72 TA : New Project

[njsteve]

You're all quite welcome. [img]<<GRAEMLIN_URL>>/beers.gif[/img]

As is the curse of every project, this one is never done. I still have bugs to get out. After the 200 miles I put on her this weekend, I found out I have an out of balance wheel. I need to find the best four of the eight honeycombs I have so the car rolls without that 55 mph jiggle.

And the darn a/c compressor sprays oil around the engine compartment. What is it with the GM A6 compressors? In 30 years of buying new, not reman compressors for the cars I have, I've only bought one compressor that didn't leak oil. And that's the one in our '75 Firebird, which has a dirty original engine compartment that doesn't need a clean compressor.

[RPOLS3]

If you get the A/C compressor thing sorted out let me know as I have been fighting that for 23 years on the Chevelle as well.

Jake

[njsteve]

I think it was dual designed as an A/C compressor and a front mounted rust-proofing, oil dispenser, kinda like the V75 Liquid Tire Chain, trunk-mounted traction compound dispenser that was available on 69 Camaros.
[img]<<GRAEMLIN_URL>>/burnout.gif[/img]

[Verne_Frantz]

I think you're right Steve; I've never seen a '60s or early '70s compressor that didn't spew out oil from the front seal. I changed THREE of them on my '63 and they all did it! [img]<<GRAEMLIN_URL>>/rolleyes.gif[/img] Still have wet hood insulation and a slimy inner fender. [img]<<GRAEMLIN_URL>>/dunno.gif[/img]

Verne [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

[njsteve]

Spent last night at my buddy's garage dismounting all eight honeycomb rims from the four radials and four Polyglasses. We found the best, non-wobbliest rims and mounted the radials on them. Those honeycomb rims are extrememly hard to balance since a normal balancer that centers a rim with a steel cone, won't work with urethane face honeycombs. The problem is that the center portion of the urethane face of the honeycomb is molded around a steel cone-shaped, support that is not set in any particular spot on the rim. As a result, the center opening on a honeycomb is not concentrically aligned with the steel portion of the rim.

We used his balancer to check each rim for lateral curb damage but when you tried to set the mounted rim on the balancer to balance the wheel assembly for out-of-round, it was like watching a merry-go-round horse. Luckily he had a friend at a muffler shop who had a different wheel balancer that had a retaining hub with the five centering posts that mounted the wheel by the lug holes, instead of the center hole. We did a static and dynamic balance that used the regular hammer-on weights on the inside edge of the rim and then mini, stick-on weights on the internal area near the center of the rim, on the back side.

Here's a version of the balancer contraption for lug-centric wheels that don't have a concentric center hub.



Worked like a charm. The car cruises up to 80 mph with no jiggles, vibrations, or rumbles. It rides like a Mercedes now. Kinda scary compared to the teeth chattering Polyglasses.

BTW, those heavy, repro Polyglasses were pretty much unbalance-able on the other four rims, so we just mounted them on the rims for show use only. When a balancing machine says you have to add the equivilent of a Porterhouse steak (16 oz) to the outside of the wheel to get it to balance, that's a little too much for me.

[njsteve]

Tuning question today. What's your opinion on how the plugs are burning. Too lean or just right? Slight tan on the electrode, pure white on the insulators. Currently running a tank of Shell premium after using up last week's tank of Sunoco plus four gallons of unleaded Cam2 100 octane.

[napa68]

Just my .02. I'd like to see a little more color there. Is that just from cruising around or is there some recent power runs on that?

[njsteve]

About 300 miles of mixed driving - highway speeds and local traffic. Engine temp running around 175 degrees even with the recently hot weather.

[VintageMusclecar]

Looks like those plugs are running a little hot. Considering this is just from &quot;normal&quot; driving, the heat line looks like it is pretty far past the bend on the ground electrode, and are there tiny little black specs on the porcelain?

What heat range are they?

Compression ratio?

Where's the timing at, and have you heard any audible signs of detonation? (Sorry for all the questions, but Pontiacs are known to be finicky about their tune)

Eric

[njsteve]

No specks on porcelain. Stock compression of 8.5 to 1. They are the stock heat range 2869 platinums. What would a colder heat range be with NGKs? No detonation, even with 91 octane. Initial timing at 12 before TDC. Total timing around 36 degrees if I recall correctly. Has a minor nosing over/power loss at around 5000 rpm.