Please Help a Dead Truck Engine

[A. G. Olphart]

There's now a dead Vortec 350 in my garage along with the dead 240Z. After reviewing the engine combinations on http://www.ryanscarpage.50megs.com/combos1.html

 

I've decided that I like combo 99, but it uses a flat tappet cam. Today's question: Is Comp Cams Xtreme 4X4 no. 08-413-8 as close to optimum as I can get for this buildup with my stock hydraulic rollers? (Combos 83 & 84 seem to show that the Vortecs are very sensitive to overcamming- No way do I want a 4400 rpm torque peak. This is/will be a road car, so mileage is important. That is also why it won't be a 383).

 

Also, has anyone run across pictures or a really good description of porting on the Vortecs? The Basic rule seems to be "Don't do much", but this buildup used 'pocket ported' heads.

 

Thanks-

[Guest Anonymous]

This site: http://www.automotiverebuilder.com/ar/ar39924.htm has a good description of pocket porting and what needs to be done. Since those are proven combo's and I didn't look at the cam specs I'm assuming they aren't exceeding the Vortec's lift maximum which is from what I understand its only big limit. (this is often fixed up to about .500 lift I think by cutting the area under the valve spring to keep the spring from binding, but thats probably a grumpy question, he could tell you for sure). Anyway, that was the one site I found on porting just doing a search on pocket porting. Good luck with it.

 

Regards,

 

Lone

[A. G. Olphart]

Thanks Lone- good site.

 

I'm really hoping to gain some insight into Vortec porting- They're reputed to respond atypically to porting techniques.

 

You presumed correctly on the cam lift- the 4X4 cam shown has .474 lift with 1.5 rockers, and the Vortecs are supposed to handle about .480.

[Guest gbvol54]

Do a search on "vortec". There's been a lot of useful info posted in the past that should be very helpful.