Possible Father and Daughter project, 88 Oldsmobile Cutlass Supreme Classic Brougham

Olds 307 and 403

Active member
Oct 4, 2018
558
196
43
Melville, Saskatchewan
Well, I took the 88 for a very long drive, 225 km there and back. It ran 210 at most, around 205 most the way. Oil pressure was 36 to 40 psi with 5W30 synthetic. It is a 47 year old bottom end, so about right. It used some oil maybe a 1/4 quart, thinking it was a bit over full. I plan on using a different stick, this one fits way too tight since removing and putting the tube back in. I have many, one goes in much better, just none the right length. Going by 4 quarts in the pan and will mark. Mileage was meh at 19 mpg imperial, but not taking it easy following our Challenger GT, 60 to 70+ mph. My speedo reads about 5 mph slow according to my GPS speedo app. I drained but left the filter, only 250km on the filter and put in 4 quarts of VR1 20W50 in, guessing that the level is right. I pulled the thermostat, 195 like I thought and put what I think is a Robert Shaw 180 high flow, no temp, just a number I can't find online. My other Robert Shaw says 160, so it must be the 180 I bought. Not that 210 degrees and 40 psi max hot oil pressure at lower rpm, 1800 to 2000ish is bad, about normal for every new LS I have driven. I just want it even a couple of degrees cooler and higher psi. The trans shifted great and leaked very little fluid. Around 20 mpg isn't what I hoped but 4 mpg better than my Dakota.
 

Olds 307 and 403

Active member
Oct 4, 2018
558
196
43
Melville, Saskatchewan
Well, I was lucky the belt didn't go flying off. It actually broke the middle bracket button head. I actually added a support up top from the alternator to the intake, so it is now very solid. It now runs around 175, it never got above 190 in the 70. Even if it hits 195 in the 88 it will be fine and still a touch cooler than it was.
 
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Olds 307 and 403

Active member
Oct 4, 2018
558
196
43
Melville, Saskatchewan
It will hit 190 till the thermostat opens then 170 to 180, might be air or just the Robert Shaw high flow thermostat. Reinforcement seemed to fix the the noise and belt flopping around. This carb is super lean at idle and there may be some wear on the throttle shafts. I have had to crank the idle to over 1000 rpm in park. One minute it runs fine at 1000 rpm in park, next time, especially once warm, idles about 600 to 700 in park and needs gas not to stall once in gear. I put it around 1200 rpm which should not be necessary. I will probably open up the idle circuits and rebush the throttle shafts this winter. I will check for leaking well plugs as well, immediate hot restart usually requires flooring the pedal.