64 FI Vacuum Measurement - NCRS Discussion Boards

64 FI Vacuum Measurement

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  • Larry M.
    Very Frequent User
    • January 1, 2002
    • 538

    #16
    Re: 64 FI Vacuum Measurement

    A couple of things.

    1 Gary Bramlett says 11-12 inches with a good guage. Mine is Sears from the 1980s....just a simple dial about 3 inches diameter. But it is consistent from one day to the next. Absolute values may not be right. Of course I don't meet a number of his other criteria.
    2. I believe for many reasons my car is 38000 original miles but have not owned it since new so I will never be sure and, even if so, the owner may have had a failure and some work done. Just after I bought this car in about 2000 we discussed on this forum the metallic brakes. I'm still running the original pads and drums (X stamped in the web). The original Michelin X 6.70X15 radials look about half worn out. But in removing the FI unit I can see that the intake manifold/plenum mounting plate gaskets are not original. They don't match what John DeGregory and others are selling. Between the front and rear plenum leg mountings on both sides they run parallel to the valve cover/head edge and do not follow the outline of the intake such that there is significant gasket exposed/not covered by the intake. I was disappointed to see this but John was sure they had been changed so the engine has been opened up for something at some time.
    3. I'll certainly follow your advice on the cam measurement but, can I use your procedure for the 30-30 cam which states that the intake and exhaust will both be on the base circle....or do I need to do it differently....even if it is not a 30-30. Remember, I'm not a gear head but I am trainable.

    Comment

    • Duke W.
      Beyond Control Poster
      • January 1, 1993
      • 15669

      #17
      Re: 64 FI Vacuum Measurement

      Originally posted by Larry Meyer (37196)

      3. I'll certainly follow your advice on the cam measurement but, can I use your procedure for the 30-30 cam which states that the intake and exhaust will both be on the base circle....or do I need to do it differently....even if it is not a 30-30. Remember, I'm not a gear head but I am trainable.
      The indexing procedure in the Hinckley-Williams valve adjustment paper will ensure the lifters are on the base circle on any mechnanical lifter camshaft.

      Duke

      Comment

      • Larry M.
        Very Frequent User
        • January 1, 2002
        • 538

        #18
        Re: 64 FI Vacuum Measurement

        Thank you. I'm going to make this my next rainy day project. I spoke with Gerry Bramlett this morning. He told me he had never obtained 13 inches on his guage in a similar situation if all other variable were properly managed. However, if the valve lash was much too high (say due to wear) then you might get 13. My gear head friend came by this morning and told me that just by ear I have a solid lifter set up, maybe not original, but not a grocery getter cam. So I'll dig into it.

        Comment

        • Larry M.
          Very Frequent User
          • January 1, 2002
          • 538

          #19
          Re: 64 FI Vacuum Measurement

          I set the valve lash using the Williams/Hinkley method but I set them at .030/.030 tight. I'll make a couple of comments on this but have one significant question: is there anything about reducing lash, and increasing overlap and duration that would make the engine run hotter? ....or would it potentially cause FI to run richer? Yesterday was over 90 with high humidity, not that unusual. But after a short test drive and some garage testing I had 200 on the temp gauge. I've never see over 180 before. This is a concern.

          General results comments...a little premature.
          1. At 1000 rpm the vacuum was about 11 inches consistent with a 30/30 cam I hope
          2. I've put very few miles on this car and had never had the valves done. Evidently the prior owner had not either. I did not measure all pre adjustment conditions but I had a couple of exhaust valves which were of .055 lash...terrible.
          3. Much quieter...much.
          4. I can idle down to the 900 range, but even at 1000 the idle is touchy...example, if I increase rpm with the bell crank and then let it drop quickly it will drop below the set point and recover or not recover and die. On one such trial I had a minor backfire which leads me to ask about running rich. The idle was very reliable before.
          5. I'm going to work with the idle mixture and speed this morning when cooler but would appreciate any comment on my questions above.

          Comment

          • Duke W.
            Beyond Control Poster
            • January 1, 1993
            • 15669

            #20
            Re: 64 FI Vacuum Measurement

            Lash should not have a significant effect on coolant temperature, and 200 is not unreasonable on a 90 degree day in urban traffic.

