Advance cam or not?

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Freezerman

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I am putting together a 5.9 magnum for my Dart. Stock bottom end with EQ heads and Hughes springs. Doug's headers. It will have 9.25 compression, I have an Oregon cam 1357 to put in. I degreed it as installed at 108. I am wondering if I should install it advance 4 degrees? It has 26" tires, 3.73 gear, 904 transmission with 2800 stall. Thanks.
 
I am putting together a 5.9 magnum for my Dart. Stock bottom end with EQ heads and Hughes springs. Doug's headers. It will have 9.25 compression, I have an Oregon cam 1357 to put in. I degreed it as installed at 108. I am wondering if I should install it advance 4 degrees? It has 26" tires, 3.73 gear, 904 transmission with 2800 stall. Thanks.

If you installed it at 108, it already is advanced 4*.
 
Yes. As you know RRR, the cam in my 360 improved quite a bit on your advice to advance it an extra 4 degrees. I just don't want to put this one together and then find out I should have pushed this one ahead also.
 
Yes. As you know RRR, the cam in my 360 improved quite a bit on your advice to advance it an extra 4 degrees. I just don't want to put this one together and then find out I should have pushed this one ahead also.

If the compression is MEASURED and ACCURATE.......I would stab it in right where the card says, because that match is "about right".
 
Yes, the compression is measured with 62cc heads. I used 3 different calculators and all were within .1 of each other. Thank you.
 
Yes, the compression is measured with 62cc heads. I used 3 different calculators and all were within .1 of each other. Thank you.

Then I would put that bad boy in per the cam card and have fun! Extra advance is needed when the cam is a poorer match. in other words, when the cam is "too big" for a given static compression ratio, you advance it more to help cylinder pressure. In your case, you won't need to.
 
Mr Freeze. Please let us know how your build performs. I am doing similar and and starting my cam selection. Would appreciate real world feedback on that and any other cams. Thank you.
 
I will. It won't be for a few months though. After winter in Minnesota.
 
I like putting in 2° just for chain stretch if using a new timing chain, but that's me.

That's probably not a terrible idea.......what I would do is use a compression gauge in conjunction with the degree wheel. Once degreed, spin the engine over and take a compression reading. If you think it's a "little low" you can bump in the extra 2*. At least "like that" you'll kinda actually know "where" you are.
 
That's probably not a terrible idea.......what I would do is use a compression gauge in conjunction with the degree wheel. Once degreed, spin the engine over and take a compression reading. If you think it's a "little low" you can bump in the extra 2*. At least "like that" you'll kinda actually know "where" you are.
I've been doing it for 35 years, I pull my junk back down for a refresh after 200 + - pass's and even the good chains are stretched.
 
Following , I’ve been wanting to build a 5.9 magnum also looking at that grind I got to call and c if I could get him to grind on a 108 or 110
 
To no one in particular,
and as applies to a streeter only;
Remember that when you move your cam, you are always trading extraction degrees and compression degrees, in a one to one ratio, and simultaneously swapping overlap from one side of TDC to the other, usually reducing the Effective overlap, in a ratio of 2 to 1. Therefore, advancing a cam by 4 degrees will change the Effective overlap by 8.

Therefor; if you decide to run a different ICA than the manufacturer recommends, you probably have the wrong cam, or the wrong compression ratio for it. The bigger the street cam, the more true this is.

Take the popular 340 cam
in at +4*/110 ICA the specs are;
268/116/104/276/44/40E ;but in at +8*/106 ICA,then
268/120/100/276/44/32E
intake/comp/ extraction/ exh/overlap/ Effective o/lap
SO;
in at 106, you gain 4 degrees of compression (120 vs 116) or about 6 psi cranking cylinder pressure;
but at the expense of 4* of power extraction, and
8 degrees of Effective overlap.
The 6 psi of additional cylinder pressure will improve performance below about 3000 rpm.
But the loss of Effective overlap is gonna kill a bit of power at the top and in the midrange.
And the loss of extraction will likely cost you fuel economy on an already poor-economy cam.
Those 4 degrees of additional advance are worth about .2 point of compression. And may drive your engine into detonation, that will require the next higher grade of gas to overcome. And so if you are already running best gas, now what do you do?
In this case;
you shouldda just started with more pressure in the first place; or a smaller cam, or a cam with a tighter LSA.
Lets tighten it up to 108, and install it at +2
268/120/112/276/56/56E, compared to
268/120/100/276/44/32E.
Thereyago, same 120* of compression, but now an extra 12* of extraction, and a huge boost to the Effective overlap , at 56* vs 32*. That's gonna make some power in Second gear! Of course whatever economy you mighta gained with the extra 12* of extraction, you will likely lose most of it by the longer Effective overlap. But the cure for that is to have a higher than "normal" cruise rpm.
That's the way uh-huh,un-huh.

You can easily go overboard with this idea tho, as the powerband gets more narrow while it gets pointy on top. Perfect for a close-ratio 4 or 5 speed, but not so good for an automatic on the street because the 1-2 split is pretty wide. The cure for that of course is a hi-stall. Until the stall becomes too much higher than the cruise rpm.
The cure for that,is a bigger engine and start all over.
 
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