The Stovebolt Site Forums Project Journals Completed Journals 1966 Chevy C-10 Short Stepside -- Step by Step

Drove the truck home from my shop a few weeks ago. Next morning my wife helped me clean it up, it's amazing how much dirt, dust & grime can get on a vehicle that's stored indoors 100% of the time.

Test drive home was in temps in the mid 90's, speed about 50 mph max. The good news is the cooling system was doing it's job, staying at about 185/190 . The bad news is the oil pressure was just too low for comfort out on the road & at those temps. Back at the beginning of this thread I described how I got this engine. It seemed to run well & had adequate oil pressure, so I decided to run it like it was was. Wrong move on my part. What would've bee an easy job while the engine was out of the truck & up on the bench turned into a real PIA with it in the truck. Thankfully it was just a straight forward job of installing new std main & rod bearings along with a new oil pump. I could've pulled the engine from the truck in order to work on it but just couldn't bring myself to do that.

I was having two other engine related problems that needed investigating & correcting while I had it up on jack stands & disassembled. One was a very slight leak from the front timing cover seal. I had installed a new one & cleaned everything up well when I installed it, so I was curious & perplexed about why the leak. Earlier in the thread I recounted installing a cheap ebay no name Chinese intake manifold that had mis-alignned water jackets (or ports) that did not properly align with the ports in the heads. I ended up with engine coolant in the oil. I thought letting the oil drain for a few days before putting in fresh oil & filter took care of all that, along with installing a new , name brand intake manifold, of course. Turns out, there is a drain cutaway in the timing cover that allows oil to rapidly drain away from the crank seal , so oil won't puddle up against the inside of the seal. That cutaway was filled with what looked like baby poop, a thick, tan mixture of oil & water that was too thick to drain or pass through the cutaway , causing oil to puddle against the oil seal.

The other problem I needed to solve is eratic ign timing. Timing started out OK, then became more & more erratic. The timing light was showing timing jumping around as much 10 degree ATDC to 20 degrees BTBC. The mechanical problems that could cause that is too much end play in the roller cam, letting the cam move back & forth changing the relationship between the distributor drive gears. The other could be too much end play in the distributor shaft, letting the shaft move up & down & changing ign timing as it movd up or down. Since I had the timing cover off, I checked the end play of the cam. I used all Gen Vi GM parts when I installed the cam & the Gen V engine is factory machined to accept the Gen VI cam, cam retainer & single row timing chain. I didn't expect the end play to be a problem but I had to recheck it. It was perfect. The distributor OTOH, had .039 endplay, should have been about 1/2 that much (with an aluminum housing). I got a shim kit from Morroso & shimed it to .015.

Spun the engine with the plugs out to prime the oil pump. Just a couple rpms is all it needed for oil pressure to register. Finished installing plugs, engine fired right up, oil pressure looks good, no leaks, But the timing light was still showing some ign scatter. Not as bad as before, but still there. As I was turning out the shop lights preparing to pack it up for the days, the dim light under the hood allowed me to see spark arcing between both the - & the + posts on the coil to the tower of the coil (where the coil wire connects) I think my coil or plug wires might have too much resistance & causing the short.

At that point I was done for the day. Going out of town for a week. I was happy to finally find a reason for the scattered timing. I'll dig into it when we get back.