Monday, September 19, 2016

Rebuilding and Upgrading the Corvette L-48 Engine | Part 6

Took my Vette out yesterday (Sunday) for a longer test drive of approximately 30 miles.

The car performed beautifully although the idle seems to be a bit on the high side for my taste. That, of course, can be easily corrected so it's not a big deal.

Since I was told by Mark at Sunrise Automotive not to exceed 3000 rpm, I drove the car gently making sure the tach did not go over 2500 rpm. And everything was fine. That is until I was about a mile from home.

As I came to a stop behind another car at a traffic light, I thought that the car in front of me was making a lot of noise. But, as I made the right-hand turn to come home, I realized it was my car making the racket, which really sounded like a lifter gone bad.

At the next traffic light I also noticed the car was running very rough and threatening to stall and die, so I made sure it kept running since I was less than a 1/4 mile from my house.

I finally made it home and parked it in the garage. I also opened the hood to allow it to cool off a bit faster.

After a few hours, I walked back out to the garage to find a puddle of fluid under the car. It appeared to be coolant so I checked the radiator only to find out it was pretty much full. The radiator overflow tank also had the normal amount of fluid so not sure what to make of it.

I texted Mark, owner of Sunrise Automotive, and he replied not to worry and that he would have Billy, one of his mechanics, stop by my house tomorrow to assess the issue.

This morning, I decided to have a better look under the hood and found at least one coolant hose that had a hole in it.




I trimmed the hose about an inch since there was enough of it to do so. I then reinstalled it and secured the clamp properly in order to avoid another failure. I also replaced a clamp they had used for the radiator overflow hose since it kept the radiator cap from seating correctly.

Plus I checked the oil level which was fine, so I then removed the valve covers in order to inspect the rockers, hoping one of then would be the culprit.


No such luck as all of them seemed to be okay. Well, I have to admit that my "inspection" was a waste of time since I did not bump the motor in order to check things properly.

By mid-morning, Billy arrived and after he looked things over—I had left the valve covers off—he said that we should button it up so we could start it. After doing so, I cranked the car and it struggled a bit but it finally started. It ran a bit better than yesterday but still very noisy. So Billy used a long screwdriver in order to listen to the motor to try to pinpoint which lifter was making all the racket. After a minute or so, he said he thinks he is pretty sure it is one of the front lifters on the left side of the motor.

Since I am not one to leave things alone for long, after lunch I decided to see if I could diagnose the problem a little more specifically, so I removed the valve covers yet again, but this time I bumped the engine a few times while checking the rockers.

After a few tries, this is what I found ...


So Billy came back after work and helped me test all the rockers and set the lash. After that, I reinstalled the valve covers and air cleaner and started the Corvette.

Happy to report that it's back to normal and sounds great and healthy again.

Just a small hiccup which happens when you rebuild things. After the 1,000-mile break-in period, I will bring it back to Sunrise Automotive for an oil change and a thorough check out.

Thanks for following my 1976 Corvette blog, and stay tuned for Part 7.