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Newbie - 1972 Valiant

Discussion in 'A Body: Duster, Valiant, Dart, etc' started by Nebraskaorville, Aug 10, 2017.

  1. CudaPete

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    The "Zinc" (ZDDP) provides a boundry between the cam and lifter on a flat tappet cam to prevent gauling. It is a very real problem, especially on a new motor with a big cam and stiff valve springs.
     
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  2. Nebraskaorville

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    195A6629-F4D8-48F4-B6C0-D6A452334A11.jpeg 07144224-8206-4EB2-9A3F-9CA190D7DE8A.jpeg 0A22F674-C8E5-465A-9157-377D81575FB5.jpeg 80D33CE4-2F78-4528-BCA7-8F2EEC2A5AF4.jpeg 41F539DD-4B89-4169-916A-5031E520C38A.jpeg E13246EA-6C39-4549-B2DA-9CAA8C8D88AA.jpeg Info from my block. Looks like this was a pro rebuild?
     
    #82 Nebraskaorville, Nov 13, 2017
    Last edited: Nov 14, 2017
  3. dana44

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    I don't know about "pro rebuild", but it is a guarantee marker to indicate, if the center is melted out, the engine was overheated, which is usually an indicator of abuse, accidentally or on purpose.
     
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  4. Nebraskaorville

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    Right - well i meant that a shop with a policy did the job, not joe schmoe in his back yard. Like me. :) Any ideas about that metal tag with the word "LOBO" stamped into it? Thanks Dana!
     
  5. dana44

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    No idea, but it may be L030, which may be the engine has .030 oversized pistons in it, but not positive on that. The rest of the numbers may be rebuild company reference numbers. Did you mic the bores and measure the pistons? Oversized pistons should have a stamping into the face to indicate oversize bore pistons, as in .010, .030, .040 or .060 on it. Hate for you to get the wrong rings to start with if it has been bored.
     
  6. Nebraskaorville

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    Ok guys i know I have a lot of questions and thanks for all the input. Here's what i know about this engine so far:
    Block was cast 6/14/78 (a Wednesday) and if the dial markings are being interpreted properly - about 3PM? date.jpg

    Built at the Mound Road plant. There is an issue with the date code in the stamp: my engine code is 8M318 06292979 - the "0629" doesn't seem to jive with the 10000 day system - unless i drop the zero, then it puts production at 6292 - which is some time in 1979.

    engine.jpg engine4.jpg
    There are no markings on the pistons to indicate an overbore, but i have not mic'd anything yet.
    The "guarantee" marker gar.jpg indicates a likely overhaul at a shop, as does the paint on the cam, cam.jpg as does the fact that these pistons are flush with the top of the block when at TDC, if the conventional wisdom that most 318s from this era were low compression with pistons sitting "pretty far down in the bore" at TDC is correct.

    If you were an engine builder in the 80's and a customer with a 1978 Dodge camper came to you needing a rebuild, would you build his engine stock or would you undo some of the poor choices Chrysler was making during that time in the compression and cam areas? Seems to me that higher compression pistons (taller) and a little hotter cam (tow cam?) would be good, simple upgrades.

    I will mic the cylinders but i'm pretty sure the bore is stock. I may cc the heads and try to calculate compression ratio, but it has to be higher than the stock 8.5:1 if the pistons come flush with the top of the bore at TDC, doesn't it?

    Dana, I zoomed in on that metal tab - it looks like a "B" instead of a 3. b.jpg I'll know more when i mic. If it's bored .030 from stock, then i'd be where - 3.94?
     
  7. Nebraskaorville

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    Also - the rod casting marks don't match. Here are two different ones. Hmmmm.. rod2.jpg rod3.jpg
     
  8. Nebraskaorville

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    Also, these pistons have a casting mark on the inside that says “NOV 93”. Looks like a date code to me, so that puts the overhaul in the mid 90s. Here’s a couple pics of these pistons- if anyone has seen these and can identify maker please speak up. Thanks!!
    9BEE698E-5E6B-4E5E-98E6-38618546EDFE.jpeg 7966E338-5788-4A80-85DB-D7113F311509.jpeg 80C05802-6EC1-4669-9019-4D6D0FFE1E2C.jpeg 63E62B44-5BA8-4628-A79B-EB9C0DA19288.jpeg 4C4412A9-E2F0-4802-A5FB-1573E4F63B8D.jpeg 86EF7908-5669-4E8A-89E9-F1B023ECB81A.png
     
