VT Cams installed... my opinions

chemojay

chemojay

New Member
Mar 23, 2003
278
0
0
West, TN
#1
Well I got a set of these cams back in Nov. from Tim and T&J but just finally got them in last weekend. A big pain in butt on the valve spring change out. I have the NA grind stage 1 for my 2002 GT. At first it was rough. not a good idle and not really a good run. I reset the cpu and backed off the timing adjuster to stock setting. let the car run for a bit and its running much smoother but I still think something is not right. there is a bit of hesitation now that wasn't there before. still a noticable power difference in the higher rpms but almost a drop at the lower ones. I also changed the fuel filter, spark plugs and what not when doing this. I seem to smell gas alot more now since the cam change. Its still not the best idle at all. but it has evened out. in the 1800-2300 RPM range though it almost I would describe jerks a little when just trying to mainain a constant speed. Anyone have similar results when installed their cams? I am hoping for some responces from others. It also noticably shakes the hell out of the car :lol: which is kinda cool. great sound and above 2500 rpm these cams really wake up the car. I am just a bit concered with the lower RPM performance. I see a tune by Tim down in atlanta at T&J performance in my future. maybe. Maybe thats what it needs. I am going to go ahead and change the rear end ratio to a 3.73 gear.
Thanks for all the feedback and anyone with questions on my install let me know. I was around for almost all of the install and helped my mechanic out and got my hands on it myself. I lack all the air tools and nessasary tools to do the job. ended up paying 540 install not to mention the extras. like filters, gaskets, injector cleaner. I installed Bosch platnuim 4 spark plugs maybe I picked the wrong ones. any idea please let me know here or email me at [email protected]
 

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#2
Cams are usually a trade off kind of thing. You pick up some power on the top end, but you lose power on the bottom. Generally speaking, adding duration tends to soften-up bottom end response, but add top end kick. Seems to me that this is how it has always been (Worked this way with my small block chevy powered car) addding duration will also roughen up the idle of the engine. I remember for my big block chevy (never got built) I wanted a cam that had a nice lopey idle and made good mid range power. The cam I got for that engine was an Isky cam, it had something like 235-240 duration at .50 (280 Adv. Duration), and had a lobe seperation angle of 110 (added to the lopiness, but also helped retain some of the bottom end grunt)
 
#3
Jesus said:
Cams are usually a trade off kind of thing. You pick up some power on the top end, but you lose power on the bottom. Generally speaking, adding duration tends to soften-up bottom end response, but add top end kick. Seems to me that this is how it has always been (Worked this way with my small block chevy powered car) addding duration will also roughen up the idle of the engine. I remember for my big block chevy (never got built) I wanted a cam that had a nice lopey idle and made good mid range power. The cam I got for that engine was an Isky cam, it had something like 235-240 duration at .50 (280 Adv. Duration), and had a lobe seperation angle of 110 (added to the lopiness, but also helped retain some of the bottom end grunt)
Click to expand...

i agree, MM&FF did one and said that they lost a little torque on the bottom, but like you said got alot more at the top...
 
#5
It sounds like you have the cams installed one tooth off. I would recheck the timing chains. With that grind you car should idle pretty good and there should be no loss of power in the low RPMs. Something is wrong.

Ken
 
#9
KenB said:
It sounds like you have the cams installed one tooth off. I would recheck the timing chains. With that grind you car should idle pretty good and there should be no loss of power in the low RPMs. Something is wrong.

Ken
Click to expand...
How exactly would I know that its one tooth off once I go back into the engine. BTW the check engine light never came back on this time. Decent idle now.
 
#14
These are the same symptoms I had...Get rid of the +4 plugs...I can tell you from experience that they are most likely the problem...I took mine out 2 days after the install, I fell for the slick advertising. I had the same thing happen to me. This should be your FIRST starting point!!! REMOVE THE PLUS 4'S

The gas you smell is unburned gas from the plugs not firing efficiently through the plug...

Use iridiums or copper....
 
#17
98SteedaStang said:
Comp make 3 stages of cams for the PI 4.6 right?
Click to expand...

Yes, and so far everyone that has tried them on various boards have had piston to valve clearance problems. That is with the stock heads and shortblock. If you have a built engine with reliefs in the pistons, they would probably be fine.
 
#18
nickthegenius said:
Yes, and so far everyone that has tried them on various boards have had piston to valve clearance problems. That is with the stock heads and shortblock. If you have a built engine with reliefs in the pistons, they would probably be fine.
Click to expand...
Everyone who has tried the stage III's? Or Just all the comp cams in general have the piston to valve problems?
 
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