Is the cam timing the problem, or something else?

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my68barracuda said:
Cranking pressures are listed in post #1.
And they are low as mentioned in post #13.
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Sorry I missed that.
That is low, I agree with the others cam my be retarded.
And it would have to be retarded a lot. I believe the rule of thumb is like 5 psi per degree of timing.
Here this will help if you want to do the math.
Cam Timing vs. Compression Analysis
 
I have tried adjusting the initial advance as far as 22*, there is no detonation that I can hear, and the MSD distributor is one that came with the car, so I have no idea what may have been done to it by the po. The oe distributor came with the engine and I have run it as high as 22* initial advance as well. The only thing noticeable at that point is the starter drag.
 
missing linc said:
I have tried adjusting the initial advance as far as 22*, there is no detonation that I can hear, and the MSD distributor is one that came with the car, so I have no idea what may have been done to it by the po. The oe distributor came with the engine and I have run it as high as 22* initial advance as well. The only thing noticeable at that point is the starter drag.
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It is not going to detonate with that low of cylinder pressure.
Adjusting the ignition timing is not going to cure the issue
 
The way the engine is running reminds me of the way my first small block Ford ran after the timing chain skipped. That was 42 years ago, so it took me a while to recall that incident and what the cause and result was. I was barely 16, had little to no tools and had never done a timing chain before. I learned pretty quickly that it was important. Since that time I have done dozens of timing chain replacements and cam swaps, but have never used a degree wheel and never had a problem, until now.
I am a firm believer in fixing things properly and have every intention of opening the engine up to correct the problem.
Unfortunately, I have learned this morning that my stepfather has been hospitalized and is not expected to have much longer.
I am very appreciative of the responses from all of you and I will keep you updated when I get the chance to get it opened up and running right.
Until then I have to be supportive of my mother and stepfather for whatever time he has left.
Thank you all.
Randy
 
missing linc said:
The way the engine is running reminds me of the way my first small block Ford ran after the timing chain skipped. That was 42 years ago, so it took me a while to recall that incident and what the cause and result was. I was barely 16, had little to no tools and had never done a timing chain before. I learned pretty quickly that it was important. Since that time I have done dozens of timing chain replacements and cam swaps, but have never used a degree wheel and never had a problem, until now.
I am a firm believer in fixing things properly and have every intention of opening the engine up to correct the problem.
Unfortunately, I have learned this morning that my stepfather has been hospitalized and is not expected to have much longer.
I am very appreciative of the responses from all of you and I will keep you updated when I get the chance to get it opened up and running right.
Until then I have to be supportive of my mother and stepfather for whatever time he has left.
Thank you all.
Randy
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Sorry to hear this, you have to take care of the important things in life first. Best wishes.
 
As for Melling cams;
I think those are measured at .001 tappet rise, so 288/298 looks like a pretty big number, but by .006/.008 where most other cams are measured, I bet it will sorta fall into line with them.
However, that 112LSA is a pressure killer.
I seriously doubt that cam-timing alone is your problem. IMO, that cam is just NOT compatible with your compression ratio; that is your problem, and the very low CCP is the proof.
As for me; If I couldn't afford to pump up the cylinder pressure, I would just swap out that cam.

As for cam timing versus pressure, you'd be lucky if it changes 1.25 to at most 1.5 psi per degree, so, if it was 4 degrees retarded and you changed the cam-timing to 4* advanced, a change of 8 degrees, you'd be lucky to see 10/12psi, and the pressure will still be soggy.
As for this;
missing linc said:
Engine will idle well once warmed up, but even in park, there is poor throttle response, and the exhaust smells very rich, regardless of where the idle mixture screws are set.
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As for the stink;
that would be a normal result for this cam; she is wanting some Idle-air bypass.
As for the the poor throttle response, that would be normal for such a low cylinder pressure. AND,
A for "regardless of where the idle mixture screws are set";
in all likelihood your throttles are just too far up the transfers.
For now; Set the mixture screws to 2 turns out, and back the Idle-Timing up to 14*, and reset the idle-speed to 750/800.. After that you will have to give her some Idle-air on a throttle bypass. No big deal, everybody goes thru this.