            A backfire is indicative of a lean, not rich condition. If it happened as you goosed the throttle, it's a lean transient condition. If the engine had a carburetor, the accelerator pump would be a prime suspect, but FI doesn't have on. When you blip the throttle the ratio lever should move briefly to the power stop, so maybe the power stop is set too lean or the linkage is sticky.

            11" @ 1000 is likely a 30-30 cam, and it might drop to 10" at 900.

            Duke

            Comment

            • Jim L.
              Extremely Frequent Poster
              • September 30, 1979
              • 1808

              #21
              Re: 64 FI Vacuum Measurement

              Originally posted by Duke Williams (22045)

              A backfire is indicative of a lean, not rich condition. If it happened as you goosed the throttle, it's a lean transient condition. When you blip the throttle the ratio lever should move briefly to the power stop, so maybe the power stop is set too lean or the linkage is sticky.
              The more usual cause of a transient lean condition is mis-adjustment of the Enrichment Diaphragm trip point. That is, the vacuum level to which manifold vacuum must drop before the Ratio Lever moves is less than the actual vacuum level achieved when goosing the throttle.

              OK, that was a long sentence. Short sentence: To eliminate lean stumble, make the link rod from the Enrichment Diaphragm to the Ratio Lever longer. Make such adjustments in one turn increments and test.

              Jim

              Comment

              • John D.
                Extremely Frequent Poster
                • December 1, 1979
                • 5507

                #22
                Re: 64 FI Vacuum Measurement

                Rule of thumb on enrichment diaphragm rod length. Pretending the nut was not on the rod and you had an original or the good repro enrichment diaphragm. From the center of the 90 degree bend to end of the threaded rod (when it is screwed into the diaphragm the rod length should be about 2-1/32". Good starting point.
                Hard to describe so will repeat myself one more time on the length as I have a hard time doing this on the phone too.
                Diaphragm has a treaded extension sticking out. Rod screws into it. From where the rod screws into the diaphragm to the center of the 90 degree bend look for about 2-1/32".
                One thing that has given us a lot of trouble over the last 50 years is this. When the manual says .040 clearance between the enrichment diaphram backing plate and the back of the diaphragm that is not gospel. You can haveatad less and a tad more.
                Object is you don't want the diaphragm slamming into the backing plate. In case you don't know the backing plate is it appears on the '58 to '65 Fi's as a separate part held on with two 1/4-28 x5/8" fillisters that are cadmium plated. That part takes the most abuse of any other part on the FI unit as it's constantly being slammed every time you touch the accelerator pedal. If the backing plate is bowed you need to attend to that. Replace the part or try and straighten it.
                '57 backing plate is built into the fuel meter casting.

                Anyhow if you have around ,.040' clearance and a rod that is 2-1/32 the unit will at least start up and run and then you can calibrate the two set screws aka economy stop and power stop from there.
                Another one of my famous phone speeches. Say you are out in the sticks and have no means of calibrating a fuel injection unit.
                If you have about 1/4" threads showing on both set screws-meaning the threads are exposed to the ratio lever (lever that swings back and forth) the FI should at least start up and run half fast and you can take it from there.
                It's not rocket science guys. Make it easy for yourself and don't be so fussy. Another thing if the engine is running and the FI seems to be decent leave it alone. Don't go nuts every time the weather goes to a 100 degrees .Figure it ain't gonna idle for crap at 100degrees with ethanol. Pure fact.
                Just leave it alone and by all means put some decent fuel into your car. Decent is the key word. John D

                Comment

                • Larry M.
                  Very Frequent User
                  • January 1, 2002
                  • 538

                  #23
                  Re: 64 FI Vacuum Measurement

                  We have success.

