Losing hope on this car. Not sure what to do with engine and trans.

Discussion in 'General Maverick/Comet' started by 29EssexRat, Jun 29, 2018.

  1. 29EssexRat

    29EssexRat Member

    Joined:
    May 19, 2017
    Messages:
    25
    Likes Received:
    4
    Trophy Points:
    10
    Location:
    Olympus Mons
    Vehicle:
    Too Many Projects
    Compression testing only tells you if there is compression in the cylinder. Unless you have a vacuum in the cylinder, which isn't possible, you will still get a compression reading. No matter if there is a bad lobe, or a wiped lobe, the cylinder will still have air in it. And when the piston comes up you will get a pressure reading as it compresses what air is in it. Now I suppose a completely wiped cam lobe the compression test may take a few cranks, but I can guarantee that none of the lobes are wiped that much. I'd be having a horrible ticking noise. But you'd assume you'd get a constant ticking from any cam wear great enough to cause this flutter.

    A leak down test is the only proper way of knowing if you have a leaky valve, or piston rings. A compression test may tell you if you have bad rings, or a bent valve that's not seating at all. I may look into purchasing/making a leak down tester.

    Only way to test for a bad cam is to measure the height of the lobe.

    Now that you mention it, this car did stutter and backfire at wot, but I chalked that up to the bad fuel pump, and distributor. Maybe I'll measure the lobe height tomorrow.
     
  2. groberts101

    groberts101 Member Supporting Member

    Joined:
    Apr 22, 2007
    Messages:
    4,068
    Likes Received:
    475
    Trophy Points:
    197
    Garage:
    1
    Location:
    Minneapolis, MN
    Vehicle:
    1971 Comet GT
    Some of what you say is partially true but all Tom is trying to say is the numbers would be skewed further than they are. Usually a tell-tale sign of wiped lobes is 1 or 2 cylinders being lower than others.

    From what your saying about metal oil sludge I'd guess the bearing linings have been wiped away and is causing lifter collapse due to low oil pressure. A quick mechanical gauge check will confirm that. A quick fix would be to run some 50 weight to pump up pressure a bit to avoid lifter collapse. A 160 degree t-stat will help some to by cooling it off and thickening oil a bit. Good luck
     
    Last edited: Jul 9, 2018
  3. 29EssexRat

    29EssexRat Member

    Joined:
    May 19, 2017
    Messages:
    25
    Likes Received:
    4
    Trophy Points:
    10
    Location:
    Olympus Mons
    Vehicle:
    Too Many Projects
    It has great oil pressure, 30 psi hot idle. I'm hesitant to say it has wiped bearings, no knocking or anything. And it's been rebuilt before, but who knows how long ago. The pan drain is on the side of the pan, higher than the lowest spot of the pan, so the metal never got drained out. I'm not sure what to do with this thing still.
     
  4. Eastern Raider

    Eastern Raider Member

    Joined:
    May 23, 2011
    Messages:
    668
    Likes Received:
    12
    Trophy Points:
    83
    Location:
    middle Ga. warner robins
    Vehicle:
    1970 maverick ford mustangs 1993 f150
    Gentlemen, I have been told numerous Times that if you have more than 20 psi difference in any Cylinder Pressure, You should check The Bore, for Limits-Maximum! Compression Test is a First do, and must on any unknown Engine!
     
  5. 29EssexRat

    29EssexRat Member

    Joined:
    May 19, 2017
    Messages:
    25
    Likes Received:
    4
    Trophy Points:
    10
    Location:
    Olympus Mons
    Vehicle:
    Too Many Projects
    Not sure if you went through the posts.

    1. 105 psi
    2. 110 psi
    3. 100 psi
    4. 100 psi
    5. 110 psi
    6. 120 psi
    7. 105 psi
    8. 105 psi

    I should have retested cyl 6, as it's an outlier. This was also on a cold motor, that had sat for a couple of days, so oil on the cylinder walls is a variable.

    But none of that would cause this flutter/miss thing. I'm 99% positive it's a top end problem. More than likely a valve sealing issue. Would be best to do get a leakdown tester, but one they're expensive, and two I don't have an air compressor that will go over 40psi... need a new one. Not sure what to do now.

    Route 1 (the free route): Find some GT40 (non p) heads, or something from the junkyard, they'll be free for me. Then use a stock 351w cam and lifter set I have, which is larger cam than the 289 cam.

    Route 2: Is to just go all out 408w with AFR 220 heads, or TFS 225 high ports. This is expensive and makes me not want to do it, but also it's something I really want to do. But I also have a vega drag car that needs and engine and transmission, that needs a 408 chevy more than the stock maverick. So this route is "eh".

    Route 3: Is to buy some nice 190ish heads, cam, and to rebuild the 289, bearings and rings.

    Route 4: Is to rebuild the 351w I have, bearings and rings. Then I need to either get some roller 351w heads, or maybe gt40 heads, and drill out the headbolt holes.

    Route 5: Is to rebuild the 351w I have, bearings and rings. Then buy some nice AFR 205 Heads.

    The crappy part is the 351w would require me to make heads, or buy crites for $566...

    Leaning towards the route 1, the free route. Because, well, it's free. Minus gaskets, but they all require gaskets.
     
    Last edited: Jul 12, 2018
  6. RMiller

    RMiller My name is Rick

    Joined:
    Dec 12, 2009
    Messages:
    2,824
    Likes Received:
    327
    Trophy Points:
    203
    Location:
    Kennewick, WA
    Vehicle:
    1971 Maverick Grabber
    You can get by with what you have provided your compression tester is one with a standard air disconnect. I have done this in the past as a quick and dirty check, put the whip from the compression tester into the cylinder and put some air to it. From there listen to the carb and exhaust, if a valve is leaking you will here the air.
     

Share This Page