Running Buick 350 for $750, Supposedly Good Compression and Oil Pressure

Discussion in 'Small Block Tech' started by patwhac, Oct 17, 2018.

  1. patwhac

    patwhac Well-Known Member

    Sorry I know I just asked about pistons, but I talked to this guy this morning and he claims this 1975 engine makes 135 to 140 compression on all cylinders and 35 to 65 psi of oil pressure when running. Has it on a test stand so I can bring my compression and leak down testers to verify:

    It's basically between this and a rebuild on my current SP motor with worn rings in #7 and #8.

    Would this be a waste of money? Guy says $750 firm . . .

    Thanks for bearing with all my "is this worth it" threads :rolleyes:
  2. alec296

    alec296 i need another buick

    It definitely won’t have the same power as the sp engine. 35 at idle not in gear doesn’t mean oil pressure is good hot in gear. See if stand has radiator. Run it until it gets hot. What do you want to do with engine is main thing. Not knowing miles and still wants 750? Seem abit high
    newmexguy likes this.
  3. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Why not just re-ring, re-bearing and re-gasket what you have for now?

    Then spend the extra $(if it there?) on a little porting for the heads maybe?

    The replacement SP cast pistons are $300 something, if you can get away with ball honing if the bores are still decent no sense in buying a low compression smog engine for what it would cost to freshen up what you have.
  4. patwhac

    patwhac Well-Known Member

    I was hoping to do exactly what you said above, a basic re ring hone job, new bearings, cam etc. But reading Jim Weise's words below is what made me think twice. From this thread:

    Can I get away with just a home rebuild? I know I've hammered this engine with detonation a few times too. :eek:

    Here are the compression test results from a long time ago on the SP 350:

    Test #1 was 3 cranks, Test #2 was 5 cranks. The number (psi) for Test #1 is given first for each cylinder:

    Cylinder # 1 - 160, 170
    Cylinder # 3 - 160, 185
    Cylinder # 5 - 160, 182
    Cylinder # 7 - 110, 130 (185, 200 after adding oil into cylinder)

    Cylinder # 2 - 160, 185
    Cylinder # 4 - 160, 187
    Cylinder # 6 - 163, 182
    Cylinder # 8 - 110, 156 (183, 225 after adding oil into cylinder)
    Last edited: Oct 17, 2018
  5. alec296

    alec296 i need another buick

    It may be stuck rings. If engine has sat for awhile. Take the two bad pistons out and do some measuring
  6. Electra man

    Electra man Older and Slower

    I don't really know Cali's emissions laws in detail but don't they have a statute that says you must maintain an engines emissions controls? Which means you'll have to use a catalytic converter, yes? Why bother it doesn't make sense, rebuild what you have. - Bill
  7. alec296

    alec296 i need another buick

    No catalytic converters until 75 . And it’s not hard to pass emissions standards from an 86 specs without them with a decent tune.
  8. patwhac

    patwhac Well-Known Member

    The engine was running and car driving up until a year ago, but blew what I believe is a freeze plug because coolant started to shoot out from behind the driver's side motor mount. Since then I have just parked it in the garage figuring if I had to pull the motor anyway might as well stick a rebuilt 350 back in or a 455 . . . Engine was running ok but burned a decent amount of oil and would ping at WOT sometimes.

    Alec is right, if you have a 1975 or older car you can pretty much do whatever you want because you're not required to do a smog check . . . ever! Technically I think a cop can pull you over and cite you for non-stock emissions equipment, but that really never happens. Even if they did pull you over it's not like they would know what to look for. Even if I stuck a blower on my motor and had it 3 feet out of the hood I doubt I would get hassled if I wasn't driving like an idiot.

    I did just go through the PITA of getting my 1977 Lincoln smogged however. The original cats were 2 way units and 40 years old. Not at all designed to deal with NOX emissions that they measure for nowadays. Catalyst was literally falling out of them on removal! So I had to buy brand new cats (2 of them) that were 3 way and CARB approved. They are $200 each, while the non CARB approved versions (which are literally the same part without the EO stamp) are only $100. Then spent a few weekends and more money installing them in the "stock location" . . . I could go on for a while about the smog laws here . . . o_O
  9. MrSony

    MrSony Well-Known Member

    I bought my SP, ran when pulled (needed a complete rebuild, full of corn, it happens) for $500, and my old '76 two barrel with th350 (long shaft, sold it) for $300, again that needed a rebuild. I'd talk him down 2 or 3 hundred bucks, then I'd get it. It's a 75, so it has the better rods (marginally, but still better) but only about 8:1.
  10. Mark Demko

