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230 straight six

Discussion in 'The Hokey Ass Message Board' started by jessechambers37, May 28, 2011.

  1. jessechambers37
    Joined: Nov 6, 2009
    Posts: 4

    from santa ana

    I have a stock 230 straight six in my '64 C-10 truck and am looking to add some H.P. to it. Any ideas?
  2. Dynaflash_8
    Joined: Sep 24, 2008
    Posts: 3,038

    from Auburn WA

  3. mart3406
    Joined: May 31, 2009
    Posts: 3,055

    from Canada

    Lot's of stuff you can do, depending on what you want to spend and what you what you want out of the engine. Assuming you're on a tight budget and just want to bump the power a bit, but still need to keep it tractable enough for daily driving in a fairly heavy and 'nearly, but not quite as aerodynamically slick as a brick'(!) pick-up truck, here's what I'd do.....

    First, a better cam. For a truck, nothing too wild - something about 230 or 240 degrees *advertised* duration max. If you've got a 4 speed (- ie - a swapped in Muncie or BW T10 "car" 4-spd. - not the heavy-duty 'granny low-gear' "truck" 4-spd.) and *3.73 or lower* rear gears, you could probably go with a bit more cam duration and still be happy - but even then, you'll probably still want a cam with no more than 250 to 260 degrees advertised duration. Anyway, there's lot's of good aftermarket cams available. Also Mercruiser and OMC sold marine marine engines based on the 230 and 250 Chevy 6's that had upgraded cams. The OMC and Mercruiser marine cams have more duration and lift but are still mild enough for a truck application and make tons of torque around 3200 rpm. You might find one of those, new or used, cheaper than a new aftermarket cam.

    Next would be an intake and carb upgrade. If you want to keep the stock intake (not recommended),you could use a slightly bigger 1-bbl carb from a 292 Chevy 6. Much better though, would be an aftermarket intake - either an Offenhauser or Clifford - with either a single 4-bbl or two-1-bbls or probably best - two-2-bbls. If you go with a single 4-bbl, I'd use either a 390 CFM Holley (expensive, new) or a (dirt cheap in just about any boneyard) - slightly reworked Rochester Q-jet. Just be sure to get an older-style, 'non-feedback' Q-jet - and be prepared to play with metering rods, jets and secondary 'air valve' spring tension to get it right. CFM-wise, at about 750 CFM, the Q-jet is huge but with the tiny primaries and "air-flow" controlled secondaries it will work ok. Buick used Q-jets on their 3.8L V6's and Pontiac used the Q-jet on the 4-bbl version of their OHC 230 and 250 inline 6's. For a two 2-bbl. set-up, I'd probably use a pair of small-base 283-type Rochester 2GCs. On an inline 6, a two-2bbl set-up in my opinion, will give much better mixture distribution than a single 4-bbl, but either one would be a huge improvement over the stock 1-bbl. If you use an Offenhauser intake, one thing to watch for. Offy made two types of Chevy 6 intakes - a standard 'open plenum and runner' design and a so-called "Dual Port" intake with a 'divided, two-level plenum' and 'two level, divided primary and secondary runners'. The "Dual Port" design was more or less a marketing gimmick, intended to improve mileage rather than power and it didn't really do that even. Avoid the "Dual-Port" intake at all costs if you want to make power. Another possibility for an intake that you might be able to pick used, for cheap. If you have a marina or a boat boneyard near you, both OMC and Mercruiser used a 4-bbl Q-jet style intake on some of their 250 Chevy marine conversions, that you could probably pick up for next to nothing. You'd need to use a bandsaw and a die grinder
    to cut away the *unusable for an automotive application* integral marine exhaust manifold section and separate it from the intake portion, which would be a fair bit of work....but if you could get a 4-bbl manifold for free or nearly so, what the heck. By the way, some of these intakes came with an an adapter plate to use a single Rochester 2GC 2-bbl in place of the Q-jet 4-bbl, but the intake itself is the same and it will work fine in an automotive application.

    The next thing would be an exhaust upgrade. If you afford them, the first choice would obviously be a set of aftermarket tube headers, but they can be pricey. Just about as good (and maybe actually even better for a mild engine) , but not so easy to find anymore, would be a set of factory split exhaust manifolds from a '68 or '69 Pontiac 4-bbl OHC 6. The Pontiac split exhaust manifolds will fit the Chevy 6 head and by doing away with the stock Pontiac 'two into one" head-pipe that bolts on and connects the two manifold sections together, you can easily build a true 'split' dual exhaust system.

