Are There Any GEAR HEADS Here?

Discussion in 'Taking a Break From Flooring' started by Bud Cline, Jul 31, 2014.

  1. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    ...that would know about re-assembling a GM 350.
  2. kwfloors

    kwfloors Fuzz on the brain Charter Member Senior Member

    Not me, even though I took auto mechanics in high school. Maybe on the
  3. epoxyman

    epoxyman Pro Member

    What year 350 ?
    I rebuilt a few older ones like 73/ 76

    But once they went to a ton of wires and no carb I got lost
  4. Elmer Fudd

    Elmer Fudd Administwative Asst. Charter Member I Support TFP Senior Member

    It is almost as cheap to buy a crate motor as it is to rebuild.
  5. Darol Wester

    Darol Wester Charter Member Senior Member

    I agree, but I also enjoy rebuilding them too. Done lots of small blocks chevys since 66. The last time I needed one for the boat, with no time for rebuilding it, I bought one from Mr. Goodwrench. Here's one example that's not a bad price with free shipping. I've had no problems with mine and boats are harder on motors than road machines.

    GM Goodwrench 350ci/260HP Engine & Packages - Free Shipping on All Orders @ JEGS
    Last edited: Aug 1, 2014
  6. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published


    This is a '90 GMC.
    Here's the problem. This engine has a "plate" adjoining the oil pump and mounted below the crank shaft. This plate is attached with three bolts. Two of the bolts thread directly into the block. One of the bolts is a combination type bolt. It is used as a bearing-cap bolt, but it is also extended and has a threaded end with a nut that attaches. The first part of the bolt has a standard hex-head for tightening the bearing cap, but then also machined to this bolt is the extension with threads at the end for mounting the plate.

    Can't figure out how to torque the bearing cap bolt without buying (yet another) open-end torque wrench. Guess I'll have to go buy a single super-deep socket.

    My son is seventeen years old. The kid is a gear-head. This is his idea, not mine. When I was his age I personally re-built a 327 from the ground up - never ever do that again. Well, until now. But back then no one was going to tell me I couldn't do it because I was gonna anyway.

    So anyway, the kid is sharper than I was with this stuff, so good on him.

    Yeah well I wanted to do that and he wouldn't hear of it. I tried to explain all the benefits of buying the crate engine but "Oh HELL NO". That would be too easy.

    So I'm all for him getting the experience. Him, NOT ME. I have all the experience I want. But, here I friggen go again.

    So far he has stripped the block to bare bones, we have had it bored and resurfaced. He has painted it. And he was in the process of installing the new (not moderately priced reconditioned) I said the "NEW" crank shaft when he discovered there was no (convenient) way to torque the one bolt.

    To be continued (I'm afraid).

    I should also mention that I am wide open to any future suggestions, recommendations, advice, help of any kind, warnings, smack on the back of the head, anyone may have on or about this type of adventure.
  7. kwfloors

    kwfloors Fuzz on the brain Charter Member Senior Member

    My oldest is the same way and has his 92 f150 torn apart in my driveway from overheating. It hasn't run in a month and he just broke 3 bolts in the block....
    I just bought a used 350 goodwrench engine for my 78 chevy plow truck and had my mechanic put it in. It runs good.
  8. Dan Schultz

    Dan Schultz Certified Wood Floor Inspector Charter Member

    This really sounds like fun!

    I've rebuilt countless numbers of two strokes. Outboards. My dad was a Mercury (since the early70's, Johnson (late 70's), Yamaha dealer ('83 when they entered the US market.) Easy peasy.

    First four stroke I ever built was a Mercury houseboat generator engine. Don't remember the cid, but I remember being told it was one bank of a Ford dump truck engine. The thing had blow-by from new. Was rebuilt once before I got ahold of it and the blow-by still existed. I found a valve with a hairline crack in the stem in the machined area. Looked like it was from the forging to me. Anyways, replaced the valve while putting it back together and fixed the blow-by issue.

    I currently have a Camaro that I use to drive the countless miles to inspections. It's a '96 with a 3.8L V-6. The thing gets 27 mpg! It has developed a knock. I really wanted to tear it down myself. I have the tools, but not the time. This is a love-hate situation. I'd love to do it myself, but can't justify the time. Been busier with inspections than ever. I'm planning to take it to my mechanic in the morning for a complete rebuild. I have the utmost confidence in this guy AND I'd rather spend my $$$ locally than send it off to a crate company elsewhere.

    His price will be more than the car is worth, but will be a solid car. Cheaper than I can buy another car, with umpteen miles, and one that I feel like I can rely on.
  9. Dan Schultz

    Dan Schultz Certified Wood Floor Inspector Charter Member

    Torque the bolt, then hold it in place. Don't let it move while torqueing the nut. Once the torque spec is met on the bolt, it will not change, if it does not move.

