Hmm, not sure what THIS one is, but I'll post here and see what you guys can tell me.

I just removed the orignal cam for the new 355. It was a GTP 6 (235/242 .568/.592 114) and have replaced it with a Combination Motorsports SCC-224-XL 224/236 .536/.555 115) for the soon-to-return emissions testing in Connecticut.

I went to fire up the new cam for the first time and it turned right over... BUT... as it is running it runs smooth and then BAM, smooth, bam, and so on. Haven't localized the noise since I shut it down upon hearing it. Could it be valve lash? Could it be a misaligned cam? It is not a backfire, but I have to wonder if I am running a bit too rich.

I have an AFR hydra-rev which I could have removed for the new cam, heck it wasn't really needed for the GTP cam with the heavy valve springs I have. But the AFR is still there. Everything is buttoned up.

I do NOT have a new program for the new cam yet. And as it was before the engine really ran PIG RICH. I currently run SVO 42lb injectors and the PCM is set to idle at 900. I have set the idle screw on the TB a little lower for now, not that it matters.

My question is: I lined up the dots on the timing set before I yanked the previous cam, and again when the new one rolled in. Is there the possibility that they could line up at two different point in the engine rotation. I turned the engine a number of times before removing it all in the first place and it looks as though it can only line up at one point.

Right now I suspect the valve lash and will go through it again. When I did the engine the 1st time the lash was right-on and there was no noise, so I wouldn't recognize the sound now.

Any ideas for other things to check?

 

no tips yet? At the rate things are going around here today, I won't be able to play with the rockers until tonight or tomorrow anyway.

 

I'm not familiar with hydra rev, but dont you need smaller pushrods when you use it? isn't a spring in between the lifter and pushrod or something? I havn't really looked into the myself.

you are right about the lining up.

when you put the opti on, was it flush or did you "make it" flush when you torque down the bolts?

 

Opti went on with no problems. It only took me two tries to get the pin lined up correctly. Good to know about the lining up on the timing gear.


As for the hydra-rev, you don't need any different pushrods. The pushrod goes down the middle of the spring, like a valve on the heads. The way the hydra-rev kit works is this:

With the pushrods and rocker arms removed, you slide an aluminum billet bar in place against the bottom side of the head in the lifter valley. Over each pair of lifters is placed a standard keeper so they don't rotate in place. Now between the keeper and the block we have our springs. Not super heavy like valve springs, but still fairly strong. I have heard them described as "lawnmower springs." Then the pushrod is slid down the middle to the lifter and the rockers are reassembled like normal.

Its a simple kit, just not so simple to install the springs without pulling the heads. The first time around it was easy since I was putting the engine together. This time, without havig the heads off, it was a pain in the *** to put them back in.

I still haven't had time to check the valve lash. I'll see what I can do tonight.

 

good to know
always wondered, too llazy to loook up

:cheers: