Is the cam timing the problem, or something else?

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missing linc

missing linc

Loose nut behind the wheel
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My 360 is not performing anywhere near how it should. It has little to no low end power, will not spin the tires, even with 4.10 gears in the rear end, even with the RPM's up, it's still gutless. I have corrected some of the issues with voltage drop to the ignition, which has helped with some of the problems, it does run smoother, but still stinkin' rich, and gutless. I have been reading up on cam timing and degreeing, and have come to the conclusion that the cam is either ground incorrectly, or significantly retarded.

The engine is a 1974 block, stock bottom end and heads and has Melling cam with these specs
Adv exh duration - 298*
Adv int duration - 288*
Exh dur @.050 - 224*
Int dur @.050 - 214*
Int lift - .444
Exh lift - .466
LSA - 112*
Cranking compression is 125 to 135 psi, according to my crappy Chinesium compression tester.

Cam was installed "straight up", with a new double roller chain.

Intake manifold is currently a stock cast iron of unknown origin, (will be swapped for a Weiand Action plus soon), paired with an Edelbrock AVS2 650 CFM carb, ignition is MSD 6 Plus, MSD Blaster coil, and MSD billet distributor. Car has TTi step headers into 2.5 inch exhaust and Flowmaster 40 series mufflers. Trans is a 727 with unknown convertor.

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.

Any help, suggestions or ideas are welcome. TIA
 
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when you say cam was installed straight up , does that mean lined up the dots and not degree'd in.?
 
It may not be the cam- I remember reading on here about a batch of timing gears (forget if it was Cloyes or Comp?) that came through mismarked; so if you just lined it up dot to dot, it could be way off... it would be worth checking into.
 
missing linc said:
...stinkin' rich...1974 block, stock bottom end and heads...unknown convertor....exhaust smells very rich, regardless of where the idle mixture screws are set...
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Some good clues to poor performance here, especially the first and last ones. I would start with ignition timing and carb...tune it good first. That's not to say the cam timing is or isn't an issue, but I've had 440s that couldn't get out of their own way because the ignition timing was late and the carb wasn't right.
 
Professor Fate said:
It may not be the cam- I remember reading on here about a batch of timing gears (forget if it was Cloyes or Comp?) that came through mismarked; so if you just lined it up dot to dot, it could be way off... it would be worth checking into.
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I was thinking that, I have a couple of other sets hanging on the wall I may try.
 
beanhead said:
Some good clues to poor performance here, especially the first and last ones. I would start with ignition timing and carb...tune it good first. That's not to say the cam timing is or isn't an issue, but I've had 440s that couldn't get out of their own way because the ignition timing was late and the carb wasn't right.
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I have gone that route, as well as swapping the ignition over to factory style Mopar with no improvements.
 
missing linc said:
My 360 is not performing anywhere near how it should. It has little to no low end power, will not spin the tires, even with 4.10 gears in the rear end, even with the RPM's up, it's still gutless. I have corrected some of the issues with voltage drop to the ignition, which has helped with some of the problems, it does run smoother, but still stinkin' rich, and gutless. I have been reading up on cam timing and degreeing, and have come to the conclusion that the cam is either ground incorrectly, or significantly retarded.

The engine is a 1974 block, stock bottom end and heads and has Melling cam with these specs
Adv exh duration - 298*
Adv int duration - 288*
Exh dur @.050 - 224*
Int dur @.050 - 214*
Int lift - .444
Exh lift - .466
LSA - 112*
Cranking compression is 125 to 135 psi, according to my crappy Chinesium compression tester.

Cam was installed "straight up", with a new double roller chain.

Intake manifold is currently a stock cast iron of unknown origin, (will be swapped for a Weiand Action plus soon), paired with an Edelbrock AVS2 650 CFM carb, ignition is MSD 6 Plus, MSD Blaster coil, and MSD billet distributor. Car has TTi step headers into 2.5 inch exhaust and Flowmaster 40 series mufflers. Trans is a 727 with unknown convertor.

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.

Any help, suggestions or ideas are welcome. TIA
Click to expand...
Boy, does this sound familiar.
 
missing linc said:
I have gone that route, as well as swapping the ignition over to factory style Mopar with no improvements.
Click to expand...
The converter is to tight for the cam.
I had the same problem myself, poor idle, no low end torque, been there.
What is the cranking compression pressure.
What is the rear gear and tire height?
 
missing linc said:
My 360 is not performing anywhere near how it should. It has little to no low end power, will not spin the tires, even with 4.10 gears in the rear end, even with the RPM's up, it's still gutless. I have corrected some of the issues with voltage drop to the ignition, which has helped with some of the problems, it does run smoother, but still stinkin' rich, and gutless. I have been reading up on cam timing and degreeing, and have come to the conclusion that the cam is either ground incorrectly, or significantly retarded.

The engine is a 1974 block, stock bottom end and heads and has Melling cam with these specs
Adv exh duration - 298*
Adv int duration - 288*
Exh dur @.050 - 224*
Int dur @.050 - 214*
Int lift - .444
Exh lift - .466
LSA - 112*
Cranking compression is 125 to 135 psi, according to my crappy Chinesium compression tester.

Cam was installed "straight up", with a new double roller chain.

Intake manifold is currently a stock cast iron of unknown origin, (will be swapped for a Weiand Action plus soon), paired with an Edelbrock AVS2 650 CFM carb, ignition is MSD 6 Plus, MSD Blaster coil, and MSD billet distributor. Car has TTi step headers into 2.5 inch exhaust and Flowmaster 40 series mufflers. Trans is a 727 with unknown convertor.

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.

Any help, suggestions or ideas are welcome. TIA
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Cranking compression of 125 to 135 is low for anything but a grocery getter motor.
 
