1968 Riviera 430

Discussion in 'Street/strip 400/430/455' started by Huckleberry1, Aug 8, 2013.

  1. Huckleberry1

    Huckleberry1 Well-Known Member


    Need some help. Are the 68 430s an interference engine? Got some help replacing the timing chain and compression is now 60psi in most of the cylinders. It was 130 to 150 psi. I am afraid of the answer and what comes next.:Dou:
  2. Briz

    Briz Platinum Level Contributor

    How did you line up the marks on the timing gears when you installed them? Also, what lead up to needing the timing set needing replaced?
  3. Yardley

    Yardley Club Jackass

    Sounds to me like the timing chain wasn't lined up correctly when replaced.
  4. Huckleberry1

    Huckleberry1 Well-Known Member

    Briz - The dots were lined up with each other (cam gear dot was down and crank gear dot was up). As far as what led up to the changing the timing set, it was first an ignition problem. I had replaced the distributor with a reman and then the condensor went bad in the new distributor. So I went ahead and replaced the distributor with an MSD 8552 distributor with electronic ignition. When that was installed, the car was running fine for a few minutes and then started missing and running very rough. At the end it wouldn't run. So that is when I called in the mechanic. He said he thought it was the timing set since the crank would move a lot when torqued and the rotor button would barely move. Kind of like there was play in the set. The mechanic changed out the old set with a set from TA performance (TA 1522). Everything buttoned back up, the car won't start. Checked compression and each cylinder ranged from 60 - 80 psi. At the beginning of this adventure, I checked compression on all cylinders and the lowest was 120.

    I am wondering what would cause all of the cylinders to have lower pressure now other than damaged valve train. What happens if the gear is off one tooth? This is the reason for my question; that is if the 430 valves will run into the pistons if the chain breaks or if there is an idiot like me putting the motor back together.

    I sure appreciate your help! Thanks

  5. 69GS400s

    69GS400s ...my own amusement ride!

    not an interference motor stock or built to spec.

    .. sounds like you still have distrb problems - maybe the pin on the gear sheared off. Pull a rocker cover and rotate crank and see if valves/rockers move
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The TA 1522 is a stock timing set, so no adjustment is possible as it only has one key way. Was this motor stock, or does it have an aftermarket cam? What kind of timing set did you take out? Was it multiple key way? If it was all stock, I would compare it to the TA set.
  7. Huckleberry1

    Huckleberry1 Well-Known Member

    Thanks for the feedback. The original distributor gear pin was sheared and that is why I replaced it with the reman. I may indeed still have an ignition problem but I can't understand the compression problem/change on all of the cylinders. I just doesn't make sense to me. Expecially since the motor is all stock except the distributor now and the timing chain.

    ---------- Post added at 01:45 PM ---------- Previous post was at 01:43 PM ----------

    Thanks for the feedback Larry. The motor is completely stock except the distributor and now timing gear. The original timing set was removed from the car and it was pretty loose. It was not multiple key way.

    Thanks again for the help and thoughts!
  8. Yardley

    Yardley Club Jackass

    You need to do some leg work. There is a fitting you can thread into the spark plug hole and then hook a compressor to it (used to hold valves closed when changing valve springs). NAPA or other auto parts stores should have it.

    Rotate the engine by hand, watching the #1 intake rocker arm (be sure it is the intake and not the exhaust rocker arm). As the arm is allowing the valve to close watch the timing mark on the balancer and rotate the engine until the timing mark is at 0*. Then attach the air hose and listen. If air is rushing out of the cylinder then the cam timing is off. It is normal to hear slight leakage but not a massive amount. Also, with the balancer at 0* look at the rotor and see if it is pointing at the #1 spark plug location on the distributor cap. Report back.
  9. 69GS400s

    69GS400s ...my own amusement ride!

    I still think he should first pull the dist cap, valve covers, and the spark plugs and spin the motor watching the rockers and the rotor
  10. Yardley

    Yardley Club Jackass

    Yes, I was kind of implying that he do that while he's doing what I suggest. His compression being down on all cylinders indicates a cam timing issue.
  11. Huckleberry1

    Huckleberry1 Well-Known Member

    Great advice guys. Legwork was done. While the engine was turned over, I watched the rockers and rotor button. All good. Checked using the air at TDC of number 1 cylinder and didn't get a lot air. Yanked the timing cover and confirmed the dots were aligned. Tried another timing gear set and re-assembled. Still had bad compression. We squirted oil down into each cylinder and then checked compression and it was much improved (110 psi). Tried to start the car and it ran for a little while and then started sputtering again. Checked compression and it was 60 psi again.

    Now comes the theory: Back about a month ago when this mess started, I smelled gas very strongly around the car. So bad in fact that I had to pull the car out of the basement because it was stinking up the upper floors. I thought that it was an external leak initially because I had just filled up the car. However, when I pulled the plugs in the beginning, the plugs were always fouled, and smelled of gas big time. I think now that the float maybe was sticking and leaking gas down the intake into the engine and perhaps ruined the rings. Does that even make sense? I can't explain why I would get compression with a couple of squirts of oil and then lose it again soon after.

