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Choosing the right cam

Steven Monteith

Steven Monteith

New member
I am in the midst of fixing up my 2000 grand prix gt. I want to do a Cam but not sure which one to go with. Any suggestions with what I should go with?
 


is this just based off of sound? because even with a cam your car is still not going to make much power being n/a.
 
I decided to go the top swap route and my main question is should i buy an m90 used or rebuilt? Considering im a full time college student and trying to save money but i want to buy good quality.
 
Something off of craigslist...must be a GenIII M90 and look like this:

Eaton-M90-GM-GenIII-1.JPG


And not like the first gen ones...

1221670257.jpg


Shouldn't pay more than a hundred bucks for one either...because you can get them for like 80~ at your local junkyard.

Only thing they should need is a coupler/oil change...maybe the needle bearings re-greased and a nice outlet port...but that's it, an afternoon's worth of work it should be back into tip top shape.
 
Thanks for the pics. So those are the only things to worry about with maintenance? How can the porting be done? And how about the rest of the parts needed for the top swap, is it safe to buy them all used or some new?
 
It's up to you...you can source out SeriesII 3800 parts and have them cleaned up and looking brand new...for about ~$500 or so...replacing tired or worn valve springs as well...get some G8 valve springs/retainers (L76) from a GM dealer...pretty cheap too...that'll help out on the valvetrain side.
 


I'm going to do a cam as well at the same time, what cams do you recommend to make a lot of power, but at the same time not have to do too much work to the engine?
 
GT2.

Or an Abbott Racing grind.

You'll still need a new timing chain/dampner...and at least Crow 105 Valve Springs.
 
Thanks for the input. I found the top swap parts on here, but now i just need injectors. I want to be able to run small pullies, what do i need to run a small pullie? bigger injectors?
 


might need bigger injectors at that point. and when you do that might as well go for the 65ers and go E85. While you have the heads off for the topswap it would be real easy to send them to a machine shop to be able to run a huge cam. I wish i would have.
 
JoRo-I know nothing about E85. Whats the cost? how do you convert? educate me if you would. Do you have a cam right now? I was thinking about the XP cam
 
I dont have a cam right now, but the xp would be a good choice as well. I hear its the largest cam you can run on stock heads.
E85 all you need is someone who can tune it for you and bigger injectors, probably a wideband too, but you'll need one anyway if youre going that far. And then maybe a fuel pump rewire and high flow filter. E85 is like race gas and boosted cars love it because it demands more fuel per unit of air so the air gets cooled by the fuel.
 
Steven Monteith said:
So with HAI, headers, ported throttle body, ported supercharger, cam, I can run a 3.25" pulley with stock injectors?
Click to expand...

Maybe on a low compression setup...with a ported TB/blower/LIM, intake/headers-exhaust/other babbles and bolt-ons/cam/springs/custom wideband tune...you MIGHT get away with a 3.4"...maybe. I'd also get 42.5lb injectors just because...they'll allow that leway incase you need the extra fuel vs. the stock GTP injectors which are...33lb?

JoRoW99 said:
might need bigger injectors at that point. and when you do that might as well go for the 65ers and go E85. While you have the heads off for the topswap it would be real easy to send them to a machine shop to be able to run a huge cam. I wish i would have.
Click to expand...

Milling the valve guides .100" is all you need to do to have clearance for up to .600 lift. XP cam only has....520~/530~ ish lift on the intake/exhaust. Ported heads make up for a pretty decent gain...and really help at killing off knock. Then you could safely run that 3.4" with an XP/Ported Heads/Full Exhaust and a tune...I'm sure.

Steven Monteith said:
JoRo-I know nothing about E85. Whats the cost? how do you convert? educate me if you would. Do you have a cam right now? I was thinking about the XP cam
Click to expand...

E85 is cheaper than premium most places...you do get worse MPG's with it...but it is the equivalent of running 113~ octane. You would however need a fuel pump re-wire kit, a better fuel pump, and larger injectors...like said...60's or even 80's depending on the setup. 60's with E85 with the XP and ported heads would...hell, probably allow you to run at LEAST a 2.8" pulley...maybe even a 2.6", but then you're at the ragged edge of pooping the transmisssion's guts out all over the place after a few WOT runs.

JoRoW99 said:
I dont have a cam right now, but the xp would be a good choice as well. I hear its the largest cam you can run on stock heads.
Click to expand...

Correct, the XP is the largest cam available from a vendor that you can run on stock heads...with THAT SAID...it doesn't mean you could have a custom one ground to be a little larger than the XP to beat that if you're afraid of diving into taking the heads to a machine shop. I'd also suggest the Intense-Racing S1X cam...it is more a low-end, midrange cam...vs. the XP...which is a little more top end based.

I ran an XP on my lower compression motor back in '08...it was my first cam...I loved it. Put over 40k on it driving it daily, in all weather conditions...never had a starting/stalling issue either. I ran a 3.4"/XP/Headers and other small crap...car ran low 13's. Put on a larger TB setup, 3.25", and had it re-tuned...it raped :D
 
Thanks for the input, I'll go with the 42.5 injectors. I was planning on taking the heads to the machine shop anyways. Since I'm doing that I was thinking of possibly the the XPZ cam or Intense stage 2 cam. That is where my road block is. What is the difference in performance between the XPZ and IS2 cam???
Thats a nice time! I really want to get into the 13's.
Will an L36 lower intake manifold gasket work on the L67 lower intake manifold?
 


Nope, the gasket's are manifold specific.

But you can get the aluminum metal ones off of Amazon pretty decently priced...think 30-40 bucks.

The IS2 isn't a great cam...seen the results from a few people a couple years back...didn't impress. If you want a big lumpy cam...I'd just clearance the heads for .600 lift...and run 1.7 or 1.8 rockers on an XP or S1X cam...factory rockers are 1.6 ratio so that'll give you a decent bump in lift that you'd be wanting without the hastle of having to deal with different pushrods like you do with the XPZ...if I remember right.

It also depends on your budget, the goals you have for the car, and the driveability of it.

My cam setup pulled like a freight train after 4k...you could feel it come into the powerband, but the downside was the driveability...it didn't like putting around town at low speeds...this was my idle quality and the build list is in the info of the video.

Big Cam GTP Idle & Rev - YouTube
GTP Big Cam Idle/Rev - YouTube
 
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