                  I could not get comfortable with a need to work on the power stop since all I'd really done was reduce valve lash and there was not an issue before. I wasn't really stumbling off idle as much as I had a poor idle. I think this is because I had lower vacuum after the valve adjustment. Operationally it was not as strong, maybe because of lower low end torque after the valve adjustment. I asked/suggested in my initial post that my idle mix screw was ineffective due to an old and less effective main diaphragm. I'd planned to change this anyway but consulted with John who was firm that I should do this before anything else. Presto: at 1100 rpm and 11 inches vacuum the main venturi signal will sustain idle even if I turn the idle mix screw all the way in, a rough idle but it does not die. Last night at 900 rpm and 9 1/2 inches it would continue to run with this screw only 1/2 turn out. To my ear I get the best idle at about 2 turns out. Personally I like the stronger idle at 1000-1100 so I settled there. On an 18 mile road test just completed with speeds up to 70 mph everything responded well and on coming to a stop the engine reduced to idle cleanly without any hint at quitting. I think I've got a better running car due to asking a simple question about vacuum without knowing anything was wrong. This speaks well of the help this discussion board provides.

                  My previous question about engine temperature is also resolved. The elevated temperature occurs when you shut it down on a hot day; the temperature rises since the cooling fan is not running. During the 18 mile test run it never got to 180. This is cool day by comparison but the temp went over 180 once shut down. There is a new (or old) issue which I experience as a result (yesterday when it was 98 degrees); that is difficulty starting when in this hot condition. I wonder if this may be due to fuel percolation and this yielding a poor starting mix. If I take my foot off the pedal (off the solenoid micro switch) momentarily to give it a shot of "extra" fuel it will start if I haven't already run the battery down. Could anyone give me some advice on this one.

                  Lastly, and this is a new question. When hot the max gap between the fast idle screw and the cam is about 1/8 inch, maybe more, if you take all the linkage play out. It is less, maybe a 1/16 if you don't touch it. The service manuals say set this to .015-.030 by bending the linkage. I'm looking at all this as my impression is that the engine comes off choke a little early. Or should I just turn the choke cover a little more to rich? Does this hurt anything as long as it comes totally off choke once warmed up?

                  Comment

                  • Duke W.
                    Beyond Control Poster
                    • January 1, 1993
                    • 15669

                    #24
                    Re: 64 FI Vacuum Measurement

                    It's normal for coolant temperature to climb after shutdown, especially on a hot day. Much of the cast iron is hotter than the coolant, and upon shutdown heat transfers to the coolant, and since it's not circulating, it heats up. As long a the pressure cap does not release and spill coolant, it's not an issue.

                    Hard hot starting in hot weather is typical for both carbs and FI due to the greater vapor pressure of today's fuel over about 120F compared to fuel from the day. With a carb this can cause an excessively rich mixture due to excess fuel vapor inside the air cleaner, and my recommendation is to use the flooded engine start procedure. Floor the throttle and keep it there until the engine starts, even if it takes multiple tries. Don't lift between tries.

                    I'm not sure if this will work better for FI since the problem may be vapor lock in the spider resulting in insufficient fuel to the cylinders - too lean a mixture to ignite. Once it starts, expect it to run snotty until the vapor is cleared out of the spider. Driving off immediately puts a load on the engine, which should help it return to normal operation ASAP.

                    ..can't help with the last question.

                    Duke

                    Comment

                    • Jim L.
                      Extremely Frequent Poster
                      • September 30, 1979
                      • 1808

                      #25
                      Re: 64 FI Vacuum Measurement

                      Originally posted by Larry Meyer (37196)

                      Lastly, and this is a new question. When hot the max gap between the fast idle screw and the cam is about 1/8 inch, maybe more, if you take all the linkage play out. It is less, maybe a 1/16 if you don't touch it. The service manuals say set this to .015-.030 by bending the linkage. I'm looking at all this as my impression is that the engine comes off choke a little early. Or should I just turn the choke cover a little more to rich? Does this hurt anything as long as it comes totally off choke once warmed up?
                      If that were my FI unit, I'd be reluctant to adjust the choke to remain on longer unless I had hard data which said the air/fuel mixture was too lean at the current time of turn off.

                      On 40 degree days, on my own FI unit which has neither choke nor cold enrichment, the air/fuel ratio will transition from extremely lean to something below 14.7:1 within the first 60 seconds of engine run time. My car is ready to be driven at that point.

