortblock gets assembled, and the piston/deck clearance is not right so everything has to be disassembled and the block decked. During the build you will be taking all kinds of measurements -- journal clearance, thrust, deck height,.... if any of these don't work out then you'll have to disassemble, take action, and measure again.

Engine building is great IMO because it is relatively straightforward. Build, measure, build, measure - everything has ranges and instructions. Body work is a different story - haven't been down that avenue yet.

You can definately handle the assembly work. An engine rebuild is a great project - it will build a lot of confidence and you will really understand how the engine works (if you don't already). I recommend the book "how to rebuild your small block chevy" by Dave Vizard. That book, along with your shop manual will get you 95% there. The other 5% can be answered here!

good luck.
Brian

 

[allcoupedup]

Decking does a few things:

1) makes the deck surface "true" and flat
2) reduces the quench distance

A quench discussion is probably best saved for another thread but I'll try to explain the important things to consider when decking a block.

Piston/deck clearnance is the distance between top surface of the piston to the deck of the block. If the piston is a flat-top, this is just the distance between the top of the piston and the deck. If the pistons are domed or dished, the distance from the outer surface of the piston head to the deck.

What this means to you: if your block is decked, it INCREASES compression ratio holding all other factors constant. Many people prefer to deck the block, and use flat-tops to minimize quench for the same compression ratio. Let;s not get into quech though.....

check this out:
http://www.rbracing-rsr.com/compstaticcalc.html

I entered these parameters for you:
Bore: 4.030
Stoke: 3.25
Head gasket: .039 (typical fel-pro composition)
Deck Height: .020
Dome: 0 (flat tops)
Combustion chamber: 64

static comp. ratio: 9.89

Since your deck will be fresh and true, you could use steel shim factory-type gaskets (.015) and get to 10.5:1 or use thinner composition gaskets (.029) and get 10.15:1. You should be good on pump premium between 10 and 10.5. I'd shoot for just under 10.5 for max performance.



My point: there are several factors that one MUST consider when designing for compression ratio:

1. Cylinder head combustion chamber volume - can unshroud to increase or mill heads to reduce
2. Piston/deck clearance - can deck the block to reduce
3. Piston dome (or lack thereof) - can purchase with various domes or dishes. Can have the domes milled off to reduce.
4. Compressed head gasket thickness - can select with various compressed thicknesses.


1-3 need to selected carefully as modification is expensive - you have some inexpensive leeway in #4.

I don't know how one would estimate the piston/deck clearance without assembling the shortblock and taking measurements. Maybe someone could comment on what a typical decked block measures.

My factory block was .041 on one side and .031 on the other (.010 difference!) I should have decked it but I already had my pistons purchased and decking at that point would have put me way over the target compression ratio + would have required another trip to the machine shop. What I don't know is how a builder measures to know how much to take off!

I ended up using two different head gaskets to account for my .010 difference in deck height and my true static compression ratio was about 9.9. I wanted to be more towards 10.5 but the CC on my heads turned out to be ~66 instead of the original 62 as someone had unshrouded the intake valves.


Hopefully this makes sense.

Brian



p.s. I purchased a different set of heads that were supposed to 64CC and when I measured them they were 56!!! Need to measure everything if you really want to avoid pinging and low performance.

 

[brumbach]

What great insight. You ought to write a book. I don't know how much the block supplier will do for me. He's agreed to deck and stamp the block and have it bored/honed for me. I'm sure he'll be willing to work with me on assessing the range for cylinder boring beforehand and honing consistent with the pistons provided. Beyond that I don't know. On the block decking issue, if he reconditions the surface to make "true and flat", then stamps w/broach marks, I'll not be able to re-deck to achieve desired compression w/o undoing his stamping. If I understand you correctly, in lieu of re-decking I could correct using your #1 or #4 solution. Am I getting it right? If so, how much out of tolerance would I have to be in the piston/deck clearance that #1 or #4 couldn't resolve it? Sorry for so many questions. Thanks -- Bill

Decking does a few things:

1) makes the deck surface "true" and flat
2) reduces the quench distance

A quench discussion is probably best saved for another thread but I'll try to explain the important things to consider when decking a block.

Piston/deck clearnance is the distance between top surface of the piston to the deck of the block. If the piston is a flat-top, this is just the distance between the top of the piston and the deck. If the pistons are domed or dished, the distance from the outer surface of the piston head to the deck.

