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1971 Vette

Discussion in 'Chevy Trucks' started by EZSnow, Sep 14, 2003.

  1. EZSnow

    EZSnow Senior Member
    Messages: 205

    I have a 1971 vette, 350, 4spd yadda yadda.

    The carb was bad, so I swapped out the Quadra-Junk for a Edelbrock 600 and Performer RPM intake. Hasn't run right since. It was acting like it had a vacuum leak or the timing was off, so I went after both at the same time. I yanked the intake off again today, verified TDC on #1, and put it back together. I used a good gasket set and am confident there are no vac leaks in the intake gasket. I confirmed the #1 wire to the #1 cyl. The firing order is the only thing I didn't COMPLETELY follow through on.
    1-8-4-3-6-5-7-2 The vette is difficult to follow the wires on- they snake under the front crossmember... later tonight.

    Now it just pops and b-fires when I try to start it. I set the static timing, but I need to know how to wire the coil... I didn't mark it. I have two wires that are supposed to go to the coil- one in switched IGN power, I have no idea what the other one is.

    WHO KNOWS POINTS????

    on edit: it also has a pertronix ignitor in place of the points/ condenser

    Thanks
     
  2. Joey D

    Joey D Senior Member
    Messages: 280

    Did you check to make sure it's at TDC on a intake stroke? If it seems correct but it's backfiring is sounds like it's 180 degrees off and you lined it up on the exhaust stroke.

    Not to start a carb debate but the Quadrajet is a much better carb than the Edelbrock. 4 Wheeler did a carb shoot out a while back and the quadrajet ranked very well.
    Is your Vette an LT 1? I have a '71 Chevelle Heavy Chevy with the LT-1. I love the sound of the Q-jet as you mash the go pedal.
     
  3. EZSnow

    EZSnow Senior Member
    Messages: 205

    I will agree, that a Q-jet is a fine carb, especially for off road use. They are VERY tunable, but they seem to require a very in-depth knowledge and a LOT of parts to get the full benefit. (jets, rods, springs, etc) An edelbrock you can more or less throw it on and go. Anyway, the reason it got the nod was I had it sitting around, including the intake... Let's go!

    I am pretty positive that I got TDC between the compression and power strokes. I first indexed it by the timing marks with the intake off, then verified it with my wife's finger over the spark plug hole.

    My main trouble I think is wiring the coil... JoeyD- do you still have the points on your car? How are they wired? I have two factory wires going to the coil, but it's been off and on so many times in the last few weeks that I need to make sure it's right. I don't trust myself for anything at this point. The way it was today when I took it apart (ran fine high RPM but wouldn't idle) looking for a vac leak was both of these wires to the (+) side of the coil. My Pertronix is set up red to (+), black to (-). One of the factory wires shows (+) with IGN in RUN, and (-) with the IGN in OFF... this is nuts. I won't have hair much longer!!!!

    -Derek
     
  4. EZSnow

    EZSnow Senior Member
    Messages: 205

    dangit! I think I'm ********... in the distrubutor, that is. I cranked some advance into 'er and it fired off, but STILL won't idle. As far as I had to crank it to get it running, I MUST still be a tooth off. This is my first try at setting "static" timing.... I must have missed by the amount of advance that needs to be in it. ARGH! I'll pull it out again tomorrow and advance it a tooth.

    back at it...
     
  5. Joey D

    Joey D Senior Member
    Messages: 280

    If you are going to pull the dist. again, pull the valve cover 1st and verify it's on intake and not exhaust and line up the crank then install the dist. and line up the #1 plug wire.
    My car is HEI so no points.
     
  6. EZSnow

    EZSnow Senior Member
    Messages: 205

    did that today with the intake and valve covers off. I forgot earlier- it's not an LT-1, it's a 275 horse 350. Still plenty of giddyup for such a light car... if it RUNS!!!!
     
  7. wyldman

    wyldman Member
    Messages: 3,265

    Sounds like you need to pop the distributor out and move it one or two teeth.You need to lift it out and rotate the rotor clockwise for advance.