    Mark Demko Well-Known Member

    '75 350's were way down on power in stock trim, if you just wanna drop it in and go compared to your current 350.
    Take the 750 and put it towards getting your current 350 freshened up:D
    Harlockssx likes this.
  11. buick64203

    buick64203 Just plum crazy Staff Member

    Its one or the other? If it were me, I'd put the used 350 in the car and have use of it while I was rebuilding the other engine. Having you car sidelined is a huge downer. You can always sell off the 75 motor when your done with it and recoup your money
  12. patwhac

    patwhac Well-Known Member

    It is kind of one or the other for me, budget wise. The slower I go with the refresh the more I can afford. I'm assuming a basic refresh with a cam will run me about $1000 in parts, so $1750 for the running engine and refresh is a lot for me. Having the car out of commission is painful, but at least I'm renting a garage to store it in and do work, if it were on the street I'd be in much more of a rush. I'm also assuming a "rebuild" will be a minimum of $1500 for just machine work to square decks, bore/hone, align hone, balance, cam bearings, grind crank, etc.

    I would really love to twin turbo a 350 or 455 at some point in the next 10 years, and I feel that if I'm going to do an "actual rebuild" of any engine someday, I may as well save up for forged pistons and good rods.

    I guess my real concern is that the refresh seems like a huge gamble. Isn't there a possibility of me spending the time and money for it and having it run worse/brun more oil than it did before? Do I need to pull the SP engine's heads off to look at the bores and see if I can "get away" with a refresh?
  13. alec296

    alec296 i need another buick

    If you had no knocks , I would think crank isn’t far off from specs. And summit racing does list a .001 bearing . It seems the Pontiac 301 has same bearing as it comes up used for that also.
    If you use autotec pistons you don’t need to deck block unless you want to get cleanup and square. This will allow your stamped numbers to stay if numbers matching Car.
    Yes you need to pull heads to check anything in the cylinders. You can’t do much at all with heads on. So yank them.
    Yes you can make things worse, but it would mostly be due to incorrect assembly, damaged or a bad part.
    Getting a used engine so you can take longer on rebuild is a decent idea.
    1750 is cheap for complete rebuild.
  14. buick64203

    buick64203 Just plum crazy Staff Member

    So refresh meaning to not touch the shortblock? But what about the issue of it burning oil? You know what happens when you try and save money right? It winds up costing you double!

    I was in a very similar situation to you. Years ago, I was living in an apartment and didnt have 2 nickels to rub together. My green Riviera was down for the count. Engine had lost oil pressure. I knew it wasnt good and likely would need a complete rebuild. I took the engine out and found a horror show- cracked skirts on the pistons, bad timing cover, wiped out cam bearings, etc. Engine had well over 150k on it. I didn't have the money to do it right. I just happened to find a running 69 Riviera sitting in a driveway for $400 that had exactly 99k miles on it. Took that engine out, put a new timing chain set in it, cleaned out the oil pan and threw it in my car just so I could keep driving it. I parted out the junker and recouped most of my expenditure. I saved the original engine and put it in the corner of my rented garage. I figured when I was better equipped financially, Id go ahead and rebuild it. That was probably 25 years ago. The junker's engine is still in the Riv, the number's engine is still sitting in the same rented garage exactly where I put it 25 years ago. And the junker engine is still running like a top. I could swing a rebuild on that engine now no problem. But why? When that $400 engine finally gives up the ghost maybe. But I'll probably be back in diapers and drooling by that time.
    BeatersRus likes this.
  15. buick64203

    buick64203 Just plum crazy Staff Member

    I wrote a whole paragraph on this, but I con condense my thoughts with this- If your not going to do it right, don't do it at all.
  16. johnriv67

    johnriv67 Well-Known Member

    Oh I will have to correct myself, I think. Jason what year is your Riv?
  17. buick64203

    buick64203 Just plum crazy Staff Member

    I have 2. One is a 68 that's a jigsaw puzzle. The other is a 69. Both Gran Sports. This February will be 35 years that Ive owned the 69. Damn, that makes me sound old!
  18. johnriv67

    johnriv67 Well-Known Member

    Ok I can still say it. Only Green 67 Riviera in New England that runs 14s:D
  19. patwhac

    patwhac Well-Known Member

    This made me laugh, I'm glad everything ended up working out!

    "Refresh" means the following to me, with questions in parentheses:

    -Completely disassemble engine - Free
    -Hone bores with a drill and 320 grit flexhone - $80
    -Install new standard size cast pistons (KB 1746?) with new rings (cast or moly?) - $220
    -Install dual grooved front cam bearing (or all of them?) - $80
    -Install new cam and lifters - $300
    -Install new timing set - $80
    -Rebuild timing cover oil pump with gears, thrust plate, regulator, shims. - $80
    -Install new main and rod bearings (standard size?) - $150
    -Install new head gaskets - $60
    -Install new rod bolts? - ??
    -New brass freeze plugs - $10

    Total : $1060 not including other gaskets or any head work.
    Last edited: Oct 18, 2018
  20. patwhac

    patwhac Well-Known Member


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