Straight Six Engine Gurus, I Need Your Help!

[MP33]

Since the 230 and 250 engines are nearly identical besides the bore diameter. Is it possible to bore out a 230 to 250 specs? I realize its quite a bit of cylinder wall to remove and may not even be possible without resleeving, maybe? I have a wore out 230 that I'm going to rebuild for my truck and was just wondering if it was a viable option. If the cost would be to great I would just look for a builder 250. Thanks

[66redw/white]

im no engine guru but 20 ci out of borein the cylinders out doesnt seem like it would be possible. 30 over on a small block only gets you 5 ci and we only have 6 cylinders. i was under the impression that the differences between the engines was in the stroke.

[61_FL_Apache]

I wouldnt do it. Its too much.. Just look for a good 250 to build up.

[kieth]

Originally Posted by MP33

Since the 230 and 250 engines are nearly identical besides the bore diameter. Is it possible to bore out a 230 to 250 specs? I realize its quite a bit of cylinder wall to remove and may not even be possible without resleeving, maybe? I have a wore out 230 that I'm going to rebuild for my truck and was just wondering if it was a viable option. If the cost would be to great I would just look for a builder 250. Thanks

I have a 250 out of my 66 gmc, it was running when we pulled it to replace it with a 350.....

[lwb66step]

forget the 250 try to find a 292, if your going to replace the entire block might as well go with the biggest 6 you can find, I hear the 292 is a beast...

[DLOE65]

Yeah 292 fo Sho!
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[Rooster's 67]

yeah but the 292 will require sourcing bracketry and other things. find ya a good running 250 and build her up.

[aerotruk63]

From what I've heard the 292 has more torque but can't rev very high. A balancing issue. The 250 I have in my truck has pistons from a 307 small block. We don't know what we rev at but it keeps pulling so we just hold out more. Sounds like a bunch of angry bee's when it's reving.
If you find a head from a 194, it"s a closed chamber head that will up the compression ratio of a stock 230,250 or 292. It dosn't flow as well though as the open chamber design of the forementioned engines.
With an inline you rev the crap out of it cause all the powers in the upper end. I have a 3000 stall in front of the powerglide.
There's a inline powerbook out there, you see it on Eplay and from online sources.

I got my information from old hot rod magazines as well as the engine rebuilder.
1.94 intake valves and 1.88 exhaust in the head. That center support in the intake ports was removed for better flow. The manifold was port matched to the head and the ports were polished. Could use more cam than the one we ordered. This was all back in the eighty's.

Today you can get all sorts of neat stuff for the inlines. There cheap to buy cause most people feel the V8 is the only way to go. I like mine, reliable, fun and economic.

[lwb66step]

I agree about the inline 6's when i was shopping for my next project i made sure I found one with an L6, from what I have heard these are becoming more popular these days. With $4.00 gas fast approaching i can see why, my 327 got terrible milage...

[MP33]

I was lucky enough to find a power steering setup for the 230 I,ve been running all summer, Boy is that nice. I'll look for a 250 and build that.

Kieth, I got your PM. I'd be interested but I think the shipping would kill me.

[rockdogg2020]

Actually, they have the same bore. The 250 is a stroked 230. So the crank and the pistons are different. Those are the main parts needed
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[T2vigil]

Aerotruck and I have almost identical L6s. The .030 flat top pistons were a great change and I had the block decked to bring the top of the pistons to within .010 from the top. The cam I used was just a little bit larger than a Marine application. Took .020 off the head, matched the gaskets and also did the porting and polishing. With all that said go for the 250 L6.

[Torqueforce]

I also agree with just buying a 250, they're great engines and plentiful, great work horses extremely reliable. I have one in my 65 and she makes great torque, horsepower isn't that impressive but its adequate, sometimes to me it seems a little under powered but it's got alot of potential. I imagine it would respond great to an offy intake, headers or cam, it would really wake that engine up. The highest I've revved mine was about 4k and I've heard that's about as high as they will go.

[bubba327]

Mine is a 230 . It has a 250 block from a '71 (230/250 are same bore) and the crank has a 194 part number(194/230 are same cranks) I believe the heads have been shaved as I have around 140 PSI compression. Stock compression from I can find should be 130-135 PSI .

