Inliners International Forums General Discussion Engines 230 Engine Advice

First, I would like to say hello. I am a newly registered member of this site. I spent some time searching the forums and found some really good information. Glad to have this resource available!

I have a 1965 Chevelle Malibu SS Convertible that came with the stock 230/powerglide. I am working on a complete frame off restore on the car, but also upgrading the suspension, brakes, etc. I threw around some ideas about replacing the engine, but I really like the idea of keeping the inline 6. Keep in mind that this engine still has oil in it, but has not run in a very long time. I have to pull the engine and break it down before I know what I am dealing with.

My goal is to have 250+ hp. From what I have read, it looks like I can use a 250 crank, 250 pistons, langdon headers, offenhauser intake (I am leaning toward the 3x1 bbl Carb)...I love the look), a mild street cam, and a 700r4 transmission. I have not figured out the head yet.

Does this seem like a good direction? This is my first inline 6 and I am really out of my comfort zone on the upgrades to look at. Any advice is appreciated.

Installing a 250 crank into a 230 block is a good simple upgrade and worth doing while you have the engine apart. You should be able to achieve your HP goal pretty easily.

I know the look of a 3x1 setup is cool and all but it's far easier to tune a single 4bbl.

I like your game plan but trying to get one HP per cubic inch from a stock compression ratio, RV cammed six is a little too optimistic. Nevertheless you will be pleased with the improvement over stock.

Thanks for the encouragement and feedback. I know that 250hp is overly optimistic, but I think that I can get at least closer than stock.

I agree that the 4bbl is easier (and much cheaper). Is there a real performance difference in the 3x1 vs. a 4bbl if it is dialed in correctly?

Honest answer: not really. Not enough to be worth the constant fight to keep the three in tune.

Here's what I would do...250 crank, and flat top pistons..(you DO NOT want dish pistons) and have the head shaved if you can...had .030 shave off my 292's head...also 0 decking the block will help with more compression. A mild cam will improve majorly and as far as the head I'd do a lump port conversion, 1.86 intake and 1.60 exhaust valves. 4 barrel and headers...can't say hp specs but can say the improvement is noticeable for sure. Have you considered just purchasing a 250 for more cubic inch? A naturally aspirated 250 I've seen make 310 hp.

@TJ: That is good advice. I will take note of the recommendations. Thank you for that. As for the 250 block, I was trying to keep the original because the car is numbers matching. Everything is original and rebuilding the 230 was appealing. This is not going to be a drag car or auto-x, more of a weekend cruiser.

I do want enough power to pass someone if I need to up on the mountain roads.

I hear ya..keeping the original engine is always nice. The 230 will be a great little engine...just was making sure you had considered a 250. lol Another thing to add on your list if you like manuals would be a 5 speed...that'll really help with performance and you'll have an od.

the 230 & the 250 are of the same Bore Just different stroke/crank and the pistons. So number wise Nobody would know
other then you an the machine show hehe.

Search Rock Auto for Chevy 307 pistons. They're the exact size as a 250 but are flat tops. That's what I have in my 255, 0.040 over 307 pistons (255). They have Sealed Power cast flat tops (which is what I got), #295P (different letters depending on overbore size). Check Summit, Amazon, etc., I ended up getting 6 pistons for $87 incl shipping. It'll make your 250 around 9.5:1 compression.

307 pistons is an interesting idea. I assume that would work with a 250 crank?

I did consider changing out the engine, but I already have the 230. I think if I decide to swap it out, I would go with a 327. I don't see spending the money on a 250 if I already have a 230.

How much can you bore a 230 before you start having issues?

Couple minor things I see that can help you in the future.

On the carb kit from Offy they provided a metal tube and a flexible one to make the throttle cable bend. I had trouble with the flexible one and had to go with the metal tube. Use grease in there so it doesn't bind.

On the plug wires: until I went with high end 80mm wires I had some arcing that would cause a rough idle. Either go with bigger wires or use wire spacers of some type. I used the plastic ones you can buy at Autozone but I wasn't happy with them. Now I'm using zip ties and they work great, actually look better, and hold the wires right where I want them.

Someone else's pics:

[img]https://scontent-lga.xx.fbcdn.net/hphoto...amp;oe=55AE1833[/img]



Mine:



It might be because I'm running HEI but I really fought that problem for a long, long time until I did this.

That is good to know. I am sure that I would have wracked my brain for a while trying to figure that out. Thanks for the tip!

In my experience the question is answered based on two key conditions: 1) how out of round are the existing bores? Which is the minimum machining you face - 2) What is available to stuff into the new holes? Stock items? What over bore sizes are in stock? Custom built pistons? Now you can have any overbore, compression height you want . . . and the budget will reflect it.

.060 over is the most you want for street. .040 would be fine for your application...your 230 already has flat top pistons stock. Or should anyway.

I just wanted to say thank you to everyone for the advice. I feel much more comfortable with what I want to do. Now it is time to pull the engine, break it down, and find a local engine shop.

Just an FYI, a 200R4 trans will drop right in with out needing to make a new driveshaft or a different cross member.
With a 700R4, you need a different length drive shaft.

I like the gear spacing better also & has a taller OD then a 700R4 so you can use a numerically higher rear axle gears = better acceleration & still get good mileage.

MBHD