I am thinking about upgrading the cam in my slant six build and was hoping to get your input on the best one for my build as follows:

1984 Dodge D100 Truck Build - Going for reliability, smooth running, good torque (250 ft-lbs), decent horse power (180 ft-lbs).

Trans is A833 4 Speed

Motor = 1986 Slant Six 225 with a previous rebuild .040 pistons. Not sure if block has been shaves 0.10 - will measure soon.
Head = Stock 1986 Head with plans for minor port matching and cleaning up. Not planning to upsize valves. Will upsize springs with cam kit.
Intake = Aussie speed mid length with Weber 38/38 Carb.
Exhaust = Dutra Duals or similar.
Ignition = HEI Mod

I would like the motor to have performance similar to a stock Jeep 4.0 with good pulling power with the 4 speed. I am not looking for a drag racing motor.

In my past builds, I have not upgraded the cam, so this is new territory for me. From the posts I have read on the site, I was thinking a mild RV cam
but was hoping that you that have more knowledge than me can help me find the right cam for my application.

Thanks!

What rear gears are in the truck?

Even with stock valves I would clean up the bowl under the seats. And you may want to plane the head some more to bump the compression a bit more. That will help with power and gas mileage. Of course check the measurements for sure.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

The stock '81-up hydraulic-lifter cam is a wimpy thing. Most of the aftermarket cams, by whatever description ("High Energy", "RV", "Torquer", etc) are ancient generic (often Chevrolet) grinds applied to a Slant-6 cam blank. There are a lot fewer options in cams for the hydraulic-lifter setup. You might want to give some thought to converting to the pre-'81 solid-lifter arrangement instead. You'd have to do a valve adjustment from time to time, but you'd have a lot more and better cam options readily available. If you were to do that, the Dutra RV-15RDP from Oregon Cam would go well with your intake setup. The RV-10RDP would be a little milder—smoother idle, etc—but still a nice improvement over the stock '71-'80 solid-lifter cam, and an even bigger improvement over the '81-up hydro cam.

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

Does anyone regrind cams for the .904 lifter size? Did the Direct Connection/Mopar aftermarket cams utilize the advantages of the "faster" ramps that the .904 lifter would tolerate?

Hughes Engines says they have mopar cam lobe profiles that are designed to work with the .904 diameter lifter

https://hughesengines.com/

see their Tech article section



On the topic of picking a cam for low rpm torque, that is the route that I took for the slant in the 83 D150.
the article linked is from that project

https://www.slantsix.org/forum/viewtopi ... 19&t=43301

and while we are talking cams, a few of my recommendations.

1) spend the $75.00 and get a copy of Dyno Sim / Desktop dyno
You can run simulations with different cam profiles, lifts, advance - retard settings and see what those changes do for torque and HP curves.
The better your inputs are for: compression, carb CFM, head flow, ignition timing the closer your Dyno Sim output will match reality.
I had the 83 D150 on a chassis dyno years ago and the torque- HP curves were right on line with what Dyno Sim had predicted.

http://www.proracingsim.com/dynosim6.htm

available through Summitt and other retailers

2) in a truck application, I would stay with hydraulic lifters. The valve cover and the rocker arms are a lot further away in a D series that thay are in an A body.

3) I would not count out a 'stock' 81 and up hydraulic cam if low RPM torque is the only goal. Do a Dyno Sim simulation with the stock cam and you will see a lot of torque way down the RPM chart. Ultimate HP is limited as the engine just runs out of air above 3000 RPM, but its worth a look if low RPM Torque is the only goal.

And here is an article with good basic camshaft information.

https://www.motortrend.com/how-to/under ... afts-work/

Regards
DT

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Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

Lots of good ideas/experience/opinions here.

The first thing I would do is decide on the static compression ratio you want, and build the engine for that, then decide on the cam. For pump 87 octane, I would go for 8.5 - 8.8:1 static CR. For 91-93 octane premium gas, I would go for 9.3 - 9.6:1.

For your application, I would suggest staying with a hydraulic cam and we can design a custom cam from Oregon that will use hydraulic lobe profiles.

Lou

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