Degreed My 340 Camshaft Today

[dibbons]

Oregon Cam #2120 Degree Comparison pdf

My observations:
It appears to me looking at .006 valve opening comparisons:
Oregon camshaft opens both valves at about the same time as the factory automatic camshaft(not the manual).

Oregon camshaft closes both valves later than both factory camshafts. In the case of the exhaust valve, much later (35 degrees later)!

My .050 measurements come close to the Oregon specs.duration wise, but opening and closing are not:
5.5 degrees off opening and 3/4.5 off closing:

My .050 int 4.5 ATDC 44 ABDC My .050 exhaust 46.5 BBDC - 0.5 ATDC

Oregon int 1 BTDC 41 ABDC Oregon exhaust 52 BBDC 5 ATDC

Results:

 

[67Dart273]

You are saying the difference is in the same direction of rotation? that could easily be due to machining errors. I helped a guy several years ago, and we wound that thing ahead A LOT just to get it to book specs then went advanced some more to get it where the guys here recommended it. I don't know to this day whether it was machining errors, or something the grinder thought he intended to build into the cam as ground.

 

[mopowers]

Does that say there's a 19* - 23.5* difference in duration between 0.002" and 0.006" lift on the intake side and 40* difference on the exhaust side? That can't be right, can it?

 

[1MeanA]

I installed that cam a few years ago. If I recall it’s ground 4 degrees advanced…not sure if that explains anything. Call Ken at Oregon.

 

[dibbons]

Does that say there's a 19* - 23.5* difference in duration between 0.002" and 0.006" lift on the intake side and 40* difference on the exhaust side? That can't be right, can it?

.002 tappet rise: intake 305 / exhaust 348

I don't understand how the exhaust valve could be off the exhaust seat so long without burning up. Or why grind it that way in the first place?

 

[dibbons]

I installed that cam a few years ago.

Did you install it in your own vehicle? How's it working out? Thank you.

 

[cookietruck]

My .050 measurements come close to the Oregon specs.duration wise, but opening and closing are about 5.5 degrees off opening and 3/4.5 off closing:

My .050 int 4.5 ATDC 44 ABDC My .050 exhaust 46.5 BBDC - 0.5 ATDC

Oregon int 1 BTDC 41 ABDC Oregon exhaust 52 BBDC 5 ATDC

Results:
View attachment 1716429197

Can you advance the cam 4 degrees on yr timing set and remeasure?

 

[dibbons]

Can you advance the cam 4 degrees on yr timing set and remeasure?

Should I do that and install it that way? My Cloyes timing set does have provisions for advance and retard.

 

[cookietruck]

Should I do that and install it that way? My Cloyes timing set does have provisions for advance and retard.

I would, just works out that way sometimes.

I installed a cam on the 6* advance keys in my set and ended up 12* advanced. A little confusing at first. Went to zero advanced on the timing set and got 5* advanced. Thought that was good and left it there.

 

[Bewy]

Post #5. The engine cycle is 720*. So the exh valve is on the seat for more than half the duration [ 348* ] of the cycle.

 

[dibbons]

The engine cycle is 720*. So the exh valve is on the seat for more than half the duration [ 348* ] of the cycle.

That makes me feel a little better.

 

[1MeanA]

Did you install it in your own vehicle? How's it working out? Thank you.

Yes. The engine is broken in and installed. The car should be on the road later this month.

 

[dibbons]

Update: Checked piston to valve clearance with both dial indicator (cylinder number one) and clay Play-Doh (cylinder number eight). I don't know if "modeling clay" is any different/firmer but I found the Play-Doh was a little too soft/soggy to get a good read after I peeled it off the combustion chamber (which I should have lubricated before hand).

Anyhow, I got some good readings with the dial indicator as follows:

Exhaust Valve .408 @ 45 BTDC; .310 @ 30 BTDC; .220 @ 20 BTDC; .203 @ 15 BTDC; .192 @ 10 BTDC; .194 @ 5 BTDC; and .205 @ TDC

Intake Valve .300 @ TDC; .225 @ 5 ATDC; .220 @ 10 ATDC; .240 @ 15 ATDC

Then I briefly checked total intake valve lift at the retainer with valve train installed and found about .425 lift (measuring at the lifter earlier I measured .290 whereby .290 x 1.5 = .435) My valve lash or measuring could be off a little in either/both cases.

 

[AJ/FormS]

The factory cam had a LSA of 114
Yours, by the numbers is 108.25
If I copied the numbers right;
Here is the big picture, using the .006 advertised numbers; first the factory, then yours;
268int/114comp/106power/276exh/44overlap/66Ica
279int/102.5comp/106pwr/311ex/78.5overlap/77.5Ica
SO;
if I copied the numbers right;
>Your overlap is way off center, like ~14 degrees. ... because, by the numbers copied, it is installed at 118*, instead of closer to 108, say 104 if yur down on Scr.
so, IMO: this is about 14* too far advanced.

If I copied the numbers right ;
Your EFFECTIVE overlap is down to ~43 degrees, which is a loss of over 30 degrees which represents maybe two cam sizes worth of overlap, say 30 horsepower over the nose. If I copied the numbers right.
and
>With just 102.5 degrees of compression, I can guarantee, that your cylinder pressure will be very low; and the bottom-end will be weak. You're gonna need a lotta lotta compression ratio for that not to be a dog down low.
>and your Power-Stroke is way outta whack as compared to the compression stroke.
>and finally, she will be a pig on gas.

