Cam numbers

[FireShadow]

I've finished collecting most of the parts for the 3.4/3400 build. I want to get a new cam while I have it all apart, nothing too crazy just a little better than the stock one which I'm sure has perfectly circular lobes by now =) I also am planning on doing a small (~75) shot of nitrous later on. I was going to get one of the comp cams packages or a custom grind but I'd like to get some input on the numbers I should be looking at. Thanks.

[FunkZ]

Re: Cam numbers

Stock 3.4 cam specs are:

Duration (Intake/Exhaust) 195/201
Lift (Intake/Exhaust) .390"/.410"
Lobe Seperation 109°

If you go with an off-the-shelf cam for streetability, I'm told by several sources that the Comp Cams 260H is one of the most popular. It's also the cam I selected for my car.

Comp Cams 260H (16-233-4)
212/212 .440"/.440" 110°

There are 3 others that you might consider, Edlebrock, Lunati or Crane.

Edelbrock 3790
204/214 .420"/.442" 112°

Lunati 06312
195/205 .405"/.427" 112°

Crane Cams H-260-2 (253902) This is the GMPP 12364059 cam.
204/216 .427"/.454" 112°

The downside to the Crane/GMPP cam is it does not have the tab for the cam sensor in the 3.4 so the SFI system can't determine TDC and will batch fire. (basically turning it into TPI/MPFI) This is not necessarily super bad, it will run a bit rich though and fuel economy might suffer.

All of these advertised numbers are with 1.5 ratio rockers. If you go to a higher ratio the lift especially will change. There are of course custom grinds also available if you want to get more extreme however the problem of tuning for the 3.4 becomes an issue at that point.