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What would be the best cam for a V-10 in a '94 Ram 2500?

Discussion in 'Repairs, Maintenance, Help' started by BlackSheep01, May 25, 2017.

  1. BlackSheep01

    BlackSheep01 Active Member

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    Can't get rid of the miss in the new-to-me OBD1 truck. Have multiple folks saying it'll take a camshaft to fix it.

    Specs:
    DGYS 4-Speed Auto 47RH Transmission
    DHAS Lock-Up Torque Converter
    DMDS 3.55 Rear Axle Ratio
    DRES Dana M70/267MM Rear Axle
    EWA 8.0L V10 MPI Engine

    It's got under 70,000 on the odometer, but it sat for several years and the TSB was not performed for the plug wires routing until last month (yep, we did that, and yep, it helped; but it didn't fix the miss completely).

    What would y'all recommend if I'm happy with the torque now and wouldn't mind getting a hair better fuel economy?

    Thanks!!!
     
  2. dana44

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    Probably not a whole lot you can do about the mileage with a different cam, 488 cubic inches and ten pistons pumping isn't going to do a whole lot different with that, especially with the size and weight of the truck. What I have learned over the years with the injected engines and computer controlling, porting of the heads, especially the combustion chambers is the key to, while not drastically improving mileage (I'll explain more later) is improving the efficiency of the burn itself,
    Once the fuel/air ratio is controlled, efficiency is essentially almost at its limits, but, combustion chamber porting for better flow and improved burn will raise the mileage at higher rpm, so, if, for example, I have a PT Cruiser, 2.4, and was able to move the mileage, which would drop off at 2800rpm from 32mpg light cruising on the highway, to 3500rpm down to 25mpg, and after porting the combustion chambers and ports, 29mpg at 3500rpm, but still only 32mpg at the lower rpm. This kind of goes along the line for most any engine, fuel/air ratio calculated several times per second pretty much gets that efficiency where it is. At the same time, I did get mileage up on a 4.9 Cadillac (1994ish, in a Fiero, fuel injected, computer controlled and all that, too, but I ported the heads, combustion chambers and intake manifold), but the comparison engine was a little sick, but it still increased mileage by 5-7mpg across the board according to the owner over a couple months of driving, again a totally stock engine otherwise, CA smog laws in place for the build.
    Now, being my PT Cruiser was totally stock otherwise (CA smog laws and all), you do have one thing that may make a slight improvement, and that is increasing your compression through a shorter duration, thus opening and closing the intake valve sooner and making more power out of what is sucked into the engine to increase its efficiency, thus better mileage because you aren't using the throttle as much.
    So, here is what you do. Lift itself does not necessarily increase or decrease mileage, so if possible, open the intake valve 6 degrees earlier, and shut the intake valve earlier combined with that added (say, .040inch lift) over stock and reducing the intake duration by 12 degrees on back side (closing it earlier) will bump the compression up by around .5:1 (half a point) on an 8.2:1 compression engine, which will keep that bottom end torque and should not interfere with top end power or cruise at all, you would just have an 8.7:1 compression engine, thus more efficient, the raising of the compression this way is much cheaper than new pistons to do the same, and, should be within specs to not interfere with the computer. And being a roller cam, these spec changes are not an issue with wear, either.
    The combustion chamber, as I have found with just about every single combustion chamber design (not the old real Hemi engines, but the new ones, yes), there are improvements there that can make some real power and improve efficiency. Sharp edges, ridges, quench area edges, and edges along the outside of the valve pockets that don't meet the edge of the head gasket (thus cylinder walls), ridges around valve seats, sharp edges on valves themselves, all cause turbulence with burn flow direction. When you think about it, when the flame starts burning from the spark plug spark, why do you want sharp edges and lips that will cause the flame to bounce back into burned fuel, ricochet off a lip, curl into itself, or get caught on a ledge and not travel outward and burn fresh fuel/air as compressed as possible? The higher the compression and sooner/faster the fuel/air burns before the piston drops, the more power you produce and less fuel you need, thus better mileage. At the same time, since things are electronically controlled, to do the same thing at a higher rpm and still have the same mileage is an efficiency improvement and it works for me. Super cool thing about doing this, you can run 87 octane all day long and she will not ping. The first engine I found this little miracle on was a 350 Chevy, running 13.5:1 compression (tiny combustion chamber heads, dished pistons about the same as the V10, and carbureted), finally got her to ping on a trip to Mexico (down to the tip of Baja, Cabo San Lucas), 75 octane would ping, but 79 octane would not, but went from 9mpg to 13mpg (4X4 shorty van, talk about a brick you could sit up underneath it was so high off the ground, and 4.10 gearing on top of it).
    Hope this helps, what you were asking is kind of buried. I'll give you more info if needed.
     