What this means to you: if your block is decked, it INCREASES compression ratio holding all other factors constant. Many people prefer to deck the block, and use flat-tops to minimize quench for the same compression ratio. Let;s not get into quech though.....

check this out:
http://www.rbracing-rsr.com/compstaticcalc.html

I entered these parameters for you:
Bore: 4.030
Stoke: 3.25
Head gasket: .039 (typical fel-pro composition)
Deck Height: .020
Dome: 0 (flat tops)
Combustion chamber: 64

static comp. ratio: 9.89

Since your deck will be fresh and true, you could use steel shim factory-type gaskets (.015) and get to 10.5:1 or use thinner composition gaskets (.029) and get 10.15:1. You should be good on pump premium between 10 and 10.5. I'd shoot for just under 10.5 for max performance.



My point: there are several factors that one MUST consider when designing for compression ratio:

1. Cylinder head combustion chamber volume - can unshroud to increase or mill heads to reduce
2. Piston/deck clearance - can deck the block to reduce
3. Piston dome (or lack thereof) - can purchase with various domes or dishes. Can have the domes milled off to reduce.
4. Compressed head gasket thickness - can select with various compressed thicknesses.


1-3 need to selected carefully as modification is expensive - you have some inexpensive leeway in #4.

I don't know how one would estimate the piston/deck clearance without assembling the shortblock and taking measurements. Maybe someone could comment on what a typical decked block measures.

My factory block was .041 on one side and .031 on the other (.010 difference!) I should have decked it but I already had my pistons purchased and decking at that point would have put me way over the target compression ratio + would have required another trip to the machine shop. What I don't know is how a builder measures to know how much to take off!

I ended up using two different head gaskets to account for my .010 difference in deck height and my true static compression ratio was about 9.9. I wanted to be more towards 10.5 but the CC on my heads turned out to be ~66 instead of the original 62 as someone had unshrouded the intake valves.


Hopefully this makes sense.

Brian



p.s. I purchased a different set of heads that were supposed to 64CC and when I measured them they were 56!!! Need to measure everything if you really want to avoid pinging and low performance.

 

[allcoupedup]

Hey Bill,
Thanks for the compliment but I must say everything I know was pulled from kind people on internet forums like this.... and I did my first rebuild last year and didn't do all the HW I needed to do before hand.


This is what I'd do if I was in your situation.

#1 - CC the cylinder heads
#2 - do some research to see what the factory deck clearance should be and then what a typical deck job takes off. You can then get a estimate of what you'll be left to work with. .025 may be a good estimate

#3 - Select your pistons based on #1 and #2. You can play with the calculator using the data from #1 and the assumption from #2. You can then modulate the dome size and and pick a middle of the road head gasket like .029. You should then be able to determine whether you need flat tops or domed pistons. Buy them and send to builder

#4 - When all the stuff arrives at your door, assemble the short block and take piston/deck clearance measurements.

Step #1-#3 above should get you close to your target compression ratio.

#5 - select a head gasket anywhere from .015 (steel shim) to .039 composition to fine tune your compression ratio with your updated piston/deck clearnace. (may even need to use different head gaskets on each side)

IF - the assumptions were bad and you can't get where you need to be with head gasket selection, you can mill the heads or unshroud the intake/exhaust valves to adjust but this is unlikely.


I'm supposed to be studying right now so I'll illustrate in order to extend my procrastination:



Measured: 62 cc combustion chamber
assumption: deck clearance: .025 , bore =.030, head gasket = .029
known: stroke = 3.25
dome = 0 (flat top)

CR from calculator: 10.26


now let's say you assemble it and the deck height is .035 and you've already selected flat top pistons.
bore = .030
stroke = 3.25
dome = 0
head gasket = .015 (you can get away with this because your deck will be true - your heads should be true too - there is little tolerance for warpage with steel shim gaskets)

CR from calculator: 10.37







on the other hand... if your heads were 66cc
deck clearance = .025
bore .030
head gasket = .029
stroke = 3.25
dome = -5.33 (OEM SHP pistons)
CR = 10.44
if you changed to .039 head gasket CR = 10.17



Just play with the calc a little bit and you'll start to see how all these factors change compression ratio.

good luck! A wise man once told me MEASURE TWICE AND CUT ONCE. Some people might think it is overkill to take all these precautions but it will help you understand what's really going on inside that motor and if you ever have to make any changes in the future, you'll know exactly what you're dealing with.

Brian

 

[vette rod]

We are use Hatak Racing Engines. Steve is a very good friend of mine and is the best around the area as far as I am concerned. Have had bad luck with R&R (skipper). If you are inteested I could hook you up with Steve.

Larry

Precision engine rebuilders in Plainfield. I wouldn't recommend them. They are probably great for big$$ race motors but I was definately a 2nd class citizen and some of the work had to be redone at my expense. I've been using R&R engineering in Addison for the little stuff lately.

Who do you use?

Brian