This saturday I set my self to do the differential lub change, bought the 80-90 oil, the posi additive and the grease gun to remove and put the oil... so lifted the car and first challenge was removing that square shape head plug the diff has...I did have the rigth tube so I tried diferent size and the 18mm tube fitted just rigth...turned and It went of smooth...Well for me..lately all the work gets stuck because of a rusted bolt, tight space..but this one came out rigth. I removed the old oil.. it came out 1.2 quarts...and I put in 4 oz of the posi lube and 1.8 quarts of new oil until it started dripping through the plug hole.....put the plug back turned the wheels, I also checked the wheels movements and no noticeable play. Went for a test drive...everything ok.. no new noise and old noises still there but just trying to soruce them out....While trying to find noises while driving I put my hand on the rear wheel well were the seat belts retractable mechanism attaches to the body (to feel any vibrations)..and voila I found a 17mm I lost inside the car 3 month ago when doing the carpet installation I remember by then having moved the carpet to search the tube and didn´t find it....
sunday I hitted the road to visit a friend, it was a 60miles round trip, clear higway so I beat up the car a little, man it has plenty of power in the high rpm!!! aroung 110 mph you step on it in it climbs real fast to 120-130-140 and so...I looked the rpm but no I can´t recall how many for the speed..will take notes next time.....
Back home I waited the engine to cool down and check the spark plugs, this is how they look after the run:








first picture has flash thats why its very different from the rest.. all the spark looked much the same

some were loose I wired brushed them and installed them back....
to much work fo rthis weekend and It all went smooth...
PLans for the next weekend unmount the headers and paint them. I will use flat silver ultra high temp paint.....
see ya

 

140? as in MPH? with a stock 74? god bless ya....

 

yep... at least thats whats the needle point. no gps so my guess its: it could be less.. Its a 1973... rebuilt 12 ago .20 overbore and some goodies but by that time I was clueless about engines. It has headers, performer intake and carb, petronix ingnition, msd 6al box etc..ah and 3.70 rear end....

 

If you were doing 140 mph with a 3.70 rear gear that must be quite an engine you've got there because that works out to 6,500 rpm (with 27 inch tire dia) or 6,700 rpm with 26 inch tires.

 

That is pretty fast for a non OD car. Turning that kind of rpm with not to hot of an engine I would kind of doubt it. And you said it was still climbing? That just seems a little far out.

 

Actually that´s my doubt as the engine would turn in the 5500 when hitting 140mph....or so..never past 6k as the rev limiter has the 6k pill...I´ll try to gps the speed this week end....my tires are 225-70-15...

 

well i did run with the gps this week end and the difference between it and the speedos is around 10 % more in the speedos...
120 mph on the speedos was around 108 on gps.. some traffic on the hw i topped 127mph @ 5400-5500 rpm....speedo bounced around 140 mph... quite a difference I guess....