Hello everyone! This is my first time posting on this site, although I’ve been active on FABO for the past year (and lurking here). At SlantSixDan’s advice over there when I was seeking some advice for my engine, I’m posting here.

I’ve got a 1964 Dodge Dart 270 with a 225 /6. I’ve daily driven the car (it’s my first car) for most of the last year, after getting lots and lots of work done to get it running and driving consistently for a few months. A month or so ago, I developed an oil leak. My best estimation is 1 qt per 2.5-3 weeks, driving at least 20 miles a day, sometimes as many as 80 in a day.

It’s the rear main seal, and after discussions with my mechanic and some others, it’s the best bet to go ahead and fully rebuild the engine while it’s out to replace the seal. I know the previous owner who neglected the car, and ran into the owner before him once and discussed the history of the car. So I can trace it back for the past 20 or so years and know it wasn’t rebuilt in that time.

Since the car is the daily driver, that’s what I want to build it for, more drive ability, especially at freeway speeds and just more comfortable and fun. I’m not very interested in going the route of making it a stroker at the moment, just because it’s expensive, or anything to increase the displacement, just tap into the power that’s there that I’m not seeing. I think that the easiest thing to do is going to be a 2bbl carb (it’s a carter bbs right now) and a bigger exhaust (single 1.25” exhaust now).

What’s your advice? Is there anything simple to do while the engine is apart to increase power? What intake/exhaust/carb/ignition will be good for this?

I’ll also be completely rewriting the car with a Ron Francis Express kit while the engine is out, fixing all of the “custom” wiring previous owners have done.

Any help or advice is appreciated, I’ll be working with a local shop that works on classics and rebuilds engines and transmissions frequently, and they’ll Be teaching me some about the process of stripping the engine and rebuilding it, so this is a learning process for me

you can do a few easy things yourself to make the engine more efficient. you can polish the combustion chambers to reduce risk of detonation and lost combustion heat, you can do some mild clean up to the ports to improve flow and reduce turbulence. you can look at making a windage plate or crank scrapers.

First car? Man, I'm having flashbacks to 2004. I was in high school, driving my first car, a 1964 Dart, with a leaky rear main seal, and we couldn't get the old rope seal out with the engine in the car. Decided if we needed to pull the engine that we may as well do a full rebuild, so we took it to a little local shop. That rebuilt engine was still running strong 30k miles and several endurance road races later, until it got a little too hot on the track and broke all the top compression rings. (It still ran and drove after that, but it made so much blow-by that you had to zip-tie the dipstick in place.)

There are a number of things you can do if you're tearing the engine apart. Just freshening up the bores and rings will make a night and day difference compared to a tired old engine. Boring the cylinders out 0.030" is pretty typical if they're no longer in spec, which will also buy you a few cubic inches. If the taper and roundness are still in spec and you don't have much of a ridge at the top of the cylinder, you can get away with a hone job and then re-use your stock size pistons (if they're in good shape) with new rings. (That can be done in your garage with pretty basic tools, if you're hurting for cash and want to avoid a trip to the machine shop.) But it sounds like you're already planning on going to the machine shop, so I'd go ahead and machine the bores out and install matching oversize pistons.

If you want to make a little more power, then decking the block or head to raise your static compression is the next step. You need to lose 0.020" or so just to account for switching from the stock steel head gasket to a thicker composite. Before everything gets taken apart, just make sure you take all the required measurements so you know your engine's existing Static Compression Ratio (SCR). Manufacturing tolerances in the 60s were pretty loose, so there can be significant variation between blocks. Then do the math to determine how much you need to shave to get to your target. For a daily driver, you'd probably want to shoot for about 8.5:1 SCR. That will allow you to run a stock camshaft on regular gas, and probably even gain some MPG with your horsepower. You can re-use your camshaft if it's in good shape, but a later 1971+ camshaft will be a little better. This should line up well with your choice of a 2-barrel and larger (say 2.25") single exhaust pipe.

If you want more power at the expense of idle quality and MPG, you can go with a more aggressive camshaft and higher SCR. If that's the case, engage the expertise of folks on this forum, like DusterIdiot or Dart270 (Lou). Unless your shop has specific experience with slant sixes, take anything they say about camshaft selection with an enormous grain of salt. A lot of the common knowledge that applies to V8s will do more harm than good when applied to these engines. There are also historical issues with oil pump gears on these engines, which may be related to bad drive gears on some aftermarket camshafts. In general, sending a known-good stock cam to be "reground" to a different profile at a place like Oregon Cams is the safest choice. If your oil pump is worn out, I've had good luck with the Melling M66C.

Good luck, and don't hesitate to ask plenty of questions!

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing