440 cam timing question.

[dodge1972]

Building a 440 for my 74 Charger. Mopar magnum cam with adjustable timing chain. Compression is 10:1. My question is timing chain advance timing verses top center. Asking about the setting timing chain to 2 degrees advance? Thanks

 

[Geoff 2]

Not sure what you are asking?
Mopar factory Magnum cam? Or Comp Cams Magnum series.
Why do you want to advance the cam 2*?

 

[dodge1972]

Not sure what you are asking?
Mopar factory Magnum cam? Or Comp Cams Magnum series.
Why do you want to advance the cam 2*?

Just asking for options. Factory stock purple shaft cam.

 

[493 Mike]

Can we assume you are degreeing that cam also? If not, install straight up.
Mike

 

[ruffcut]

Should be degreed to insure correct installation. Or as mentioned, straight up!

 

[diesel_lv]

Most big name cam grinders, Comp Hughes, add 4° advance in the cam. So when installed straight up, there's actually 4°. This is to give a little more bottom end. Not sure if Mopar purple shaft cams did that or not. The cam card should say something like 110° lobe separation angle, 106° intake centerline. If it doesn't, you need to degree your cam and find out exactly what it is at straight up and then adjust appropriately.

 

[lewtot184]

stock magnum cams are ground with 2 degrees of advance. this would put the installed centerline at 113. i wouldn't advance the cam any more than that with 10:1 compression and assuming pump gas.

 

[dodge1972]

stock magnum cams are ground with 2 degrees of advance. this would put the installed centerline at 113. i wouldn't advance the cam any more than that with 10:1 compression and assuming pump gas.

Appreciate your response

 

[Gunner1]

The PO had the engine in mine built with flat tops and 452 heads And 9.4 to 1. The cam he chose was a 270 magnum. 224 at 50. Should have been ok. 110 lobe spread 4 degrees adv when installed straight up at 106. Problem is he put it in at +4 on the multi slot t chain at 102 ICL. It had 175 cranking pressure and pinged with only 24 degrees total. Cost me a lot of bucks to fix it. Now I have 80cc heads at 10.2 and 150 psi. 34 degrees total with a 292 Isky 108 LS in at 104 ICL. Works slick. Don’t over advance.

 

[Geoff 2]

Even if you had retarded the Mag cam to say 112 ICL, I doubt it would have cured the pinging.
The Isky cam has 20* more duration at 050.

 

[451Mopar]

If you have the P4452783 cam that specs 268/284 advertised 115 LSA, the factory timing events (21/67/79/25) are with the cam installed at 113 ICL.
That is actually 2 degrees retarded from split overlap. at 111 ICL, the timing events are 23/65/81/23
I would probably go with the 111 ICL split overlap timing and if the timing chain wears/stretches, it will just get closer to the factory timing anyway.

I'm in Aurora too!

 

[Geoff 2]

If the cam is ground with 115 LSA & installed at 113 ICL, it is advanced 2 degrees, not retarded.
Installing it at 111 ICL will make it 4* advanced.

 

[451Mopar]

If the cam is ground with 115 LSA & installed at 113 ICL, it is advanced 2 degrees, not retarded.
Installing it at 111 ICL will make it 4* advanced.

Yes, 2 degrees advanced from the Lobe Seperation angle, and 2 degrees retarded from "split overlap". To have "split overlap" where the intake opens the same degrees before TDC that the exhaust closes after TDC, the cam would need to be advanced 4 degrees from the Lobe Seperation Angle because the intake and exhaust lobes are different duration.
If both intake and exhaust were the same duration, the straight up would be "split overlap", and advanced would be advanved from both the LSA and the overlap.

 

[Geoff 2]

Uh no, that is not how split overlap [ SO ] works or means. SO is not related to duration, only the ICL & ECL.
If the LSA is 115, then split overlap would mean that the ICL is 115*....& so is the ECL. If it was a dual pattern cam, with more exh duration, the exh tappet would be he higher than the int. There is a good description in the Isky catalog.