How far can you "wind" it? Does it seem to perform better on top end? If so that is normally RETARDED cam timing rather than ADVANCED, which tends to help lower RPM

If you changed the cam drive, IE sprockets and gears, that is replaced them, with same physical cam, that could do it. What they are talking about is MACHINING TOLERANCES in the cam/ drive. You can check cam "degree" if you are careful without removing the cam. You likely will have to remove intake, but you might pull it off by not doing so. You have to think and think outside the box and get creative. Maybe buy / find some junk pushrods and convert them into extra long so that you can bring them up /out far enough to "get ahold of them" with a dial indicator. This of course only works if you know for sure just exactly what cam you have in there and access to the "cam card" (cam specs

HOW ABOUT TIMING?? Where do you have timing set and

CAVEAT:: Some timing marks are not accurate (use a piston stop) AND SOME TIMING LIGHTS are not accurate with MSD ignition. This is a well known fact. Find yourself an old timing light that is NOT a "delay" or "dial up" light

I assume?? (maybe I should not?) that you have checked jetting/ plug readings, and DOES THE THROTTLE open all the way?
 
It will wind up, but it seems lazy, have pulled it to around 5500, have tried adjusting the timing all over the place. I will be pulling the intake off to change it, so I will be able to check everything. I think I am going to order a degree wheel kit before I go much further. Right now I'm looking for ideas or suggestions. All are appreciated.
Throttle opens fully as well.
 
512Stroker said:
The converter is to tight for the cam.
I had the same problem myself, poor idle, no low end torque, been there.
What is the cranking compression pressure.
What is the rear gear and tire height?
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I have considered the convertor as well, but that shouldn't keep it from winding up in park, no load.
 
missing linc said:
I have considered the convertor as well, but that shouldn't keep it from winding up in park, no load.
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No
A tight converter will load the engine at idle.
Even in park it will load the engine because it does not slip.
Edit: A tight converter goes not slip enough.
 
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missing linc said:
It will wind up, but it seems lazy, have pulled it to around 5500, have tried adjusting the timing all over the place. I will be pulling the intake off to change it, so I will be able to check everything. I think I am going to order a degree wheel kit before I go much further. Right now I'm looking for ideas or suggestions. All are appreciated.
Throttle opens fully as well.
Click to expand...
Do the simple things first, KISS theory.
Show us the cranking cylinder pressures, plugs out WOT
This will give you a good idea of what is going on inside your engine.
Dont reinvent to wheel before you have to.
 
512Stroker said:
Do the simple things first, KISS theory.
Show us the cranking cylinder pressures, plugs out WOT
This will give you a good idea of what is going on inside your engine.
Dont reinvent to wheel before you have to.
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Cranking pressures are listed in post #1.
And they are low as mentioned in post #13.
 
What's the bottom end made of?

You said you have 125-135lbs cyl at cranking?

Put 4 degree more advance, maybe 6.
You want 150lbs 'or more'..like at the least. No matter how small the cam is.

That's why you aren't turning tires.
As soon as you saw 125-135... you knew it!

Fix it.
 
I agree with the other about the camshaft timing......BUT......since you can do it basically without doing ANY engine work, put a decent timing curve in it first, JUST TO SEE. Sometimes that alone can wake one slap up. With cylinder pressure that low, I would try 20 degrees initial with 34 -36 total and you want that total to be "all in" by 2500 RPM. I don't think there's any chance in the world it'll spark knock, so try that and see how it does. You can temporarily see if it will help by simply pulling in 20 degrees initial timing and doing a test drive. Report back when you've done that and if you want to continue further, we can help you pull the distributor, disassemble it and put a good curve in it. If you want to go ahead and tear into it, you can do that.

If it was mine, I would work with the distributor first. You may can get it pretty responsive like it is, rather than tearing into it to change the camshaft timing.

Now, after having said all that, I'm a big advocate for getting camshaft timing right. But there's nothing wrong with trying the distributor FIRST, because you will at least learn that and then, if that doesn't give the complete results you're looking for, you can continue.
 
RustyRatRod said:
I agree with the other about the camshaft timing......BUT......since you can do it basically without doing ANY engine work, put a decent timing curve in it first, JUST TO SEE. Sometimes that alone can wake one slap up. With cylinder pressure that low, I would try 20 degrees initial with 34 -36 total and you want that total to be "all in" by 2500 RPM. I don't think there's any chance in the world it'll spark knock, so try that and see how it does. You can temporarily see if it will help by simply pulling in 20 degrees initial timing and doing a test drive. Report back when you've done that and if you want to continue further, we can help you pull the distributor, disassemble it and put a good curve in it. If you want to go ahead and tear into it, you can do that.

If it was mine, I would work with the distributor first. You may can get it pretty responsive like it is, rather than tearing into it to change the camshaft timing.

Now, after having said all that, I'm a big advocate for getting camshaft timing right. But there's nothing wrong with trying the distributor FIRST, because you will at least learn that and then, if that doesn't give the complete results you're looking for, you can continue.
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Just pull the heavy spring, 18 initial and 36-38 total. Bet It wont ping anyways. But I hear ya. It's too weak in umph, advance the cam or change to a smaller one.
 
MOPAROFFICIAL said:
Just pull the heavy spring, 18 initial and 36-38 total. Bet It wont ping anyways. But I hear ya. It's too weak in umph, advance the cam or change to a smaller one.
Click to expand...

I agree.....but he can get the distributor DANG CLOSE now and see what just changing that can do. It sure won't hurt anything. And I don't think even advancing the cam timing can get him into spark knock territory, do you? Even so....it will add a good bit for sho and fo certain.
 
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