    One trick to torque. Run the correct drill tap into each and every bolt hole or nut that has a torque spec. Same for the bolts, except use a die. This cleans the threads. Any possible debris on any threads will give over time with heating and cooling and will affect the torque! This helps prevent gasket failure and subsequent fluid leaks.
  10. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    As it turns out, a deep 5/8" spark plug socket will fit over the upper portion of the bolt (when you remove the inner rubber spark plug gripper) and covets the bolt just enough to torque it. Hell I was complicating the process more than necessary.

    Chasing all the threading's is an excellent idea, never thought about that. All the bolts are being cleaned as we go but and are easy enough to see but the threaded borings are a different story.
  11. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    Here's an update:

    I'll be damned if he doesn't have the engine fully assembled and he and two friends are out there dropping that sucker back in the hole as I type this.

    This is his second pickup. His first pickup dropped the tranny after driving it for only about two weeks. He pulled the tranny and we took it to a shop to be rebuilt. We picked it up, he installed it the same day. We put in a new battery and filled the tank with gas.

    About three hours after re-installing the tranny he calls me and says; "Dad my truck is on fire, should I call the fire department?"

    WELL HELL YES CALL THE FIRE DEPARTMENT then get away from sucker, way away, it has a full tank of gas.

    He was about seven miles from me at the time so I headed in his direction. I no sooner drove out of our driveway and I could see the plume of black smoke. I thought I was going to cry. When I got there the fire department was just rolling up on the seen also. The damned pickup was fully engulfed in flames and the highway was on fire.

    After the fire was out we walked the highway to discover an oil leak had begun suddenly about 100 yards up the road. It became worse as he travelled down the road. He could smell something burning so he stopped and that was all she wrote, when he stopped the fire took off.

    We assume it was tranny fluid that sprung a leak and sprayed the exhaust manifold. Since he was the tranny installer he owned the fire I guess. Damn I felt sorry for him.

    Now I am hearing some hootin' and hollerin' coming from outside so the engine must have landed in its new home. A few more hours of reconnecting peripherals and then its "see if it starts" time. I'm excited for him to tell you the truth.
  12. Jim McClain

    Jim McClain TFP Owner/Founder Administrator

    I'd be excited to - running all over the place gathering fire extinguishers. ;)
  13. JohnnyMemphis

    JohnnyMemphis Member

    I always thought "blow-by" was primarily a diesel issue. It's burnt fuel "blowing by" the piston into the crankcase at detonation, which is why you see smoke coming out of the crankcase breather tube.

    The piston(rings)/valves/cylinders form a semi air-tight box: if the valves don't seal well, you get poor compression or misses, potentially fire in your intake, or backfiring, because the leak is going into the "in" or "out" path of the fuel/air mixture, depending on which valve is bad; bad rings, cracked/burnt pistons, or a compromised cylinder leaks the "other" way, into the crankcase, so you get exhaust pushed into the crankcase with exhaust coming out of the breather tube, or oil into the fuel and white smoke coming out the exhaust.

    In gas engines I've seen with bad rings, you get oil burned in the fuel and white smoke coming out the exhaust. In a diesel with bad rings, etc., you get exhaust "blow-by" around the piston, because the compression is close to double what you'd have in a gas engine. The oil is never going to come into the cylinder in a diesel because the pressure difference is so large––the exhaust will always push out during detonation.

    So, Bud, did your boy get the truck running?
    Last edited by a moderator: Aug 9, 2014
  14. Jim McClain

    Jim McClain TFP Owner/Founder Administrator

    Blow-by is not exclusive to diesel engines. It is usually caused by worn or faulty rings on a piston, allowing the fuel/air mixture to be forced into the crank case. Pistons and rings are used in both gas and diesel engines.

  15. Dan Schultz

    Dan Schultz Certified Wood Floor Inspector Charter Member

    Here's one explanation:


    Worn valve guides can also put combustion chamber gasses into the valve cover. In this case it was that pesky valve stem
  16. JohnnyMemphis

    JohnnyMemphis Member

    Ok, I read your reference about blow-by and his connection between the valve cover & crankcase is that it's all "crankcase air" because the pressure is meant to equalize between the two. But that's not exactly true, because PCV valve is a check valve, allowing flow in only one direction. So, nothing is "blowing by" into the crankcase unless it's coming from the weak rings. It's all "crankcase air" IF the crankcase has positive pressure that opens the PCV valve.

    If they're both called "blow-by" I'm just ignorant about it. Not saying it can't happen from the valves, just that the name doesn't make much sense then.

    Ok, re: gas & Diesel engines, but it isn't fuel/air mixture from stroke 3, its combustion gases from the power stroke. The compression during the third stroke is btw 8:1 and 10:1 in a gas engine and upwards of 15:1 or 16:1 in a Diesel engine. Many diesels are also turbo diesels, which is another way of increasing the density and therefore pressure of the combustion air, so effectively the diesel compression could be significantly higher compared to ambient air. Pressure and volume have a direct linear relationship, so the pressure makes the same change as the volume. But after combustion, the power stroke pressure is a multiple of the compression stroke pressure so that's where the blow-by would happen, IMHO.
    Last edited by a moderator: Aug 10, 2014

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.