I took stock of where I'm at with the venture into getting my old 71 cutlass supreme back on the road. I started to smell gas today and thought it might be running rich. I decided to check the miles since I had the drivetrain swapped. I've put about 4,700 miles on it and replaced more parts than I ever thought I would in the last 6 months, learned more about cars than the first 53 year of my life, and spent many more $ than I could imagine. The parts include the following:
--73 F serif 455 block originally from a manual transmission car but out of a 78 jet boat with with E heads and shallow dish pistons, original intake, unknown cam,
--a 700r4 transmission that lasted 200 miles replaced with a TH400,
--323 limited slip rear end,
--Edelbrock 750 cfm carburator which was a complete dog and replaced with a rebuilt numbers-correct 73 Quadrajet to replace the worn out carb from the 73 motor (No one wanted to part with a 70 core),
--rear disk brake conversion,
--new tires
--new shocks,
--headers, 2.5" exhaust with series 40 Flowmasters,
--vacuum advance restrictor
-- new cap, rotor, advance springs and weights, ignition wires, plugs

Not sure if there's anything else, but after 1700 miles on the 1st oil change its gone through a little under half a quart of oil. After 4700 miles the motor longer looks new which is okay. The car runs at about 185 degrees. The timing seems to work best at 14*idle, 34* with mechanical advance and about 10* of the vacuum advance restricted (about 1/2 the range of travel). I have the idle set at about 700 rpm and it really purrs at stoplights. Not exactly sure how quick it is, but it will smoke both tires and hasn't embarrassed me since I replaced the carburator. Strange thing is, it will only do about 120 mph at about 4900 rpm in about 1/2 mile and gets right up there, but just hits a brick wall at 120. Not sure if this is normal, but I really don't need to go that fast anyway. I think the gas smell was a leaking hose clamp just above the fuel pump which I tightened. Will need to drive it to know for sure. I don't believe the car is running rich. Pulled a spark plug and it is a sandy color and the spark area is shiny. Picks of plug and motor:

 

If the ultimate goal is to drive and enjoy, I think you made it. Good looking car.

Your timing and tuning settings are inline with mine. I'd say your top speed is indicative of power output pushing an aerodynamic brick that these cars are. You're making more power than I am. Have Fun!

 

it's a lot of fun. Looks like you have about the same set up as mine from your profile. What does you 455 have that's different?

 

Hose/ hose clamps on the pressure side of the fuel pump? Isn’t using hose as opposed to pipe asking for trouble?

 

Not sure but my 350 was set up that way for decades and never had any problems

 

6 psi for mechanical fuel pump. Up to 40 psi for cooling system, but radiator cap generally 12 psi from what I saw online. Of course failure of the fuel line could result in more dire consequences.

 

I had noticed the same thing with my 1970 Supreme back in high school. With a 2.56 rearend, it would top out at 120, then after swapping to a 3.55 rearend, it would still top out at 120 (speedometer corrected). I figured it was aerodynamic limitations.

 

I'll assume many things are similar. What's different? I can only assume your engine is in better health than mine. Meaning mine is high mileage and a bit worn bumping 200K. I still have a quadrajet, unknown headers low comp. and an Engle JM16-18 camshaft. It will do mid 15's in the quarter at about 90MPH. I think with the weight considered and doing some math, I have about 215hp give or take,at the tire. I think you have more considering the top end speed. MIne won't do that.

 

this is what the motor looked like when we pulled the heads. The previous owner said it was recently rebuilt but you never know until you pull the heads

 

I’m betting your fuel pump is maxed out at your observed top speed. Think about how much fuel a healthy 455 needs at 5000 rpm, and the amount of fuel it will use at WOT for a 1/2 mile. The style fuel pump your using is limited on fuel delivery, I bet by the time you accelerate up to your top speed, the float bowl is almost empty. What fuel the pump will supply is enough to keep the engine running, but isn’t enough to really make any power.

 

[QUOTE=matt69olds;1345280]I’m betting your fuel pump is maxed out at your observed top speed. Think about how much fuel a healthy 455 needs at 5000 rpm, and the amount of fuel it will use at WOT for a 1/2 mile. The style fuel pump your using is limited on fuel delivery

Interesting. I wouldn't have thought of that. It's the marine fuel pump from the jet boat. The 455 is healthy. Super clean. You can't easily see the oil on the dipstick for the first couple hundred miles after a change.

 

I would THINK given enough room, and enough
“testicular fortification”, a healthy 350 and especially a 455 would easily push a A body over 120. I have a book with old car magazine road tests, the 69 W31 was reported to have a 135mph (at 6600 rpm!) top speed, and the Olds Delmont police cars were listed at 143 topped out.

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I have a feeling your fuel pump theory is likely the case. The 455 easily pushes it up to 120. Not like it drifts up to that speed. It blows right past 100 and in no time it maxes out. I wonder if trying to hit top end more gradually would result in a higher speed. I don't think I want to risk getting caught running for that long at that speed. Don't know what kind of pump it had, but from what I've read the W31 was a high revving giant slayer that would do 0 to 60 in under 6 seconds. How many 442s could do that? The only ones I've heard about with that kind of performance are the Hurst W30s. And my 455 doesn't have the intake or carburator of a 442. I don't know what cam I have so not sure if or how that could be a factor. Hard to compare road tests from a time when octane ratings were 98 to 101. My stock motor will not perform like it would have on 1969 rated gas.

 

i think I figured out the issue. The throttle cable had too much slack and the throttle stop pin that hits the cable mount plate still had about a quarter inch of rotation to the plate when the gas pedal was floored. I adjusted the mount to remove the slack and the pin rotates to the stop now. I didn't take it to top end but it seems to have more acceleration.