    The coil should have the ign feed from the switch or ballast resistor to the positive side.The negative side will go to the points or pertronix connection on the distributor.Your firing order is correct as posted earlier.
     
  8. PDQ Pete

    PDQ Pete Senior Member
    Messages: 139

    You can take the horseshoe clip off that holds the distributor and lift up a little and turn the rotor. I have a 72 vette just about the same thing mines nothing fancy, they sure have a lot of vacum lines. Hey Joey how come you give those guys such a hard time over on G-M diesel








    :D :D Pete
     
  9. Joey D

    Joey D Senior Member
    Messages: 280

    Pete, Not to change the subject but it's all in good fun. Those guys seem pretty smart and give a good debate. Once in awhile it gets carried away but I am laughing the whole time.
     
  10. PDQ Pete

    PDQ Pete Senior Member
    Messages: 139

    Just messin around with you Joey. My smilies did not go were I wanted them:D Pete
     
  11. wyldman

    wyldman Member
    Messages: 3,265

    Any luck getting your Vette running yet ?
     
  12. EZSnow

    EZSnow Senior Member
    Messages: 205

    No, but I'm getting close to figuring it out... I've been on the tech lines with both pertronix and edelbrock...

    Pertronix helped me diagnose a resistor wire between the IGN and the coil... got that fixed... no change. The coil and ignitor check out ok. Good strong spark.

    I was a little wary of my install job the intake, so I pulled it up and laid it down again. I used a fresh gasket set with the rubber end seals- again, which I have since been told to just use RTV on the ends.

    Edelbrock suggested that there may be too much fuel pressure for the carb. The e-brock carb can only handle about 5.5psi, whereas the q-jet can take up to 8-9. They suggested that the primary needle may be unseating and creating a rich condition.

    While I had the intake up, I found TDC on compression, static timed it and it still ran like poop. It only pulls about 9" of vacuum at idle. By 2,000rpm is sucking about 20-25" In order to even SEE the timing mark, I had to bury the vac can in the firewall (yes, it was unooked and plugged) which is ********. Even then, it was just showing up from behind the water pump- nowhere near the timing tab. SO.... we surmised that it MUST still be one tooth off, so we ******** it a tooth (28*) Then it REALLY ran like crap.

    Because of the low vac and bouncing needle, e-brock suggested trying to diagnose a vac leak in the lifter valley.... GET THIS:
    1. Remove the PCV with the engine running
    2. Use an unlit (preferably) propane torch to put propane into the valve cover. If it changes the idle at all, there is an internal vacuum leak.... :eek:

    Is this a standard procedure?

    Anyway, HOT ROD also had a detailed description of static timing a 1969 vette with a 71 motor this month in Marlan Davis' tech inspection column.

    So, I'm gonna get 'er on the right tooth, follow ALL of the wires (pain in the butt on a vette) and re-confirm proper placment, then run it. If it still runs like poo I'll try the propane deal.
     
  13. wyldman

    wyldman Member
    Messages: 3,265

    It's OK to use propane in the rocker cover to diagnose an intake valley pan leak.

    If you turned the distributor housing until the vac advance hit the firewall,then your are retarding,not advancing.Advancing would be turning counter-clockwise.

    If you want to take the dist out and move it a tooth,the rotor is opposite of the dist when advancing or retarding.Turning the rotor clockwise will advance the timing,and counter-clockwise is retarding.

    Normally on most SBC the timing marks are either at 12 o'clock behind the water pump,or at 2 o'clock by the PS pump.Could it be possible that you have the wrong timing tab\balancer,or timing cover ? Maybe it was changed when it was rebuilt or something ?

    I'd get it running,and try going both ways with the dist,and see if it runs better.If you can get it running decently,and the marks are way off,then just time it by feel.
     
  14. BWhite

    BWhite Senior Member
    Messages: 496

    Edelbrock carbs

    one thing they do very well is burn lots of extra gas compared to a Quadra-Bog
     
  15. EZSnow

    EZSnow Senior Member
    Messages: 205

    the bad part is when I check tdc it *feels* like the timing tab is right on the seeds!

