What camshaft should I use?

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John Martin

John Martin

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I have a 1970 Dart Custom with a 225. It has 111,000 miles and it’s never been rebuilt. I was thinking of doing a camshaft.

I’m looking for a good camshaft that makes a lot of vacuum, gets good fuel economy, idles smooth, and has a focus on low and mid range power.

I found a Hughes camshaft that sound good:
Hughes Engines

I also know there is the Erson camshaft, but it never seems to be in stock:
http://www.pbm-erson.com/Catalog/Erson/Camshafts/Mechanical Flat Tappet_E/ERSE470301
 
With no other modifications, leave it stock.
 
I fear the original cam has a couple wiped lobes. I will be verifying this weekend. If it ran perfectly I would not be asking.

It has had a head gasket done, intake/exhaust, carburetor rebuild, tune up with plugs, wires, cap, rotor, condenser, points, and has had the timing checked and rechecked. Nothing makes a difference. It gets a couple pops out of the tailpipe, and smooths out when running on 5 cylinders.
 
John Martin said:
I fear the original cam has a couple wiped lobes. I will be verifying this weekend. If it ran perfectly I would not be asking.

It has had a head gasket done, intake/exhaust, carburetor rebuild, tune up with plugs, wires, cap, rotor, condenser, points, and has had the timing checked and rechecked. Nothing makes a difference. It gets a couple pops out of the tailpipe, and smooths out when running on 5 cylinders.
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Then do some research. There is one stock camshaft that has more lift than all the rest. It's like .410 or some such. That's the one you want.
 
RustyRatRod said:
Then do some research. There is one stock camshaft that has more lift than all the rest. It's like .410 or some such. That's the one you want.
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That’s what I’m trying to do. I hear the Erson cam talked about a lot on the Slant Six Forum but it never seems to be in stock.

toolmanmike said:
Stock cam and lifters made by Melling. A good brand name. Price is right. 1970 DODGE DART 3.7L 225cid L6 Camshaft & Lifter Kit | RockAuto
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I did not see that one. I will see what my engine builder friend recommends, as well. I was thinking of doing something a little more that stock but nothing wild. It’s a daily driver.
 
John Martin said:
That’s what I’m trying to do. I hear the Erson cam talked about a lot on the Slant Six Forum but it never seems to be in stock.



I did not see that one. I will see what my engine builder friend recommends, as well. I was thinking of doing something a little more that stock but nothing wild. It’s a daily driver.
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If you get anything above stock, it will need other mods such as better induction and exhaust. Slant sixes are not as forgiving as larger engines when looking for more power. They respond to the "complete package approach" whereas a V8 will respond to individual pieces. I'm not saying this to waste my breath.
 
RustyRatRod said:
If you get anything above stock, it will need other mods such as better induction and exhaust. Slant sixes are not as forgiving as larger engines when looking for more power. They respond to the "complete package approach" whereas a V8 will respond to individual pieces. I'm not saying this to waste my breath.
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I understand. I don’t think that something that is not exactly stock will make the car just quit though. I plan to put an Accurate Hi-Po exhaust on it for the slant six.
 
John Martin said:
I understand. I don’t think that something that is not exactly stock will make the car just quit though. I plan to put an Accurate Hi-Po exhaust on it for the slant six.
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Well of course not. Whoever even insinuated that ridiculousness? If you want to see the best results, upgrade the exhaust and put the Super Six 2 barrel system on it.
 
RustyRatRod said:
If you get anything above stock, it will need other mods such as better induction and exhaust. Slant sixes are not as forgiving as larger engines when looking for more power. They respond to the "complete package approach" whereas a V8 will respond to individual pieces. I'm not saying this to waste my breath.
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Yeah smaller power return ratio because it makes less power to begin with the increase is going to be so small it might not be noticeable there for you need to package approach it like a full-on everything.
RV cam and a header....but a header and exhaust system at the least before a cam change. Probably go up a jet size or two with the header upgrade.
Ignition,header... then get a 2 barrel intake and a Weber Progressive 2 Barrel on it.
That's the mileage n power increase but with mileage a priority...the a cam or head work.

With every step up in cam size your Shifting the torque higher in the RPM and you're going to have to compensate with a torque converter or some good gears at a certain point and a slant 6 is sensitive because of the lack of v8 umph to begin which makes any low end loss very noticeable.
Really ...it's just another engine
 
It runs a 54 jet in the Holley 1920 right now, it gets 10mpg. I had a 55 and it got 7mpg I had a 56 and it got 5mpg. Something is seriously wrong when a 440 gets better fuel economy than a 225.
 
MOPAROFFICIAL said:
Yeah smaller power return ratio because it makes less power to begin with the increase is going to be so small it might not be noticeable there for you need to package approach it like a full-on everything.
RV cam and a header....but a header and exhaust system at the least before a cam change. Probably go up a jet size or two with the header upgrade.
Ignition,header... then get a 2 barrel intake and a Weber Progressive 2 Barrel on it.
That's the mileage n power increase but with mileage a priority...the a cam or head work.

