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

Olds 307 and 403

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Oct 4, 2018
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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

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Oct 4, 2018
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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

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Oct 4, 2018
616
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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.
 

Olds 307 and 403

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Oct 4, 2018
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Melville, Saskatchewan
Well, I plan on swapping Qjets between the 88 and my 70S tonight. Simple except running electric choke on the 70S and hot air on the 88. Mainly because my Daughter is driving the 88 and I am driving the 70S. Having a 1200 rpm idle in park is ridiculous. Of course sometimes it is 1000 rpm or less, almost positive the primary shaft bushings are wasted. Honestly these cars are very close in performance. The Everyday Performance tuned Qjet, 214/214 can and 2300 stall make it a close race despite 2.78 vs 3.42 gears. I am betting this swap will give the 88 a good advantage. I plan on getting a bushing kit, the slotted metric mixture screws and the high performance kit from Cliff Ruggles. I will also do the idle circuit mods, this carb is probably even more restrictive than the late 70's carbs which are all ready super lean. I am looking at about $150 US, $209 Canadian.
 

Olds 307 and 403

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Oct 4, 2018
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Melville, Saskatchewan
I did the swap, the performance is about the same. For some reason the flexplate is contacting the plastic cover more now under full throttle, sounds like a blower. What a difference the cam makes for the idle screw setting. I turn the mixture screws in one turn and the APT another 1/2 turn and turned up the throttle screw maybe an 1/8 of a turn on the custom modified by Everyday Performance 76 403 800 cfm carb. The idle seamed high and it was, it was 500 rpm high with the choke fully open. I set it from 1500 to 1000 in park, maybe 750 in gear. Now the 83 Canadian Olds 307 800 cfm carb, same thing, except the opposite I had to crank up the idle screw up about 500 rpm. I have the idle screws pretty much all the way out. The exhaust stinks on this carb, maybe it is just super lean at idle. I seem to remember the last 83 307 carb I ran was passable at idle but was stupid lean at part throttle, a bad stumble. It is possible some played with the APT. I also swapped choke housings as I had blocked off the hot air port on the 76 carb but looks like I removed the blockage I was in the carb, still switched them. I had the choke on about the maximum setting on 83 carb for hot air where it would have maximum spring tension and still fully come off. I have the electric choke set fairly tight as well. So hot air still on the 88 and electric on the 70S. I also moved over the rear choke pull off onto the 76 carb for the 88. I actually have a canister Accel coil mounted on the 70S where that pull off goes. Funny part is the 83 has no big vent tube for a charcoal canister, so I stuck a fuel filter in the end of my charcoal canister on my 88 and a fuel filter and hose on the 70S, not necessary on either now. Hopefully the choke doesn't act up on the 76 carb and stick again, going to do a cold start on it today to test it out.
 

Olds 307 and 403

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Oct 4, 2018
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Melville, Saskatchewan
I ended stealing all the choke parts off the 260 Dualjet, should have done it awhile ago. The 76 parts were sticking again without the washer. The Dualjet parts move as they should, a morning run will tell if it is working properly.
 

Olds 307 and 403

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Oct 4, 2018
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Melville, Saskatchewan
Choke operated as it should, had to set down the fast idle down this morning, at 1500. Will see how it starts tomorrow morning and runs. Actually kicked down from the fast idle blipping the throttle, a good sign.
 

Olds 307 and 403

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Oct 4, 2018
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Melville, Saskatchewan
I think this carb is tuned about perfect. One tap of the gas cold starts it and one tap to bring down the 1300 rpm fast idle to around 950, 1000 rpm when fully warm in park. I set the air door slightly tighter, it helped with the full throttle bog, I may go slightly more.
 

Olds 307 and 403

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Oct 4, 2018
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Melville, Saskatchewan
Well, the pinion nut backed off again on my 88. My daughter noticed a strange gear grinding noise just as she came back into town, said it was fine till then. I take it for a small drive, a slight noise coming from the rear over bumps. I saw a dripping at the pinion seal. Checked the level, still full. The pinion I can move. This is the second time this has happened. I staked the pinion nut, obviously not well enough. I will try some mid strength Locktite.
 

Olds 307 and 403

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Oct 4, 2018
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Melville, Saskatchewan
Well, the pinion seal came in for the 88, geez $22 later. Remove the straps and easy spin off the pinion nut by hand. I removed the yoke and changed the seal. I hammered it the nut with my impact to make sure the bearing fully seated. I cleaned up the threads with carb then brake cleaner after brake taking the nut right off. I impact till it just touches, perfect torque according to my torque wrench with permanent thread locker on the threads. Put a liter of 75W140 to top it up. I bag the piss out of it, all good
 

Olds 307 and 403

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Oct 4, 2018
616
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Melville, Saskatchewan
Last night I went from getting a ride in a 2017 Mustang GT convertible 5L 6spd with 3" aftermarket exhaust to the Burnout machine. Ironically it doesn't burn out very easy but it is no slouch. Yes, the GT is way quicker but not as night and day as you would imagine. Two totally different V8 motors with totally different characteristics. That 5L has good torque for its displacement but is obviously designed for high rpm performance, it just keeps pulling. The bone stock inside 73 8 to 1 peanut cam Olds 350 with a custom tuned 800 cfm Qjet, Sanderson shorties and 2.5" X pipe exhaust performs. Yes it has a 2004R with a bigger boost valve but 4200 rpm shift points and stock stall, maybe 1900 along with 3.42 and fairly tall 26.3" tires. By the way, I found a poor man's supercharger. Buy one of the universal plastic torque converter covers. They fit so tight that under hard throttle only, with all that low end twist, the flywheel contacts the cover, seriously sounds like a supercharger winding up. It adds to the driving experience.
 
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Olds 307 and 403

Active member
Oct 4, 2018
616
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Melville, Saskatchewan
The car runs great, runs hard for what it is and earning its name. There is just one issue the throttle is sticking after WOT runs. Not every time but too often. I am running the factory Dualjet dual return spring bracket. I wonder if the cable is catching some how or if the gasket is hanging up still? I have a thin Mr Gasket 4 hole cut to an open gasket, a 1/2" open and a 4 hole thin Mr Gasket on a stock #17 iron intake manifold. I did this to keep a bit of heat off the carb and it is as high as you can go with the stock hot air choke parts.
 

Olds 307 and 403

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Oct 4, 2018
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Melville, Saskatchewan
So I have been enjoying the hell out of driving my 88 Cutlass. Good power and remembered what the issue was with the throttle sticking, the cruise control rod is the issue. I removed it but plan on putting it back on for the 5 hour round trip this weekend. It was surging a lot so I will reseal the servo with RTV since new ones are no longer available. It actually seemed to work better with play in the rod setting, should it be tight?
 

Olds 307 and 403

Active member
Oct 4, 2018
616
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Melville, Saskatchewan
Well a great 5 hour round trip, 430 km. The 88 performed flawlessly, 165 to 180 temp, 45 psi steady cruising oil pressure at a steady 65 to 68 mph, around 2000 rpm. My Optimum Grey fix on the cruise servo fixed it, now rock steady, no more surging up and down. The best part, 24 mpg Imperial. I could probably knock down 25 mpg just by doing 60 mph. Somehow my speedometer is only 1 or 2 mph fast comparing against my gps speedo app, thought it was off by 5 mph. Just a great cruising car, used nothing as far as oil, trans or antifreeze.