  3. ImperialCrown

    Level III Supporter

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    The 1995-1997 plug wire routing TSB # 18-16-98 mentions the possibility of cylinder wall scuffing/piston damage if the misfire is allowed to continue for too long. I don't know why the 1994 isn't included in the bulletin unless the plug wire routing was different that year:
    TSB 18-16-98 (at http://dodgeram.info/tsb/1998/18-16-98.htm )
    I'm glad that you corrected the plug wire routing and glad that it helped, but you should check for possible # 7 cylinder damage. You might actually want to replace the plug wires if they are more than a few years old. You may want to perform a cylinder leak down test on cylinder # 7 to confirm this.
    Has the camshaft been verified as being worn? Is there any valve train noise? It is a roller cam/lifter arrangement and not really subject to wear like the conventional lifters are.
    Finding a misfire on a V10 'by ear' is a challenge due to a combustion stroke every 75°, but it can be done with engine diagnostic tools. Finding a misfire on engines with fewer cylinders is much easier than a V10. Being OBD1, you don't have the misfire monitor that would tell you which cylinder is misfiring like OBD2 does.
    I would confirm this through diagnosis before suspecting a camshaft. If the cam does prove to be needed, replace the chain set and lifters as well.
    I see a Mopar part # of 53020842 (AB) for the camshaft. Use this part # in your search. Someone may have a NOS sitting around.
     
  4. KOG

    KOG KOG
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    The advancing the cam timing trick is tricky. I tried this on a 360 in a B van chassis. Dually axle (from B box van), 4.10 gear. Installed COMP 252H cam which specified 6 degree advance from stock. I tried everything known to man to get that thing to stop knocking. Finally had to bite the bullet, take it apart and retime it straight up. The 6 degree advance did improve low end torque, which was the point, but also improved cylinder filling to the point of raising effective compression past anything that premium fuel and octane boost could handle.
     
  5. dana44

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    KOG, in your case, those sharp edges along the side of the open combustion chambers was part of the culprit, it's all the way around the cylinder, and second, a reduction in the advance curve to slow the spark timing advance down fixes that issue. On my 13.5:1 engine and the super low octane, I ran 0 degrees at the crank and a slow advance curve and never had pinging problems with 86 octane gas. On top of that, before I did this swap I could go through the mountains in second at 35mph, afterwards, 70mph and having to back off the throttle it was so amazing a change on a smogger engine it wasn't even funny. The thing is, the advance curve is what helps the most, reduction of advance prevents the pinging and you still have the advantage of the compression to make the power without the pinging. I have done it on several different engines now so it isn't just the brand of engine.
     
  6. BlackSheep01

    BlackSheep01 Active Member

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    Plugs and wires got changed right after I bought it. I didn't see the plugs' condition from the internal end, but we had to reseat plug wires for the test-drive and I do know the wires had been exposed to varmints.
    The noise is on the passenger side cylinder bank. Compression's good on all cylinders. I don't have oil in the coolant or coolant in the oil, and it runs like a champ, except for that persistent miss between about 14
    and 1700 rpm (in other words right where it runs mostly, driving in town -- It's 3.55 gears). On the highway, the miss seems to go away, and it'll chirp the tires (at least) any time I ask it to. I'm not afraid to drive it.
    It still has exactly these key-dance codes: one flash, two flashes, five flashes, five flashes. I just don't want to tear it up, especially as the xmission and differential are recent, proper rebuilds. (Well, I do, but not the
    motor. I'd love to have a quad-cab swapped onto it, and a truck bed with no holes in it. No hurry there. The plan's to eventually have one really good truck, not two that need work.) The '97 now has 223,128 miles
    on its clock, it's 100 degrees F where I live, and neither one of the AC systems in my trucks blows cold air ... I snagged a 134a recharge kit I hope will help that, and I'll have trained adult help on hand this weekend.
    Full disclosure: I have no tools, unless you count elbow grease, a crescent wrench, and a leatherman.
     
  7. AC TC

    AC TC Well-Known Member

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    lazy lambdas gives a miss/ stumble/ rough feeling....
     
  8. BlackSheep01

    BlackSheep01 Active Member

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    I am not familiar with that term. Could you explain it to me?
     
  9. KOG

    KOG KOG
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    Tired O2 sensors.
     
  10. dana44

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    You know, one of the few problems we have seen with the V10s is fuel injectors causing problems, as in burned valves. There have been several rebuilds done, well past 200,000 miles on the odometer, but usually a sticking or partially blocked injector is a major culprit causing the malfunction and damage. Tell you the truth, about a year ago, friend of mine is into Lightning trucks, picked up an engine and trans and wiring harness, all the stuff necessary to install without a hassle into a truck. Timing chain was messed up (we found out later), and four bent valves on one bank of the engine, so we pulled it apart, I ported the heads, intake and combustion chambers, put her back together. She didn't sound quite throaty enough, but she would rev pretty nicely, so pulled out the thermal gun, found five exhaust ports that were 150 degrees cooler at idle, so pulled injectors and found they were completely stuck shut. Just to get them to work we forced air through them while activating power to them, but got them to work. It was about then that I learned the engine sat in a garage in the desert for seven years after it was pulled out. Anyway, bad injectors or plugged injectors might actually be the issue, which can be easily checked by moving the injector on the cylinder that is missing with another one, see if the miss moves or stays on the current bad cylinder. But hey, a V8 running on three cylinders and able to rev decently, all I can say is, too much electronics!
     
  11. BlackSheep01

    BlackSheep01 Active Member

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    It's a V-10.
    I think it's running on at least 7, maybe 9. :)
     

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