It will be similar vacuum to a XE262-268H which has about the same tune up on it.
Just my sperience with it.
Just my sperience with it.
Anybody running the '68 4 speed 340 cam?
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What installed centerline does Ken recommend with that cam?
I told him it was on 110.5 icl and he said that is where he would put it unless compression was low.
And that's the missing piece. But hey, if you're happy with it, screw it.
Hard to wind a cam with that 114 LSA forward a bunch and keep the exhaust lobe where it doesn't get of bounds on an NA engine.
110 ICL is about the max IMO with that cam.
110 ICL is about the max IMO with that cam.
He said he might advance it too 108 deg with low mechanical compression....didn't define what low comp was. I was happy to get an opinion from him.
The engine is very responsive down low. All I want is a well tuned cruiser which is why it is nearly stock. I haven't got into WOT tuning but the carb tuning is getting close last time that I had it out with the O2 meter. Winter is upon us with freezing temps at night and daytime highs under 50F.
Low cylinder pressure is what he means. That's why the suggestion for the compression test.
I meant he did not specify what calculated pressure is considered to be low. Mine is not low as its 9.75:1
You're confusing compression ratio with cylinder pressure. The two are totally different. Cylinder pressure is what the engine physically produces in a give configuration, fully assembled. Compression ratio is the comparison of the cylinder volume from bottom dead center to top dead center. You've already said your cylinder pressure on one measured cylinder was 150. That's pretty low for that camshaft. I can't beat it into your head enough how important this is IF you want to tune this engine. But, like I said, if you're happy with it, don't worry about it.
Thanks but comparisons with other cams don't really tell me anything. Most of the specs like LSA, overlap and valve timing are different. Also I was measuring at 700 rpm. What initial timing were you running?
The problem is, there are so FEW original 340 4 speed engines out there. You are going to be VERY lucky if someone comes forward with the information you need. I sure wish you luck, though.
I am well aware of the differences. Ken used the terminology calculated compression which is why I was referring to it. He knows the valve timing.
I've never seen any guidelines about what tuning parameter you would change based on cylinder pressure. Got any? All my engines have run with about 15-20 degrees initial and 34-36 all in. Most every recommendation you will find falls between 34-36 (street engines anyway). Initial timing isn't critical and can vary in that you should be more concerned about total timing.
Thanks. Its not that important though. I was just curious. Lots of repro cams like this were sold so you think someone here would be running one.
This is from an old thread about the cam in discussion. The intake closing is 10* later than the Comp 268H bleeding cylinder pressure (dynamic compression) off...
"I worked with another member here and we sent one of my cams that was custom ground to be a clone of the 68 340 4-speed cam to Ken Heard at Oregon Cams and they measured it so they can duplicate it and now have it available for sale."
Here are the Oregon Cam specs/details:
#2120
221/227 @ .050”, 276/286 adv, .438”/.456” lift, 114 sep
Per the 68 Plymouth service manual, the factory specs are:
276/284 dur, .444"/.453" lift
Int op = 26° BTC
Int cl = 70° ABC
Exh op = 78° BBC
Exh cl = 26° ATC
From calculations:
Intake centerline = 112° ATC
Exhaust centerline = 116 BTC
Lobe separation = 114°
Comp 268H specs:
| 268 |
| 268 |
| 218 |
| 218 |
| 0.454 |
| 0.454 |
| 0.302 |
| 0.302 |
| 110 |
| 106 |
| 0.006 |
| 20 |
| 28 |
| 68 |
| 60 Intake closing event timing. |
Mattax
Just the facts, ma'am
The service manual durations are based on the ramp geometry in engineering drawings, not the SAE or other common standards. You can do a search for @Wyrmrider and maybe a key word like 'drawings'.
Oregon's '68 4-speed cam may be about as close as can be easily purchased.
There was someone who was going to reproduce it more precisely if there were enough participants but the ignorant hecklers drove him off.
Later in the same thread I show the simulated hp curves assuming incorrectly the service manual specs were .006, and then correcting as much as the program would allow using .004 from some of the catalogs.
That was a two way street. That guy has an attitude. Everything you say is wrong and all of what he says is right. That's what got him heckled. I for one will WELCOME any possibility for more Mopar parts. But when someone comes in here like his poop don't stink and nobody else is right about anything, that's what he's gonna get.Oregon's '68 4-speed cam may be about as close as can be easily purchased.
There was someone who was going to reproduce it more precisely if there were enough participants but the ignorant hecklers drove him off.
To add to that, there is nothing wrong with telling someone the product is already available so they don't make an investment in something that isn't going to sell in any significant volume.
Mattax
Just the facts, ma'am
The product is not available. There is something close, but thats not the same.
It may be good enough for some, but others were interested in the original - surviving examples of which is hard enough.
It's like saying a Tisas 1911A1 is the same as an US purchased Colt or Rem Rand. its close and reasonably priced, but its not the same.
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I agree. If I remember right, the cam Oregon ended up with was ONE DEGREE different "somewhere" than the factory four speed cam. And that guy went off on that like it was ten miles off. I'm glad Oregon has it on file, because they can grind it on whatever LSA you want at no extra charge. If there's enough meat on the core to go to a 108 LSA, that's be a neat little street cam. It was pretty good just like it was.
Mattax
Just the facts, ma'am
That's thing. We don't really know because we don't have a full cam profile. Oregon knows (and its been posted) where it differs at one of the key points. So where it cracks open and how the cams are shaped is one the interesting little mysteries.
Anyway my point was that the shop manual durations not advertised durations for .006" lift. And using them that way results in a different cam
@krazykuda Karl knows and has posted it several times. I just cannot remember. No surprise there.
Has anyone ever approached Schneider to see if he can replicate the OEM grind from his patterns?
It's tough to measure whether any of them are correct, because Chrysler was so proprietary with their measurements. We all know MP used the .850 for figuring duration at .050", instead of the industry standard of .750. But almost without fail, when you use that .850 to verify, it still doesn't math out. Same with their stock cams. The only real way to figure it is to map it on a cam machine or degree wheel.
Its a free world. If someone wants to spend double for the supposed 1 degree that's fine. The point is that informing other members that the cam is already available (lots of threads on it) is fine too.
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