350 Going Boom, Won't Start

Discussion in 'Small Block Tech' started by patwhac, Aug 17, 2015.

  1. sean Buick 76

    sean Buick 76 Buick Nut

    Has the carb been rebuilt? After sitting for 10 years it should be rebuilt.
     
  2. alec296

    alec296 i need another buick

    He said Ken from everyday rebuilt it.
     
  3. Gary Farmer

    Gary Farmer "The Paradigm Shifter"

    It would be a damn shame to bugger up the engine while trying to figure out what's going on.

    Maybe consider putting in some sort of octane booster or a few gallons of race fuel per tankful until you can get it sorted.

    Try tuning it with the higher octane fuel in it and see if it runs better/has more power.

    This will be another clue.

    Have you tried the 160* thermostat yet? (if you have and I missed it, sorry) If you can get it to stay cooler with this, does the pinging go away?

    Car runs fine when cooler. Remember this clue. Higher compressions won't detonate as bad (or at all) when the ambient temps are down. When temps increase, higher octane is required.

    If spark/timing and fuel are fine, consider what else could be going on inside your engine.
     
  4. patwhac

    patwhac Well-Known Member

    Still working this one out, have backed off the timing little by little and I think I've gotten rid of it (the ping). I know that the flex fan the previous owner put on the car is not doing a great job cooling (way to far inside the shroud) so my next step is to install a 7 blade OEM fan and new thermostatic clutch. Perhaps the better cooling will help the ping as Gary mentioned, but it's also just something that the car needs regardless. If that doesn't work I will try the 160 stat.

    Meanwhile I rebuilt the oil pump this weekend with all TA parts: gears, booster, shims, regulator. Had to do it with the engine still in the car so I'm not sure if my end clearance calculations are the most accurate. it was a PITA! Before I was getting 30psi hot on the freeway (not sure what rpm, but cruising from 60mph-80mph) and 5 - 8 psi hot idle. It's been like this since I got the car.
    After the rebuild, my readings were pretty much the same, but then I checked yesterday and I was 2 quarts low on oil :Dou: and it's only been a month since my last oil change (Brad Penn 10W-30), and only a couple weeks since I checked the oil! Where did that oil go? Well I topped off the oil so I'm still driving around to try and get an idea of what the rebuild did or didn't do. I will be playing with the regulator too. Hopefully this motor isn't burning a ton of oil.

    Stupidly I have both a compression tester and leak-down tester sitting at home but have yet to use them . . . Will do soon!

    Just an update!
     
  5. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Not sure if the plug heat range was mentioned or not, if not if you go down a couple, maybe 3 heat ranges that could get rid of the pinging?(spark plug heat range, something easily Binged) Worth a try, you may be able to bring the timing back up? GL



    Derek
     
  6. Mart

    Mart Gold level member

    If this doesn't work, you need a new radiator.
     
  7. 8ad-f85

    8ad-f85 Well-Known Member

    Do this first and the rest of your problems become easier.
    Don't try it, do it.
    [edit, along with the cooler plugs! Once you establish a safe baseline, you can work your way towards warmer therm's and plugs]

    You have a combination that's on the edge. Put it away from the edge, give it some margin.
    Forget DCR calculators and any other hoo haw, one of THE biggest factors when you are on the edge IS temperature...coolant and air intake.
    Thermostat first, radiator and cooling system as needed, then adjust your timing back where it needs to be and tune it.

    Depending on the severity of your 'ping' problem, you are possibly unseating the rings or distorting everything and pushing oil past during the detonation events.
    Remember... if you can hear it, it's severe.
     
  8. patwhac

    patwhac Well-Known Member

    I will give that a shot. When I did the oil pump I had to pull the #1 spark plug to find tdc before pulling the distributor and I remeber it looked a little white from the pinging so I could stand for new plugs anyways.

    Got it. Yes I am very worried of damaging the engine, so my next paycheck is going towards these cooling components (160 stat included).

    I'd like to go aluminum eventually, but the US made ones are $$$, but it's on my long list of parts to buy . . .
     