With every step up in cam size your Shifting the torque higher in the RPM and you're going to have to compensate with a torque converter or some good gears at a certain point and a slant 6 is sensitive because of the lack of v8 umph to begin which makes any low end loss very noticeable.
Really ...it's just another engine
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Exactly so. Thanks. That's the approach I was referring to. But you already knew that. LOL
 
John Martin said:
It runs a 54 jet in the Holley 1920 right now, it gets 10mpg. I had a 55 and it got 7mpg I had a 56 and it got 5mpg. Something is seriously wrong when a 440 gets better fuel economy than a 225.
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Well I don't have a crystal ball... but there's a couple things that could be going on here, the distributor...make sure the advance weights aren't stuck to the plate....the other is the economizer valve in the carburetor... which is probably more common than the advance plates being stuck so check there. Does it whistle at idle.?
Lastly... Check that little exhaust manifold butterfly below the intake manifold.dl Does that open all the way or is it stuck partially open and not allowing the exhaust out...

Typical slant wors.
Other is the nylon distributor gear failing.
I have lost teeth so many on those with aftermarket cams and some 5500 rpm 1 st gear down shifting. Lol
 
MOPAROFFICIAL said:
Well I don't have a crystal ball... but there's a couple things that could be going on here and the first one is in the distributor...make sure the advance weights aren't stuck to the plate....the other is the economizer valve in the carburetor... which is probably more common than the advance plates being stuck so check there. Does it whistle at idle.?
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The distributor works fine. I have checked it, the weights are free, the vacuum advance is a new NOS unit, and it has new points, condenser, cap and rotor.

I said above, that the carburetor has been rebuilt, I put a new economizer into the carburetor.
 
John Martin said:
It runs a 54 jet in the Holley 1920 right now, it gets 10mpg. I had a 55 and it got 7mpg I had a 56 and it got 5mpg. Something is seriously wrong when a 440 gets better fuel economy than a 225.
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Yeah like you're measuring WRONG.
 
I have never had a vehicle that only got 7 mpg.... my dually got 10 and that was my worst ever..... that was a 2 bbl 360, 4.10 gears, granny low 1st gear 4 speed stick.... in a HEAVY truck. My 79 D100 shortbed, with a slant, and 3 speed manual, got like 18 in town and 22 on a solid highway cruise back when I had it a lot more weight there than your Dart. something is definitely WRONG there...… Ive had a few slants over the years, as have my son, Dad, and brothers..... none were that bad//// surprised your engine isn't hydrolocking with that much gas going thru it....
the slant was always the "economy" choice..... a HP fire breathing 340 in an A body would be more efficient than what you are claiming.
 
volaredon said:
I have never had a vehicle that only got 7 mpg.... my dually got 10 and that was my worst ever..... that was a 2 bbl 360, 4.10 gears, granny low 1st gear 4 speed stick.... in a HEAVY truck. My 79 D100 shortbed, with a slant, and 3 speed manual, got like 18 in town and 22 on a solid highway cruise back when I had it a lot more weight there than your Dart. something is definitely WRONG there...… Ive had a few slants over the years, as have my son, Dad, and brothers..... none were that bad//// surprised your engine isn't hydrolocking with that much gas going thru it....
the slant was always the "economy" choice..... a HP fire breathing 340 in an A body would be more efficient than what you are claiming.
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I know. I have measured using the odometer, which is accurate. There was a stretch of Washington I-90 with a “speedometer” check and it was perfect down to the tenth of a mile. So I do them math when I fill up.

I had another 70 Dart with a 225 and a Holley 1920 and it got 24mpg with a 56 jet.
 
volaredon said:
you have another carb you can swap on?
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Not one that works. The carb on there is a 1920-6156 which had a bad metering block. It would fall flat on its face and stumble. I tried to use the correct 1920-4354 and it turned out to have a bad air horn, so I took the two and made one good carburetor and the car runs without a stumble.
 
John Martin said:
The distributor works fine. I have checked it, the weights are free, the vacuum advance is a new NOS unit, and it has new points, condenser, cap and rotor.

I said above, that the carburetor has been rebuilt, I put a new economizer into the carburetor.
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Well goddammit, SOMETHING ain't right. You can go on and on about how your crap is "right" or "new" or whatever the hell else you want to call it, but if it's getting 10 MPG like you said something is WRONG. You're just gonna have to dig through it like any of the rest of us and find it. There's no magic bullet like you might want to believe, you're just gonna have to find it. With a little more info, we might can help, but YOU are the ultimate power here.
 
RustyRatRod said:
Well goddammit, SOMETHING ain't right. You can go on and on about how your crap is "right" or "new" or whatever the hell else you want to call it, but if it's getting 10 MPG like you said something is WRONG. You're just gonna have to dig through it like any of the rest of us and find it. There's no magic bullet like you might want to believe, you're just gonna have to find it. With a little more info, we might can help, but YOU are the ultimate power here.
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I’m tell you what has been done because someone will eventually ask what has been done. I am trying to give as much information as possible, but if there is something that I missed, let me know.

I know there is no magic fix to it, but I have replaced a lot of worn maintenance parts. I can’t think of anything in common that is in bad condition that would cause this. It seems to be an issue with cylinder 6. I unplug it and the engine runs smoother. All others unplugged one by one result in a rough idle and the engine bucking and shaking.

If it were the distributor or anything before it, the misfire would be random. I can only think of the issue being a mechanical one related to cylinder 6 because it had a strong and consistent compression test.
 
John Martin said:
Not one that works. The carb on there is a 1920-6156 which had a bad metering block. It would fall flat on its face and stumble. I tried to use the correct 1920-4354 and it turned out to have a bad air horn, so I took the two and made one good carburetor and the car runs without a stumble.
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Leak down test the motor, then we can give you better advice.
 
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