Bore new Bow small block or buy pistons that fit?

[dieselhead]

I bought some new forged Wiseco 4.03" pistons a few years for an engine I am planning on rebuilding and then a few years after that I found a new 24502503 Bowtie Chevy small block with the 3.98" bore. This is the factory blueprinted bow tie block that can be bored to 4.155". I've decided to use the Bowtie block since I don't have the original block for my car and I can't do a numbers matching restoration anyway. I hate to bore a new block but am considering it since I already have the 4.03" pistons. This block already has all the freeze plugs and oil gallery plugs installed but no cam bearings. I'm wondering is if I can have this block bored and honed with the freeze and gallery plugs installed ( I guess it's really not a big deal to remove and reinstall the plugs). This block has 2" cam bearing bores that can be bored larger so I considering roller cam bearings. I don't know any machinists to talk to but there are a lot of very knowledgeable people on this website. Any opinions or suggestions?

Thanks,
Victor

[DanStokes]

This is not a simple question. Of course, an overbore yields more displacement and that's always a plus (unless it takes you out of class as it might in LSR) but it IS a bit painful to mess with a known good block. A lot depends on what you WANT to do - new pistons of the right bore size might be cheaper and you can sell the Wisecos or keep them back for the next build.

As far as pulling the plugs - are you sure the block is clean enough as shipped? It SHOULD be but is it? My point is that you might want to pull the plugs and inspect/clean the block whether or not you bore it. Just another part of the equation.

EDIT: I don't know where you are in Texas but I know that there's a good machine shop in San Antonio. My bro knows the guys a bit and they're Land Speed Racers who run a Corvette and they're familiar with Chevy performance engines. If you're interested I'll contact my bro and get a name.

I don't think you'll go wrong either way but I'm no SBC guy. Hopefully others can chime in.

Dan

[Barry Donovan]

brand new needing a bore. Why not.
Even easier. No conical sleeves or swells.

I like the roller cam idea.

Not sure why plugs would have to be removed. A machinist could help.

Ever checkout blue print engines? you could get a full wet sleeve 350. Mellow build, but nice.

[Beagle]

The odds of finding pistons in 3.98 are not good, plus, you finish the bore to your piston size anyway... the machinist should ask for your pistons before boring it. They'll fit it to the largest one usually. Point being, you're probably going to end up paying for a bore either way. I'd use the Wiseco's if they meet your other needs (Compression ratio)... you've got a ton of cylinder wall there for a 4.040,4.060, 4.125, etc. if you need to bore it again later.

[dieselhead]

Dan,
I live about an hour and 15 minutes away from either San Antonio or Waco so if you can get the name of a machinist in San Antonio that would be great. There's a machine shop in Waco I have heard good things about so I will check with them also. There's a couple of machine shops around here but haven't heard anything good about either one. I know the camshaft roller bearings are overkill but I may run this engine at the Texas Mile one of these days. I like overkill anyway. These forged pistons call for a 4.030' bore and .0035" clearance. I measured the pistons with the dial caliper that I use for reloading ammo and they measure 4.0265" which will leave .0035" clearance. I always wondered how they came up with the proper piston clearance. I thought they honed the block to fit the pistons but I guess it's kind of the opposite. I'm decided to use this Bow Tie block and have it bored for the Wiseco pistons I already have. GM rates this block for 700HP, I'll be happy with around 600HP. Thanks for the other replies.

Victor

[JamesMayberryIII]

The bowtie block is 3.98 and is not finished bored/honed.. you finish hone it to your 4" pistons.. depending on what type piston and it's required wall clearance..
Me I'd buy new pistons.. I'd never overbore 30 over just because.. taking one rebuild out to use a piston.. if it was for max cubes then it be bored to the blocks max and that isn't the 30 over pistons you have..
either put them on the shelf for when it or another needs a 30 over piston.. or sell them and help fund the new correct 4" size..
if you are going to take the block all the way down to have it over bored, you might as well go for all the cubes you can.. and that will require new pistons..
It should not be hard to sell off 30 over chevy pistons.. t get the correct sized ones.. then have the machine shop hone the cyl walls to the pistons..
again the bores are 3.98 because they are not finished machined.. the builder does this.

[DanStokes]

I have a note off to my bro to get the name of the shop.

I suspect that James is right as far as the as-delivered bore. The intention is probably to hone fit the bores to the pistons. A 0.030 overbore is no big deal when the block is at the shop anyway.

Dan

[cstmwgn]

You asked another question that doesn't seem to have been answered. You should ask your machinist about roller cam bearings. On a Ford when you run roller cam bearings you have to run billet camshafts which significantly adds to the build cost.