    I think either I misspoke or was misinterpreted on ******/ advance... whether or not I typed it right, I was doing it as you suggested. I understand the rotor being opposite, as well. It's all about what makes the rotor tip and distributor post meet earlier/ later.

    Isn't it only the later SBCs with centerbolts that are timed at noon? I have no idea, but that seem like to screwy things that chevy might do at the same time! Also, I *THINK* vettes have a "short" water pump?? Would that have anything to do with timing tab placement?

    What about the gaskets? I used a Fel-Pro set MS 90314-2. It had the blue intake gaskets and the two sets of rubber end gaskets. The guy at e-brock claimed that "the good sets come with cork"... well SOR-RY!! (as sarcastic as I could possibly be in type) that's not what I put under it. And I used the rubbers on the ends. He told me that even with the 'good' cork sets, the cork may prohibit the intake from seating fully into the heads. Is this a typical problem? If so, why even include those gaskets- just pack some rtv in there and call it square!
     
  16. PDQ Pete

    PDQ Pete Senior Member
    Messages: 139

    When you have the car running take some carb cleaner and squirt small amounts by all intake gaskets and vacum lines if it starts to die thats a good spot to look for a leak. You could also swap in a spare distributer if you have one.
     
  17. EZSnow

    EZSnow Senior Member
    Messages: 205

    I re-verified and baselined the static timing, added a few degrees, verified all the wires and firing order, ran poopy, tried spinning her 180... lots of popping, none in the combustion chamber, lots through the carb. Put it back to static plus a few degrees (6-8). Still runs like crap. Got it warm, idled it down (1400!!!) and tried the propane test. Couldn't really tell, but with the idle so high, who knows. With the vac so low, (9-10) who knows.

    Are the rubber end seals THAT problematic? I really don't feel like taking this intake up a third time, but it's kinda looking like that might be the next step.

    ALSO- this intake was on my brothers V8 S-10. When he first fired it to break in the cam, he had the static set ********. It was firing so late that the headers started to glow during cam break-in... and the motor was overheating, too. It got to 240- 250 a couple times, hot enough to brown the clearcoat over the heat risers on the intake and spontaneously combust a spark plug boot. Could the intake be warped? Could the block have been decked? Could a couple cam lobes be rounded?

    I'm questioning EVERYTHING!!!

    -Derek
     
  18. Joey D

    Joey D Senior Member
    Messages: 280

    Derick, The intake could be your problem. One thing to do is if you remove it again install the old intake and the new carb. You can get a adapter for a sq bore to a spread bore. This will eliminate the manifold problem. Don't use the end gaskets use the rtv like you said. Get a fuel regulator and a guage and check that as well.
    Just a side note here but the peformer RPM a high rpm intake. You should be using the performer intake unless you have a mid to high range cam. The stock GM manifolds flow well they just are cast iron.
     
  19. EZSnow

    EZSnow Senior Member
    Messages: 205

    the whole idea behind the swap was that it was a cheap option... I had what I had diagnosed as a throttle-shaft leak on the q-jet, and it was just running generally poor. I blamed it on the carb. I had a intake/ carb set around, so I plopped it on. No biggie, and it'll only cost me 8 bucks for the gasket set... RIGHT! So, now I'm into this thing for two intake sets (about to be three), a carb gasket, a new air cleaner (to fit e-brock), a set of valve cover gaskets, throttle return springs, spark plugs, multi-meter (needed it anyway), radiator hoses, and a set of vacuum plugs. (backfires kept shooting the screws out of the vacuum tubes... DUCK!!) None of it REAL expensive, but it all adds up. Almost adds up to a professional rebuild on the q-jet!!
    But it is a close-ratio 4-speed, so once you get it off the line, it can make good use of the upper RPM range that the Performer RPM provides. RPMs don't drop much between shifts.

    But mommy- I don't WANNA use the iron intake!!!:mad:
     
  20. Joey D

    Joey D Senior Member
    Messages: 280

    But it is a close-ratio 4-speed, so once you get it off the line, it can make good use of the upper RPM range that the Performer RPM provides.

    The only thing is the cam needs to match the intake.
    Time to bite the bullit, I will make you a great deal on a brand new in the box Holley Pro Injection with every part in it.....