I read from several sources that the 4l80e has clearance issues with most headers. Forum member MDPOTTER also mentioned this in his build thread where he used the same headers that I plan to use. So, I was expecting some issues here. First thing to do mate the transmission to the engine.
The headers that are chose are the Speed Engineering 25-1021. These are polished stainless shorty headers made specifically for C10s with LS conversion. These have to be the nicest, most affordable, best looking headers out there. Lots of great reviews made this purchase a no brainer. V-bands to boot!
As expected, there are definitely clearance issues. The headers by themselves fit fine. When you try to add the v-bands and collectors, that is where the fun begins. The clearance is so bad on the driver side that I couldn't tighten the header bolt all the way. I marked the areas I need to trim for minimum clearance and separated the transmission from the engine.
Before I started grinding, I decided to research this one last time. The more I looked, the more I could see that this is not just a C10 issue. I found several places where people are trimming to maximum clearance. My original thought was trimming a little at a time. Then, the thought of taking the engine on and off the stand to do this a bunch of times turned my stomach. So, maximum clearance it is.
Time to grind...
Time to check progress. Glad I decided to go max clearance. I can fit a small dog between there now.
Last thing to do was trim the inspection cover to match the transmission. I couldn't exactly match the passenger side. If I did, it would expose the starter gear and the flexplate. Since I bought the transmission new, I didn't have an inspection cover. I decided to buy a new GM part. After the trim, everything fit perfect. Back on the engine stand, for now...