    #88 Nebraskaorville, Nov 14, 2017
    Last edited: Nov 14, 2017
  9. Nebraskaorville

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    Rod bearings are .010 over and I just measured the bore with a machinists rule- 3 and 60/64” = 3.3975. Allowing for human error that’s 3.94 and that’s .030 over stock of 3.91. Still no piston stamp indicating oversized. Gonna take a piston to a shop and have it mic’d. Thanks for listening!
    8410A922-DB22-41D8-A549-9A793718DDF1.png 019A4C87-ECCA-4AEB-9E32-3FFBE8DE91CC.png BC08091F-BE90-4B8B-B8FE-3AB46301F46B.png 766B31B7-12FA-4E69-A2E4-763D11379CB3.png
     
  10. dana44

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    Well, some interesting stuff there. With the rods, being different castings and all, make sure they are of the same weight, a difference of a small amount will make things work against each other, as in what is going on with the bearings themselves. The looks of them does look a little like a bad crank grind, or, if a shop says the journals are OK, the difference in weights of the rods can make this occur. Get or borrow a balance scale, or a three beam scale. find the lightest one and make them weigh the same by sanding the casting seam off the sides of the rods, do NOT use a bench grinder to grind off the weight, the chatter is good for causing grind fractures. I would have the big end of the rods checked and resized first, then balance them, then do the same to the pistons. I like using carbide burr cutters to remove material in balancing, the cuts work similar to shot peening the surface better than any grinding or sanding disc, because it chips the metal instead of scraping the metal. I've had excellent results with them over the past 35 years.

    Next question is, what does the crank itself look like? Specifically the oil holes in the journals? If they are smooth across the holes, without a dimple to each hole, this is not only wrong, but there is an easy fix before polishing with 600 wet/dry paper for proper oiling. A regular old metal countersink can be used to knock off the edges, preventing oil from being scraped by the sharp edges of the hole while spinning. Only takes about ten seconds a hole to make that correct, and you can do it prior to polishing the crank journals.
     
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  11. pt006

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    I've seen that blue paint dab on stock Chrysler cams before. The lobes look good. Newer cam designs might give a little improvement. Depends what vehicle it's going in.

    The rod casting numbers tells me that they probably came from different engines. They should interchange, but I'd weigh them first.

    My memory tells me that the mid/early 1970's 318 pistons had a flat top and no valve notches. And were about flush with the block when at TDC. Never saw the grooves around the pistons before. Really really clean.

    3 and 60/64" = 3 and 15/16" = 3.9375" = ~ 3.94" ------- Your math was off but your conclusion was right [.030 oversize].

    The bearings look normal for a 100,000 mile engine. The pistons look like a 10,000 mile engine???????

    I think the piston notches were for when they put 360 heads and 4 bbl manifolds on 318 police engines? Valiant 67 or others might know.
     
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  12. Nebraskaorville

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    Thanks man! I built a VW type4 engine about ten years ago -all the forum guys said "balance everything!" and i said "nahhh"...and that engine ended up sounding like a tractor trying to rape a lawnmower. Wont make that mistake (or others i made on that build) again.

    Thanks PT! So, I'm .030 over for sure. Yes, thats what i said about the pistons - there was a light layer of carbon that i took off with a wheel before i pulled them, but they're so damned clean! I did have a couple of rings i had to break out of the grooves, but that was from sitting.
    The bearings - although showing wear -feel nice and smooth with no catches on a fingernail test. One of the pics up there shows some surface scratches i made with my fingernail. I wasnt going to pull the crank but i reckon i need to now. Sigh. Bearings and seals, bearings and seals. I'm just trying to keep from dropping a lot of coin into this build while at the same time not having something nagging at me while on a trip.."is that a rod or a main...should've had the deck surfaced..."

    The saga continues. Thanks guys!
     
  13. Nebraskaorville

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    BTW, pt first pic is engine donor, next is recipient. Thanks! camper.jpg car.jpg
     
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  14. Nebraskaorville

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    Dana here's a shot of the oil galleys on a journal. Also - some more cam shots. Be advised, there is debris from teardown all over everything in these shots.

    Thanks!

    cam1.jpg cam2.jpg crank.jpg
     
  15. dana44

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    Oil holes look chamfored enough, so that is a plus, but that middle picture cam lobe is toast, looks like the rewelded lobe broke off. Sorry, time for a new cam on that one.
     

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