                      On recent summer days with temps hovering around 90, air/fuel is below 14.7:1 within the first 30 seconds of engine run time.

                      If your car can drive away without stumbling by the time choke turns off, I'd say you don't need any longer choke duration.


                      As for starting procedure:

                      Hot start: Wide open throttle and crank until engine fires, which will be very quickly. You may have to tickle the throttle for a moment or two while the nozzle lines purge themselves of fuel vapor. Better, though, to just start driving. Engine will instantly smooth out.

                      Warm start: Start with wide open throttle and crank the engine. If it doesn't fire immediately, it's telling you it needs fuel. Remove your foot from the accelerator and crank the engine.

                      Jim

                      Comment

                      • John S.
                        Very Frequent User
                        • May 4, 2008
                        • 424

                        #26
                        Re: 64 FI Vacuum Measurement

                        Larry,
                        Glad to see you are getting your issues worked out. you are getting the best advice in the world from guys like John D., Jim L., and Gerry B. As for your hard start on warm up, I see some of the same issues when I start my 65. Sometimes it takes that wide open throttle to start and sometimes it takes the "tickle" that Jim talked about. What I have started doing recently is start cranking with my foot off the pedal for less then a second and then floor it. Usually starts right up. I think the term used earlier of purging the spider is what is happening. I can also tell you that the best way to learn about how your car runs/operates in different conditions is to drive it a lot. You will learn a lot this way. I personally love to see all of these fuel cars driven!
                        John Seeley
                        67 Black/Teal
                        300 hp 3 speed coupe
                        65 Maroon/Black
                        35k mile Fuelie coupe

                        Comment

                        • John D.
                          Extremely Frequent Poster
                          • December 1, 1979
                          • 5507

                          #27
                          Re: 64 FI Vacuum Measurement

                          Story. When the 65's were brand new and lined up at the dealers I will always remember a salesman friend trying to start a new '65 FI car. He had no clue and wouldn't listen.
                          Finally the owner of Grabiak Chevrolet walked over and said to his nephew. Said GTH out of the car and let JD try to start it.
                          It was easy. I just reached in the window and held the key to the start position and the poor car started right up.
                          '64-'65's have a starting solenoid. Known as a Skinner Valve that was made in New Britain, CT. They are for starting ONLY and have nothing to do for a shut off valve (misconception).
                          You have a burgundy or maybe a black micro switch that controls the starting solenoid. The wiring is connected to your engine starting harness.
                          You need a nice shot of fuel for cold starting. Hence the starting solenoid. When the car is warm/hot like Lockwood said then you shouldn't need assistance from the starting solenoid. See Lockwood's post.

                          Restorations shops and car owners have more trouble with the '64-'65 fuel injections. Why??? Because they don't understand the wiring and the theory.
                          It's actually a plug in job. The '64 Aims has a page on installing fuel injection emblems and shows the wiring for the Fi units.
                          The microswitch has a purple wiring harness. Harness is "Y" shaped. The end of the "Y" plugs onto the bottom of the switch with a tiny and rare terminal end (repros today). The other two terminals from the harness plug into the neutral safety switch terminals that are not used unless one had an automatic transmission on a low HP.
                          Simple wiring but it causes a lot of grieve.
                          The '64-'65 Fi unit was and is the best FI unit RP made in the old days. Instant starting and no pesky cranking signal valve.
                          Make it easy. Read the owners manual. Read the shop manual. No need to refer to boo coo forums for all of this. It's in the manuals.

                          When us old timers are gone what are you fuel car owners going to do? Don't worry about it. THE Fi's are not that difficult. Study the manuals.
                          Later as Corvette Carlisle is around the corner. Whew!!!!

                          Comment

                          • George J.
                            Very Frequent User
                            • March 1, 1999
                            • 775

                            #28
                            Re: 64 FI Vacuum Measurement

                            Larry,
                            with my '65 on a hot restart, I begin with a wide-open throttle, and if it doesn't start within a few cranks, I start to back off the throttle. It usually fires withing the first inch, or so, of backing off. I find if I completely take my foot off the throttle, it floods it.

                            George

                            Comment

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