cam shaft/valve spring question - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

irish108 · 04-26-2019, 05:44 AM

according to the specs, the PAC 1218 springs have a max lift of .600 thou. Does this mean that the cam shaft lift can be no more than .600 thou to avoid coil bind. I'm trying to figure out what my limits are on a cam with the PAC 1218's. Looks like most of the TSP and BTR cams are more than .600 thou. I may have to look at other brands.

Thanks in advance guys.

Benman · 04-26-2019, 09:25 AM

Yes that means .600 net valve lift, if you are wanting to stay with those springs maybe you would be interested in one of the ASA cams, lower lift with added duration. Not really that much savings IMHO, but still a step up in performance from stock.

irish108 · 04-26-2019, 12:42 PM

Quote:

Originally Posted by Benman

Yes that means .600 net valve lift, if you are wanting to stay with those springs maybe you would be interested in one of the ASA cams, lower lift with added duration. Not really that much savings IMHO, but still a step up in performance from stock.

yeah that what I figured. I'm looking at the comp cam XR275HR13

222 int/ 234 exh duration @.050
.566 int/ .576 exh lift
113 lobe seperation

I think I should be able to run that cam. Would you agree?

Not really looking for anything to radical. Just a nice sound and a step up in performance.

Benman · 04-26-2019, 01:37 PM

My understanding is that cam will work with those springs, I am also looking at Howards cams, and GMPP offers one as well. Staying with stock heads dictates max lift is not necessary to increase airflow. Air velocity through the intake runners will help fill the cylinder. As with any performance cam install, pay close attention to valve timing events as well as piston to valve clearance, although with less lift clearance becomes less of an issue.

Benman · 04-26-2019, 02:08 PM

I will add that although I am interested in an ASA type cam, I am more than likely going to go with GPI SS4 NFC or TSP F35, mostly because I have plans to increase CI later and don't want to re-buy a cam more suited to a bigger displacement.

irish108 · 04-26-2019, 05:20 PM

Thanks Benman. Much appreciated

04-26-2019, 05:44 AM	#1
irish108 Drives: chevrolet camaro Join Date: Mar 2019 Location: south carolina Posts: 28	cam shaft/valve spring question according to the specs, the PAC 1218 springs have a max lift of .600 thou. Does this mean that the cam shaft lift can be no more than .600 thou to avoid coil bind. I'm trying to figure out what my limits are on a cam with the PAC 1218's. Looks like most of the TSP and BTR cams are more than .600 thou. I may have to look at other brands. Thanks in advance guys.

04-26-2019, 09:25 AM	#2
Benman Drives: 13 IOM 2ss RS manual Join Date: Jun 2018 Location: Euless,TX Posts: 213	Yes that means .600 net valve lift, if you are wanting to stay with those springs maybe you would be interested in one of the ASA cams, lower lift with added duration. Not really that much savings IMHO, but still a step up in performance from stock.

04-26-2019, 01:37 PM	#4
Benman Drives: 13 IOM 2ss RS manual Join Date: Jun 2018 Location: Euless,TX Posts: 213	My understanding is that cam will work with those springs, I am also looking at Howards cams, and GMPP offers one as well. Staying with stock heads dictates max lift is not necessary to increase airflow. Air velocity through the intake runners will help fill the cylinder. As with any performance cam install, pay close attention to valve timing events as well as piston to valve clearance, although with less lift clearance becomes less of an issue.

04-26-2019, 02:08 PM	#5
Benman Drives: 13 IOM 2ss RS manual Join Date: Jun 2018 Location: Euless,TX Posts: 213	I will add that although I am interested in an ASA type cam, I am more than likely going to go with GPI SS4 NFC or TSP F35, mostly because I have plans to increase CI later and don't want to re-buy a cam more suited to a bigger displacement.

04-26-2019, 05:20 PM	#6
irish108 Drives: chevrolet camaro Join Date: Mar 2019 Location: south carolina Posts: 28	Thanks Benman. Much appreciated