Oregon Cam #346 - questions

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Hope you can read this... getting data out is a pain... I was close the OGC 346 really is a mid band cam.. flat torque from 2500 to 3500 and the highest horse power at 4200 RPM. But it has lower torque than anything else up until 3500 RPM

The Comp Cam has the highest torque beating out the OCG 2106 only by a bit but it drops off faster than anything but the stock

The Dutra RV10 is the lower RPM torque cam and the RV15 pushing that up in the power band a little.. The are very similar

Don't take the absolute values here as gospel, this is more of direct comparison holding everthing else equal.

1) Stock Exhaust
2) 400 CFM carb
3) 8.8:1 compression
4) Real flow number of a head with some port cleanup and oversized valves

In my book the 2106 is the perfect sweet spot for those who want torque under 3500 RPM

[relooking at this data... something looks wrong... I did it quick and may have has something not setup right]
CamSelection.jpeg
 
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215 60 14 is a small rear tire. I would run a 255 60 15x7 and run 3.55-3.91 gears
Also some porting with some tube Headers, with higher compression your distributor will need to be reworked. Nice combo
 
All actually seen awful close, other than that stock cam drops off a little sooner.
 
Does anybody know if Comp ever got their issues with the camshaft gear corrected? They had a terrible time with gear failures for a while. So much so, that I wouldn't trust one no matter what they said.
 
Slantsix64 said:
215 60 14 is a small rear tire. I would run a 255 60 15x7 and run 3.55-3.91 gears
Also some porting with some tube Headers, with higher compression your distributor will need to be reworked. Nice combo
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My runs on the highway are for 2-3 hours one-way, I am being conservitative on the gearing. I'd go 3.55 otherwise :)

Porting is outlined in a couple of my responses, it's on! Same for compression - more is better - but not too much. Headers - ah, now there's one I missed! I'm running the old MP 6/1 long-tubes now and will keep, I like them. Dist is is good shape, but will certainly need a recurve - good details @Slantsix64 !! Thank you for all your
 
volaredon said:
All actually seen awful close, other than that stock cam drops off a little sooner.
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Yup that was my take away from this for the most part you are talking about differences that will likely not be noticeable to the average driver IF you are staying in the same class of cam. These are all 108 LCA with relatively short durations so unless you are doing some sort of racing where you are trying to get some tiny edge in the class it does not matter a whole lot. The odd ball here is the comp cam and that is because it is moving up to a 110 LCA with a longer duration (254) and it moves you to the next class of cam which moves the peak HP and torque up in RPM the next level. The 819 is a 110 LCA so it moves into the same class as the Comp cams. The rule of thumb I have read about is that 20 ft lbs of torque is noticeable in the seat so you will be able to notice the difference at lower street RPMs between the 108 LCA cams and the 110 LCA class cams but between cams in each class you would likely be hard pressed to notice any difference behind the wheel.
 
So bottom line here there are 2 things that pick a cam for optimal performance where you care about (low torque or high rpm), the overlap and the the LCA. Once you choose those two for your engine the duration just falls out (with a symmetrical lobe). These numbers are defined through the cubic inches of the motor, valve size and a few other things. If you run through the math for a oversized valve 225 here is what falls out:

Torque Cam - 21 degree of overlap (The RV, OCG 2106)
Street Cam - 44 degrees of overlap ( Comp Cam, OCG 819)
Strip Cam - 59 degrees of overlap
Crazy Cam - 101 degrees of overlap

Then if you do the math for LCA using compression ratios in the 8.5-9.5 range and valve area to cylinder cubic inches

107 LCA for stock valves
108 LCA for oversized valves

you can't get enough valve to cylinder ratio in a 225 to utilize a higher LCA. So if you take the cam you are thinking about using and put it in a cam calculator that will tell you the overlap then you can compare it to this and decide what class it fall in.
 
Jim, this is amazing information, thank you very much.
  • Are you able to compare the OG 346 to 2106 & 819?
  • Can you run that data with a 390 (as in 9266) and 500 (as in 1901) CFM carbs?
  • Long-tube (6/1) headers?
  • 9.5 & 9.7 compression?
  • 1.78 & 1.45 valves?
  • Can lighter a valvetrain and pistons be pumped into the equation?
  • Converter stall speed recommendations
Message me if you want to set up a call, I should be in the office in about 45 minutes. By the way, what cam are you running?
 
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csheehy said:
Jim, this is amazing information, thank you very much.
  • Are you able to compare the OG 346 to 2106 & 819?
  • Can you run that data with a 390 (as in 9266) and 500 (as in 1901) CFM carbs?
  • Long-tube (6/1) headers?
  • 9.5 & 9.7 compression?
  • 1.78 & 1.45 valves?
  • Can lighter a valvetrain and pistons be pumped into the equation?
  • Converter stall speed recommendations
Message me if you want to set up a call, I should be in the office in about 45 minutes. By the way, what cam are you running?
Click to expand...

What are you doing with this car? Step one is what RPM so you care about? A driver? Take it to the strip once in a while and care about taking a few tenths off the time at the expense of loosing some torque in day to day driving? A track car that will need to run at a nice peak RPM and wide power band? Full on drag racer at WOT?
 
@Jim Kueneman - from my opening "Most of my driving is twisty and hilly back roads at about 40 to 50 mph The other 40% of my travels are highway 65-70." In hindsight, I was clearly missing some details...

I'm not sure of what RPM range I'll be in with the gear change, but like you, I'm not a racer, and don't wind-up the engine, nor do I do donuts - although I may spin a tire now and then - I'm not going to do long-hard burnouts. I'm looking for a stout (torque) street engine. This is a toy for me that doesn't see snow, but I will take it out in the rain.
 
csheehy said:
@Jim Kueneman - from my opening "Most of my driving is twisty and hilly back roads at about 40 to 50 mph The other 40% of my travels are highway 65-70." In hindsight, I was clearly missing some details...

