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  • SBC rebuild questions

    As the title suggestions I'm in process of rebuilding my sbc 350. The catch is the motor has never ran since I rebuilt it twenty years ago. Can't believe it's been that long and I hate admitting that but sometimes life gets in the way....

    In any case, I plan on taking to my machinist more as we're going to dissect the paperwork from last time to figure exactly what we did, but I have questions and I'll have more as I go back through this motor. We, machinist and I, decided best to at the least go through and replace gaskets, so that's where I'm starting.

    I have both heads off and they are 993 heads. I know not the best but it's what I have and had. I might look at a switch now, BUT not sure I want to buy a new intake. I currently have an Edelbrock performer 4 barrel intake. If the heads are ok I'll likely leave for now. Easy enough to replace later, if the valve are stuck, I'll be back asking questions.

    Push rods and rocker arms.....I pulled one had a year ago when I started stripping motor to store. I lost track of what rocker and push rods went where. Is that killer? I might just buy a new set of push rods, but what about the rocker arms? I may even consider new roller rockers, but wasn't to discuss with machinist as last time I recall him saying not that important with what I have....hmmm.

    What about the the lifters? I'd like to pull them to inspect and possibly soak in oil. I don't recall if they just pop in or not or if it takes special tool. I'll know more when I go out again to work on it. The rockers were tightened so there has been pressure on them....do I need to get them back in same holes or not? Done things say soak in oil overnight and that's much easier IF I don't have to separate.

    The cylinder walls all look great, so no worries there and everything turns nicely.

    When lubing this back up, what is the best thing to use? When put together I used engine assembly grease, but I'm sure it's worn down/out. Machinist suggesting pulling everything well. What about the cam? Should I slide it out and put new cam grease on it? Same with the crank...do I undo the caps pull it and the pistons and start over or just lube while in place?

    For assembly is better to use conventional oil our synthetic? I have two cases of synthetic sitting in garage.

    I'll add more as I get further into this, thanks for now.

  • #2
    Re: SBC rebuild questions

    For what's it's worth the motor is stamped ? le 304 behind the intake. 23 gm followed by 3970010 behind driver side head. I know it's a mid 70-early 80's block.

    In any case the motor is going in a 3500lb 1960 suburban. I'm looking for a nice sound and basically just a cruiser with ability to light up tires if need be and pocketbook allows. It'll never see a drag strip and probably won't see much major highway time.

    So far what's been done is:
    4 barrel 600cfm Edelbrock carb with performer intake
    10:1 flat top pistons 60 over
    Polished and balanced crank
    Valve job, don't recall specifics
    Isky 270/280 mega hydraulic cam
    I'm sure there is more but for now that's what I'm looking at.

    Any suggestions are great. If the crank needs work I might consider a 383 stroker, if not I'm leaving it alone. Same with heads for now. The way I see it is I have a seized 350 in the suburban now, so that can become the next engine if not happy with this one or if I decide I have to have the stroker. I will likely find out what heads are in that and consider swapping if they are better.

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    • #3
      Re: SBC rebuild questions

      Here's the million dollar question.

      I went to drain the oil pan prior to removing it, there wasn't much left, I'm guessing at very most 2 quarts, but everything seems decently lubed. BUT, the first thing to come out was about a 1/4-1/2 cup of water. I'm guessing condensation, that was follwed by some milky syrup consitancy sludge, then the oil. SO, the water was trapped at the very bottom of the pan. I see NO signs of any rust on the timing chain, the cylinder walls all look great, EXCEPT you can see where the pistons sat for an extended period of time, but I can't feel any ridges or grooves, just some discoloration. I also see no signs of any rust on the wrist pins...well haven't pulled the crank, so all I can go by is the ends of the pins that are exposed. The caps appear perfect in color and I see no signs of rust anywhere on the bottom. So, do I pull the crank, have it honed to get rid of the piston marks, change the rings and physically check each and every bearing or leave alone? I will say a couple of the lifters were a bit difficult to get out and had a small wear mark on them, but they didn't appear rough. I'll try to upload some pictures later....

      I'm also wondering about the oil pump, since it had the sludge on it and obviously goes into the bottom of the pan, do I change it or since it didn't suck anything up should it be ok?

      I'm also wondering if I should pull the cam out and double check it, maybe re-lube it while out and then stick it back in or just lube it in place if I check it through the openings in block. Again, everything spins very nicely!

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      • #4
        Re: SBC rebuild questions

        Like the other thread... I figure an oil pump is one of the most crucial pieces, no sense in taking a chance. The one I suggested will work just fine with the scope of your plan. Since you didn't really run it at all I'm guessing the walls are still fine but a hone will be suggested to clean up anything that may have made its way into the grooves of the cross hatch that's already in the walls, I'd leave that up to what the machinist thinks though, he has more experience than I do... Far as the rockers/pushrods, repair manuals typically say keep them in order, but if the parts are new or have little wear I wouldn't worry about it, any minute variance in pushrod length will be accounted for when the valves are lashed. If the cam is what you want to run, I'd make sure it's clean, and go ahead & give the lifters a bath - if the cam was already broken in, this is where you want to be sure you have your lifters in order, they wear specifically to whatever lobe they were broken in on, and mixing up the order can be asking for trouble (may or may not have problems if they're mixed up).

        I don't know what the budget is, but it's possible to use your current rods and a 400 crank & 383 pistons to make it a 383, will probably add about $450-600 to the bill plus whatever the machinist charges.

