Need Opinions On Stupid Big Comp Cam
04-14-2011, 12:45 PM
#1
Need Opinions On Stupid Big Comp Cam I am trying to diagnose a car prior to tuning that has a pretty big cam in it. The car is a 02 TA stock LS1 block and heads with a Procharger. Everything ran pretty good with just the procharger installed. Then this stupid big cam was installed on Comp Cams Tech Line recommendation. It is a 243/259 .624/.624 116 LSA ICL 111 so +5 advance in the cam. Comp 924 springs, still stock push rods. The pistons were not fly cut. Without us pulling the valve covers yet does anyone think we might have bent valves and or bent pushrods? The Comp Cams tech rep didn't tell him it would require fly cutting but it wasnt specifically asked either. Who thinks this cam required fly cutting???
04-14-2011, 12:51 PM
#2
Launching!
iTrader: (21)
Join Date: Apr 2006
Location: Parma, Oh
Posts: 242
Likes: 0
Received 0 Likes
on
0 Posts
The Trex is one of the largest, if not the largest cam you can put in a stock headed LS1 with some PTV clearance. Still though some people have issues. The rex is 242/248. A 243/259 I would say bent valves and pushrods at least IMO.
04-14-2011, 01:26 PM
#5
Launching!
iTrader: (21)
Join Date: Apr 2006
Location: Parma, Oh
Posts: 242
Likes: 0
Received 0 Likes
on
0 Posts
Bummer... I would start by pulling all the bent pushrods and posting pics. Hopefully all the pushrods just bent and there were not PTV kisses. Did you guys just crank the motor or run it? What sounds did it make? Pull the pushrods and fill the cylinders with air and see if it holds compression. Keep us updated.
04-14-2011, 01:40 PM
#6
The car was just brought to me for tuning. The customer started the car after he installed the cam. Right now I am dealing with really screwed up scanner data. With the injectors scaled way smaller than what they actually are, LTFTs disabled, I'm seeing STFTs 50% at 2000 rpm, and O2 sensors staying below 350 mv. I'm guessing a lot of air in the exhaust with bent exhaust valves. I finally decided this is a mechanical issue and stopped hacking the tune to get the fuel trims down. We did smoke test the intake tract and found no leaks that might account for high fuel trims.
Right now the customer is wondering why Comp would even recommend a cam like this for his application. (my thoughts too) He called them twice and two different Comp reps recommended this cam. Like I said this is a stock cube stock head LS1.
Right now the customer is wondering why Comp would even recommend a cam like this for his application. (my thoughts too) He called them twice and two different Comp reps recommended this cam. Like I said this is a stock cube stock head LS1.
04-14-2011, 02:14 PM
#7
10 Second Club
iTrader: (27)
Join Date: Mar 2009
Location: Kissimmee, FL / Vienna, VA
Posts: 810
Likes: 0
Received 1 Like
on
1 Post
I don't find that hard to believe considering I had the same thing happen to me. Luckily, I didn't go with their gigantic recommendation and when I specifically asked them about flycutting they said I needed to check regardless of what cam I installed. I've called them a couple of times over the years and they don't seem to get close to what other custom cam grinders come up with. However, I'm sure it's hard to keep up with every application.
Trending Topics
04-14-2011, 04:14 PM
#9
I just found out he used Comp 1.8 roller rockers too. 
He called Comp Tech and they told him he couldn't use those with that cam and all he had to do was put his stock rockers back on and everything would be OK. 
He took the car back home on a trailer and is going to pull the rockers off and check the push rods and valve stem heights.
He called Comp Tech and they told him he couldn't use those with that cam and all he had to do was put his stock rockers back on and everything would be OK. He took the car back home on a trailer and is going to pull the rockers off and check the push rods and valve stem heights.
04-14-2011, 04:30 PM
#10
Just for your info, I ran a Trickflow cam (238/242 .595.595 112 lsa) with .040" milled off my 241s.... ran good, but when I pulled my heads off again you could see where the valves just touched the pistons, but luckily didn't bend any valves.
04-15-2011, 01:49 PM
#11
I was just told that after disassembly that there are no bent valves and no bent pushrods. The no bent valves was verified by pressurizing the cylinders. The stock rockers went back on it along with hardened 7.4 pushrods and I will see the car again Tuesday to try and finish the tune. This is really hard to believe.
04-15-2011, 04:20 PM
#17
actually, it probably runs pretty dam good in a stock heads ls1...but it probably wont start pulling until about 4000rpm's
you can go quite a bit larger on the exhaust on ls1 heads without any downsides..
that is a tight squeeze cam, but it should barely fit... probably a bit less than the recommended .80/.100 clearance
with a good set of heads, a big intake, and supporting suspension and rearend, he could be deep 11's on motor with that cam.. .especially if its an automatic with a 4k ish stall
04-16-2011, 10:58 AM
#18
comp cams advise for the loss...I still don't believe there was no contact unless the motor was not taken in the upper rpms...that biach is going to be really close...why didn't he measure since he had the chance...so if a valve seals it is not bent? 
you guys have fun with this one, let us know how it turns out and how long it lasts...
you guys have fun with this one, let us know how it turns out and how long it lasts...
04-16-2011, 03:00 PM
#19
Im not expert, but i find it hard to believe nothing is bent! That is a BIG damn cam, and with 1.8s its THAT much worse!
So it seems that they just pulled the rockers/pushrods then pressurized the cylinders? If it were me (well, i sure as **** wouldnt be running that cam) but if it were me, id pull the heads and check the tops of the pistons!! The valves may not be bent enough to hang open, but they may be bent enough to wreck some valve guides.
So it seems that they just pulled the rockers/pushrods then pressurized the cylinders? If it were me (well, i sure as **** wouldnt be running that cam) but if it were me, id pull the heads and check the tops of the pistons!! The valves may not be bent enough to hang open, but they may be bent enough to wreck some valve guides.
04-16-2011, 05:52 PM
#20
We looked in the #3 cylinder last Thursday with a Snap On scope/camera tool and couldn't see any marks in the top of that piston at that time. There was so much black soot from it running so bad that it was hard to see real clear though. Everything about this situation just didn't/doesn't make sense. That was when we started thinking that the Comp roller rockers maybe being adjusted wrong maybe why the car was running so bad. I will update this thread after I see the car again this Tuesday. Everything will be the same except the stock rockers and hardened pushrods will be on it. The customer did say that the only thing that looked wrong when they removed the Comp rockers was that you could see where the stock pushrods were rubbing on the guide plates that were installed with the Comp rockers.