If I copied the numbers right;
IMO, that cam wants to be in at no less than 104.5 installed centerline....
Unless you just want to idle it around the parking lot, like a Whiplash/ThumpR,

Of course, if you did retard it back to "normal", you'd have to recheck your piston to valve clearance. And if the thing has already been running like that, then it will need a completely new tune.


In any case, if that cam was in my engine, and
If I copied the numbers right;
I would for sure reset the installed centerline closer to 105, cuz 102.5 degrees of compression is not very much.
Even my 292Purple cam, ran more compression degrees than that (110), and it was a dog down low with Scr of 11.3. It was so disappointing that I moved it several times to no good advantage, and ultimately pulled it out. In 25 years I have never really missed that cam.

If I copied the numbers right.
If I didn't copy the numbers right, color my red, cuz I'd be so embarrassed.
But if the 311 is wrong, or anything is wrong, well then I did a lotta work for nothing.

 

[dibbons]

According to the info listed from KrazyCuda on other threads, this Oregon cam is ground like this:

Lobe separation 114
Lobe centerline intake 110
Lobe centerline exhaust 118

 

[cookietruck]

Update: Checked piston to valve clearance with both dial indicator (cylinder number one) and clay Play-Doh (cylinder number eight). I don't know if "modeling clay" is any different/firmer but I found the Play-Doh was a little too soft/soggy to get a good read after I peeled it off the combustion chamber (which I should have lubricated before hand).

Anyhow, I got some good readings with the dial indicator as follows:

Exhaust Valve .408 @ 45 BTDC; .310 @ 30 BTDC; .220 @ 20 BTDC; .203 @ 15 BTDC; .192 @ 10 BTDC; .194 @ 5 BTDC; and .205 @ TDC

Intake Valve .300 @ TDC; .225 @ 5 ATDC; .220 @ 10 ATDC; .240 @ 15 ATDC

Then I briefly checked total intake valve lift at the retainer with valve train installed and found about .425 lift (measuring at the lifter earlier I measured .290 whereby .290 x 1.5 = .435) My valve lash or measuring could be off a little in either/both cases.

You should also check centerline on the intake (and exhaust if you want to check LSA)
Its easy.
Just rotate to max lift. Zero your dial indicator. The keep going to .050” past max lift. Record that number.
Then rotate back to the other way about .070” and then get it to .050” before max lift.
Record that number.
Add the two numbers and divide by two. That should be yr centerline.

 

[AJ/FormS]

According to the info listed from KrazyCuda on other threads, this Oregon cam is ground like this:

Lobe separation 114
Lobe centerline intake 110
Lobe centerline exhaust 118

Well not by your included .006 numbers it ain't.
Lemme work it out with the 050s
I' be back, lol.

 

[dibbons]

I must be off on the closing point of the exhaust valve (or the cam is just ground crazy that way).

I found an alternate measurement for the exhaust at .006 I made a day earlier:


.006 74 BBDC + 180 + 36 ATDC = 290 ALTERNATE

But Oregon still lists as 309!

 

[crackedback]

paralysis by analysis... good god.

It looks to be 4-5* retarded if you are correct on your .050 numbers. Advance it and check it again. It's likely 114 lsa with a 110 ICL per oregon.
110 ICL and 118 ECL. Basic stock 340 style camshaft LSA grind.

Whiplash style idle.... LOL NOT A CHANCE. Install that cam at 104 and you'll regret it.

 

[cookietruck]

paralysis by analysis... good god.

It looks to be 4-5* retarded if you are correct on your .050 numbers. Advance it and check it again. It's likely 114 lsa with a 110 ICL per oregon.
110 ICL and 118 ECL. Basic stock 340 style camshaft LSA grind.

Whiplash style idle.... LOL NOT A CHANCE. Install that cam at 104 and you'll regret it.

Just curious. Why would a 104 icl be regretful?

 

[crackedback]

It will likely ping like a ****. That was my experience with an engine built by someone else. Same type cam and way ahead. 10:1 340 Mid 20's total timing wouldn't stop it from pinging under cruise loads.

Plus you are putting the exh valve pretty far out of an acceptable range with a NA engine. Line in the sand for me is ~118 ecl... not any higher on an NA deal

 

[RustyRatRod]

paralysis by analysis... good god.

It looks to be 4-5* retarded if you are correct on your .050 numbers. Advance it and check it again. It's likely 114 lsa with a 110 ICL per oregon.
110 ICL and 118 ECL. Basic stock 340 style camshaft LSA grind.

Whiplash style idle.... LOL NOT A CHANCE. Install that cam at 104 and you'll regret it.

Not on a 114 it sure ain't. LOL

 

[dibbons]

Oregon 318 camshaft break-in video today (go to the end of video to hear it). However, poster did not give the grind number.

 

[crackedback]

Not on a 114 it sure ain't. LOL

So what are the actuals CL's for both lobes? I did the math in my head, cause nerd math ability LOL

Maybe this might help clear things up.

Based on his .050 numbers.

Pretty darn near 114 LSA, No?

 

[dibbons]

I don't know how to interpret these charts, but I entered some data and here is what was generated: