440 Rebuild & Upgrade

Engine, Transmission & Driveline

  1. 73Coupe

    73Coupe Well-Known Member

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    I'm going to reserve some space here for the rebuild thread because the time is approaching.

    I was driving back from Christmas last week, cruising down the freeway at about 60, and all of a sudden the engine just cut out. After pulling over, cranking the engine revealed a different sound. Something internal.

    Finally having some time to tinker with it yesterday, I have the following data: Compression in all cylinders, although about lower than I had when last checked 50k miles ago, and now more variation too. Now they're about 125 - 145 psi where last time they were all around 150.

    Distributor rotor turns and TDC seems to line up with the wires. There is some gas being blown out of the carb, though. All rockers are moving. Fuel and spark are present.

    Anyways, I am 95% sure that it's the timing chain or gear. These have a plastic tipped cam gear which is the engine's Achilles heel. I am going to replace that for now with a double roller timing set and hopefully do the full rebuild next summer, including some performance enhancements to make it more like an earlier 440 (higher compression, etc). The 1973 version is a dog.

    Just another sign that the inevitable is on the horizon. She gave me 60k miles in 4 years, on top of the 80k original miles that she had when I got her. So not too bad.

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  2. PurpleBeeper

    PurpleBeeper Member

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    Just thinking out loud here....
    a) gas shouldn't blow out the carb - Is it a carburetor problem?
    b) if the timing chain jumped a tooth, it would just run really, really bad....BUT, the fact that it happened all of a sudden while driving is a reasonable sign the timing chain is bad (since you still have spark)
    c) your compression test doesn't sound horrible....but now that I think of it, a timing chain jumping a tooth might affect the compression since you'd have the valves open (or partially open) when they're not supposed to be.
     
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  3. 1978 NYB

    1978 NYB Warfighter FCBO Gold Member

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    That's why I replaced my engine in my 78 NYB. The 40 year old nylon timing gear teeth were overdue coming apart. My old engine was still running well. Consuming a lot oil through the valve guides and seals. I'm sure some oil was getting past the rings. It was a faithful rel in able engine.
     
  4. CBODY67

    CBODY67 Senior Member

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    At the mileage you stated, you're well past the (generally) 80K mile life of a factory timing chain set. Many might have made it past 80K, but they were on borrowed time, from my observations back then.

    Cloyes Plus Roller is the choice I made on another motor. When I had the chain replaced in my '70 Monaco, it was with the Mopar Perf roller chain. I put over 500K miles on the motor I put the Cloyes Plus Roller in, fwiw.

    Compression sounds higher than it should be for your model year. Seems like the FSM states abiut 100psi for compression test? Don't worry about the difference of about 5psi lower from the prior tests! All the compression test checks is the condition of the top ring, not the oil rings and such under it on the piston.

    Piston availability for the older RB engines can be a little flaky, from what I've found, unless you want to go to a forged piston rather than a cast one (which is OEM). It would be easier to put some closed chamber heads on it to bump the compression up if all you can find are the 8.2CR factory pistons. Or perhaps Hughes Engines has some step-dome pistons to make an open chamber head engine into a closed chamber head engine?

    A good valve job with hardened seats, bronze heli-coil valve guide inserts, and the orange silicone valve seals will keep the top end oil under control. In many respects, you can spend a lot of "trick of the week" money on engine component upgrades that are not really a whole lot better than the OEM stock stuff that Chrysler used. Just be sure to spec "OEM Quality of better" in the parts you buy. A good engine builder will know what that means, or should know what it means.

    If you want to spend money, get the block line-honed (main caps), decked, and then bored/hones with deck plates. Rottler or Sunnen has one big machine that can do all of that, as I recall. Then get the heads cut on a lathe for the final surfacing operation. Doing all of this machine work on a seasoned block will make a better engine than when using a new/uncured block.

    Very NICE looking Chrysler! Made that roll-back wrecker look better, too!

    CBODY67
     
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  5. mrfury68

    mrfury68 Well-Known Member

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    When your timing chain goes you can have gasoline burping out of the carb and your tailpipe could be sucking air.
     
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  6. ImpJay

    ImpJay Senior Member

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    How high compression ratio are you thinking?
    BTW, your NYB is gorgeous!
     
  7. david hill

    david hill Active Member FCBO Gold Member

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    I agree it's probably a timing chain. Another good check is to hook up a vacuum gauge, erratic vac needle movement a sure fire give away to timing chain / bent or sticking valves. A quick tip, when checking to see if your engine is in time, turn crank by hand on till the timing spec mark lines up. pop your distributor cap off and see if the distributor reluctor on the lines up w/ the dist. pick up. Should be very close or lined up. If not lined up the plastic coated cam gear has given out. Time for a timing chain and gear replacement.