If the cam is in good shape and you want to keep her, you will need to to do one or more of the following;
1) increase the CCP with Static compression ratio, or
2) increase the stall speed to more than 2800.
3) install adjustable valve gear and put some lash into the system.
Option one is best
Option three is worst
option two is what most guys do.

BTW-1
what is your elevation out there in Southern Alberta?
BTW-2
I ran a 223/230/110 cam in my 367 at 180psi and she was a ripper! A total animal, even with a manual trans and 3.23s.
With 3.55s she would bust the tires loose in Second gear at up to 50 mph.
BTW-3
112LSAs are not for low-compression streeters
 
missing linc said:
I have tried adjusting the initial advance as far as 22*, there is no detonation that I can hear, and the MSD distributor is one that came with the car, so I have no idea what may have been done to it by the po. The oe distributor came with the engine and I have run it as high as 22* initial advance as well. The only thing noticeable at that point is the starter drag.
Click to expand...

Ok, cool, then you've tried elevated timing. Did it help at all? If it helped AT ALL, even the smallest amount, then changing the camshaft timing might help even more.
 
RustyRatRod said:
Ok, cool, then you've tried elevated timing. Did it help at all? If it helped AT ALL, even the smallest amount, then changing the camshaft timing might help even more.
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It does help some to increase timing, but I really believe that the cam is still not in correctly. I was hoping to get at it this weekend, but with the recent family development I may have to put everything on hold.
 
dartfreak75 said:
I was just about to mention this thread!
My timing gear was marked or cut wrong. With the dots lined up my cam was 24 degrees retarded.
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I seem to remember you were having some problems with your cam timing, another reason why I believe that is what the trouble is with this one. I may just pull the cam out and use one that came with my engine.
 
missing linc said:
I seem to remember you were having some problems with your cam timing, another reason why I believe that is what the trouble is with this one. I may just pull the cam out and use one that came with my engine.
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Can you post the cam card for the new cam you would use?
 
What is the most accurate out of the box timing chain these days?
 
missing linc said:
It does help some to increase timing, but I really believe that the cam is still not in correctly. I was hoping to get at it this weekend, but with the recent family development I may have to put everything on hold.
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That's what it sounds like then. I hope everything works out ok.
 
missing linc said:
I seem to remember you were having some problems with your cam timing, another reason why I believe that is what the trouble is with this one. I may just pull the cam out and use one that came with my engine.
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Why would you do that when the cam you have hasn't been degreed and essentially isn't in the engine "right"? You really have zero basis for comparison. Swapping cams may put you in the same place you are, maybe worse.
 
jammied said:
What is the most accurate out of the box timing chain these days?
Click to expand...

Probably the JP/Rollmaster or any of the high end billet sets. Or a high end gear drive.
 
missing linc said:
Elevation here is around 3000 ft.
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That's what I thought.
That's worth 15/20 psi right there;
or about 3 cam sizes,
or about a point and a half in Scr.
Yur in big trouble.................
That cam, at low rpm (to about 3000/3500) wants an Scr of around 10.2....... minimum.
But from there to peak torque and beyond, 10.2 might be too much for open-chamber iron heads and pumpgas.

As best as I can figure, using the Wallace Calculator,
for 3000ft elevation;
your tester is actually reading a higher pressure than the Wallace predicts for an 8/1 Scr; So I really really doubt that your cam is out by much, if at all.
If anything, I would imagine that your compression tester is being optimistic, and your true pressure may actually be lower.
Edit; or your Scr could be higher than 8/1 ......... at around 9/1 the predicted pressure starts to come to your measured number.
 
Last edited:
missing linc said:
Don't have a cam card, it was in the motor when I got it. I expect it will be an oe piece probably.
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Without the cam data you are just taking a shot in the dark.
May make things worse, not worth the risk.
 
RustyRatRod said:
Why would you do that when the cam you have hasn't been degreed and essentially isn't in the engine "right"? You really have zero basis for comparison. Swapping cams may put you in the same place you are, maybe worse.
Click to expand...
That is true, I don't need to have to revisit this problem repeatedly, frustration is taking over, once I get it apart and can at least find out if it is not installed right or if there is something else wrong, I will have an option if I need or want.
 
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