Road Testing, Problems and Troublestooting

(These notes revised, 1/30/2018.)

After four months of planning, searching for parts, my own maintenance on the car, and weeks of work by the two Olsen shops, mechanic Ed Olsen had about finished the re-install of the engine.  On Feb. 14, he took the car for its first road test.  "It ran rough and didn't have much power," he said, adding that he never drove the car before removing its engine. His excuse for not knowing how it was supposed to feel!  Why didn't he take it for a drive beforehand?  I think he was negligent in that regard.  Getting an impression of performance before the removal sounds to me like a no-brainer!  It should have been common sense to me too, but I'm not the mechanic.

After the test run a leak showed up at the rear of the engine.  I took it on myself to search the slantsix.org engine forum for any posts on oil leaks after a rebuild. I found one that said the rebuild included a cam grind by Oregon Cam, number "2106", the same grind done on my cam.  But the leak had nothing to do with the cam grind!  Just a coincidence.  With the post was a youtube video showing the leak.  Ed agreed it looked the same. The post read, "First an oil leak at the back on the pan.  This video was taken with engine at 1500 rpm's".  Whatever was the source of the leak in the video at slantsix.org, my leak was caused by a defective rear crank seal.  The remedy included dropping the transmission to replace the seal.  The accompanying picture shows a smear of RTV rein-forcing the fix.  Click on the picture to see the same area of the engine before the rebuild.

The picture to the right shows car's original flexplate: p/n 2801 745, "Plate, torque converter drive".  If bent, the plate will cause vibrations due to out-of-center condition between crankshaft and torque converter, creating harmonic imbalance, a possibility considered by machinist Charlie Olsen after he drove the car on a short test run.  A new flexplate was ordered in case it would be needed.  No problem was found with the original flexplate, which was replaced anyway with the new one.  See picture below showing engine compartment without the motor.  The cylindrical projection in the center of the torque con-verter is its "pilot".  Charlie fabricated a sleeve, .007 thick, to tighten fit of pilot into the female connection at the end of the crankshaft. The crank connection is visible dead-center in the flexplate.  Also shown in this picture, new thermal wrap running from exhaust pipe flange to just ahead of catalytic converter.

With the car back on the lift, Olsen found two other problems.  One, the rear U-joint was worn out and had to be replaced; and, two, the insulation on the speedometer cable is worn through at one place, causing a slight leak of transmission fluid.  See picture at left margin below.  I found a NOS Mopar cable, part number 3593590, for sale on ebay.  As of January 2018, it hasn't been put in.  Olsen's shop assistant, John Botkus, wrapped the length of the worn cable with electrical tape.  It's doing fine to date (1/24/2018).

I got to do my first road test about a week later.  I didn't need 60 miles to confirm Olsen's first impression.  Idling and acceleration were rough, with severe vibration felt on the floor, in the steering wheel and in the seat.  The hood orna-ment and hood outline shook like a dragster. The speedo needle flickered.  Acceleration, weak; engine seemed loud, which was improved by lowering idle speed.  At 60 mph there is a whirring noise that Olsen blames on fan noise.  He recommended going with a clutch fan, but that didn't exactly sound like a fix for the noise that had never been noticed before the rebuild.  I paid Olsen's bill for work to date, including addition charges for dropping the transmission to fix the oil leak, on Feb. 20th.

In a second phase of adjustments, Ed replaced the NOS Mopar distributor and Standard Blue Streak cap and rotor with my original Mopar distributor, and a new brown Mopar cap and rotor.  He initiated work on the transmission mount, including modification of a new mount using part of the old mount.  Will describe my second test drive and my impressions.  As of my third and fourth trips behind the wheel, the ride seems steadier, but there is still vibration, not as bad.  It's felt in the steering wheel.  Acceleration from a standing start is still slow and there's still the whirring noise.  To correct the vibration and the noise, Ed recommended softer subframe isolators and a fan clutch.  But the car didn't have a vibration problem before the rebuild, and there was never anything like the noise.  Andy Wittenborn recommended keeping the hard isolators.  Before the carb rebuild, hesitation and stalling was common.  That is no longer happening but the car was still kind of slow to move from a standing start, and at noticeably higher rpm than I remember from before the rebuild.

Through September, I was not happy with the car's performance.  Troublesome vibrations and noise continued despite much troubleshooting and tweaking.  Finally, I was led to question our initial tuning and I checked out the 1977 shop manual instructions.  Valve lash is recommended to be set at .010 intake and .020 exhaust with the engine running and hot.  That was not how we did it; we followed the cam shop's recommendation of .015 intake and exhaust.  Two Slant Six veterans, Andy Wittenborn again, and Steve Unger, disputed that, so I decided to retune.  Adjusting valves with the engine running and hot was not something Ed Olsen wanted to try.    At a Mopar event at Englishtown, I met Dan Juhasz, operator of a shop in Cranford, New Jersey, Accurate Automotive, who had prior experience with it.  At his shop, Dan did the valve adjustment and went through standard checks for vacuum leaks.  He found cylinder compression to be normal at 170, 170, 170, 165, 175, 175.  His reading for manifold vacuum was in the range 15-16 HgIn, with an unsteady gauge needle; which he thought might indicate a problem with the machining of the block, or with the valves.  He said he would have considered a reading in the range 18-20, with the needle steady, as representing a "healthy engine."  He found ignition timing to be set in a range of 15°-17° which he didn't like either.

Inspecting the car's undercarriage for possible faults contributing to the vibration problem, Dan found movement on the driveshaft at the rear U-joint.  The car's original U-joint had been broken and was replaced by Olsen (see above), but here it was broken again.  Damage appears in red circle in the accompanying picture.  Click to view a picture of the newest U-joint now in the end of the driveshaft.  It had been a productive visit to Dan's shop, and I drove home feeling the car was running smoother. We hadn't done anything about the ignition timing, manifold vacuum, or the U-joint.  In following days, the U-joint was replaced at Olsen's shop (Sept. 28). The same day, I road-tested the car driving a 200-mile round-trip north along Palisades Parkway and Route 9W.  The car is driving smoother, though I think I'll wait for more mileage before I declare the vibration situation resolved.

Transmission mount parts, counterweight bracket and counterweight.  Click on picture to open window ac-cessing set of pictures showing the car's crossmember and trans mount components, stepping through Ed Olsen's modification of the mount.

Thanks for looking.  For info, email: e13gene@gmail.com.