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Pontiac of the Month

Damon Lewis' 1977 Can Am

2021 July
of the Month

Grandprix723

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  • Location
    Oregon
  • Interests
    Cruising

Forever Pontiac

  • Year
    1977
  • Car
    Grand prix
  • Trim
    LJ
  • Engine
    400
  • Style
    Coupe
  • Color
    Blue

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Community Answers

  1. Thanks for being there everyone who tried to help me figure this thing out.
  2. Runs nice and smooth with backflow transducer installed. I romped on it and it goes like it should. Paper inline fuel filter went bad using pump gas in two months.
  3. I omitted the transducer and put it back together. It still stumbles at idle and running without the transducer it also hesitates when you take off. Guess I'll reinstall it now. I haven't opened it up yet to see if I cured that problem yet. I don't get how that transducer is so important.
  4. So left work early to look at this egr valve see photo. I remember last time I took it apart a couple years ago that the transducer had been braised sometime many years ago. It does not hold vacuum. The egr is good I was hoping to find a chunk of carbon holding it open, nope. Any thoughts about the transducer.
  5. I will investigate that later after work. I installed it right but there is a leak at the manifold where the egr mounts to it.
  6. It's a 4-barrel. I replaced that little in line fuel filter last night. I didn't have time to take it out yet. Since I was running pump gas, I think the filter wasn't designed for ethanol, it was slowing the flow of fuel. Also I'm going to reach into the wallet and buy a vacuum gage and pump to check manifold pressure and my egr to pinpoint that unsteady idle. I replaced the egr a couple years ago. It's only held on by one bolt, not a good design. I sprayed brakleen around it yesterday and smoothed the idle for a minute. I'd like to just block it but there's only one bolt.
  7. The coastals are only 1500 feet. It does the same thing at sea level. It ran fine till a couple days ago. It's a mechanical fuel pump and it's fine. It's narrowed down to an issue with the secondaries. Frosty suggested checking to see if the secondaries open all the way. I don't think they are and as a result it's too rich for high gear.
  8. Just back from a test drive. First I leaned the air fuel mixture screws about a half turn. It smells cleaner running now. Did the 50 romp it downshifted to 2nd secondaries kicked in then at around 65 or 70 shifted into 3rd and there's a problem. It starts to bog or surge up and down. Once I get off it and run on just the primaries it works great. So it seems for some reason the secondaries are not functioning correctly under load in 3rd gear. How far are they supposed to open. When I open the throttle manually they barely open after a few seconds. Oh maybe the float is off and I'm draining the bowl?
  9. I tuned the quadrajet myself with no special tools other than a timing light and rpm meter. The window on the air fuel mixture is very small. Half a turn too far in and its lean and half a turn out you can smell the richness. So it's pretty close unless there is another adjustment specific to altitude??? It did seem like a lean condition to me as well.
  10. Thanks for the reply. I just limited it home but on level it seemed fine. I didn't romp on it any more though. All ignition parts were replaced by me not long ago with careful precision. No points on this car and a reman carb was installed by me and dialed in by ear and nose. I did time it with a light. It used to screem any time I romped on it any where any time so this is of concern. The fuel filter will be the first thing I look at. But it was replaced a couple months ago with the carb. It has a new fuel tank and pump too. After work today I'll run it again and try to figure it out. Thanks
  11. Took the car out to the casino at spirit mountain today. Going up the mountain on the way home at 50 mph I punched it to pass another car near the top. It downshifted to 2nd and accelerated it shifted to 3rd then started this up and down surge. I got off it and it smoothed out. Sounded like some top end engine noise also. It's got the 400 and high octane non ethanol fuel in it.
  12. It does. As much as I hate to admit it. I replaced the trans modulator awhile back. The old one was allowing fluid to run up the line to the carb. Whats cool about that is at least it kept the intake nice and clean. I thought I found the culprit but to no avail. Question is why does it run smooth at idle in gear withe a/c on? Then you put it in park and it's mostly smooth but unsteady.
  13. Ran it around today. In drive at 550 rpms it's pretty smooth. I replaced the factory carburetor a few months ago because the throttle shaft was worn. It gave me an erratic idle and puked fuel at the accelerator pump even after my backyard reman. I used a metal float though! The new(reman)carb is much cleaner running. The intake is clean all the fuel is being contained and processed correctly. The other issue I have is when in park the idle is a bit erratic. I mean it's not very noticeable accept to the trained eye and ear. It smells like it should. The old carb was worse. Maybe I'll spray some carb cleaner around the shaft to see if it's sucking air there. It seems like an ignition problem because the idle will be pretty smooth then suddenly drop and smooth out again. A lifter used to tap when cold and the book says it's okay if after warm it goes away, and it did. I decided to go back into the distributor and replace the vacuum advance and figured why not just replace all the tune up parts. Did that and started it up with no lifter noise. I learned that thru ignition the lifters get loaded. I guess I had another ignition problem at that time that I accidently corrected.
  14. That's why the cylinder walls on the 403 are thin. The 1977 grand prix SJ also came with the 403. I've been turning the idle up just a smige every day. It's been idling low and slow the way I like it. However that extra smige of air could be all it needs to start right up after warm.
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