  9. 8ad-f85

    8ad-f85 Well-Known Member

    T stat and plugs are the least expensive and most important first steps anyways.
    Retarding the timing a long ways adds heat to everything too, greater demand on the cooling system.
    Even though it's a quick diagnostic check, it's counterproductive in the long run.
    Your baseline should be cool and safe.
     
  10. patwhac

    patwhac Well-Known Member

    Finally put in the 160 stat, still pings. Going to put in new plugs this weekend. Also put in the stock fan that I bought off of a board member and new thermostatic clutch. New fan helped traffic temps by 10 degrees.

    I also noticed that sometimes my temp still gets up to 170 and 180 while sitting in traffic even with the 160 stat, so it looks like I do need a new radiator.
    Us it really worth the extra $$ to buy a US made Al radiator?
     
  11. hugger

    hugger Well-Known Member

    180/190 is perfect temp, I wouldn't mess with it
     
  12. Buick#455

    Buick#455 Well-Known Member

    ^^^^^^
    What he said.....
     
  13. 8ad-f85

    8ad-f85 Well-Known Member

    It would be perfect if there weren't detonation problems, lol
    I haven't re-read this frustrating mess but I thought the idea was to bring him to a safe starting point and then steer in the tuning from there?
    :):):):Dou::):):):)

    [The observation above that there still is some temp creep while sitting in traffic suggests that the radiator cools just fine and that the airflow needs more attention.]
     
  14. hugger

    hugger Well-Known Member

    There's not an older engine out there that doesn't creep while in traffic
     
  15. 8ad-f85

    8ad-f85 Well-Known Member

    Indeed.
    I think suggestions pop up on these ongoing threads that sometimes escapes what other issues the OP might be having, due to the inability to go over everything.
    Everyone always has good suggestions and valid viewpoints.
    I miss a lot of things too!
     
  16. alec296

    alec296 i need another buick

    Mentioned in separate post crank pulley loose. That very well could have been the "detontation " Try resetting timing again
     
  17. patwhac

    patwhac Well-Known Member

    Alright, got blue loctite on the pulley bolts.

    I finally got around to messing with the carb jets. I just went out and swapped my .68" jets that came with the carb when it was rebuilt to .69" on both sides. Took it for a drive and still pings under hard acceleration from a roll. From a stop it doesn't ping but is definitely lacking in acceleration, I'm guessing due to my very low idle timing.

    So I'm at .69" jets and big block secondary rods with a total timing of about 28 degrees and an idle timing of about 2 degree, 160 stat, medium blue advance springs with no vac advance (plugged), with enough Seafoam down the carb to hopefully burn away any carbon on the pistons (2 bottles). I feel like I have 4 directions to go from here:

    -Increase jetting to .70"

    -Change to heavier advance springs and or further decrease total timing.

    -Change spark plugs (still haven't done that yet. Can plugs that have been "detonated" on cause more detonation? Plugs that are in there are the new copper ones I put in when I first got the car)

    -Do compression and leak down tests to check for other problems

    Which way should I go here?

    I'm almost at the point where I want to take it to a professional because I don't want to mess up my engine . . .
     
  18. hugger

    hugger Well-Known Member

    Plugs are cheap throw some in it
     
  19. 8ad-f85

    8ad-f85 Well-Known Member

    How many times are you going to pound detonation into your engine? :)
    Back way off and come up on it.
    One jet size would not be enough (if that is the singular cause of the problem).
    Get your ignition curve safe before playing much with the carb, changes are invalid until then.
    The timing curve affects (determines) how the carb draws and affects rich/lean. YOUR settings would not be equivalent to anyone else's.
    Plugs can easily be read for signs of det. and yes...they are cheap
    Start colder with plugs (general advice), and move hotter when they show signs of fouling or not idling right.
    These minute changes aren't doing anything IF the engine is indeed detonating. It is a severe condition.

    The problem with going to a professional is even finding a shop that can profitably sort out your combo and tune it.
    Whenever I take on an already put together deal and sort out these kinds of problems, it's usually expensive because of the changes needed along the way.
     
  20. patwhac

    patwhac Well-Known Member

    Got it. I will adjust the total timing until the ping goes away completely! I'm just worried that my idle timing will be ATDC at that point. Does that mean I have to do something to my distributor to get less built in timing so my idle isn't screwed?
     

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