I am new here but not new to Mopars or even The leaning tower of power so first off hello to everyone. My question is how can I get a little more top end out of my 82 225 Super six? It resides in a short wheel base D-150 with the overdrive 833. The only problem is that out on the open rode at HWY speeds (anything over 55) its dead, that is in overdrive. The motor runs great and around town it performs really well, but I get passed by everything on the road when in overdrive. I don't want to go to a V motor I know it wouldn't be that hard to do and I have all the partd to do it, its just that I want to leave my little sixxer in its place. Any input will be greatly appreciated.

Welcome on the board! By 1982, the poor ol' slant-6 was strangled into truly pathetic low output. There are a lot of reasonable upgrades you can make to get more vim out of it, but first let's assess the condition of the engine as it sits now. How many miles are on it? How old's the timing change? How long since a tune-up? How old's the catalytic converter? Is this a California, Canada, or 49-state vehicle? What kind of emission tests do you have to pass with this vehicle?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Welcome.First ,try to answer Dan's questions,next,personaly having used 833od's in A-100's and 108's for the past 15years, I can tell you that unless you run a 3.91 or 4.10 rear ratio, at 60mph in heavy trucks ,the /6 just labors along ,power and milage both suffer.

The odometer shows 88600 but it could easily be 188600. I know it has just been tuned up, the motor doesn't smoke or use oil although the rear main seal does leak like a sift. I'm unsure as to any internal maintance that has been done to the motor. It runs smooth basically it does as I would expect one with that kind of miles. I would like to up the power via cam swap or bringing up the compression. I am gonna atleast do a good rebuild on it sometime this summer. I'm just unsure as to what I can do to bring up power without sacrifising the drivability fuel milage. It gets about 23-24 mpg now. I know I can't have my cake and eat it to but it would be nice.

That's really excellent mileage for that engine in that vehicle — you sure your odometer's not running fast?

Need info on the other questions I asked about the exhaust system, emission tests, etc., but if you're thinking it's 188k on it, then you're probably (over)due for at least a timing chain and sprocket replacement to restore cam timing. Be a fine idea to pick out a cam more optimally suited for your kind of usage than the factory item, but don't go overboard or you will spoil mileage and driveability. When it's time, get on board the Erson deal.

Recurved and upgraded ignition, Dutra Duals, a 2bbl ("Super Six") intake and carburetor swap…all can substantially improve driveability while maintaining or improving mileage.

But we really need to know what kind of emission tests you have to pass and what the exhaust system configuration is.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Sorry I forgot to answer those questions. It has the original exaust and I don't have to worry about any emmision test. It already has the super six intake and carb. I made what is known to be a 150 mile trip and I used 6.5 gallons of fuel. I know there is alot of info on here about milling the block and head to bring up compression so I won't ask you guys to get into alot of detail on that, just want to know if it would be something I should consider.

I am assuming you don't mean it has all the original exhaust components (muffler, catalytic converter, etc.) because they don't last that long, but rather that the system configuration is stock. You will want to consider the Dutra Duals eventually in conjunction with a thoughtfully-specced new exhaust system, but it sounds like your lack of oomph is at the very low engine RPMs you'd see at highway speeds in Overdrive, so it's a fairly safe guess especially with that fuel economy that you haven't got any grossly excessive exhaust restriction.

So, next round of questions to narrow in on how best to proceed:

-What's the vehicle's rear axle ratio?
-Is the EGR system intact and functioning?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

The axle ratio is 3.21, the EGR is inop. You are correct my lack of power comes in at low engine rpm's at higher speeds.

Wow, 3.21 is a really tall ratio with 833OD. That right there could explain the total lack of pickup when in fourth gear, which will have an effective final drive ratio of 2.25(!). What's your tire size? That'll let me figure out engine RPMs at various speeds in various gears.

Assuming a typical tire size on vehicles like yours, if you were to swap to 3.91 rear gears, you'd have four usable gears around town, you'd actually make some use of that 2bbl setup, and your final drive ratio would be a much more reasonable 2.73. Still a cruisy highway gear, but the vehicle wouldn't be such a slug while cruising. Your overall economy would likely remain similar. I'd definitely start there before touching the engine, because whether the cam is stock or not, you'll want a more realistic set of rear gears than 3.21.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I have a 8 3/4 with 3.91's out of a 65 or 66 A-100 that I could put in it. I guess your right because if I can efficiently use my power then economy shouldn't change or it might even get better. Gearing would even help the clutch, its pretty hard ob it when taking off especially on any kind of grade. I really do appreciate the advice you guys offer. Hopefully I will be able to learn more about these little engines help someone that needs info.

Bummer the rear axle I spoke of is about two inches narrower than the rear end thats in my truck now.