        '92 Sierra (TBI 383/Vortecs/Comp 08-412-8/EBL/4L60/3.08s), '78 Malibu (Vortec'd 350/4-speed/2.29s), '87 Pontiac Fiero GT (2.8 v6/5-speed)

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        • #5
          The cams not broken in, machinist sold me some additive to add to oil as well as cam lube for lifters. He said NOT to pull crank, BUT I want to replace the rear main seal and question if I should replace the front seal, but if it should be ok I don't mess with. The rear main is two peace, can I just undo that cap or do I have to loosen all of them and then reset them?

          What about the front seal? I kind of hate having to redo the timing chain and everything, but I'll do what's necessary. I have to double check my timing advance anyway.

          I'll go ahead and look into the oil pump.

          From what I recall when setting the caps originally I had to use plasti-gage. That waa just to check the machinist clearances correct? If all good originally, I'm guessing I'm good now. What about lock tite on bearing bolts. I can't recall and have a lot to relearn....luckily I think I'm getting there and I bought a suggested book.....

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          • #6
            Here's where I'm at. I have one head cleaned and opening closing with a large diameter wood dowel and light taps from a hammer onto the dowel. I also turned it over and put fluid in the domes and they seem to hold tight with no leaking of fluid. I was a bit worried about some corrosion on the valve stems, but with some cleaning with toothbrush and mineral spirits they cleaned up very nicely. Machinist said if I can get them to open and close by pushing on them, then they'd be good to go. I was looking at the timing chain and cam & crank gears and if I'm reading it correctly, I have timing set at 0* TDC. Something I read seemed to state I should be at 4* advanced with a cam. I looked at Cam paperwork and it seems to say this, I also called ISKY and asked a few questions and that was one of them and they said yes, that cam (ISKY Hydraulic Mega 270/280) should be advanced 4*. Does that seem correct? The papers say 4* advance creates more low end torque. As for the oil pump, I'm still not sure what I'm doing there. Machinist said don't worry about, I asked my uncle who's a mechanic and he said nothing to go bad if it hasn't ran, unless there is rust present. He suggested opening it up and taking a look....so if I do that, will I need a new gasket or just RTV black or something? Maybe there's a gasket for it in the gasket kit, I haven't looked yet. Any pointers as for when/where to use RTV, and what colors, is greatly appreciated. I have plenty of blue, maybe some black on hand and I picked up gray and red. I also have red and blue locktite. My understanding is Black if I'm not taking the surface apart, blue if it's something prone to going out. So oil pan either gray or black RTV and likely blue locktite. I'll use RED locktite if it calls for it on the Rear main seal cap. blue RTV on the valve covers and water pump, things like that. Red RTV on the heads? As for the lifters, should I soak them in oil bath overnight? Is it ok to clean them with solvent just before so they are good and clean? I worry about the holes getting plugged in removal and/or sitting for 20yrs, but they went immediately to ziplock bags when removed and I kept track of where they came from.

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            • #7
              Regarding cam timing. I've been trying to read on this but like everything there's a million different answers. Right now I'm set at 0

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              • #8
                Regarding cam timing. I've been trying to read on this but like everything there's a million different answers. Right now I'm set at 0

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                • #9
                  Regarding cam timing. I've been trying to read on this but like everything there's a million different answers. Right now I'm set at 0

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                  • #10
                    Ignition/cam timing are different... both are in relation to the position of crank TDC. Unless the timing set has adjustments, your only option is pretty much straight up. Ignition is going to be whatever you set it at. With EFI it uses a table and references whatever you tell it (i.e. if you set base timing to 0 or 4 or 10 and tell the ECM that, it uses that as a zero-point). With a carb it's whatever you find to be best, I'm guessing anywhere between 12-18

                    '92 Sierra (TBI 383/Vortecs/Comp 08-412-8/EBL/4L60/3.08s), '78 Malibu (Vortec'd 350/4-speed/2.29s), '87 Pontiac Fiero GT (2.8 v6/5-speed)

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                    • #11
                      Regarding cam timing. I've been trying to read on this but like everything there's a million different answers. Right now I'm set at 0

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                      • #12
                        Not sure why my posts are duplicating....

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                        • #13
                          Well, what I tried to reply earlier was.... My timing set does allow for +4*, 0* & -4*. Right now I'm at 0* on the timing chain set. On that paperwork I noticed that 20yrs ago when I originally built this motor, I had written set timing to Adv 4* TDC at Chain. For some reason I obviously didn't do that as I am set at 0*. I called ISKY, my cam manufacturer, and the guy I spoke with said yes, set it to Adv 4* TDC. The cam has no advance built in, the paperwork says Lobe Center 112* and Cam Advance 0*. It also says that 4* Adv increases low end torque, 4* Ret increases top end HP. Since my goal is just a street cruiser and I want the ability to spin the tires if I so desire, then I'm guessing 4*Adv is what I want....am I correct? Another question I'm curious about right now is ensuring the cam and the crank are well lubed after sitting for 20yrs. As I've been cleaning gaskets and tearing this down, I'm been spinning the engine over and squirting oil into the cylinder walls, the needs and cap bearings, etc. Since I plan to change the timing, should I slide the cam out and put new cam lube on it or just soak it in oil, then put cam lube on the lifters after soaking them in oil bath.

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                          • #14
                            That should be fine, I used break-in lube in the oil and put a coating on the lobes every time I did a flat tappet cam. I believe your thinking is correct far as your cam advance too.

                            '92 Sierra (TBI 383/Vortecs/Comp 08-412-8/EBL/4L60/3.08s), '78 Malibu (Vortec'd 350/4-speed/2.29s), '87 Pontiac Fiero GT (2.8 v6/5-speed)

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