Question about cams

[98bluevert]

how high of a lift cam will a stock nPI motor handle without PTV issues. also would i have to get new springs.

 

['13_ImpactBlue_GT]

I dont know about the NPI motor but the VT Stage 1s for my GT dont require new valve springs, just a tune.

 

[98bluevert]

i know if i go with stage 2's i need springs but since my stock lift is like .473 i didn't know if i could use something like .550

 

[jasonh_86]

When my VT Stage 2 N/A cams came in, the spec sheet read ".562/.576 lift".. I went with the manley Nextek springs.

But i'm sure the NPI motor could use the VT Stage 2's without ptv issues, since it's a pi/npi cam.

But you can't go wrong with the Stage 1 from VT

 

['13_ImpactBlue_GT]

You are quite correct sir, when I first crank her up the sound is pure heaven....blubblublblubblubblubblub, I will have some vid. clips up this weekend :SNSign:

 

[98bluevert]

ok did a search and finally found this by DropTopPony and TGJ

if you still have stock 98 heads you can't use VT cams or any other PI Aftermarket cams. The stock PI cams are a direct swap and Comp/Crower make NPI Cams.

Ummm, the Comp PI cams will work in NPI heads. You will need the Crower Offset retainers and upgraded springs to run some higher lift cams in the NPI heads. You will need these for the higher lift PI Comps. I would say the ideal cam for a mild modded car would be the Comp 262AH( PI ) Cam.

So if i get aftermarket PI cams like COMP or VT's then will they work with nPI heads with offset retainers? Also if i get the 262ah or stage 1 do the springs have to be upgraded?

Anyone with more info please chime in.

 

[xmikevankuikenx]

Comp cams makes 3 different cams for the npi heads:

XE262H
XE268H
XE274H

 

[COramprat]

I installed Comp 262ah's in my NPI 96 with about 120k. Didn't swap the springs and have had no issues with valve float and now pushing 170K. Anything more than the mild cams though I would suggest valve springs. Just a thought though...the HP difference between the 262 or stage 1's and more aggressive cams is not too much...around 5-15HP depending on the set. I can live with my 25HP bunp from the 262's.

 

[Cantslowdown]

Dang thats alotta miles with those cams...Says something about 4.6s they are good motors if taken care of..

 

[TGJ]

VT Stg II cams will not work in NPI heads with just Crower Offset retainers. To run more than .545 lift cams in NPI heads requires more. .545 lift is the actual lift of Comp's off the shelf PI modular cams, just an FYI. I know they advertise .550, but if you actually check, they turn out to be .545.