[Beagle]

man, if you live 15 minutes from Waco or San Antonio, I'm thinking your daily driver is a Gulfstream or an F16 out of Killeen... The last time I was in San Antonio, it took 15 minutes to get to the beer store across the street!

cstmwgn, how much are you talking about? Is a 500.00 cam out of line with a 2300.00 block? Compared to fueling up the F16, that's chump change.

I have to admit, I'd have to spend some quality time talking to the cam guy before buying one.

[cstmwgn]

Beags, I get myself in trouble here when I try to relate my personal experience with other's projects. My new engine has roller cam bearings in it. So I have to run a billet camshaft which means I have to run roller lifters and a "special" distributor gear. Neither of those items have proven to be high mileage parts for me! SO the cost of a $500 camshaft has additional costs of $1000 lifters that seem to need to be replaced frequently (I have not gotten over 6,000 miles on a set). I actually drive my car over 5,000 miles a year and would like to drive it more but the though of doing a lifter change on the side of the road makes me a little anxious!

Anyway, just thought I would mention the cam bearing issue in case it wasn't something he was aware of. I am not a chevy guy so I don't know why babbitt bearings would not be the preferred approach on a street motor.

[Beagle]

Roger that... but I can't see that causing trouble. That is the experience sharing the OP is looking for I bet. Thanks! My guess is that your idea of a mild cam and mine vary a bunch. lol. I think your version of mild is under .750 lift and 300 lbs of pressure resting on the seat My idea of mild is something that won't wear out a flat tappet lobe running 3 quarts low.

I was kidding about the cost, the block on this build costs more than I want to spend on the whole engine but it's well known that I'm a cheap bostich ..

[dieselhead]

I have a note off to my bro to get the name of the shop.

I suspect that James is right as far as the as-delivered bore. The intention is probably to hone fit the bores to the pistons. A 0.030 overbore is no big deal when the block is at the shop anyway.

Dan

Thanks. I knew that if I bought 4" pistons the block would have to be honed for the correct clearance. I didn't have much luck finding aftermarket 4" forged pistons when I was searching for them, everybody has 4.030" pistons. I guess I could special order some if I decide to go that route. I'm just a little hesitant to bore a new block that has all machined surfaces within .001" tolerance, everything is square and round.

[dieselhead]

Beags, I get myself in trouble here when I try to relate my personal experience with other's projects. My new engine has roller cam bearings in it. So I have to run a billet camshaft which means I have to run roller lifters and a "special" distributor gear. Neither of those items have proven to be high mileage parts for me! SO the cost of a $500 camshaft has additional costs of $1000 lifters that seem to need to be replaced frequently (I have not gotten over 6,000 miles on a set). I actually drive my car over 5,000 miles a year and would like to drive it more but the though of doing a lifter change on the side of the road makes me a little anxious!

Anyway, just thought I would mention the cam bearing issue in case it wasn't something he was aware of. I am not a chevy guy so I don't know why babbitt bearings would not be the preferred approach on a street motor.

Thanks. I don't know much about the costs of roller bearing camshafts yet but I will be running a billet cam and solid roller lifters. Which brand billet cam are you using? The Lunati cam and solid roller lifter kit that I'm thinking about using costs a little over $700 plus they will charge $70 more to make it with the larger cam bearing journals for this block. I haven't priced the Lunati valve springs, retainers and seals yet but the AFR heads I plan to use comes equipped with all that. Only 6000 miles on a set of roller lifters? I hate to hear that but I doubt I'll drive more than 3000 miles a year. This will be the first "hot rod" I've ever built that won't be my daily driver (I'm retired). The first hot rod I built in 1963 was a '56 Chevy 283" with a Melling solid lifter "drag only" cam and 4.56 gears that I drove daily for 2 years with no problems. The cam was pretty hot for it's day with valve lift of .494"I/.512"E and duration of 304I/312E. With headers and ported heads it pulled real hard to 7500rpm. I'll probably drive this car only on weekends (if it's not raining).

[dieselhead]

man, if you live 15 minutes from Waco or San Antonio, I'm thinking your daily driver is a Gulfstream or an F16 out of Killeen... The last time I was in San Antonio, it took 15 minutes to get to the beer store across the street!

cstmwgn, how much are you talking about? Is a 500.00 cam out of line with a 2300.00 block? Compared to fueling up the F16, that's chump change.

I have to admit, I'd have to spend some quality time talking to the cam guy before buying one.

An HOUR and 15 minutes but that's only if I travel during the middle of the night. The traffic on IH35 is usually bumper to bumper all the way from SA to Dallas because of commuters and truck traffic. Our brilliant Texas DOT had a toll road built around Austin to relieve the truck traffic but the toll is so high they won't use it (I won't either). I live near Austin.

[CTX-SLPR]

Where near Austin? I'm from Pflugerville originally but hardly know anything about stuff there anymore. Place has changed so much since I moved away!