    If this is the case, is the only way to fix this a rebuild? Thanks for all of the help as you can tell I have no idea what I am doing.
  12. Briz

    Briz Platinum Level Contributor

    Can you post up a pic of the timing set with the dots aligned and the balancer on and pointing at TDC? Something is just not adding up. Putting oil in the cylinders will temp seal up bad rings but a gas bath would not ruin the rings so they would not seal. Didnt you say the oil pump shaft sheared recently and you ran it a short time without oil pressure? once that was fixed did you have good compression at that point?
  13. Mark Demko

    Mark Demko Well-Known Member

    Just a thought, his low compression reading MAY be from his lifters being bled down from all the cranking and fiddling around he's been doing.:Do No:
  14. Huckleberry1

    Huckleberry1 Well-Known Member

    Will work on getting the pics. I sheared the distributor gear pin in May and that is when all of this mess started. It took me a while to figure that out so I cranked the car over a lot trying to figure out why it wouldn't run until I finally noticed the rotor button not moving while trying to start it. That was the only time the engine moved without oil pressure.
    Car only has about 64k miles so I wouldn't think that there is a lot of wear on the engine but that is just me thinking and I think that I have proved I don't know a lot about cars.
    Anyway, thanks for the ideas. I am going to hold off before I dive in to rebuild it to try all of the ideas.
  15. Briz

    Briz Platinum Level Contributor

    A Lot of cranking and some run time with no OP could have damaged the rings(and possibly bearings) enough to cause the low comp readings. The oil in the cylinders confirmed they are not sealing. Its a shame on such a low milage engine. Place an ad on the board and see if you cant come up with another useable engine ,430/455, to stick in there and take your time on a rebuild to that one if your so inclined to do it.
  16. Schurkey

    Schurkey Silver Level contributor

    Is this true? I would not expect so. You're saying a valve can be fully-open, and still not hit a piston?

    Adding too much oil raises compression pressure because the oil takes up room in the combustion chamber.

    1. Is the compression tester gauge accurate? How do you know?

    2. Was the throttle open during the compression test?

    3. Did the battery/starter crank the engine at a normal speed?

    4. ARE THE INTAKE AND EXHAUST VALVES BOTH OPEN SLIGHTLY AT TDC-EXHAUST? If not, cam timing is not right. This does assume that the cam is ground with some slight amount of overlap, and the lifters don't bleed down so far and so fast as to cover-up the overlap during inspection.
  17. Huckleberry1

    Huckleberry1 Well-Known Member

    Latest info on this trouble shooting. Took the carb apart and rebuilt, cleaned and re-adjusted the float. I think that the valve seats were stuck open so I cleaned the valves out. I changed the oil last night and it had between half a quart to one quart of gasoline in the oil. I suspect and hope that the engine would not run well and kept losing compression earlier because of flooding due to the seat sticking in the carb. Next I am going to remove the plugs and squirt some trans fluid into the cylinders and let it sit overnight. Replace plugs and add some oil. I got some cheap stuff because I am going to add some oil additive (Lucas, Rislone compression repair, or something) hoping that the thicker viscosity will help the rings seat and stay seated this time. If this works :pray:, then I will change the oil in a week or so to get the heavy junk out and go back to my old 10W40.

    Not holding my breath here at all but I am hoping that maybe the reason that the repair crew couldn't get it running was because of the excessive fuel and not due to mechanical failure of the rings. I will let you know how it goes.
  18. Schurkey

    Schurkey Silver Level contributor

    There's no reason to play games with "additives" you're only going to leave in for a week. Change the oil, if the engine runs right now that the carb is fixed, leave the oil in until your next regular oil change--3000 miles or whatever. The additives will not do you a bit of good.

    You squirt oil or trans fluid in the cylinders, be sure to crank the engine to distribute the oil.

    "I" would change oil and filter, clean the spark plugs with a propane torch, squirt a LITTLE oil in the cylinders. Crank the engine with the plugs out, put the plugs in and FIRE THAT MOTHER UP.. There is nothing to be gained by letting it sit overnight.
  19. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Having low cranking compression and finding gas in the oil is a bad sign that the rings could be "washed" out,which will glaze the cylinders. If this is the problem,the only way to fix it is to re-hone the cylinders and replace the rings.As long as the bores are still in spec,you can use the same pistons,but if this problem went on for to long and the bores are to oversized,you'll need to have the block bored and honed for new pistons and rings.

    This is a worst case senerio,but from the info that you wrote,I'm sorry to say,this may be the case here. I hope I'm wrong,but I've seen this happen before and it was not good. GL

  20. Huckleberry1

    Huckleberry1 Well-Known Member

    Well - I feel defeated. Cleaned the plugs, changed the oil. Added a bit of oil to cylinders and turned it over to blow the excess out. Replaced the plugs and checked compression in #1 before assembling the wires and had 120 psi of compression. Great!! Now though, it sounds like there is a lot of friction in the engine and it doesn't really want to turn over. Not a battery problem. It will barely turn over and I don't want to lock it up if that is what is going on. I did add that Lucas heavy duty oil additive stuff hoping that it would slickify the cylinder walls and keep them sealing. That stuff is way thick and that might be my problem. Maybe not though. I expect the damage is done and I will be yanking out the old 430 for rebuild. :ball: Was really hoping not to spend any more money on the car but that is the way it goes. Thanks for the help through this guys.

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