Running Rich Please Help!
Thread Starter
Racer
Joined: May 2007
Posts: 338
Likes: 0
From: London KY
Running Rich Please Help!
I have a 1998 c5. I just built a 383ci with trickflow 215 heads and a vrx5 cam from vengeance racing. Everything went together and ran great for about 1000 miles then I started breaking rocker arms. I found out the exhaust pushrods were too long so I went with .100 shorter pushrods on the exhaust. I am running comp cams promagnum rockers so they are adjustable. I can adjust the rockers to zero lash and the car acts like there is a valve being held open. I have been through them about 10 times to make sure they weren't too tight. All the primarys on the headers glow red the car backfires on decel and between shifts and is running warm. It used to run about 180 to 184. Now it is running 207 to 210 in traffic and cools down to about 184 when driving. I have checked the rockers to be sure there was no contact with the retainer, checked the o2 fuse, and replaced the o2s. It was running great til the last rocker broke and I wne twith shorter pushrods and it started all these problems. Can someone please help me out. I am so frustrated with this thing right now.
Thanks
Thanks
Thread Starter
Racer
Joined: May 2007
Posts: 338
Likes: 0
From: London KY
The rockers are at zero lash. Mike at TEA said they need preload. I ran the rockers really loose and broke one of them. But when they were loose i didnt have the heat problem but it didn't have any power.
Burning Brakes
Joined: Apr 2009
Posts: 946
Likes: 2
Yeah the lifters need preload or you're not opening the valves all the way.
Put a cylinder at TDC and take a look at both valve stems (from the top staring straight down) -- but make sure you are at TDC and not splitting the valves. If the arm tip is around the middle or slightly behind (say up to 3/4 of the way to the back of the valve) your pushrods are the right length. If they are farther back than 3/4's the rods are too short. Too far towards the front and the rods are too long.
Put a cylinder at TDC and take a look at both valve stems (from the top staring straight down) -- but make sure you are at TDC and not splitting the valves. If the arm tip is around the middle or slightly behind (say up to 3/4 of the way to the back of the valve) your pushrods are the right length. If they are farther back than 3/4's the rods are too short. Too far towards the front and the rods are too long.
Thread Starter
Racer
Joined: May 2007
Posts: 338
Likes: 0
From: London KY
I took a marker and colored the tip of the valve and readjusted the rocker. Turned the engine over several times and that is how I found out I needed shorter pushrods on the exhaust. I intalled the shorter pushrods and did the test again. The intake and exhaust are both running the same now. I still don't understand why the car is all of the sudden running rich as hell when I installed shorter pushrods and a new rocker. Like I said I can back off the rockers and the richness goes away but the rockers are too lose and the power is gone. I can tighten them up to zero lash and its too rich.