I'm not sure of what RPM range I'll be in with the gear change, but like you, I'm not a racer, and don't wind-up the engine, nor do I do donuts - although I may spin a tire now and then - I'm not going to do long-hard burnouts. I'm looking for a stout (torque) street engine. This is a toy for me that doesn't see snow, but I will take it out in the rain.
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Ok so your requirements to get the most fun out if it driving and a lumpy cam are at odds. You will loose a some torque where it makes me smile just driving through the country and stepping on it if you want a lumpy idle. Here is just my opinion on what you asked:

  • OG 346 or 2106 which will not give you a lumpy idle but at minimum 20 ft-lbs loss of torque in the normal grocery getting power band
  • Modeling says if optimizing for low end torque and using the above cams then you run out of cam before you run out of CFM if you have around a 350CFM carb setup and for low end torque error on the low side
  • 6:1 header.. What is the tube distance from the port to the collector? What is the tube inner diameter?
  • 9.5 vs 9.7 compression ratio is barely a tickle on the graph. The gain is getting it from 7.0 to around 9.0
  • Larger valves... I did it... would I do it again now I know more? Likely not... It is fun to throw around at car shows but again with a torque cam you run out of cam before you run out of valve for the most part
  • Lighter valve train can be modeled in the software but it is a second order effect at the RPMs for a torque motor... if you had a 170 with a hyper pak running at 6000 RPM then it may be worth looking at but otherwise better places to spend resources
  • Torque Converter: if your are not drag racing what does it matter? If you build a torque motor it will come in around 2000-2500 RPM. The factory is what 1800 RPM? I can really feel it turn on at around in that 2000 RPM range so maybe it would be more fun launching it if I had a bit higher stall speed converter but I don't really plan on racing it so the more efficient 1800 is fine for me

    The cam, exhaust, get the 7:1 compression up to around 9:1 and a bit more CFM in the carburetor are all you really need to focus on for a torque engine in my opinion based on all my simulation work.
 
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csheehy said:
@Jim Kueneman - from my opening "Most of my driving is twisty and hilly back roads at about 40 to 50 mph The other 40% of my travels are highway 65-70." In hindsight, I was clearly missing some details...

I'm not sure of what RPM range I'll be in with the gear change, but like you, I'm not a racer, and don't wind-up the engine, nor do I do donuts - although I may spin a tire now and then - I'm not going to do long-hard burnouts. I'm looking for a stout (torque) street engine. This is a toy for me that doesn't see snow, but I will take it out in the rain.
Click to expand...

This is why I made a comment regarding the duration figure. It's pretty big. Mine, at 250@ .050.....I did for two reasons. One, because it was necessary because the static compression came out too high, due to the head being milled too much.....that was actually an accident, but I still must utilize it.

Two, because simply, I want it to sound nasty. I want it to be FUN. It's a light car, 64 Valiant 2 door about 2650 pounds with 3.55 gears and 13" tires. Probably has an effective gear ratio closer to 3.91. It WILL have a 4.10 after I put the ford 9" in it. So, my situation is a little different. I don't mind a little loss on the bottom end, plus, I'm replacing a 170 with a 225. 55 more cubes, a lot more compression four barrel carburetor, bigger cam, bigger exhaust......it may NOT experience a loss of bottom end in comparison. It's gonna be FUN and that's all that matters to me!
 
RustyRatRod said:
This is why I made a comment regarding the duration figure. It's pretty big. Mine, at 250@ .050.....I did for two reasons. One, because it was necessary because the static compression came out too high, due to the head being milled too much.....that was actually an accident, but I still must utilize it.

Two, because simply, I want it to sound nasty. I want it to be FUN. It's a light car, 64 Valiant 2 door about 2650 pounds with 3.55 gears and 13" tires. Probably has an effective gear ratio closer to 3.91. It WILL have a 4.10 after I put the ford 9" in it. So, my situation is a little different. I don't mind a little loss on the bottom end, plus, I'm replacing a 170 with a 225. 55 more cubes, a lot more compression four barrel carburetor, bigger cam, bigger exhaust......it may NOT experience a loss of bottom end in comparison. It's gonna be FUN and that's all that matters to me!
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Exactly Rob, what you are after is more like a road racing engine... 4 speed, low gears and keeping her wound up that is where the 819 cam and the more street grinds are made for. If you have higher gears, automatic and are just cruising around and want it to pull hard when you do get the urge are 2 different builds.
 
Jim Kueneman said:
So bottom line here there are 2 things that pick a cam for optimal performance where you care about (low torque or high rpm), the overlap and the the LCA. Once you choose those two for your engine the duration just falls out (with a symmetrical lobe). These numbers are defined through the cubic inches of the motor, valve size and a few other things. If you run through the math for a oversized valve 225 here is what falls out:

Torque Cam - 21 degree of overlap (The RV, OCG 2106)
Street Cam - 44 degrees of overlap ( Comp Cam, OCG 819)
Strip Cam - 59 degrees of overlap
Crazy Cam - 101 degrees of overlap

Then if you do the math for LCA using compression ratios in the 8.5-9.5 range and valve area to cylinder cubic inches

107 LCA for stock valves
108 LCA for oversized valves

you can't get enough valve to cylinder ratio in a 225 to utilize a higher LCA. So if you take the cam you are thinking about using and put it in a cam calculator that will tell you the overlap then you can compare it to this and decide what class it fall in.
Click to expand...

"All of that" is exactly why the stock slant six cams are ground on a 109 LSA.
 
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