cardsfan119

Hello all, I'm a long time reader, first time poster. I have a dilemma I can't seem to solve with my truck. So here goes, I bought my 1995 K1500 4.3 (VIN Z) almost 2 years ago with about 118,000 miles on. When I bought it I noticed it was running rich, but had other issues I wanted to address first. Last December, I noticed I was losing coolant and discovered I had a blown head gasket. I elected to pull the engine and just go through it to make sure no other issues were lurking. I'm glad I did because once I had it out and apart, it had some pretty good pitting on one of the cylinder walls, and a fair amount of wear on the crank bearings. (I considered doing the 5.7 swap, but as luck would have it when I was looking for a good used one in a donor truck I couldn't find one and I needed to get my truck back going.) So I sourced another 4.3 from a gut I knew. It came out of an S10 with a comparable amount of miles, however it was a VIN W engine. I was impressed with how good the engine looked inside compared to mine. As I had already ordered a gasket kit for my engine, I figured I just as well go through the donor engine while I had it on the stand. So I had the heads milled and surfaced at the local machine shop and he magna-fluxed it and put the new valve seals in. I then re-assembled the engine with the new gaskets and timing set and put all of my VIN Z components on it and re-installed it. I had a couple of issued that concerned me when I started it, so I decided to pass it off to my local guy to double check my work. One of the issues was it was still running rich, the other was the temp gauge showed it was overheating quickly, but he was able to put it on his scanner and determine this was just due to not getting the block and radiator completely refilled. (My main concern there was that I had not torqued the head bolts properly (yes, I used new head bolts) and was losing coolant again, but he confirmed my torque settings and that no coolant was getting into the oil. He lined up the timing mark to TDC and removed the #1 plug and decided to check the compression on the #1 cylinder, it was low (I don't remember exactly what he said). So he hooked an air hose onto the fitting an blew air into the cylinder to see if he could tell where it was losing compression. The air came right back out the intake manifold. So he said it just turned the engine over ever so slightly past the timing mark, the valve closed, and the compression reading was right where it should be. He asked me if the cam had been changed. It was the stock cam. I checked the O'Reilly website, and sure enough VIN Z and VIN W have different cams. Side note - the harmonic balancer, with the timing marks, on the engine came off of my VIN Z engine. The reason I did that was because the VIN W engine had a crank position sensor that my VIN Z did not have. The VIN W harmonic balancer was slightly shorter because of the reluctor plate that sat behind it on the front of the crank and I was concerned that would throw my belt alignment off (I could have left the reluctor in hindsight, but I had already replaced the timing cover). So anyway after he turns the engine a little past the timing mark and times it, he tells me to take it and drive it. That was in February, and 2500 miles ago and it's been doing fine, except for the pesky running rich problem. I have scoured these and other forums looking for a clue as to why. Nearly every sensor is new on the engine, some I broke removing others I changed throwing parts at it. Coil is new, plugs are new, wires are new. I put a different ECU in it. Rebuilt the throttle body, new injectors. Fuel return line is new and open (when I discovered this I thought I had solved it and while it did make a huge difference, didn't fix it). Fuel pump is new, filter is new. A friend suggested the distributer (it was original) was the likely culprit, replaced it last week and while again it runs way smoother, still does not appear to have solved it completely. Parts are all genuine AC Delco, except the distributor, it's a Cardone. My guy suggested with the VIN W cam, it may always run rich. I'm still perplexed though as this seems to be an issue that carried over from the previous engine. Here's my question for any engine builder on here - do I possibly need to advance the timing with the bigger cam of the VIN W? The reason I ask is, when I replaced the distributor I was careful to align it as close as I could to the old one. By ear, I seemed to be real close, but I had to run it into town to a buddy with a timing gun. It seemed to run better than it ever had. He checked the timing and adjusted it slightly and while it runs good and smooth, seems just a bit sluggish to me. (Side note - I had saved the harmonic balancer from the VIN W and compared the timing marks to my VIN Z and they were the same.) I think that's everything. I have the specs of the VIN Z and VIN w cams, such as duration and lift, but I didn't want to bore anyone with it by posting here. But if that matters I can post in a reply. Thanks for any and all help.