No power in my 430

Discussion in 'Jeeps with the Buick Heartbeat' started by fadec, Jun 24, 2018.

  1. fadec

    fadec Member

    Recently I bought a '69 J-3500. It has a '69 430 with a newer Edelbrock 1406 carb and stock ignition. It was running but not well. Over the last couple weekends I was able to do a simple tune up. Replacing the rotor, cap, points, condenser, wires and plugs. After everything was replaced things did run a lot better. Idle was now holding and things seemed to be doing better.

    The old plugs looked wet, like it was far too rich. I next leaned the mixture to something more believable. Using the Edelbrock lean idle instructions. Again things were running little better. I next moved on to the timing and advance. It was set to zero TDC at idle. It is now set to 10 deg. at idle with a 30 deg. of advance at 2500 rpm. So far every step has helped, but things are still not right... not even close to right.

    I've noticed a bit of a vibration/shake when coming off idle. It feels more like an out of balance on the engine. If I'm just running in the garage it isn't bad, but under power while driving this shimmy is insane. When I put it into gear the engine will drop a good 300 rpm. Then when I try to move the power just isn't there. There is a really big vibration/shimmy that starts to get bad about 1500 rpm and stays until about 2000-2500 rpm. Going up a hill there is nothing there. It can barely keep up 30 mph. If I floor the throttle there is little response which will eventually get going. Though nothing like it should.

    I should add there is no knocking or smoking. No water in the oil or oil in the water. It doesn't smell overly rich anymore. There are no leaks. Other than looking old and dirty there is no outside indications that this would be a bad motor. Though everything I feel when driving says the engine is toast.

    Anyone have any ideas's as to what to check next or if I missed something? I know I need to do a compression test. Other than that, what else can I look at before throwing in the towel and saying this engine needs a full overhaul?
     
    Last edited: Jun 24, 2018
  2. lemmy-67

    lemmy-67 Gold Level Contributor

    10 degrees initial advance on a stock distributor is too much. The initial timing for the 430 should be 2.5 degrees BTDC. Your distributor may have worn advance weights or gear parts, and also there may be vacuum leaks to seal.
     
  3. Harlockssx

    Harlockssx Brother Graw Mad

    Throw a bottle of Seafoam in it too...always helpful on an older engine with dubious maintenance history.
     
  4. gsgnnut

    gsgnnut Well-Known Member

    Check your vacuum advance. Very simple test using a mighty vac tool or even just suck on the vac line and see if the actuator pulls in. When they fail the symptoms can range from no power to shaking vibration and poor idle. Also make sure the vac advance is on the ported signal fitting. Also those edlebrock carbs are great but the primary air bleeds plug easily and make it surge at cruise and idle poorly. I know I have one on my gs and have to blast the air bleeds with compressed air or carb clean periodically. Good luck
     
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Get the part number off the distributor. That will determine what the timing should be. It's a big assumption that the engine has the distributor it left the factory with. It sounds to me like either you have the firing order wrong, or, you have some dead cylinders.
     
  6. fadec

    fadec Member

    Sorry for the late reply. Had to go out of town for work and only returned late yesterday. Anyway.... since I posted I have made several discoveries. First the ballast resistor was shot. Only putting out about 3-4 volts to the coil. I was actually surprised it would even start with such low voltage. Well, a new ballast resistor and coil are now installed. (bought as a matched set.) I then checked the end play on the distributor shaft. Yeah, that too was toast. I got a good 3/16" end play (up/down) movement. Since it would cost almost as much to rebuilt it myself, I just bought a replacement. I now have a new rebuilt distributor installed which my local speed shop had on hand. Things were starting to look up until I got to the total timing. Even though this is a new distributor it does however lack the proper advance limit bushing to keep the total advance where it needs to be. With 30 degrees of dwell angle and 2.5 degrees idle I have over 55 degree's total advance. (actually went beyond the limits of my timing lite.) I can get it to run at the proper 28-32 total advance per the manual, but then the idle is so off things won't idle. Due to this I now have bushings and an advance adjustment kit on order that should bring both ends of the idle and advance closer together and into spec. I'll be posting more once parts come in and I get the chance to install them.
     
    Last edited: Jul 1, 2018
  7. flynbuick

    flynbuick Super Moderator Staff Member

    Was the total timing checked with or without the vacuum advance line connected?
     