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  8. 73Coupe

    73Coupe Well-Known Member

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    Thank you sir! I guess I was on borrowed time from the start and should have changed the timing set upon arrival, knowing the road time that would be had. I'm lucky the plastic teeth gave up when I was only 5 miles from home and not 500.

    Yes, the FSM states 100 psi. I previously got 150, and now about 130. So good there but still burning a lot of oil past the rings. I replaced the valve stem seals a few years ago as they were rock hard.

    Luckily my friend owns a machine shop nearby in San Mateo. We can do all the work there except for align-honing. For that, I'll take it to Wade at Al Hubbard Machine across the bay. My friend has a powerstroker honing machine, and Berco surfacer with the CBN cutter (for a dry cut) for decking the block and surfacing the heads. I want to install bronze guides with provisions for modern silicone stem seals.

    Not sure about compression or combustion chamber yet. Would prefer to keep the heads I have and just change the pistons. 440 source has some pistons available for different compression ratios but that's all I know. I need to do lots of research and reading before I start speculating.

    Here's a good article on big block heads: Cylinder Heads Part I - Tech Articles - Mopar Muscle Magazine
     
  9. CBODY67

    CBODY67 Senior Member

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    Once, I bought the Mopar Perf "Inspection Gasket Set", which was stated to have all gaskets/seals to do a "winner's teardown" at the races. What it turned out to be was EVERY gasket/seal you'd ever need to rebuild a B/RB motor (I got the 383 one, I believe). The price was more like a partial gasket set to pull the heads, so it was a better deal than I ever suspected, when I opened it and saw what all was in there. Might check that out.

    If it has the black valve seals in it, you can check out the orange silicone ones for a 454 Chevy pickup truck application. Might need to trim them for a shorter height? It's been a while since I'd thought of them.

    When you get the heads off, OR with a borescope probe for your computer, you can see where the oil might be coming from. If the edges of the pistons are clean, then it's rings. If it's deposits ON the pistons, then it's from the top side. Probably a combination of both, I suspect.

    If the guide to stem clearance is toward the "tight" side, valve stem seals really aren't needed, it's claimed. Some engines didn't use them on the exhaust side, which also meant that as they wore, they'd smoke when they were started, many times. KEY thing is to allow just enough lube into the guide to decrease wear, but NOT get it too dry (as the "scraper" seals might). Even the OEM-Chevy "0-ring" valve seals work well as long as the stem to guide clearance is decently in-spec.

    Plan on a .030" over-bore to get the bores cleaned up to "new metal". Seems like the max overbore size for the later blocks is .040"?

    Enjoy!
    CBODY67
     
  10. 73Coupe

    73Coupe Well-Known Member

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    I just got me a bore scope, Ryobi with smart phone used as screen, we'll see how it works. I'm going to first use it to check the pan for plastic chunks from my cam gear.
    My flathead 230 L-6 in my B-series Dodge truck uses no seals, just the clearance (and valve orientation) as a "seal". Too loose = smoke during high vacuum. When I installed new guides and valves, I made sure them suckers were tight!
     
  11. 73Coupe

    73Coupe Well-Known Member

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    Ok, here we go...confirmation. This is the first time that the crank case has seen light since Nixon was president. I've been working on it a little each night. This is ridiculous! The old chain just came off with out unbolting the gears. New parts in hand. Tomorrow I will try to button this up if the rain holds off.

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  12. CBODY67

    CBODY67 Senior Member

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    Be sure to put assembly lube on EVERY thing in there, (front, back, teeth, etc.) when you put it back together. The only lube in that area is typically from "splash" rather than a pressurized lube source.

    LOTS of things that move upon one-another in that timing chain! Much less the teeth on the sprockets.

    Great pictures!
    CBODY67
     
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  13. Dobalovr

    Dobalovr Friend to Elitists FCBO Gold Member

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    Might be a good opportunity to check the length of your rod......fuel pump rod that is :)
     
  14. Ripinator

    Ripinator Senior Member

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    And while yer at it, you may as well go ahead and install a new cam to make it cackle a little bit. . .
     
  15. david hill

    david hill Active Member FCBO Gold Member

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    With that much debris ( aluminum and plastic gear ) removal of the oil pan would be a very good idea. You don't want aluminum circulating w/ the oil though the engine. It will quickly shorten engine life. A good cleaning of the engine block behind the timing gear and a freshly cleaned oil pan and oil pickup tube and you will be good for many miles of driving. Keep it hospital clean and your good to go.
     
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