    The next upgrade would be the cylinder head. You can mill your stock head up to .100, to boost the compression about 1 full point, or find a smaller chamber head from a 194 Chevy 6. The next cylinder head upgrade would be the valves. You can cut the seats bigger to take stock SBC 1.94 intakes and 1.50 exhaust valves. These work better on a 230 or 250 head, as the smaller chambers on the 194 head tend to shroud the bigger valves, reducing flow. You can grind the 194 chambers to reduce the shrouding, but the grinding defeats much of the purpose of using the small chamber 194 head in the first place. Finally, a small bit of port work does wonders on these engines. Don't do anything radical - just smooth and clean up the ports as best you can and match the mouth of each port to the intake and exhaust gasket size and shape. Be sure to "port match" the intake and exhaust manifolds to the gaskets too while you're at it.

    Finally, I'd upgrade the stock ignition. If the stock distributor is still in good shape and you want to keep it, I'd at least get rid of the points and install a Pertronix or similar electronic conversion. Better still would be an HEI distributor from a '74 or newer Chevy 6. In either case, I'd put a kit in the distributor to quicken up the mechanical advance curve. If you don't mind *probably* needing premium gas, I'd shoot for about 10 or 12 degrees initial timing with about 34 to 36 degrees total - and set the mechanical advance curve up so that full advance is all in by about 2200 to 2400 rpm. Add a good quality cap, rotor and ignition wire set up (- ie - MSD or similar) and you're all set. If you still have a few bucks left, probably the final "best thing" you could do to boost both power and mileage would be to also add an MSD-6 box. The MSD-6 will work with the stock points or you can trigger it with either a Pertronix or a GM HEI. Don't forget too, that with either a stock GM HEI and/or with an MSD-6 box, that even thought the voltage and spark *potential* is greatly increased, the ignition will still only ever put out exactly enough voltage to jump the existing plug gap. Going to an HEI and/or an MSD-6 allows you to create a bigger, hotter spark, but only if you increase the plug gap - so experiment a bit by opening the plug up until you find out what the engine wants. A rule of thumb though is with the HEI and a reasonably rich mixture, about .040 to .050 plug gap will work good and with an MSD-6 added, maybe as much as .060 or even .065. You need a really good cap, rotor and wires though, to run this much plug gap. With the stock points or Pertronix conversion and no MSD box, you probably want to keep the plug gap at around .030.

    Hope some of this info helps. Good luck and have fun :)
    Last edited: May 28, 2011
    OldoginMd likes this.
  4. OldBuzzard
    Joined: Mar 8, 2008
    Posts: 878


    All good suggestions by mart3406, or, you could start at a higher level with a 292 and add a few things for a lot less money. A 292 would involve moving the pass. side motor mount a bit. If you are thinking economy, cubic inches and gas mileage are not necessarily related. I have gotten 10 mpg on 305 &307 engines and 30 mpg from a 350 engine.

  5. bob cutler
    Joined: Jul 8, 2009
    Posts: 291

    bob cutler

    Transdapt makes a adaptor that you can run a rochester 2 bl carb or one for a holley 2bl. Im trying the rochester.
  6. boucher racing
    Joined: Oct 11, 2007
    Posts: 135

    boucher racing
    from nashville

  7. dragsta
    Joined: Apr 11, 2010
    Posts: 589


    don't sink $ into that pos 230. just look around for a nice 283.
  8. belair
    Joined: Jul 10, 2006
    Posts: 8,875


  9. kustomd
    Joined: Mar 2, 2001
    Posts: 1,218


    You can out run a 283 with a nicely built and correctly geared inline six. I've been running sixes for years and love em. My 60 with a set of 4.11 or lower gears in my huge car would eat up v8s. To bad I sold the low gears:[ I need to change the cam in my engine so it will work better with the High gears I'm running now.

    V8s are way to common. I'm planning on building a six to run in my panel truck that I'm plannin on using as a tow pig.
    Joined: Jan 28, 2008
    Posts: 518


    I got a 230 30 over big cam Offenhauser four-barrel intake Holley 390 carb. Split exhaust with a four speed transmission. It is a blast!
  11. milltownrodz
    Joined: Feb 11, 2007
    Posts: 1,105


    I am also in the middle of this?65 chevy c10... Bumm cylinder? No 6? Gonna do a compression test tonight? If screwed im lookin for a used or crate motor to get this baby goin again? Any suggestions?
    If cam will replace?
  12. milltownrodz
    Joined: Feb 11, 2007
    Posts: 1,105


    I am also in the middle of this?65 chevy c10... Bumm cylinder? No 6? Gonna do a compression test tonight? If screwed im lookin for a used or crate motor to get this baby goin again? Any suggestions?
    If cam will replace?

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