The inline 6 does all I have ever asked of it , runs 65-70 mph all day but pulls down pretty quick on an incline. (3.08 axle and 235 -15 tires)
It averages about 15-16 MPG even with a Offenhauser intake and a Holley 7448 2 barrel (with velocity stack and 1" carb spacer) I had to increase 3 jets up when I added the velocity stack. go figure..........

[Heater63]

I have a "tweaked" 292. My advice to you is the 250.

The best value for dollar spent, and best mpg, is the 250. Leave the bottom end stock except for maybe using the flat top 307 pistons. Upgrades are a mild cam (Comp or Schnieder), HEI, an Offy intake, headers and you will have a solid performer. You can do lump ports also for not much.

Do your research at inliners.org

[DLOE65]

Heater you been driving your 292 now?
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[1Bad62Pro/Street]

Langdon's Stovebolt Engine Co.
Specializing in GM 6 Cylinder High Performance Parts.
http://stoveboltengineco.com/

Clifford Performance
http://www.cliffordperformance.net/index.html

Hotsixes - History on the 6 cylinder inline Chevy straight six engines.
http://www.hotsixes.com/index.php?op...&id=2&Itemid=3

Chevy Six Cylinder Casting Numbers
http://67-72chevytrucks.com/vboard/s...d.php?t=356268

Online engine resources (casting numbers, calculators, etc.)
http://67-72chevytrucks.com/vboard/s...d.php?t=382583

Mighty6 =-> Modified 1968 Chevrolet 292 Straight-six cylinder engine that has been overbored .060″ for an actual displacement of 301 Cubic Inches.
Best E.T. 8.44 @ 160 mph
http://www.mighty6.com/

MIGHTY6 NEW PERSONAL BEST ET & MPH ON DOT...

[rudyyloverboiii]

Hoping this works to the fellow 292 gurus.
I have one n I'm getting water from the exhaust manifold. Leak g. It's a new manifold n new gasket aswell. I'm hoping the head isn't warped. I torqued the manifold 30ft lbs. Could it b that it's warped or may I have a cracked head? Thanks

[RANDY COX]

I had a 250 in my 70 Burb 4x4 it was factory, while it wasn't a lot of horsepower it had torque that little engine pulled that suburban around pretty good I had a 4" lift with 33's with 3:73's and a 3spd tranny...

[TJ's Chevy]

Originally Posted by rudyyloverboiii

Hoping this works to the fellow 292 gurus.
I have one n I'm getting water from the exhaust manifold. Leak g. It's a new manifold n new gasket aswell. I'm hoping the head isn't warped. I torqued the manifold 30ft lbs. Could it b that it's warped or may I have a cracked head? Thanks

Where's the water coming from? You said the exhaust manifold but can you be more specific as to Where on the exhaust manifold?

[rudyyloverboiii]

Oh ok ha. Towards where it bolts to the head?

[TJ's Chevy]

Reason I asked for more specifics was it might be a blown head gasket...have you done a compression check or do you see any white smoke coming out of the exhaust pipe when the engine is running?

[62 Barnfind]

Originally Posted by MP33

Since the 230 and 250 engines are nearly identical besides the bore diameter. Is it possible to bore out a 230 to 250 specs? I realize its quite a bit of cylinder wall to remove and may not even be possible without resleeving, maybe? I have a wore out 230 that I'm going to rebuild for my truck and was just wondering if it was a viable option. If the cost would be to great I would just look for a builder 250. Thanks

My buddy just rebuilt his 230. The machine shop bored it 30 over and used a 250 engine crank. So basically it's now a 250.

[TJ's Chevy]

You don't want to Bore out a 230 to a 250. The 250 is a stroked 230...That's all. The 230-250-292 All had the same 3.875 bore but different strokes even though the 292 is a different block. You can overbore as much as .060 to stay streetable. Put a 250 crank in the 230 and over bore it .040 and you sell 255 or a little more.

[72step]

I believe what TJS said is right. It's not the bore but the stroke that determines the displacement of many chevy engines even V8s. Also longer stroke equals more torque and hp but less rpm resistance.