  8. rkammer

    rkammer '71 GS455 Arctic White

    I think the compression test will tell you a lot. Hope you find the issue is all external and not a fried motor. :)
     
  9. fadec

    fadec Member

    Actually I tried it both ways with the same results. I started with the vacuum disconnected and when I saw how far it was out, I then tried with it connected to see just how far it would go. The results ended up being the same. Just with a different curve. With it connected things advanced faster as expected.

    I agree! I ordered a new compression test set at the same time I ordered the advance kit. I'm very curious to see what it comes up with too. ;)
     
  10. Nailhead Ronnie

    Nailhead Ronnie Political Analyst

    Is that how that Jeep came stock? With the 430?
     
  11. fadec

    fadec Member

    No! It originally came with the AMC-327 Vigilante. From looks of the similar amount and type of rust on the frame and modified engine mount, I believe it was swapped a looong time ago. My best guess is probably sometime in the early seventies. I actually mis-wrote the original post. The truck is a 1968, but going by the casting numbers on the engine I've found so far, the engine dates to 1969.
     
    Nailhead Ronnie likes this.
  12. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    That can’t be, it means the vacuum advance isn’t working. The total would have to be more. Maybe you couldn’t tell how much because the total was already off the dial without the vacuum advance?
     
  13. flynbuick

    flynbuick Super Moderator Staff Member

    Did you verify that the plug wires are in the correct firing order?
     
  14. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    You need to verify fuel pressure. If it idles ok but has no power under load that's a pretty sure sign. The 1406 is not the best for the 430 but it should run ok. You're leaving a lot on the table using such a small carb. Being that it's an engine swap I'd put a visual on all the fuel lines from the carb to the sender. Check for kinks and bad routing.
     
  15. fadec

    fadec Member

    Actually it can be. Total advance is determined by the physical limit pin. It doesn't matter how it get's to that limit pin, either via the weights spinning or the vacuum advance pulling on the plate, it will only go so far. Vacuum advance does not add more timing over the mechanical timing, it only really comes into effect when coming off the throttle while the engine needs more advance for better economy. Normally the vacuum advance does not run at full advance, but rather someplace in between depending on your advance rate. It can however go to full advance at high throttle settings with a ported vacuum system, though normally the weights have taken over by then.

    Yup... They are all in the right place.

    Everything so far looks to be strait and with no restrictions. It idles and goes to full throttle with no problems. If it was low fuel pressure issue wouldn't I have problems getting to full throttle even under no load? The problem is only when a torque load is on the engine. I'll still look into fuel pressure more, as it is very suspect.

    Also to note, this swap was originally made decades ago. If it was swap issue, I think they would have seen and fixed those problems meny years ago. I do agree with the carb being undersized. This would not have been my choice of carb's to put on this engine. Bad part is that this is what it came with and I don't have the funds to buy a better carb right now. I have to deal with what I have right now.
     
  16. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Nope, that is incorrect. Mechanical advance and vacuum advance operate independently from one another. Mechanical timing works by moving rotor position, vacuum advance moves the entire advance plate. Vacuum advance can add timing even after the mechanical advance is maxxed out. Vacuum advance operates on vacuum, the vacuum must overcome the canister spring tension to advance the timing. Stock advance units supply 14-18* of timing at 16" of vacuum. At light load cruise, vacuum is high leading to full vacuum advance. At high load, and large throttle openings, vacuum is low, even at or near zero at WOT. The canister spring pulls out any vacuum advance there was at high vacuum. Mechanical advance is controlled by the weights and spring tension. It is limited by the pin/slot to the size limitations of the particular distributor. Most Buick stock distributors did not allow full mechanical advance until about 4600 RPM. At cruise RPM, only part of the mechanical advance was in. It was supplemented by the vacuum advance for a total up around 40*. Nail the gas, and the vacuum advance goes away as the mechanical advance increases to it's limits.
     
  17. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    The engine will idle and rev easy with little to no fuel pressure. Only under a load will fuel delivery issues be an issue. The first thing to do would be run it without the fuel cap to test for a vent issue. Otherwise put a gauge on it.
     
  18. fadec

    fadec Member

    Ok... fuel pressure is on the list to be checked. Already installed a new fuel filter when I bought the truck. Also going to look for any blockages in the carb. Now I just need a day off to go through several of these items. Hopefully that day off will be this weekend. As I really won't know until after the holiday and we see how the work load looks for next weekend.

    Thanks guys for all the ideas and advice... it truly is appreciated.
     

Share This Page